Preparation method and application of modified white clay adsorbent for deolefination / decolorization

Abstract

The present invention provides a preparation method and application of a modified white clay adsorbent for deolefination / decolorization, including: mixing tetrabutyl titanate with anhydrous ethanol to obtain a precursor solution; mixing anhydrous ethanol, glacial acetic acid and deionized water to obtain a composite solvent, dispersing the modified white clay in the composite solvent to obtain a white clay dispersion; under stirring, dropping the precursor solution into the white clay dispersion, mixing uniformly to obtain a mixed sol, and performing static aging, heating and drying, and high-temperature roasting on the mixed sol to obtain a modified white clay adsorbent. The present invention is treated with acid activation and modified by intercalation of quaternized carboxymethyl chitosan, and a sol-gel method is used to fix catalytically active titanium dioxide nanoparticles between the interlayers of the modified white clay, thereby further improving the adsorption effect of the modified white clay adsorbent on olefins and organic dyes.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry and relates to a preparation method and application of a modified white clay adsorbent for deolefination / decolorization. Background Art

[0002] Bentonite, also known as kaolin, is a natural, multifunctional clay mineral primarily composed of montmorillonite, with small amounts of impurities such as quartz and feldspar. Due to its unique layered structure and large surface area, kaolin exhibits excellent adsorption, ion exchange, and catalytic properties. It plays an irreplaceable role in various fields, including petrochemicals, environmental protection, and daily chemicals. In particular, kaolin, as an adsorbent, can effectively remove impurities from oil products, improving product purity and quality.

[0003] For olefin removal, clay, particularly activated clay, is widely used due to its excellent adsorption properties. Modification with inorganic acids further enhances its adsorption and reactivity, making it effective for removing olefins from mixed xylene fractions. However, traditional granular clay refining technology also has drawbacks, such as high adsorption saturation, short cycle life, and difficulty in regeneration. To address these issues, research and development of new deolefination catalysts and processes are underway both domestically and internationally to replace or improve clay refining technology.

[0004] White clay also plays a vital role in decolorizing printing and dyeing wastewater. Printing and dyeing wastewater contains numerous dye molecules, which are often difficult to effectively remove using conventional treatment methods. White clay, particularly modified white clay, exhibits excellent adsorption properties for dye molecules, effectively removing color and organic matter from wastewater, improving its transparency and biodegradability. Furthermore, modified white clay exhibits excellent stability and regeneration properties, reducing treatment costs and improving both economic and environmental benefits.

[0005] However, during the deolefination process, clay easily becomes saturated and difficult to regenerate, resulting in a short lifespan. This increases the frequency of clay replacement, which in turn increases production and treatment costs. Furthermore, while clay can adsorb some dye molecules in printing and dyeing wastewater, it is not ideal for decolorizing certain difficult-to-degrade dye molecules. Therefore, there is an urgent need to modify existing clay adsorbents to address these technical issues. Summary of the Invention

[0006] In response to the shortcomings of the prior art, the present invention aims to provide a method for preparing a modified clay adsorbent for olefin removal / decolorization and its application. The present invention first uses acid activation treatment to effectively open the interlayer structure of the bentonite ore, increasing its specific surface area and porosity, thereby improving its adsorption capacity for olefins and dye molecules. The activated clay is then intercalated with quaternized carboxymethyl chitosan, further improving the clay's adsorption properties and imparting a stronger affinity and capture capacity for olefins and dye molecules. Finally, catalytically active titanium dioxide nanoparticles are loaded and fixed between the interlayers of the modified clay using a sol-gel method, further enhancing the modified clay's adsorption and decolorization performance for organic dyes.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a modified white clay adsorbent for deolefination / decolorization, the preparation method comprising:

[0009] (I) Concentrated hydrochloric acid, concentrated sulfuric acid, oxalic acid, and deionized water are mixed to obtain an acidifier, bentonite ore is crushed and sieved to obtain bentonite powder, and the bentonite powder is mixed with deionized water to obtain a bentonite slurry; the bentonite slurry, the acidifier, and sodium chloride are uniformly mixed to obtain a raw material mixture, the raw material mixture is heated and activated to obtain an activated product, and the activated product is rinsed, centrifuged, dried, and crushed to obtain activated clay;

[0010] (II) chitosan powder is subjected to carboxymethyl modification treatment using sodium chloroacetate to obtain carboxymethyl chitosan; the carboxymethyl chitosan is subjected to quaternization modification treatment using dimethyl diallyl ammonium chloride to obtain quaternized carboxymethyl chitosan; the quaternized carboxymethyl chitosan is dissolved in acetic acid solution to obtain a quaternized carboxymethyl chitosan solution, the activated clay obtained in step (I) is added to the quaternized carboxymethyl chitosan solution, the mixture is mixed, stirred and heated, and then centrifuged, washed and dried to obtain modified clay;

[0011] (III) Tetrabutyl titanate and anhydrous ethanol are mixed uniformly to obtain a precursor solution; anhydrous ethanol, glacial acetic acid and deionized water are mixed uniformly to obtain a composite solvent, and the modified clay obtained in step (II) is dispersed in the composite solvent to obtain a clay dispersion; under stirring conditions, the precursor solution is dropped into the clay dispersion, and the mixture is mixed uniformly to obtain a mixed sol, and the mixed sol is sequentially subjected to static aging, extrusion molding, heating and drying, high-temperature roasting and crushing and screening to obtain the modified clay adsorbent.

[0012] The present invention first uses acid activation treatment to effectively open the interlayer structure of the bentonite ore, increasing its specific surface area and porosity, thereby improving its adsorption capacity for olefins and dye molecules. The activated clay is then intercalated with quaternized carboxymethyl chitosan, further improving its adsorption properties and enhancing its affinity and capture capacity for olefins and dye molecules. Finally, catalytically active titanium dioxide nanoparticles are loaded and fixed between the interlayers of the modified clay using a sol-gel method, further enhancing the modified clay's adsorption and decolorization performance for organic dyes.

[0013] The main mineral component of natural bentonite ore - montmorillonite, belongs to the monoclinic system and has a 2:1 crystal structure. It is composed of two layers of silicon-oxygen tetrahedrons sandwiched by an octahedron composed of aluminum-oxygen and hydroxyl groups. 4+ Can be Al 3+ Substitution, partial Al in octahedron 3+ Can be substituted for Mg 2+ The substitution of cations makes the crystal negatively charged. In order to achieve charge balance, the natural bentonite layered skeleton is adsorbed with Ca 2+ Mg 2+ , K + and Na + The present invention uses an acidifying agent composed of concentrated hydrochloric acid, concentrated sulfuric acid and oxalic acid to perform acid activation treatment on bentonite. During the acidification process, some non-adsorbable impurities, soluble impurities and minerals in the bentonite are decomposed by the acid and dissolved in the liquid phase system. In addition, the interlayer cations in the bentonite can be dissolved by hydrogen ion exchange. At the same time, a pair of aluminum ions and two pairs of hydroxyl groups in the montmorillonite octahedral structure are also dissolved, so that part of the bentonite crystal lattice is destroyed, the interplanar spacing is increased, the pores of the bentonite are opened, the pore diameter is increased, and the number of adsorption sites is increased, forming a porous active material with a microporous network structure, a large specific surface area, strong adsorption and ion exchange properties - activated white clay. The surface of the activated white clay after acid activation treatment has a large number of acid sites, which can cause olefins to undergo alkylation and condensation superposition reactions, thereby achieving efficient removal of olefins.

[0014] The activated clay obtained after acidification has hydrophilicity and poor affinity for olefins, and the interlayer structure of the activated clay is not fully opened, resulting in weak adsorption capacity for dyes. In order to improve the affinity and adsorption capacity of the activated clay and make full use of its huge specific surface area, the present invention performs carboxymethyl modification and quaternization on chitosan to obtain quaternized carboxymethyl chitosan, and uses the quaternized carboxymethyl chitosan to perform intercalation modification on the activated clay. After ion exchange between the dimethyl diallyl ammonium chloride organic cations grafted on the quaternized carboxymethyl chitosan and the inorganic cations between the activated clay layers, the cationic portion adheres to the activated clay layers, and the organic portion remains between the layers, thereby increasing the interlayer spacing of the activated clay, making the structure looser, the porosity higher, and causing partial lamellar peeling.

[0015] Chitosan has good solubility only in acidic solutions with low pH values, and its solubility in alkaline or neutral aqueous solutions with high pH values ​​is not very ideal. In order to enhance its water solubility, the present invention performs carboxymethyl modification on chitosan. In the chitosan molecular structure, the -NH2 at the C2 position and the -OH at the C3 and C6 positions of the glucosamine unit ring all have active hydrogen atoms, which are easy to be chemically modified. Therefore, the present invention performs carboxymethyl modification on these two functional groups using sodium chloroacetate. After the carboxymethylation reaction, hydrophilic carboxyl functional groups are introduced into the chitosan molecular chain, thereby enhancing the water solubility of chitosan.

[0016] In addition to the carboxyl functional groups, carboxymethyl chitosan also contains free hydroxyl groups and amino groups that are not completely reacted during the carboxymethylation of chitosan, so that the carboxymethyl chitosan has a sufficient number of reactive functional groups. To this end, the present invention uses dimethyl diallyl ammonium chloride to perform quaternization modification on the carboxymethyl chitosan. The quaternization modification not only retains and improves the water solubility of the carboxymethyl chitosan, but also grafts the dimethyl diallyl ammonium chloride copolymer onto the carboxymethyl chitosan molecular chain through the graft copolymerization reaction of dimethyl diallyl ammonium chloride and carboxymethyl chitosan. The effect of the graft copolymerization reaction is as follows:

[0017] On the one hand, nano-titanium dioxide particles have a small particle size and a high surface energy, and are very easy to agglomerate in the solution. Agglomeration will affect their absorption of light, thereby affecting the photocatalytic efficiency. Dimethyldiallyl ammonium chloride copolymer is an organic cation. In the subsequent intercalation modification process, dimethyldiallyl ammonium chloride copolymer can exchange cations with inorganic cations between the activated clay layers, thereby entering the activated clay layers and stretching the activated clay layers. The activated clay with expanded interlayer spacing serves as a carrier of titanium dioxide photocatalytic material, achieving load fixation of nano-titanium dioxide particles, and can effectively prevent the agglomeration of nano-titanium dioxide particles loaded between its layers. The layered structure of the activated clay and its strong adsorption for colored substances are used to improve the photocatalytic activity of the loaded nano-titanium dioxide particles. At the same time, the peeled activated clay layer can expose the nano-titanium dioxide particles, which is more conducive to their absorption of ultraviolet light, thereby improving their photocatalytic efficiency.

[0018] On the other hand, nano titanium dioxide particles can catalyze the degradation of organic pollutants under the irradiation of ultraviolet light due to the strong oxidizing properties of their electron-hole pairs, thereby removing the organic dyes in the printing and dyeing wastewater and realizing the decolorization of the printing and dyeing wastewater. Dimethyldiallyl ammonium chloride copolymer, as a water-soluble cationic polymer, has the advantages of high positive charge density, good water solubility, easy control of molecular weight, high efficiency, non-toxicity, and low cost. Traditional organic dyes, such as methylene blue and Congo red, are all anionic dyes with strong stability, serious environmental pollution, and are difficult to degrade. After the dimethyldiallyl ammonium chloride copolymer is grafted onto the carboxymethyl chitosan molecular chain, the organic dye can be adsorbed onto the interlayer of the modified white earth adsorbent through electrostatic interaction, thereby increasing the effective collision probability of the organic dye and the titanium dioxide nanoparticles, making it convenient for the organic dye to fully contact with the titanium dioxide nanoparticles, and greatly improving the photocatalytic degradation efficiency of the titanium dioxide nanoparticles.

