Sepiolite-based decolorizing material as well as preparation method and application thereof

Abstract

The invention relates to the field of preparation of solid decolorizing materials, in particular to a sepiolite-based decolorizing material and a preparation method and application thereof, the preparation method comprises the following steps: soaking natural sepiolite in an activating agent, activating and centrifuging under the assistance of ultrasonic waves, filtering out supernate, and washing to be neutral; mixing with a modifier, stirring, and adding a pH regulator to regulate the pH value at the same time; then carrying out aging; and finally, carrying out suction filtration, washing, drying, grinding and sieving to obtain the sepiolite-based decolorizing material. Stable layered double hydroxides are formed on the surface of the sepiolite in situ, and active adsorption sites are increased. Mg < 2 + > existing on the surface of the sepiolite and MgAl-LDHs synthesized on the surface of the sepiolite in situ can adsorb dye molecules through electrostatic attraction, complex reaction and the like, the problems that a decolorizing agent material is poor in performance, easy to agglomerate, poor in application effect and the like are solved, and the decolorizing effect on dye wastewater is remarkably improved. In the preparation process, adopted equipment is simple, operation is easy and convenient, conditions are mild, and the problem that the material preparation technology is complex is solved.

Description

Technical Field

[0001] The present invention relates to the field of preparation of solid decolorizing materials, and particularly to a sepiolite-based decolorizing material, a preparation method thereof and an application thereof. Background Art

[0002] As a natural layered silicate clay mineral, sepiolite has been widely used in the field of adsorption treatment of dye wastewater in recent years due to its large specific surface area, strong ion exchange ability and low cost. Its unique pore structure and surface active sites can effectively bind dye molecules, especially suitable for treating industrial wastewater containing anionic dyes, and is more environmentally friendly than traditional chemical coagulation methods.

[0003] There are mainly three defects in the existing technology: First, the selective adsorption ability of raw sepiolite for specific dyes is limited, and its performance needs to be improved by acid / alkali modification or loading nanomaterials, but some modification processes are complex and may introduce secondary pollution; Second, the regeneration efficiency after adsorption saturation is low, the energy consumption of high-temperature calcination regeneration method is high, and the chemical elution method is easy to cause structural damage; Finally, it is difficult to separate solid and liquid in practical applications. Although nano-scale sepiolite improves the adsorption rate, it exacerbates the separation difficulty, restricting the engineering application.

[0004] These bottlenecks lead to an increase in treatment costs and limit the large-scale promotion of this technology. Layered double metal hydroxides (LDHs) have the advantages of large specific surface area, low cost, simple synthesis, etc., and can be used as adsorption materials. However, LDHs itself also has some defects, such as easy agglomeration. In order to make up for the above defects and improve the adsorption effect on dyes, the present invention uses sepiolite as the base material and in-situ grows LDHs on its surface to construct a sepiolite-based decolorizing material. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a new type of sepiolite-based decolorizing material with stable material properties, high decolorization efficiency, large adsorption capacity, simple preparation process and environmental friendliness.

[0006] In order to solve the above technical problems, the embodiment of the present invention first provides a preparation method of a sepiolite-based decolorizing material, and the steps include:

[0007] S1. Immerse natural sepiolite in an activator, activate it under ultrasonic assistance, centrifuge and filter off the supernatant, and wash it until neutral;

[0008] S2. Mix and stir the product obtained in step S1 with a modifier;

[0009] S3. While performing step S2, add the prepared pH regulator to adjust the pH;

[0010] S4. Age the product obtained in step S3;

[0011] S5. Filter, wash, dry, grind, and sieve the product obtained in step S4.

[0012] Preferably, in some embodiments of the present invention, the activator is hydrochloric acid.

[0013] Preferably, in some embodiments of the present invention, the concentration of the activator is 0.1 mol / L.