[0019] Therefore, the modified clay adsorbent prepared by the present invention can simultaneously realize the adsorption and degradation functions. First, the electrostatic effect between the dimethyldiallyl ammonium chloride copolymer and the organic dye is used to adsorb the organic dye molecules into the interlayer of the modified clay adsorbent. At the same time, the modified clay adsorbent itself also has a certain adsorption capacity. In the early stage of the photodegradation reaction, the modified clay adsorbent mainly plays an adsorption role on the organic dye. After reaching the adsorption equilibrium, the concentration of the organic dye remains constant. Under ultraviolet light irradiation, the photocatalytic effect of the titanium dioxide nanoparticles loaded in the interlayer of the modified clay adsorbent is exerted, and the adsorbed organic dye is catalytically degraded into inorganic small molecules. Due to the synergistic effect of adsorption and degradation, the photodegradation efficiency of the modified clay adsorbent can be greatly improved, and efficient decolorization treatment of printing and dyeing wastewater can be achieved.

[0020] The present invention uses a sol-gel method to prepare nano-titanium dioxide particles with good dispersibility. During the preparation process, tetrabutyl titanate is first dissolved in anhydrous ethanol to form a uniform precursor solution. By adding an appropriate amount of glacial acetic acid and deionized water, the tetrabutyl titanate undergoes a hydrolysis reaction to generate a mixture of metal hydroxide and alcohol. Under appropriate pH and stirring conditions, these hydrolysis products gradually polymerize to form a mixed sol. Subsequently, the mixed sol is aged. Aging is a process of slow polymerization between sol particles. During the aging period, the particles in the mixed sol gradually grow and connect with each other to form a three-dimensional spatial network structure. This process helps to enhance the stability and viscosity of the mixed sol and lays the foundation for subsequent gel formation. As the aging process proceeds, the particles in the mixed sol gradually aggregate into larger aggregates to form a gel. A gel is a spatial network structure formed by cross-linking colloidal particles or polymer molecules, which is filled with a solvent that has lost its fluidity. In order to obtain titanium dioxide nanoparticles with good crystallinity, the gel needs to be heated, dried and calcined at high temperature. During the heating and drying process, the solvent in the gel will evaporate, leaving a solid skeleton. During the high-temperature calcination process, the gel skeleton will undergo thermal decomposition and recrystallization, eventually forming nano-titanium dioxide particles evenly loaded between the modified white clay flakes.

[0021] The nano-titanium dioxide particles prepared by the present invention interact with organic dyes through both physical and chemical adsorption. During physical adsorption, dye molecules interact with the surface of the titanium dioxide nanoparticles primarily through van der Waals forces and electrostatic forces. Van der Waals forces allow the dye molecules to be attracted to the porous structure of the titanium dioxide nanoparticle surface and firmly adsorbed thereon. Electrostatic forces also play an important role, particularly when the dye molecules and the titanium dioxide nanoparticle surface have opposite charges, as the electrostatic attraction between them further enhances the adsorption effect.

[0022] Chemical adsorption involves the formation of chemical bonds or hydrogen bonds between dye molecules and the surface of titanium dioxide nanoparticles. The hydroxyl groups (OH-) on the surface of titanium dioxide nanoparticles are key sites for chemical adsorption, reacting with certain functional groups in the dye molecules (such as carboxyl and amino groups) to form stable chemical bonds. This chemical bonding not only improves the firmness of adsorption but also makes it more difficult for dye molecules to desorb from the surface of titanium dioxide nanoparticles. In addition, the positive charge on the surface of titanium dioxide nanoparticles can also electrostatically interact with the negative charge in the dye molecules, forming ion pairs or ionic bonds, further enhancing the chemical adsorption effect. This electrostatic interaction is particularly important in the treatment of printing and dyeing wastewater because it allows dye molecules with opposite charges to be more effectively adsorbed and removed.

[0023] In addition to physical adsorption and chemical adsorption, titanium dioxide nanoparticles also have unique photocatalytic effects. Under the irradiation of ultraviolet light, titanium dioxide nanoparticles can absorb light energy and generate excited electrons and holes. These excited species have extremely high reactivity and can undergo redox reactions with dye molecules adsorbed on the surface of titanium dioxide nanoparticles, decomposing them into low-molecular substances (such as carbon dioxide, water, etc.). This photocatalytic effect not only improves the treatment efficiency of printing and dyeing wastewater, but also achieves deep purification of wastewater, making the treated wastewater more in line with environmental protection requirements.

[0024] As a preferred technical solution of the present invention, in step (I), when preparing the acidulant, the concentrated hydrochloric acid is first slowly added to deionized water and mixed evenly to obtain dilute hydrochloric acid; then concentrated sulfuric acid is slowly added to the dilute hydrochloric acid to obtain a mixed acid solution; finally, oxalic acid is added to the mixed acid solution and mixed evenly to obtain the acidulant.

[0025] In some optional examples, the mass fraction of the concentrated hydrochloric acid is 35~37wt%, for example, it can be 35wt%, 35.2wt%, 35.4wt%, 35.6wt%, 35.8wt%, 36wt%, 36.2wt%, 36.4wt%, 36.6wt%, 36.8wt% or 37wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] In some optional examples, the mass fraction of the concentrated sulfuric acid is 95-98 wt%, for example, it can be 95 wt%, 95.5 wt%, 96 wt%, 96.5 wt%, 97 wt%, 97.5 wt% or 98 wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] In some optional examples, the volume ratio of the concentrated hydrochloric acid, concentrated sulfuric acid and deionized water is 1:(1.4~1.6):(35~40), for example, it can be 1:1.4:35, 1:1.42:35.5, 1:1.44:36, 1:1.46:36.5, 1:1.48:37, 1:1.5:37.5, 1:1.52:38, 1:1.5:38.5, 1:1.56:39, 1:1.58:39.5 or 1:1.6:40, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] The present invention specifically limits the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid, and deionized water to 1:(1.4-1.6):(35-40). The hydrogen ion concentration ionized by sulfuric acid is too high, which destroys the bentonite crystal layer structure, causing the aluminum ions and magnesium ions in the interlayer of the bentonite to be dissolved by hydrogen ions, thereby collapsing the bentonite skeleton and destroying the octahedron. The hydrogen ion concentration ionized by hydrochloric acid is relatively low, and the activation effect in the acid modification process is not as good as that of mixed acid. The hydrogen ion concentration ionized by the mixed acid composed of hydrochloric acid, sulfuric acid, and oxalic acid is moderate. After the addition of oxalic acid, the hydrogen ion can form insoluble salts with calcium ions and magnesium ions, which is conducive to replacing the calcium ions and magnesium ions between the bentonite layers and has the best activation effect.

[0029] In some optional examples, the mass fraction of oxalic acid in the acidulant is 5 to 10 wt %, for example, 5.0 wt %, 5.5 wt %, 6.0 wt %, 6.5 wt %, 7.0 wt %, 7.5 wt %, 8.0 wt %, 8.5 wt %, 9.0 wt %, 9.5 wt % or 10.0 wt %, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] As a preferred technical solution of the present invention, in step (I), the particle size of the bentonite powder is 100-200 mesh, for example, it can be 100 mesh, 110 mesh, 120 mesh, 130 mesh, 140 mesh, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh or 200 mesh, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] In some optional examples, the bentonite powder and deionized water are mixed in a mass ratio of (0.6~0.7):1 to obtain the bentonite slurry, for example, it can be 0.6:1, 0.61:1, 0.62:1, 0.63:1, 0.64:1, 0.65:1, 0.66:1, 0.67:1, 0.68:1, 0.69:1 or 0.7:1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0032] In some optional examples, the mass ratio of the bentonite slurry, the acidifier and the sodium chloride is 1:(0.6~0.7):(0.08~0.1), for example, it can be 1:0.6:0.08, 1:0.61:0.082, 1:0.62:0.084, 1:0.63:0.086, 1:0.64:0.088, 1:0.65:0.09, 1:0.66:0.092, 1:0.67:0.094, 1:0.68:0.096, 1:0.69:0.098 or 1:0.7:0.1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] The present invention particularly limits the mass ratio of bentonite slurry, acidulant and sodium chloride to 1:(0.6-0.7):(0.08-0.1). When the amount of the acidulant is lower than the lower limit of the range defined by the present invention, the replacement of calcium ions by hydrogen ions is incomplete, and the quality of the activated clay finally obtained is poor. As the amount of the acidulant increases, the hydrogen ion concentration increases, and the activity of the activated clay obtained after acid activation increases rapidly, indicating that the calcium ions and magnesium ions between the bentonite layers are fully replaced by hydrogen ions, and the activated clay is modified by acidification to have a larger specific surface area and stronger adsorption. When the amount of the acidulant exceeds the upper limit of the range defined by the present invention, the excessive hydrogen ion concentration causes the aluminum ions in the bentonite tetrahedron structure to be exchanged and dissolved, destroying the skeleton structure of the bentonite, and significantly reducing the activity of the activated clay finally obtained.

[0034] In some optional examples, the heating activation step includes:

[0035] The raw material mixture is heated to a first activation temperature and kept warm, and then the temperature is further raised to a second activation temperature and kept warm, and then cooled to room temperature after the temperature is maintained to obtain the activated product.

[0036] In some optional examples, the first activation temperature is 80~90℃, for example, it can be 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃ or 90℃, but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable.

[0037] In some optional examples, the first activation temperature is kept warm for 2 to 3 hours, for example, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] In some optional embodiments, the second activation temperature is 100~110°C, for example, it can be 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C or 110°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] In some optional examples, the second activation temperature is kept warm for 2 to 3 hours, for example, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] In some optional embodiments, the activated product is rinsed with deionized water until the pH value of the activated product reaches 4 to 5, for example, it can be 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] In some optional examples, the centrifugal speed is 3000~4000rpm, for example, it can be 3000rpm, 3100rpm, 3200rpm, 3300rpm, 3400rpm, 3500rpm, 3600rpm, 3700rpm, 3800rpm, 3900rpm or 4000rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] In some optional examples, the centrifugation time is 5 to 10 min, for example, it can be 5.0 min, 5.5 min, 6.0 min, 6.5 min, 7.0 min, 7.5 min, 8.0 min, 8.5 min, 9.0 min, 9.5 min or 10.0 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] As a preferred technical solution of the present invention, in step (II), the carboxymethyl chitosan is prepared by the following method:

[0044] The chitosan powder and sodium hydroxide are put into a ball mill for primary ball milling, and then sodium chloroacetate and sodium iodide are put into the ball mill for secondary ball milling, and a solid product is obtained after the mixed ball milling is completed; the solid product is uniformly mixed with deionized water to obtain a product solution, and a hydrochloric acid solution is added to the product solution to adjust the pH value of the product solution to 7; and then the product solution is filtered, washed and dried to obtain the carboxymethyl chitosan.

[0045] The present invention uses sodium chloroacetate as a carboxymethyl modification agent and sodium iodide as a catalyst, and adopts a mechanochemical method to induce a chemical reaction, thereby introducing carboxymethyl functional groups into the chitosan molecular chain. The introduction of the carboxymethyl functional groups significantly improves the solubility of the chitosan. The chitosan molecular chain contains numerous hydroxyl groups, amino groups, and acetylamino groups, which form numerous intramolecular and intermolecular hydrogen bonds. Combined with the good regularity of the chitosan structure, crystalline regions are formed within the molecules, resulting in a certain degree of crystallinity. The present invention adopts mechanical ball milling to promote the progress of alkalization reaction and carboxymethylation reaction. During the ball milling process, the ball milling medium and the reaction material are subjected to the combined force of rotation and revolution in the ball mill, so that the centrifugal acceleration of the ball milling medium can reach 10-20g. At the same time, the pressure between the ball milling medium and the ball mill can reach 5-6 times of the weight of the ball milling medium itself. When the chitosan molecules are subjected to the strong mechanical force of the ball milling medium, the impact force and shear force subjected to the chitosan particles can destroy the crystal structure of the molecules. During the ball milling alkalization process, sodium hydroxide can better enter the interior of the chitosan molecules, thereby playing the effect of alkalization expansion. At the same time, during the carboxymethylation reaction, as the external mechanical force breaks the hydrogen bonds within the chitosan molecules and between the molecules, the hydroxyl groups and amino groups in the chitosan molecules are exposed to the outside, thereby providing targets for attack to the carboxymethyl groups in the system and promoting the occurrence of the carboxymethylation reaction.

[0046] The mechanochemical method for preparing carboxymethyl chitosan provided by the present invention is simple to operate, has a mild preparation process, low energy consumption, does not require the use of organic solvents, and has low pollution. It avoids the shortcomings of traditional wet processes such as the use of large amounts of organic solvents, cumbersome operations, long time consumption, and harsh conditions.

[0047] As a preferred technical solution of the present invention, the mass ratio of the chitosan powder to sodium hydroxide is 1:(3.5~4.5), for example, it can be 1:3.5, 1:3.6, 1:3.7, 1:3.8, 1:3.9, 1:4.0, 1:4.1, 1:4.2, 1:4.3, 1:4.4 or 1:4.5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] The present invention particularly limits the mass ratio of chitosan powder and sodium hydroxide to 1:(3.5~4.5), and along with the increase of sodium hydroxide consumption, the productive rate and substitution degree of product are the variation trend that first increases and then reduces.In the alkalization reaction process, sodium hydroxide plays the effect of alkalization expansion, and when the consumption of sodium hydroxide is lower than the scope lower limit limited by the present invention, can not play good alkalization expansion effect, has affected follow-up carboxymethylation reaction.Along with the raising of sodium hydroxide consumption, the active center formed also increases thereupon, and the structure of chitosan is destroyed, and particle expansion makes it better react with sodium chloroacetate, makes carboxymethylation reaction carry out smoothly, and therefore, substitution degree and yield of product all rise. When the amount of sodium hydroxide used exceeds the upper limit of the range defined in the present invention, the sodium hydroxide is excessive, which not only hinders mass transfer, but also the excess sodium hydroxide will neutralize a portion of the sodium chloroacetate, affecting the progress of the carboxymethylation reaction, resulting in a decrease in the reaction efficiency of the carboxymethylation reaction. At the same time, since the generated by-products are wrapped in the surface layer of the chitosan, it is difficult for the sodium chloroacetate to contact the interior of the chitosan, which to a certain extent hinders the progress of the carboxymethylation reaction. Therefore, the degree of substitution and yield of the product are reduced.

[0049] In some optional embodiments, the rotation speed of the primary ball milling is 500~600rpm, for example, it can be 500rpm, 510rpm, 520rpm, 530rpm, 540rpm, 550rpm, 560rpm, 570rpm, 580rpm, 590rpm or 600rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] In some optional embodiments, the time for one ball milling is 4 to 5 hours, for example, it can be 4.0 hours, 4.1 hours, 4.2 hours, 4.3 hours, 4.4 hours, 4.5 hours, 4.6 hours, 4.7 hours, 4.8 hours, 4.9 hours or 5.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] The present invention particularly limits the time of primary ball milling to 4-5 hours. As the mixing ball milling time is extended, the yield and degree of substitution of the product show a trend of first increasing and then decreasing. When the mixing ball milling time is shorter than 4 hours, the collision probability between chitosan, sodium hydroxide and the ball milling medium is reduced, which hinders the alkalization and expansion effect of sodium hydroxide. As the mixing ball milling time is extended, mechanical activation reduces the particle size of the reaction materials and increases the specific surface area, which is conducive to promoting the progress of the carboxymethylation reaction. Therefore, the yield and degree of substitution of the product are increased. When the mixing ball milling time exceeds 5 hours, the microparticles in the reaction system will agglomerate into secondary particles under the action of surface energy, van der Waals force and electrostatic force. When the agglomeration rate of the microparticles exceeds the generation rate of the microparticles, the specific surface area of ​​the particles in the reaction system is sharply reduced, the reaction rate is rapidly reduced, and the yield and degree of substitution of the product are reduced.

[0052] In some optional examples, the mass ratio of the chitosan powder to sodium chloroacetate is 1:(3~4), for example, it can be 1:3.0, 1:3.1, 1:3.2, 1:3.3, 1:3.4, 1:3.5, 1:3.6, 1:3.7, 1:3.8, 1:3.9 or 1:4.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] The present invention particularly limits the mass ratio of chitosan powder and sodium chloroacetate to 1:(3-4), and along with the increase of sodium chloroacetate consumption, the substitution degree of product is a variation trend that first increases and then decreases, and the productive rate of product is a variation trend that first increases and then tends to be stable. When the mass ratio of chitosan powder and sodium chloroacetate is within the numerical range limited by the present invention, along with the increase of sodium chloroacetate consumption, the probability of collision of chitosan active center with it increases, so that carboxymethylation reaction is carried out to the forward direction, so the productive rate and substitution degree of product rise gradually. When the consumption of sodium chloroacetate exceeds the upper limit of the range limited by the present invention, excessive sodium chloroacetate can consume a part of sodium hydroxide, promotes the generation of side reaction, reduces the utilization rate of sodium hydroxide, makes the substitution degree of product decline, and the productive rate of product no longer continues to increase.

[0054] In some optional examples, the mass ratio of sodium chloroacetate to sodium iodide is 1:(0.5~0.7), for example, 1:0.5, 1:0.52, 1:0.54, 1:0.56, 1:0.58, 1:0.6, 1:0.62, 1:0.64, 1:0.66, 1:0.68 or 1:0.7, but is not limited to the enumerated values, and other unlisted values ​​within the numerical range are equally applicable.

[0055] In some optional examples, the rotation speed of the secondary ball milling is 550~650rpm, for example, it can be 550rpm, 560rpm, 570rpm, 580rpm, 590rpm, 600rpm, 610rpm, 620rpm, 630rpm, 640rpm or 650rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] The present invention particularly limits the rotating speed of secondary ball milling to 550~650rpm. As the ball milling speed increases, the degree of substitution of the product presents a trend of first increasing and then tending to be stable, and the yield of the product presents a trend of first increasing and then decreasing. When the rotating speed of the ball mill is within the range of 550~650rpm, accelerating the ball milling speed can improve the collision probability and the number of collisions of chitosan powder, sodium hydroxide, sodium chloroacetate and sodium iodide. When the mechanical force is large enough, the stress generated by the chitosan powder instantaneously far exceeds its mechanical strength, and the powder particles are broken thereupon, so that the chitosan powder is better alkalized and expanded, and the progress of carboxymethylation reaction is promoted. Therefore, the degree of substitution of the product and the yield are all on an upward trend. When the ball milling speed exceeds 650rpm, the too fast rotating speed causes the contact time of the reaction mass and the ball milling medium to be too short, the excessive mechanical force may cause the ether bond to break, and the material particle size no longer continues to decrease or the speed of decreasing is very slow after reaching the limit. Therefore, after the ball milling speed exceeds 650rpm, the degree of substitution of the product tends to be stable.

[0057] In some optional embodiments, the secondary ball milling time is 5 to 6 hours, for example, it can be 5.0 hours, 5.1 hours, 5.2 hours, 5.3 hours, 5.4 hours, 5.5 hours, 5.6 hours, 5.7 hours, 5.8 hours, 5.9 hours or 6.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0058] The present invention particularly limits the secondary ball milling time to 5-6 hours. As the carboxymethylation reaction time is extended, the degree of substitution of the product shows a trend of first increasing and then decreasing, and the yield of the product shows a trend of first increasing and then tending to be stable. When the secondary ball milling time is within the range of 5-6 hours, as the secondary ball milling time is extended, the chitosan molecules expand more fully, the hydroxyl and amino groups on their molecular chains can fully extend, increasing the chance of contact with the carboxymethyl group, allowing the carboxymethylation reaction to be complete, and therefore, the degree of substitution and yield of the product are increased. When the secondary ball milling time exceeds 6 hours, by-products will increase accordingly, and small particles will agglomerate to reach a pulverization equilibrium during the ball milling process, thereby reducing the degree of substitution of the product, while the yield remains almost unchanged.

[0059] In some optional examples, the mass fraction of the hydrochloric acid solution is 8~10wt%, for example, it can be 8.0wt%, 8.2wt%, 8.4wt%, 8.6wt%, 8.8wt%, 9.0wt%, 9.2wt%, 9.4wt%, 9.6wt%, 9.8wt% or 10.0wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] In some optional examples, the filtration and washing steps include:

[0061] The product solution is filtered once, and then the filter residue obtained after the first filtration is washed once with a methanol aqueous solution with a mass fraction of 70~80wt%, and filtered twice after the first washing. The filter residue obtained after the second filtration is washed twice with anhydrous ethanol, and filtered three times after the second washing. For example, it can be 70wt%, 71wt%, 72wt%, 73wt%, 74wt%, 75wt%, 76wt%, 77wt%, 78wt%, 79wt% or 80wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0062] As a preferred technical solution of the present invention, in step (II), the quaternized carboxymethyl chitosan is prepared by the following method:

[0063] The carboxymethyl chitosan is dissolved in an acetic acid solution and mixed evenly to obtain a carboxymethyl chitosan solution; a dimethyl diallyl ammonium chloride solution is added dropwise to the carboxymethyl chitosan solution under continuous stirring and water bath heating conditions; after the dimethyl diallyl ammonium chloride solution is completely added, mixing, stirring and heating are continued to obtain a reaction product; acetone is added to the reaction product, and white floccules are generated after mixing, which is then filtered, washed and dried to obtain the quaternized carboxymethyl chitosan.

[0064] As a preferred technical solution of the present invention, the mass fraction of the acetic acid solution is 1-2wt%, for example, it can be 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2.0wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0065] In some optional examples, the ratio of the carboxymethyl chitosan to the acetic acid solution is 1g:(50~100)mL, for example, it can be 1g:50mL, 1g:55mL, 1g:60mL, 1g:65mL, 1g:70mL, 1g:75mL, 1g:80mL, 1g:85mL, 1g:90mL, 1g:95mL or 1g:100mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0066] In some optional examples, the mass fraction of the dimethyldiallylammonium chloride solution is 50-60wt%, for example, it can be 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt% or 60wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0067] In some optional embodiments, the water bath heating temperature is 50~60℃, for example, it can be 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃ or 60℃, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0068] The present invention specifically limits the water bath heating temperature to 50-60°C. As the reaction temperature increases, the grafting rate of the quaternization reaction shows a trend of first increasing and then decreasing. Within the reaction temperature range of 50-60°C, the reaction system produces a large number of active free radicals, thereby stimulating a large number of grafting sites. At the same time, the increase in temperature promotes the diffusion rate of the dimethyldiallylammonium chloride monomer in the solution to the carboxymethyl chitosan main chain, resulting in a significant increase in the grafting rate of the quaternization reaction. However, when the reaction temperature exceeds 60°C, the active center of the carboxymethyl chitosan will become unstable, resulting in accelerated homopolymerization of the dimethyldiallylammonium chloride monomer, which is not conducive to the quaternization reaction and reduces the grafting rate of the quaternization reaction. In addition, too high a temperature will also cause the synthesized quaternized carboxymethyl chitosan to have a jelly-like texture and unstable properties.