[0014] Preferably, in some embodiments of the present invention, the activator is prepared by diluting concentrated hydrochloric acid with pure water at normal temperature and pressure.

[0015] In some embodiments of the present invention, in step S1, the activation is carried out by mixing natural sepiolite with the activator at a solid-liquid ratio of 1:75 g / mL to 1:85 g / mL.

[0016] Preferably, in some embodiments of the present invention, the solid-liquid ratio of the natural sepiolite to the activator is 1:80 g / mL.

[0017] In some embodiments of the present invention, in step S1, under the auxiliary condition of an ultrasonic power of 100 W, the activation is carried out for 20 min to 30 min, the centrifugation time is 8 min to 15 min, and the rotation speed is 4000 rpm.

[0018] Preferably, in some embodiments of the present invention, the activation time is 25 min and the centrifugation time is 10 min.

[0019] In some embodiments of the present invention, in step S1, after filtration, it is washed with pure water until neutral.

[0020] Preferably, in some embodiments of the present invention, the modifier is a mixed solution of magnesium chloride and aluminum chloride.

[0021] Preferably, in some embodiments of the present invention, the modifier is prepared by using magnesium chloride hexahydrate and aluminum chloride hexahydrate as raw materials, respectively preparing solutions with a concentration of 0.1 mol / L, and then mixing and stirring at a volume ratio of 3:1 mL of the magnesium chloride solution to the aluminum chloride solution at normal temperature and pressure for 8 min to 15 min.

[0022] Preferably, in some embodiments of the present invention, during the preparation of the modifier, the concentrations of the magnesium chloride solution and the aluminum chloride solution used are both 0.1 mol / L.

[0023] Preferably, in some embodiments of the present invention, the stirring time of the constant temperature magnetic stirrer during the preparation of the modifier is 10 min.

[0024] In some embodiments of the present invention, in step S2, a modifier is added to the product obtained in step S1 at a solid-liquid ratio of 1:15 g / mL to 1:20 g / mL, and they are mixed and stirred.

[0025] Preferably, in some embodiments of the present invention, the solid-liquid ratio of the product obtained in step S1 to the modifier is 1:16 g / mL.

[0026] In some embodiments of the present invention, in step S2, the mixing and stirring are carried out under the condition of uniform stirring in a constant-temperature magnetic stirrer, the stirring time is 8 min to 15 min, and the rotation speed is 150 rpm.

[0027] Preferably, in some embodiments of the present invention, the pH regulator is a sodium hydroxide solution.

[0028] Preferably, in some embodiments of the present invention, the concentration of the pH regulator is 0.1 mol / L to 0.15 mol / L.

[0029] Preferably, in some embodiments of the present invention, the pH regulator is prepared by dissolving solid sodium hydroxide in pure water at normal temperature and pressure.

[0030] In some embodiments of the present invention, in step S3, a pH regulator is added dropwise to adjust the pH range to 9 to 10.

[0031] In some embodiments of the present invention, in step S4, the aging is carried out under the condition of uniform oscillation in a constant-temperature water bath oscillator, the aging temperature is 60 °C, and the aging time is 10 h to 14 h.

[0032] Preferably, in some embodiments of the present invention, the aging time is 12 h; the rotation speed of the uniform oscillation of the constant-temperature water bath oscillator is 150 rpm.

[0033] In some embodiments of the present invention, in step S5, the washing is carried out with pure water until it is neutral.

[0034] In some embodiments of the present invention, in step S5, the drying is carried out in a constant-temperature drying oven.

[0035] Preferably, in some embodiments of the present invention, the drying temperature is 100 °C.

[0036] In some embodiments of the present invention, in step S5, the grinding is carried out with an agate mortar.

[0037] In some embodiments of the present invention, in step S5, the sieving is carried out through a combined sieve of 100 mesh and 200 mesh, and the material on the 200-mesh sieve is taken.