[0069] In some optional examples, the mass ratio of carboxymethyl chitosan in the carboxymethyl chitosan solution to dimethyl diallyl ammonium chloride in the dimethyl diallyl ammonium chloride solution is 1:(0.6~0.7), for example, it can be 1:0.6, 1:0.61, 1:0.62, 1:0.63, 1:0.64, 1:0.65, 1:0.66, 1:0.67, 1:0.68, 1:0.69 or 1:0.7, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0070] The present invention particularly limits the mass ratio of carboxymethyl chitosan and dimethyl diallyl ammonium chloride to be 1:(0.6~0.7), along with the increase of dimethyl diallyl ammonium chloride consumption, the grafting rate of quaternization reaction is the variation trend that first increases and then decreases, this is because, within the numerical range limited by the present invention, improve the concentration of dimethyl diallyl ammonium chloride, reaction system can produce a large amount of active free radicals, and then cause a large amount of grafting sites, so that the reaction efficiency of quaternization reaction is greatly improved. However, due to the steric hindrance of dimethyl diallyl ammonium chloride larger, more inclined to copolymerization, therefore, when the concentration of dimethyl diallyl ammonium chloride is too high, the homopolymerization reaction of dimethyl diallyl ammonium chloride monomer can be caused to accelerate, hindering the generation of graft copolymerization between dimethyl diallyl ammonium chloride and carboxymethyl chitosan to a certain extent, thus causing the grafting rate of quaternization reaction to decline.

[0071] In some optional examples, after the dimethyldiallylammonium chloride solution is completely added, mixing and stirring are continued under heating conditions in a water bath for 20 to 30 minutes, for example, 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes or 30 minutes, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0072] The present invention particularly limits the reaction times to be 20~30min, along with the extension of the reaction times, the grafting rate of quaternization reaction is the variation trend that first increases and then tends to be stable, because carboxymethyl chitosan is a long-chain macromolecule with a complex structure, there is the mutual repulsion of the existing same electrical groups on the molecular chain, and there is also the resistance of the homosexual groups on different molecular chains, so extending the reaction times is conducive to the full contact of the active functional groups on dimethyl diallyl ammonium chloride and the carboxymethyl chitosan molecular chain, making the quaternization reaction carried out more completely. When the reaction times is lower than 20min, there is no sufficient time contact between the active functional groups on dimethyl diallyl ammonium chloride and the carboxymethyl chitosan molecular chain, and quaternization reaction is not thorough, which is unfavorable for improving the grafting rate of quaternization reaction. After the reaction times exceeds 30min, the grafting rate of quaternization reaction tends to be stable, and considering the time cost, the present invention particularly limits the reaction times to be 20~30min.

[0073] In some optional examples, the volume ratio of the reaction product to acetone is 1:(1-1.2), for example, 1:1.0, 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.1, 1:1.12, 1:1.14, 1:1.16, 1:1.18 or 1:1.2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0074] As a preferred technical solution of the present invention, in step (II), the mass fraction of the acetic acid solution is 1-2 wt%, for example, it can be 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2.0 wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0075] In some optional examples, the concentration of quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution is 10-20 g / L, for example, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L or 20 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0076] In some optional examples, the mass ratio of quaternized carboxymethyl chitosan to activated clay in the quaternized carboxymethyl chitosan solution is 1:(3~5), for example, it can be 1:3.0, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4.0, 1:4.2, 1:4.4, 1:4.6, 1:4.8 or 1:5.0, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0077] In some optional examples, the mixing and stirring time of the quaternized carboxymethyl chitosan solution and the activated clay is 5 to 7 hours, for example, it can be 5.0 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours, 6.0 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours or 7.0 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0078] In some optional examples, the heating temperature of the quaternized carboxymethyl chitosan solution and the activated clay during mixing and stirring is 50-60°C, for example, it can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0079] As a preferred technical solution of the present invention, in step (III), the volume ratio of tetrabutyl titanate to anhydrous ethanol is 1:(3-4), for example, it can be 1:3.0, 1:3.1, 1:3.2, 1:3.3, 1:3.4, 1:3.5, 1:3.6, 1:3.7, 1:3.8, 1:3.9 or 1:4.0, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0080] In some optional examples, the volume ratio of anhydrous ethanol, glacial acetic acid and deionized water is (5~6):(1.2~1.3):1, for example, it can be 5:1.2:1, 5.1:1.21:1, 5.2:1.22:1, 5.3:1.23:1, 5.4:1.24:1, 5.5:1.25:1, 5.6:1.26:1, 5.7:1.27:1, 5.8:1.28:1, 5.9:1.29:1 or 6:1.3:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0081] In some optional examples, the mass fraction of the modified white clay in the white clay dispersion is 2~5wt%, for example, it can be 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt%, 4.5wt% or 5.0wt%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0082] In some optional examples, the ratio of tetrabutyl titanate in the precursor solution to the modified white clay in the white clay dispersion is 1mL:(0.3~0.5)g, for example, it can be 1mL:0.3g, 1mL:0.32g, 1mL:0.34g, 1mL:0.36g, 1mL:0.38g, 1mL:0.4g, 1mL:0.42g, 1mL:0.44g, 1mL:0.46g, 1mL:0.48g or 1mL:0.5g, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0083] The present invention specifically limits the ratio of tetrabutyl titanate in the precursor solution to the modified clay in the clay dispersion to 1 mL: (0.3-0.5) g. As the amount of tetrabutyl titanate increases, the decolorization rate of the modified clay adsorbent shows a trend of first increasing and then decreasing. This is because when the amount of tetrabutyl titanate is lower than the lower limit of the range defined by the present invention, too little titanium dioxide is generated by the reaction, and the specific surface area of ​​the modified clay adsorbent cannot be effectively increased, and the adsorption capacity and photocatalytic ability cannot be significantly enhanced. As the amount of tetrabutyl titanate increases, the generated titanium dioxide particles are evenly distributed on the surface and between layers of the modified clay without agglomeration, and the specific surface area of ​​the modified clay adsorbent gradually increases, and the adsorption capacity and photocatalytic ability gradually increase. When the amount of tetrabutyl titanate exceeds the upper limit of the range defined by the present invention, the titanium dioxide particles attached to the surface and between layers of the modified clay begin to agglomerate, resulting in a decrease in the specific surface area of ​​the modified clay adsorbent obtained, a decrease in the effective contact area with the molecules to be adsorbed, and an impact on its adsorption capacity and photocatalytic ability.

[0084] In some optional examples, the dripping rate of the precursor solution is 4~6mL / min, for example, it can be 4.0mL / min, 4.2mL / min, 4.4mL / min, 4.6mL / min, 4.8mL / min, 5.0mL / min, 5.2mL / min, 5.4mL / min, 5.6mL / min, 5.8mL / min or 6.0mL / min, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0085] In some optional examples, the stirring speed of the precursor solution during the dropwise addition process is 180~200r / min, for example, it can be 180r / min, 182r / min, 184r / min, 186r / min, 188r / min, 190r / min, 192r / min, 194r / min, 196r / min, 198r / min or 200r / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0086] In some optional examples, after all the precursor solutions are added dropwise, the obtained mixed solution is further mixed and stirred for 1 to 2 hours to obtain the mixed sol, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0087] In some optional examples, the static aging time is 24 to 48 hours, for example, it can be 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours, 40 hours, 42 hours, 44 hours, 46 hours or 48 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0088] In some optional embodiments, the heating and drying temperature is 60~70℃, for example, it can be 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃ or 70℃, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0089] In some optional examples, the heating and drying time is 10~12h, for example, it can be 10h, 10.2h, 10.4h, 10.6h, 10.8h, 11h, 11.2h, 11.4h, 11.6h, 11.8h or 12h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0090] In some optional examples, the high-temperature calcination temperature is 500~550℃, for example, it can be 500℃, 505℃, 510℃, 515℃, 520℃, 525℃, 530℃, 535℃, 540℃, 545℃ or 550℃, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0091] In some optional examples, the high-temperature calcination time is 3 to 4 hours, for example, it can be 3.0 hours, 3.1 hours, 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.6 hours, 3.7 hours, 3.8 hours, 3.9 hours or 4.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0092] In a second aspect, the present invention provides an application of a modified clay adsorbent for deolefination / decolorization prepared by the preparation method described in the first aspect, wherein the modified clay adsorbent is used in the fields of deolefination and decolorization.

[0093] Compared with the prior art, the present invention has the following beneficial effects:

[0094] The present invention first uses acid activation treatment to effectively open the interlayer structure of the bentonite ore, increasing its specific surface area and porosity, thereby improving its adsorption capacity for olefins and dye molecules. The activated clay is then intercalated with quaternized carboxymethyl chitosan, further improving its adsorption properties and enhancing its affinity and capture capacity for olefins and dye molecules. Finally, catalytically active titanium dioxide nanoparticles are loaded and fixed between the interlayers of the modified clay using a sol-gel method, further enhancing the modified clay's adsorption and decolorization performance for organic dyes. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 Flowchart of modified clay adsorbent for deolefination / denitrification provided in Examples 1-5 of the present invention; wherein Figure 1 (a) is a schematic diagram of the preparation process, Figure 1 (b) is a specific preparation process flow chart;

[0096] Figure 2 This is a schematic structural diagram of the deolefination evaluation device used in the present invention;

[0097] Among them, 1-raw material tank; 2-feed pump; 3-reactor; 4-cooler; 5-product collection tank;

[0098] Figure 3 The infrared spectra of bentonite and the activated clay prepared in Example 1 of the present invention are shown in FIG.

[0099] Figure 4 This is the infrared spectrum of the chitosan used in Example 1 of the present invention;

[0100] Figure 5 This is the infrared spectrum of the carboxymethyl chitosan prepared in Example 1 of the present invention;

[0101] Figure 6 This is the infrared spectrum of the quaternized carboxymethyl chitosan prepared in Example 1 of the present invention;

[0102] Figure 7 XRD patterns of bentonite powder, activated clay and modified clay prepared in Example 1 of the present invention;

[0103] Figure 8 (a) is a transmission electron micrograph of the activated clay prepared in Example 1 of the present invention; Figure 8 (b) is a transmission electron micrograph of the modified clay prepared in Example 1 of the present invention; Figure 8 (c) is a transmission electron micrograph of the modified clay adsorbent prepared in Example 1 of the present invention;

[0104] Figure 9The XRD patterns of bentonite powder, titanium dioxide and the modified clay adsorbent prepared in Example 1 of the present invention are shown. DETAILED DESCRIPTION

[0105] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0106] The chemical reagents used in the specific embodiments of the present invention are all commercially available products, and their models, specifications, and manufacturers are as follows:

[0107] Concentrated hydrochloric acid: analytical grade, purchased from Tianjin Damao Chemical Reagent Factory;

[0108] Concentrated sulfuric acid: analytical grade, purchased from Tianjin Damao Chemical Reagent Factory;

[0109] Oxalic acid: analytical grade, purchased from Shandong Zhengxing New Materials Co., Ltd.

[0110] Sodium chloride: R21092-500ml, purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0111] Chitosan: S11064-100 g, purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0112] Isopropyl alcohol: purity 99%, purchased from Nanjing Chemical Reagent Co., Ltd.

[0113] Sodium hydroxide: purity 99%, purchased from Nanjing Chemical Reagent Co., Ltd.

[0114] Sodium chloroacetate: purity 99%, purchased from Nanjing Chemical Reagent Co., Ltd.

[0115] Sodium iodide: purity 99%, purchased from Nanjing Chemical Reagent Co., Ltd.

[0116] Hydrochloric acid: industrial grade, purchased from Tianjin Damao Chemical Reagent Factory;

[0117] Acetic acid: industrial grade, purchased from Shandong Tongfengqi Chemical Co., Ltd.

[0118] Dimethyldiallylammonium chloride: S50184-100 ml, purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0119] Tetrabutyl titanate: S48406-500ml, purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0120] Anhydrous ethanol: 95%, purchased from Nanjing Chemical Reagent Co., Ltd.

[0121] Example 1

[0122] This embodiment provides a method for preparing a modified clay adsorbent for deolefination / decolorization, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0123] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 35 wt% into deionized water and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 98 wt% into the dilute hydrochloric acid, the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water being 1:1.4:35, and mix well to obtain a mixed acid solution; finally, add acetic acid into the mixed acid solution and mix well to obtain an acidifier, wherein the mass fraction of oxalic acid in the acidifier is 5 wt%;

[0124] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 100 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.6:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.6:0.08 to obtain a raw material mixture, the raw material mixture is heated to 80° C. and kept warm for 3 hours, and then further heated to 100° C. and kept warm for 3 hours after the insulation is completed, and then cooled to room temperature after the insulation is completed to obtain an activated product; the activated product is rinsed with deionized water until the pH value of the activated product reaches 4, and then centrifuged at a speed of 3000 rpm for 10 minutes, and the precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0125] (2) Chitosan powder and sodium hydroxide were put into a ball mill at a mass ratio of 1:3.5, and mixed and ball-milled at a speed of 500 rpm for 5 h. Then, sodium chloroacetate and sodium iodide were put into the ball mill, and the mass ratio of chitosan powder and sodium chloroacetate was 1:3, and the mass ratio of sodium chloroacetate and sodium iodide was 1:0.5. The mixed and ball-milled were continued at a speed of 550 rpm for 6 h. After the mixed and ball-milled, a solid product was obtained. The solid product was mixed evenly with deionized water to obtain a product solution with a mass fraction of 20 wt%. A hydrochloric acid solution with a mass fraction of 8 wt% was added dropwise to the product solution to adjust the pH value of the product solution to 7. Subsequently, the product solution was filtered once, and the filter residue obtained after the first filtration was washed once with a methanol aqueous solution with a mass fraction of 70 wt%, and filtered twice after the first washing. The filter residue obtained after the second filtration was washed twice with anhydrous ethanol, and filtered three times after the second washing. After the three filtrations, it was dried to obtain carboxymethyl chitosan.

[0126] The carboxymethyl chitosan was dissolved in an acetic acid solution with a mass fraction of 1 wt %, and the ratio of the carboxymethyl chitosan to the acetic acid solution was 1 g:50 mL, and the mixture was uniformly mixed to obtain a carboxymethyl chitosan solution; a dimethyl diallyl ammonium chloride solution with a mass fraction of 50 wt % was added dropwise to the carboxymethyl chitosan solution under continuous stirring and heating in a water bath at 50° C., and the mass ratio of the carboxymethyl chitosan in the carboxymethyl chitosan solution to the dimethyl diallyl ammonium chloride in the dimethyl diallyl ammonium chloride solution was 1:0.6. After the dimethyl diallyl ammonium chloride solution was completely added dropwise, the mixture was continued to be stirred under heating in a water bath for 30 minutes to obtain a reaction product; acetone was added to the reaction product in a volume ratio of the reaction product to acetone of 1:1, and white flocs were generated after mixing, which was then filtered, washed, and dried to obtain quaternized carboxymethyl chitosan;

[0127] The quaternized carboxymethyl chitosan is dissolved in an acetic acid solution having a mass fraction of 1 wt % to obtain a quaternized carboxymethyl chitosan solution, wherein the concentration of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution is 10 g / L; the activated clay obtained in step (1) is added to the quaternized carboxymethyl chitosan solution, wherein the mass ratio of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution to the activated clay is 1:3, and the mixture is stirred at 50° C. for 7 h, and then centrifuged, washed and dried to obtain modified clay;

[0128] (3) Tetrabutyl titanate and anhydrous ethanol were mixed in a volume ratio of 1:3 to obtain a precursor solution; anhydrous ethanol, glacial acetic acid and deionized water were mixed in a volume ratio of 5:1.2:1 to obtain a composite solvent, and the modified clay obtained in step (2) was dispersed in the composite solvent to obtain a clay dispersion, wherein the mass fraction of the modified clay in the clay dispersion was 2wt%; at a stirring speed of 180r / min, the precursor solution was dripped into the clay dispersion at a speed of 4mL / min, and the content of the precursor solution was 100%. The ratio of tetrabutyl titanate to the modified white clay in the white clay dispersion is 1 mL:0.3 g. After all the precursor solutions are added dropwise, the obtained mixed solution is continuously mixed and stirred for 2 hours to obtain a mixed sol. The mixed sol is sequentially subjected to static aging, extrusion molding, heating and drying, high-temperature calcination, and crushing and sieving to obtain the modified white clay adsorbent, wherein the static aging time is 24 hours, the heating and drying temperature is 60° C., the heating and drying time is 12 hours, the high-temperature calcination temperature is 500° C., and the high-temperature calcination time is 4 hours.

[0129] Figure 3 The infrared spectra of bentonite and activated clay prepared in Example 1 of the present invention are compared. It can be seen that 1653 cm -1The corresponding absorption peaks are the stretching and bending vibrations of the hydroxyl groups of water molecules in the bentonite crystal structure, 1043 cm -1 、471cm -1 and 823cm -1 The 3628cm-1 infrared absorption peaks correspond to the Si-O stretching vibration absorption peak, the Si-O-Si bending vibration absorption peak, and the O-Si-O asymmetric stretching vibration absorption peak. -1 The peak intensity at 1043 cm-1 increases, which is due to the stretching vibration of OH, indicating that the exchangeable cations are replaced by protons during the acid activation treatment, thereby increasing the number of hydroxyl groups available for further functionalization. -1 and 471cm -1 The band intensity of the Si-O stretching vibration absorption peak and the Si-O-Si bending vibration absorption peak at 823 cm -1 The energy band intensity of the O-Si-O asymmetric stretching vibration absorption peak at is enhanced, which indicates that after acid activation treatment, the Si environment changes due to acid corrosion, the organizational structure of the activated clay changes, and the active sites increase.

[0130] Figure 4 and Figure 5 The infrared spectra of chitosan and carboxymethyl chitosan prepared in this embodiment are respectively Figure 4 It can be seen that in the infrared curve of chitosan, 1652 cm -1 The characteristic absorption peak of the NH-CO (Ⅰ) band in the residual amide group is 1598 cm -1 The corresponding absorption peak of NH bending vibration in -NH2 is 1321cm -1 The bending vibration absorption peak of CN is 1076 cm -1 and 1029cm -1 The corresponding stretching vibration absorption peak of CO. Figure 5 It can be seen that in the infrared curve of carboxymethyl chitosan, 1606 cm -1 and 1417cm -1 The corresponding -COO - The antisymmetric and symmetric stretching vibration absorption peaks, 1313 cm -1 The stretching vibration absorption peak corresponding to CN is 1064 cm -1 The corresponding stretching vibration absorption peak of CO. Figure 4 and Figure 5 The comparison shows that the absorption peaks of chitosan and carboxymethyl chitosan are mostly similar, but there are also obvious differences. Due to the interaction between the groups, the absorption peak of chitosan at 1652cm -1 and 1321cm -1The bands at 1606cm -1 and 1417cm -1 -COO appears - This shows that carboxymethyl functional groups are introduced to the amino and hydroxyl groups of chitosan to varying degrees, and carboxymethyl chitosan is formed by carboxymethylation reaction.

[0131] Figure 6 This is the infrared spectrum of the quaternized carboxymethyl chitosan prepared in this example. As can be seen from the figure, 1612 cm -1 and 1417cm -1 The corresponding -COO - The antisymmetric and symmetric stretching vibration absorption peaks, 1477 cm -1 and 2921cm -1 The absorption peaks at 1324 cm correspond to the CH bending vibration absorption peak and CH stretching vibration absorption peak of -CH3 in the quaternary ammonium functional group introduced by the quaternization reaction, respectively. -1 The CN stretching vibration absorption peak corresponding to the secondary amine is 1066 cm -1 The corresponding CO stretching vibration absorption peak of secondary alcohol. Figure 5 and Figure 6 By comparison, it can be seen that the infrared curve of quaternized carboxymethyl chitosan obtained by quaternization of carboxymethyl chitosan is similar to that of carboxymethyl chitosan to a large extent, but there are also obvious differences. In the infrared curve of quaternized carboxymethyl chitosan, 1477 cm -1 and 2921cm -1 A vibration absorption peak representing -CH3 in the quaternary ammonium functional group appeared at , which indicates that the quaternary ammonium functional group was introduced into the molecular structure of carboxymethyl chitosan after quaternization modification, and the target product, quaternized carboxymethyl chitosan, was synthesized.

[0132] Figure 7The XRD patterns of bentonite powder, activated clay and modified clay prepared in this embodiment are shown. Using the Bragg equation: 2dsinθ=nλ, where n is 1 and λ is 0.15406nm, the interlayer spacing of bentonite powder, activated clay and modified clay can be calculated. Calculations show that the interlayer spacing of bentonite powder is 1.25nm, the interlayer spacing of activated clay is 1.49nm, and the interlayer spacing of modified clay is 1.53nm. It can be seen that the interlayer spacing of the activated clay obtained after acid activation treatment is significantly increased compared to that of unmodified bentonite powder. This is because during the acid activation process of the bentonite powder, the hydrogen ions in the acid replace the metal cations between the bentonite powder layers, causing the bentonite to undergo interlayer cation exchange, further increasing the interlayer spacing of the bentonite. Compared with activated clay, the interlayer spacing of the modified clay obtained after intercalation modification with quaternized carboxymethyl chitosan is further increased, the specific surface area is improved, and the number of active sites is increased, which is beneficial to the improvement of the adsorption performance of the modified clay.

[0133] Figure 8 (a) Figure 8 (b) and Figure 8 (c) are transmission electron micrographs of the activated clay, modified clay, and modified clay adsorbent prepared in this example, respectively. Figure 8 (a) and Figure 8 (b) Compared with the activated clay, the activated clay prepared by the present invention is dispersed and peeled, and the interlayer distance is significantly increased. Figure 8 (c) It can be seen that TiO2 nanoparticles are loaded in the activated clay after stripping.