[0038] An embodiment of the present invention also provides a sepiolite-based decolorization material, which is prepared by using the preparation method of a sepiolite-based decolorization material described in any one of the above.

[0039] An embodiment of the present invention also applies the above sepiolite-based decolorization material to the adsorption treatment of industrial wastewater.

[0040] As a preference of some embodiments of the present invention, the above sepiolite-based decolorization material is applied to the adsorption treatment of printing and dyeing wastewater.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1. For the decolorization material of the present invention, stable layered double metal hydroxides are in-situ formed on the surface of sepiolite, increasing the active adsorption sites. Mg existing on the surface of sepiolite 2+ and MgAl-LDHs synthesized in-situ on the surface of sepiolite can adsorb dye molecules through electrostatic attraction, complexation reaction, etc., solving the problems of poor performance of the decolorizer material, easy agglomeration, and poor application effect, and significantly improving the decolorization effect on dye wastewater.

[0043] 2. H in the activator + replaces Mg in the sepiolite - Si - O - Mg - O - Si skeleton 2+ to form - Si - O - H bonds. In addition, impurities in sepiolite can be removed, increasing the pores of sepiolite and providing more sites for the subsequent formation of MgAl-LDHs.

[0044] 3. The metal ions contained in the decolorization material of the present invention are common metal ions in water bodies, and there is no problem of secondary environmental pollution caused by the leaching of metal ions.

[0045] 4. The equipment used in the preparation process of the present invention is simple, the operation is convenient, and the conditions are mild, solving the problem of complex material preparation process. Description of the Drawings

[0046] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for description in the specific embodiments or the prior art. Obviously, the following drawings are only one embodiment of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0047] Figure 1 It is a process schematic diagram of an embodiment of the present invention;

[0048] Figure 2 It is a scanning electron microscope image of the sepiolite-based decolorization material prepared in an embodiment of the present invention;

[0049] Figure 3 XRD pattern of the sepiolite-based decolorization material prepared in the embodiment of the present invention;

[0050] Figure 4 Influence diagram of the number of cyclic adsorption times of the sepiolite-based decolorization material in the embodiment of the present invention on the adsorption effect of congo red. Specific embodiments

[0051] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the technical solutions in the specific embodiments of the present invention are clearly and completely described below to further illustrate the present invention. Obviously, the described specific embodiments are only a part of the embodiments of the present invention, rather than all of them.

[0052] The decolorization material of the present invention is synthesized by a coprecipitation method, using natural sepiolite as the base material and magnesium chloride and aluminum chloride as the main modifiers. Its performance characteristics not only combine the advantages of each single component, but also greatly improve the performance of the material and the decolorization effect on dye wastewater through ratio control. It is a new type of sepiolite-based decolorization material with stable performance, high decolorization efficiency, large adsorption capacity, simple synthesis process and environmental protection. The general idea of its preparation and application is as follows:

[0053] Aiming at the problems of poor performance and ineffective decolorization effect of natural sepiolite materials, hydrochloric acid is used as an activator in the modification process of the embodiment of the present invention. Mg in sepiolite 2+ is replaced by H in hydrochloric acid + to change Si-O-Mg-O-Si in the sepiolite structure to Si-OH. In addition, impurities in sepiolite can be removed, increasing the pores of sepiolite, which is beneficial to subsequent modification. Mg in the modifier 2+ , Al 3+ in situ form stable layered double metal hydroxides (MgAl-LDHs) on the surface of sepiolite under the regulation of NaOH, increasing the active adsorption sites. Mg existing on the surface of sepiolite 2+ and MgAl-LDHs in situ synthesized on the surface of sepiolite can adsorb dye molecules through electrostatic attraction, complexation reaction, etc. In addition, water molecules coordinated with Mg 2+ can form hydrogen bonds with dye molecules.

[0054] In order to better understand the above technical solutions, the above technical solutions are described in detail below with specific embodiments.