[0134] Figure 9: The XRD patterns of bentonite powder, titanium dioxide and the modified white clay adsorbent prepared in this embodiment. It can be seen from the figure that in the XRD curve of bentonite powder, diffraction peaks appear at 2θ values ​​of 19.7°, 20.9°, 26.5°, 29.5°, 36.0°, 39.6°, 43.1°, 47.6°, and 48.7°, which correspond to the main diffraction peaks of bentonite, respectively. In the XRD curve of titanium dioxide, the diffraction peaks at 2θ values ​​of 25.3°, 38.6°, 48.1°, 53.9°, 55.1°, 62.7°, 70.4°, and 75.4° correspond to the (101), (112), (200), (105), (211), (204), (220), and (215) crystal planes of anatase phase TiO2, respectively. The diffraction peaks at 2θ values ​​of 27.3°, 36.1°, and 69.1° correspond to the (110), (101), and (301) crystal planes of rutile phase TiO2, respectively. In the XRD curve of the modified clay adsorbent, not only the characteristic diffraction peaks of TiO2 appear, but also the characteristic diffraction peak corresponding to montmorillonite appears at 2θ=30.8°, which indicates that the modified clay has been composited with TiO2, achieving the immobilization of titanium dioxide by the modified clay.

[0135] Example 2

[0136] This embodiment provides a method for preparing a modified clay adsorbent for deolefination / decolorization, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0137] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 35.5 wt% into deionized water and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 97 wt% into the dilute hydrochloric acid, the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water being 1:1.45:36, and mix well to obtain a mixed acid solution; finally, add acetic acid into the mixed acid solution and mix well to obtain an acidifier, wherein the mass fraction of oxalic acid in the acidifier is 6 wt%;

[0138] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 120 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.62:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.62:0.085 to obtain a raw material mixture, the raw material mixture is heated to 82° C. and kept warm for 2.8 hours, and then further heated to 102° C. and kept warm for 2.8 hours after the end of the heat preservation, and then cooled to room temperature to obtain an activated product; the activated product is rinsed with deionized water until the pH value of the activated product reaches 4.2, and then centrifuged at a speed of 3200 rpm for 8 minutes, and the precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0139] (2) Chitosan powder and sodium hydroxide were added to a ball mill at a mass ratio of 1:3.8, and mixed and ball-milled at a speed of 520 rpm for 4.8 h. Subsequently, sodium chloroacetate and sodium iodide were added to the ball mill at a mass ratio of chitosan powder to sodium chloroacetate of 1:3.2 and a mass ratio of sodium chloroacetate to sodium iodide of 1:0.55. The mixed and ball-milled were continued at a speed of 580 rpm for 5.8 h. After the mixed and ball-milled, a solid product was obtained. The solid product was evenly mixed with deionized water to obtain a mass product. A product solution with a mass fraction of 20 wt %, a hydrochloric acid solution with a mass fraction of 8.5 wt % is added dropwise to the product solution to adjust the pH value of the reaction product to 7; subsequently, the product solution is filtered once, the filter residue obtained after the first filtration is washed once with a methanol aqueous solution with a mass fraction of 72 wt %, the filter residue is filtered twice after the first washing, the filter residue obtained after the second filtration is washed twice with anhydrous ethanol, the filter residue is filtered three times after the second washing, and the filter residue is dried after the three filtrations to obtain carboxymethyl chitosan;

[0140] The carboxymethyl chitosan was dissolved in an acetic acid solution with a mass fraction of 1.2 wt %, with the ratio of carboxymethyl chitosan to acetic acid solution being 1 g:60 mL, and the mixture was uniformly mixed to obtain a carboxymethyl chitosan solution; a dimethyl diallyl ammonium chloride solution with a mass fraction of 52 wt % was added dropwise to the carboxymethyl chitosan solution under continuous stirring and heating in a water bath at 52° C., with the mass ratio of carboxymethyl chitosan in the carboxymethyl chitosan solution to dimethyl diallyl ammonium chloride in the dimethyl diallyl ammonium chloride solution being 1:0.62; after the dimethyl diallyl ammonium chloride solution was completely added dropwise, the mixture was continuously stirred under heating in a water bath for 28 minutes to obtain a reaction product; acetone was added to the reaction product at a volume ratio of the reaction product to acetone of 1:1.05, and white flocs were generated after mixing, which was then filtered, washed, and dried to obtain quaternized carboxymethyl chitosan;

[0141] The quaternized carboxymethyl chitosan was dissolved in an acetic acid solution having a mass fraction of 1.2 wt % to obtain a quaternized carboxymethyl chitosan solution, wherein the concentration of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution was 12 g / L; the activated clay obtained in step (1) was added to the quaternized carboxymethyl chitosan solution, wherein the mass ratio of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution to the activated clay was 1:3.5, and the mixture was stirred at 52° C. for 6.5 h, and then centrifuged, washed and dried to obtain modified clay;

[0142] (3) Tetrabutyl titanate and anhydrous ethanol were mixed in a volume ratio of 1:3.2 to obtain a precursor solution; anhydrous ethanol, glacial acetic acid and deionized water were mixed in a volume ratio of 5.2:1.22:1 to obtain a composite solvent, and the modified white clay obtained in step (2) was dispersed in the composite solvent to obtain a white clay dispersion, wherein the mass fraction of the modified white clay in the white clay dispersion was 3wt%; at a stirring speed of 185r / min, the precursor solution was dripped into the white clay dispersion at a speed of 4.5mL / min, and the precursor solution was The ratio of tetrabutyl titanate to the modified white clay in the white clay dispersion is 1 mL:0.35 g. After all the precursor solutions are added dropwise, the obtained mixed solution is further mixed and stirred for 1.8 hours to obtain a mixed sol. The mixed sol is sequentially subjected to static aging, extrusion molding, heating and drying, high-temperature calcination, and crushing and sieving to obtain the modified white clay adsorbent, wherein the static aging time is 30 hours, the heating and drying temperature is 62° C., the heating and drying time is 11.5 hours, the high-temperature calcination temperature is 510° C., and the high-temperature calcination time is 3.8 hours.

[0143] Example 3

[0144] This embodiment provides a method for preparing a modified clay adsorbent for deolefination / decolorization, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0145] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 36 wt% into deionized water and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 96 wt% into the dilute hydrochloric acid, the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water being 1:1.5:37, and mix well to obtain a mixed acid solution; finally, add acetic acid into the mixed acid solution and mix well to obtain an acidifier, wherein the mass fraction of oxalic acid in the acidifier is 7 wt%;

[0146] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 150 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.65:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.65:0.09 to obtain a raw material mixture, and the raw material mixture is heated to 85° C. and kept warm for 2.5 hours. After the insulation, the temperature is further increased to 105° C. and kept warm for 2.5 hours. After the insulation, the mixture is cooled to room temperature to obtain an activated product; the activated product is rinsed with deionized water until the pH value of the activated product reaches 4.5, and then centrifuged at a speed of 3500 rpm for 7 minutes. The precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0147] (2) Chitosan powder and sodium hydroxide were put into a ball mill at a mass ratio of 1:4, and mixed and ball-milled at a speed of 550 rpm for 4.5 h. Then, sodium chloroacetate and sodium iodide were put into the ball mill, and the mass ratio of chitosan powder to sodium chloroacetate was 1:3.5, and the mass ratio of sodium chloroacetate to sodium iodide was 1:0.6. The mixed and ball-milled were continued at a speed of 600 rpm for 5.5 h. After the mixed and ball-milled, a solid product was obtained. The solid product was mixed with deionized water to obtain a product solution with a mass fraction of 20 wt%. A hydrochloric acid solution with a mass fraction of 9 wt% was added dropwise to the product solution to adjust the pH value of the reaction product to 7. Subsequently, the product solution was filtered once, and the filter residue obtained after the first filtration was washed once with a methanol aqueous solution with a mass fraction of 75 wt%, and then filtered twice after the first washing. The filter residue obtained after the second filtration was washed twice with anhydrous ethanol, and then filtered three times after the second washing. After the three filtrations, it was dried to obtain carboxymethyl chitosan.

[0148] The carboxymethyl chitosan was dissolved in an acetic acid solution with a mass fraction of 1.5 wt %, with the ratio of carboxymethyl chitosan to acetic acid solution being 1 g:70 mL, and the mixture was uniformly mixed to obtain a carboxymethyl chitosan solution; a dimethyl diallyl ammonium chloride solution with a mass fraction of 55 wt % was added dropwise to the carboxymethyl chitosan solution under continuous stirring and heating in a water bath at 55° C., with the mass ratio of carboxymethyl chitosan in the carboxymethyl chitosan solution to dimethyl diallyl ammonium chloride in the dimethyl diallyl ammonium chloride solution being 1:0.65; after the dimethyl diallyl ammonium chloride solution was completely added dropwise, the mixture was continuously stirred under heating in a water bath for 25 minutes to obtain a reaction product; acetone was added to the reaction product at a volume ratio of the reaction product to acetone of 1:1.1, and white flocs were generated after mixing, which was then filtered, washed, and dried to obtain quaternized carboxymethyl chitosan;

[0149] The quaternized carboxymethyl chitosan is dissolved in an acetic acid solution having a mass fraction of 1.5 wt % to obtain a quaternized carboxymethyl chitosan solution, wherein the concentration of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution is 15 g / L; the activated clay obtained in step (1) is added to the quaternized carboxymethyl chitosan solution, wherein the mass ratio of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution to the activated clay is 1:4, and the mixture is mixed and stirred at 55° C. for 6 h, and then centrifuged, washed and dried to obtain modified clay;

[0150] (3) Tetrabutyl titanate and anhydrous ethanol were mixed in a volume ratio of 1:3.5 to obtain a precursor solution; anhydrous ethanol, glacial acetic acid and deionized water were mixed in a volume ratio of 5.5:1.25:1 to obtain a composite solvent, and the modified clay obtained in step (2) was dispersed in the composite solvent to obtain a clay dispersion, wherein the mass fraction of the modified clay in the clay dispersion was 4wt%; at a stirring speed of 190r / min, the precursor solution was dripped into the clay dispersion at a speed of 5mL / min, and the precursor solution was The ratio of tetrabutyl titanate to the modified white clay in the white clay dispersion is 1 mL:0.4 g. After all the precursor solutions are added dropwise, the obtained mixed solution is continued to be mixed and stirred for 1.5 hours to obtain a mixed sol; the mixed sol is sequentially subjected to static aging, extrusion molding, heating and drying, high-temperature roasting and crushing and screening to obtain the modified white clay adsorbent, wherein the static aging time is 36 hours, the heating and drying temperature is 65°C, the heating and drying time is 11 hours, the high-temperature roasting temperature is 520°C, and the high-temperature roasting time is 3.5 hours.

[0151] Example 4

[0152] This embodiment provides a method for preparing a modified clay adsorbent for deolefination / decolorization, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0153] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 36.5 wt% into deionized water and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 96 wt% into the dilute hydrochloric acid, the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water being 1:1.55:38, and mix well to obtain a mixed acid solution; finally, add acetic acid into the mixed acid solution and mix well to obtain an acidifier, wherein the mass fraction of oxalic acid in the acidifier is 8 wt%;

[0154] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 180 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.68:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.68:0.095 to obtain a raw material mixture, the raw material mixture is heated to 88° C. and kept warm for 2.2 hours, and then further heated to 108° C. and kept warm for 2.2 hours after the end of the heat preservation, and then cooled to room temperature to obtain an activated product; the activated product is rinsed with deionized water until the pH value of the activated product reaches 4.8, and then centrifuged at a speed of 3800 rpm for 6 minutes, and the precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0155] (2) Chitosan powder and sodium hydroxide were added to a ball mill at a mass ratio of 1:4.2, and mixed and ball-milled at a speed of 580 rpm for 4.2 h. Subsequently, sodium chloroacetate and sodium iodide were added to the ball mill at a mass ratio of chitosan powder to sodium chloroacetate of 1:3.8 and a mass ratio of sodium chloroacetate to sodium iodide of 1:0.65. Mixing and ball-milling were continued at a speed of 620 rpm for 5.2 h. After the mixing and ball-milling, a solid product was obtained. The solid product was evenly mixed with deionized water to obtain a mass product. A product solution with a mass fraction of 20 wt %, a hydrochloric acid solution with a mass fraction of 9.5 wt % was added dropwise to the product solution to adjust the pH value of the reaction product to 7; subsequently, the product solution was filtered once, the filter residue obtained after the first filtration was washed once with a methanol aqueous solution with a mass fraction of 78 wt %, the filter residue was filtered twice after the first washing, the filter residue obtained after the second filtration was washed twice with anhydrous ethanol, the filter residue was filtered three times after the second washing, and the filter residue was dried after the three filtrations to obtain carboxymethyl chitosan;

[0156] The carboxymethyl chitosan was dissolved in an acetic acid solution having a mass fraction of 1.8 wt %, with the ratio of the carboxymethyl chitosan to the acetic acid solution being 1 g:80 mL, and the mixture was uniformly mixed to obtain a carboxymethyl chitosan solution; a dimethyl diallyl ammonium chloride solution having a mass fraction of 58 wt % was added dropwise to the carboxymethyl chitosan solution under continuous stirring and heating in a water bath at 58° C., with the mass ratio of the carboxymethyl chitosan in the carboxymethyl chitosan solution to the dimethyl diallyl ammonium chloride in the dimethyl diallyl ammonium chloride solution being 1:0.68; after the dimethyl diallyl ammonium chloride solution was completely added dropwise, the mixture was continuously stirred under heating in a water bath for 22 minutes to obtain a reaction product; acetone was added to the reaction product in a volume ratio of the reaction product to acetone being 1:1.15, and white flocs were generated after mixing, which was then filtered, washed, and dried to obtain quaternized carboxymethyl chitosan;

[0157] The quaternized carboxymethyl chitosan was dissolved in an acetic acid solution having a mass fraction of 1.8 wt % to obtain a quaternized carboxymethyl chitosan solution, wherein the concentration of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution was 18 g / L; the activated clay obtained in step (1) was added to the quaternized carboxymethyl chitosan solution, wherein the mass ratio of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution to the activated clay was 1:4.5, and the mixture was stirred at 58° C. for 5.5 h, and then centrifuged, washed and dried to obtain modified clay;

[0158] (3) Tetrabutyl titanate and anhydrous ethanol were mixed in a volume ratio of 1:3.8 to obtain a precursor solution; anhydrous ethanol, glacial acetic acid and deionized water were mixed in a volume ratio of 5.8:1.28:1 to obtain a composite solvent, and the modified clay obtained in step (2) was dispersed in the composite solvent to obtain a clay dispersion, wherein the mass fraction of the modified clay in the clay dispersion was 4 wt%; at a stirring speed of 195 r / min, the precursor solution was dropped into the clay dispersion at a rate of 5.5 mL / min, and the precursor solution was The ratio of tetrabutyl titanate to the modified white clay in the white clay dispersion is 1 mL:0.45 g. After all the precursor solutions are added dropwise, the obtained mixed solution is further mixed and stirred for 1.2 hours to obtain a mixed sol. The mixed sol is sequentially subjected to static aging, extrusion molding, heating and drying, high-temperature calcination, and crushing and sieving to obtain the modified white clay adsorbent, wherein the static aging time is 42 hours, the heating and drying temperature is 68° C., the heating and drying time is 10.5 hours, the high-temperature calcination temperature is 530° C., and the high-temperature calcination time is 3.2 hours.

[0159] Example 5

[0160] This embodiment provides a method for preparing a modified clay adsorbent for deolefination / decolorization, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0161] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 37 wt% into deionized water and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 95 wt% into the dilute hydrochloric acid, the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water being 1:1.6:40, and mix well to obtain a mixed acid solution; finally, add acetic acid into the mixed acid solution and mix well to obtain an acidifier, wherein the mass fraction of oxalic acid in the acidifier is 10 wt%;

[0162] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 200 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.7:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.7:0.1 to obtain a raw material mixture, the raw material mixture is heated to 90° C. and kept warm for 2 hours, and then further heated to 110° C. and kept warm for 2 hours after the end of the heat preservation, and then cooled to room temperature to obtain an activated product; the activated product is rinsed with deionized water until the pH value of the activated product reaches 5, and then centrifuged at a speed of 4000 rpm for 5 minutes, and the precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0163] (2) Chitosan powder and sodium hydroxide were put into a ball mill at a mass ratio of 1:4.5, and mixed and ball-milled at a speed of 600 rpm for 4 h. Then, sodium chloroacetate and sodium iodide were put into the ball mill, and the mass ratio of chitosan powder to sodium chloroacetate was 1:4, and the mass ratio of sodium chloroacetate to sodium iodide was 1:0.7. The mixed and ball-milled were continued at a speed of 650 rpm for 5 h. After the mixed and ball-milled, a solid product was obtained. The solid product was mixed with deionized water to obtain a product solution with a mass fraction of 20 wt%. A hydrochloric acid solution with a mass fraction of 10 wt% was added dropwise to the product solution to adjust the pH value of the reaction product to 7. Subsequently, the product solution was filtered once, and the filter residue obtained after the first filtration was washed once with a methanol aqueous solution with a mass fraction of 80 wt%, and then filtered twice after the first washing. The filter residue obtained after the second filtration was washed twice with anhydrous ethanol, and then filtered three times after the second washing. After the three filtrations, it was dried to obtain carboxymethyl chitosan.

[0164] The carboxymethyl chitosan was dissolved in an acetic acid solution with a mass fraction of 2 wt %, with the ratio of carboxymethyl chitosan to acetic acid solution being 1 g:100 mL, and the mixture was uniformly mixed to obtain a carboxymethyl chitosan solution; a dimethyl diallyl ammonium chloride solution with a mass fraction of 60 wt % was added dropwise to the carboxymethyl chitosan solution under continuous stirring and heating in a water bath at 60° C., with the mass ratio of carboxymethyl chitosan in the carboxymethyl chitosan solution to dimethyl diallyl ammonium chloride in the dimethyl diallyl ammonium chloride solution being 1:0.7; after the dimethyl diallyl ammonium chloride solution was completely added dropwise, the mixture was continued to be stirred under heating in a water bath for 20 minutes to obtain a reaction product; acetone was added to the reaction product at a volume ratio of the reaction product to acetone of 1:1.2, and white flocs were generated after mixing, which was then filtered, washed, and dried to obtain quaternized carboxymethyl chitosan;

[0165] The quaternized carboxymethyl chitosan is dissolved in an acetic acid solution having a mass fraction of 2 wt % to obtain a quaternized carboxymethyl chitosan solution, wherein the concentration of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution is 20 g / L; the activated clay obtained in step (1) is added to the quaternized carboxymethyl chitosan solution, wherein the mass ratio of the quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution to the activated clay is 1:5, and the mixture is mixed and stirred at 60° C. for 5 h, and then centrifuged, washed and dried to obtain modified clay;

[0166] (3) Tetrabutyl titanate and anhydrous ethanol were mixed in a volume ratio of 1:4 to obtain a precursor solution; anhydrous ethanol, glacial acetic acid and deionized water were mixed in a volume ratio of 6:1.3:1 to obtain a composite solvent, and the modified clay obtained in step (2) was dispersed in the composite solvent to obtain a clay dispersion, wherein the mass fraction of the modified clay in the clay dispersion was 5wt%; at a stirring speed of 200r / min, the precursor solution was dropped into the clay dispersion at a speed of 6mL / min, and the content of the precursor solution was 100%. The ratio of tetrabutyl titanate to the modified white clay in the white clay dispersion is 1 mL:0.5 g. After all the precursor solutions are added dropwise, the obtained mixed solution is further mixed and stirred for 1 hour to obtain a mixed sol. The mixed sol is sequentially subjected to static aging, extrusion molding, heating and drying, high-temperature roasting, and crushing and screening to obtain the modified white clay adsorbent, wherein the static aging time is 48 hours, the heating and drying temperature is 70° C., the heating and drying time is 10 hours, the high-temperature roasting temperature is 550° C., and the high-temperature roasting time is 3 hours.

[0167] Comparative Example 1

[0168] This comparative example provides a preparation method for a modified white clay adsorbent for deolefination / decolorization. The difference from Example 1 is that in step (1), the mass ratio of bentonite slurry, acidifier and sodium chloride is adjusted to 1:0.5:0.08, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0169] Comparative Example 2

[0170] This comparative example provides a preparation method for a modified white clay adsorbent for deolefination / decolorization. The difference from Example 1 is that in step (1), the mass ratio of bentonite slurry, acidifier and sodium chloride is adjusted to 1:0.8:0.08, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0171] Comparative Example 3

[0172] This comparative example provides a preparation method for a modified white clay adsorbent for deolefination / decolorization. The difference from Example 1 is that in step (2), the mass ratio of chitosan powder to sodium hydroxide is adjusted to 1:3, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0173] Comparative Example 4

[0174] This comparative example provides a preparation method for a modified white clay adsorbent for deolefination / decolorization. The difference from Example 1 is that in step (2), the mass ratio of chitosan powder to sodium hydroxide is adjusted to 1:5, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0175] Comparative Example 5

[0176] This comparative example provides a preparation method for a modified white clay adsorbent for deolefination / decolorization. The difference from Example 1 is that in step (2), the mass ratio of chitosan powder to sodium chloroacetate is adjusted to 1:2, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0177] Comparative Example 6

[0178] This comparative example provides a preparation method for a modified white clay adsorbent for deolefination / decolorization. The difference from Example 1 is that in step (2), the mass ratio of chitosan powder to sodium chloroacetate is adjusted to 1:5, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0179] Comparative Example 7

[0180] This comparative example provides a preparation method for a modified clay adsorbent for deolefination / decolorization. The difference from Example 1 is that in step (3), the ratio of tetrabutyl titanate in the precursor solution to the modified clay in the clay dispersion is adjusted to 1 mL:0.2 g, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0181] Comparative Example 8

[0182] This comparative example provides a preparation method for a modified clay adsorbent for deolefination / decolorization. The difference from Example 1 is that in step (3), the ratio of tetrabutyl titanate in the precursor solution to the modified clay in the clay dispersion is adjusted to 1 mL:0.6 g, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0183] The activity, pore size, dye removal rate and olefin removal rate of the modified clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-8 were tested. The specific testing steps are as follows:

[0184] (1) Activity test:

[0185] Activity is an important indicator to measure the adsorption performance of modified clay adsorbents. It is usually expressed as the volume (mL) of NaOH standard solution [c(NaOH=1.000mol / L] consumed to neutralize 1000g of modified clay adsorbent sample.

[0186] The present invention measures the activity of the modified clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-8 with reference to the industry standard HG / T 2569-2007 "Activated Clay".

[0187] (2) Aperture test:

[0188] The pore sizes of the modified clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-8 were analyzed and detected using a fully automatic gas adsorption analyzer. Before the test, they were degassed at 150° C. under vacuum conditions for 7 h, and then nitrogen adsorption-desorption performance tests were performed.

[0189] (3) Dye removal rate test:

[0190] Pipette 1.0mL, 3.0mL, 5.0mL, 7.0mL, 10.0mL, 15.0mL, 20.0mL, and 25.0mL of the prepared 100mg / L pink dye standard solution into a 100mL volumetric flask, dilute to 100mL with distilled water, shake well, and use a 1cm glass cuvette with distilled water as the reference solution to measure its absorbance at its maximum wavelength of 532nm. The obtained data were linearly fitted to obtain the fitting equation between the absorbance and concentration of the pink dye solution: y = 8.081×10 -4 +0.02188x, linear correlation coefficient R 2 =0.9998.

[0191] 20 mL of a certain concentration of pink dye solution was transferred into a 40 mL centrifuge tube, and the modified white clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-8 were added respectively. The amount of modified white clay adsorbent added was 2 wt % of the pink dye solution. The mixture was shaken under ultraviolet light for 30 min, and then centrifuged at 6000 r / min for 10 min. An appropriate amount of supernatant was taken and the absorbance was measured at a wavelength of 532 nm using a 1 cm quartz cuvette. According to the fitting equation y = 8.081 × 10 -4 +0.02188x to calculate the concentration of the pink dye solution before and after decolorization, and use the following formula to calculate the dye removal rate:

[0192]

[0193] Where: c0 is the concentration of the pink dye solution before decolorization (mg / L); c is the concentration of the pink dye solution after decolorization (mg / L).

[0194] (4) Olefin removal rate test:

[0195] The raw material for the deolefination activity evaluation was reforming oil provided by a petrochemical company, with a bromine index of 670 mgBr / 100 g.

[0196] Deolefin evaluation unit such as Figure 2As shown, it includes a raw material tank 1, a feed pump 2, a reactor 3, a cooler 4, and a product collection tank 5. The reactor 3 is divided into three sections: upper, middle, and lower. The upper and lower sections are respectively filled with a certain amount of 20-40 mesh quartz sand. The middle section is a constant temperature section, filled with 5 mL of adsorbent and hammered with a leather hammer. The evaluation conditions are temperature 170 ° C, pressure 1 MPa, and volume space velocity 10 h -1 , sampling was taken every 2 hours, and the bromine index of the raw materials and products was determined using the national standard GB / T 5177-2017 "Industrial Linear Alkylbenzene". The smaller the bromine index of the aromatic deolefination product, the lower the olefin content, indicating that the adsorbent has a better deolefination effect.

[0197] The olefin removal rate of aromatic products is calculated using the following formula:

[0198]

[0199] The test results are shown in Table 1.

[0200] Table 1 Performance test results of modified clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-8

[0201]

[0202] It can be seen from the test data provided in Table 1 that the activity and average pore size of the modified white clay adsorbents prepared in Examples 1-5 of the present invention are higher than those in Comparative Examples 1-8, and the dye removal rate in printing and dyeing wastewater and the olefin removal rate in the reforming product oil are both higher than those in Comparative Examples 1-8, showing excellent deolefination and decolorization capabilities.

[0203] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a modified clay adsorbent for deolefination / decolorization, characterized in that: The preparation method comprises: (I) mixing concentrated hydrochloric acid, concentrated sulfuric acid, oxalic acid and deionized water to obtain an acidifier, crushing and sieving bentonite ore to obtain bentonite powder, and mixing the bentonite powder with deionized water to obtain a bentonite slurry; uniformly mixing the bentonite slurry, the acidifier and sodium chloride to obtain a raw material mixture, wherein the mass ratio of the bentonite slurry, the acidifier and the sodium chloride is 1:(0.6-0.7):(0.08-0.1); heating and activating the raw material mixture to obtain an activated product, and rinsing, centrifuging, drying and pulverizing the activated product to obtain activated clay; (II) chitosan powder is subjected to carboxymethyl modification treatment using sodium chloroacetate to obtain carboxymethyl chitosan; the carboxymethyl chitosan is subjected to quaternization modification treatment using dimethyl diallyl ammonium chloride to obtain quaternized carboxymethyl chitosan; the quaternized carboxymethyl chitosan is dissolved in acetic acid solution to obtain a quaternized carboxymethyl chitosan solution, the activated clay obtained in step (I) is added to the quaternized carboxymethyl chitosan solution, the mixture is mixed, stirred and heated, and then centrifuged, washed and dried to obtain modified clay; The carboxymethyl chitosan is prepared by the following method: Chitosan powder and sodium hydroxide are put into a ball mill for primary ball milling, wherein the mass ratio of chitosan powder to sodium hydroxide is 1:(3.5-4.5); sodium chloroacetate and sodium iodide are then put into the ball mill for secondary ball milling, wherein the mass ratio of chitosan powder to sodium chloroacetate is 1:(3-4); and a solid product is obtained after the mixed ball milling is completed; the solid product is uniformly mixed with deionized water to obtain a product solution, and a hydrochloric acid solution is added to the product solution to adjust the pH value of the product solution to 7; and the product solution is then filtered, washed, and dried to obtain carboxymethyl chitosan; (III) Tetrabutyl titanate and anhydrous ethanol are mixed uniformly to obtain a precursor solution; anhydrous ethanol, glacial acetic acid and deionized water are mixed uniformly to obtain a composite solvent, and the modified clay obtained in step (II) is dispersed in the composite solvent to obtain a clay dispersion; under stirring conditions, the precursor solution is dropped into the clay dispersion, and the ratio of tetrabutyl titanate in the precursor solution to the modified clay in the clay dispersion is 1 mL: (0.3~0.5) g, and after uniform mixing, a mixed sol is obtained, and the mixed sol is sequentially subjected to static aging, extrusion molding, heating and drying, high-temperature roasting and crushing and screening to obtain the modified clay adsorbent.

2. The preparation method according to claim 1, characterized in that In step (I), when preparing the acidulant, the concentrated hydrochloric acid is first slowly added to deionized water and mixed uniformly to obtain dilute hydrochloric acid; then concentrated sulfuric acid is slowly added to the dilute hydrochloric acid to obtain a mixed acid solution; finally, oxalic acid is added to the mixed acid solution and mixed uniformly to obtain the acidulant; The mass fraction of the concentrated hydrochloric acid is 35-37 wt %; The mass fraction of the concentrated sulfuric acid is 95-98wt%; The volume ratio of the concentrated hydrochloric acid, concentrated sulfuric acid and deionized water is 1:(1.4-1.6):(35-40); The mass fraction of oxalic acid in the acidulant is 5-10 wt %.

3. The preparation method according to claim 1, characterized in that In step (I), the bentonite powder has a particle size of 100-200 mesh; The bentonite powder and deionized water are mixed in a mass ratio of (0.6-0.7):1 to obtain the bentonite slurry; The heating activation operation steps include: The raw material mixture is heated to a first activation temperature and kept warm, and then the temperature is further raised to a second activation temperature and kept warm after the insulation is completed, and then cooled to room temperature after the insulation is completed to obtain the activated product; The first activation temperature is 80-90°C; Keeping the temperature at the first activation temperature for 2 to 3 hours; The second activation temperature is 100-110°C; Keeping the temperature at the second activation temperature for 2 to 3 hours; Rinse the activated product with deionized water until the pH value of the activated product reaches 4-5; The centrifugal speed is 3000-4000 rpm; The centrifugation time is 5 to 10 minutes.

4. The preparation method according to claim 1, characterized in that The rotation speed of the primary ball milling is 500-600 rpm; The time of the first ball milling is 4 to 5 hours; The mass ratio of the sodium chloroacetate to the sodium iodide is 1:(0.5-0.7); The rotation speed of the secondary ball milling is 550-650 rpm; The secondary ball milling time is 5 to 6 hours; The mass fraction of the hydrochloric acid solution is 8-10wt%; The operation steps of filtration and washing include: The product solution is filtered once, and then the filter residue obtained after the first filtration is washed once with a methanol aqueous solution with a mass fraction of 70-80wt%, and then filtered twice after the first washing. The filter residue obtained after the second filtration is washed twice with anhydrous ethanol, and then filtered three times after the second washing.

5. The preparation method according to claim 1, characterized in that In step (II), the quaternized carboxymethyl chitosan is prepared by the following method: The carboxymethyl chitosan is dissolved in an acetic acid solution and mixed evenly to obtain a carboxymethyl chitosan solution; a dimethyl diallyl ammonium chloride solution is added dropwise to the carboxymethyl chitosan solution under continuous stirring and water bath heating conditions; after the dimethyl diallyl ammonium chloride solution is completely added, mixing, stirring and heating are continued to obtain a reaction product; acetone is added to the reaction product, and white floccules are generated after mixing, which is then filtered, washed and dried to obtain the quaternized carboxymethyl chitosan.

6. The preparation method according to claim 5, characterized in that The mass fraction of the acetic acid solution is 1-2 wt %; The ratio of the carboxymethyl chitosan to the acetic acid solution is 1 g: (50-100) mL; The mass fraction of the dimethyldiallylammonium chloride solution is 50-60 wt %; The water bath heating temperature is 50-60°C; The mass ratio of carboxymethyl chitosan in the carboxymethyl chitosan solution to dimethyl diallyl ammonium chloride in the dimethyl diallyl ammonium chloride solution is 1:(0.6-0.7); After all the dimethyldiallylammonium chloride solution has been added dropwise, continue mixing and stirring in a water bath for 20 to 30 minutes; The volume ratio of the reaction product to acetone is 1:(1-1.2).

7. The preparation method according to claim 1, characterized in that In step (II), the mass fraction of the acetic acid solution is 1-2 wt%; The concentration of quaternized carboxymethyl chitosan in the quaternized carboxymethyl chitosan solution is 10-20 g / L; The mass ratio of quaternized carboxymethyl chitosan to activated clay in the quaternized carboxymethyl chitosan solution is 1:(3-5); The mixing time of the quaternized carboxymethyl chitosan solution and the activated clay is 5 to 7 hours; The heating temperature of the quaternized carboxymethyl chitosan solution and the activated clay during mixing and stirring is 50-60°C.

8. The preparation method according to claim 1, characterized in that In step (III), the volume ratio of tetrabutyl titanate to anhydrous ethanol is 1:(3-4); The volume ratio of the anhydrous ethanol, glacial acetic acid and deionized water is (5-6):(1.2-1.3):1; The mass fraction of the modified clay in the clay dispersion is 2-5 wt %; The precursor solution is added at a rate of 4 to 6 mL / min; The stirring speed of the precursor solution during the dropwise addition process is 180-200 r / min; After all the precursor solutions have been added dropwise, the resulting mixed solution is continuously mixed and stirred for 1 to 2 hours to obtain the mixed sol; The time of the static aging is 24 to 48 hours; The heating and drying temperature is 60-70°C; The heating and drying time is 10 to 12 hours; The high temperature calcination temperature is 500-550°C; The high temperature roasting time is 3 to 4 hours.

9. An application of a modified clay adsorbent for deolefination / decolorization prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The modified white clay adsorbent is used for removing olefins or decolorizing printing and dyeing wastewater.

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