[0055] Example 1: This example is a preparation method of a sepiolite-based decolorization material, such as Figure 1As shown, natural sepiolite is mixed with hydrochloric acid with a concentration of 0.1 mol / L as an activator at a solid-liquid ratio of 1:80 g / mL, and activated for 25 min under the assistance of an ultrasonic power of 100 W; the centrifugation time is 10 min, the rotation speed is 4000 rpm, and after suction filtration, it is washed with pure water until neutral to obtain activated sepiolite. 30 mL of magnesium chloride (0.1 mol / L) and 10 mL of aluminum chloride (0.1 mol / L) are mixed and stirred at a normal temperature and pressure for 10 min at a rotation speed of 200 rpm to obtain a modifier. The obtained modifier is mixed with the activated sepiolite at a solid-liquid ratio of 1:16 g / mL, and then stirred evenly at a rotation speed of 150 rpm in a constant-temperature magnetic stirrer for 8 min to 15 min. Then, 0.1 mol / L sodium hydroxide solution is used as a pH regulator to adjust the pH to 10. Aging is carried out by uniformly oscillating at 150 rpm in a constant-temperature water bath oscillator for 12 h at a temperature of 60 °C. Then, suction filtration is carried out, washed with pure water until neutral, dried in a constant-temperature drying oven at 100 °C, ground with an agate mortar, and finally passed through a combined sieve of 100 mesh and 200 mesh, and the material on the 200-mesh sieve is taken to obtain the sepiolite-based decolorization material.

[0056] The scanning electron microscope image of the sepiolite-based decolorization material is as Figure 2 shown. It can be seen from Figure 2 that the presence of MgAl-LDHs makes the loose natural sepiolite fibers become more compact. The material presents a typical lamellar structure, and the surface roughness increases.

[0057] The XRD pattern of the sepiolite-based decolorization material is as Figure 3 shown. By comparing with the standard card of MgAl-LDHs (PDF#35-0964), it is found that 7 characteristic diffraction peaks belonging to MgAl-LDHs and 5 characteristic diffraction peaks belonging to natural sepiolite appear in the XRD pattern of this material, indicating that the formation of MgAl-LDHs does not damage the original structure of sepiolite, and MgAl-LDHs are successfully loaded on the surface of sepiolite.

[0058] Example 2: In this example, the sepiolite-based decolorization material prepared in Example 1 is used to decolorize the simulated Congo red dye wastewater. The concentration of the simulated Congo red dye wastewater is 30 mg / L, the chromaticity is 200, and the pH of the wastewater is 6.80. The dosage of the sepiolite-based decolorization material is 0.4 g / L, the reaction time is 10 min, the reaction temperature is 25 °C, and the rotation speed of the constant-temperature magnetic stirrer is 150 rpm.

[0059] In this example, the treated simulated wastewater is measured with reference to "Determination of Water Quality Chromaticity - Dilution Multiple Method" (HJ 1182-2021). The chromaticity is 2, and the decolorization rate is 99.28%.

[0060] The desorption and regeneration of the sepiolite-based decolorization material after adsorbing Congo red dye was carried out by alkali impregnation. The specific experimental steps are as follows: First, the sepiolite-based decolorization material after adsorbing Congo red dye was dried and ground into a fine powder. 0.12 g of the sepiolite-based decolorization material after adsorbing Congo red dye was desorbed with 10 mL of potassium hydroxide at different concentrations (0.1 mol / L to 5 mol / L). The desorption conditions were 50 °C, desorption for 24 h, and the rotation speed of the constant temperature magnetic stirrer was set at 150 rpm. Then, filtration was carried out, and the desorbed sample was washed to neutral, dried, and ground, and then the adsorption experiment was carried out again. The adsorption conditions were: Congo red concentration of 30 mg / L, dosage of 0.4 g / L, adsorption temperature of 25 °C, adsorption time of 10 min, and pH of 6.8. The above process was repeated 4 - 5 times. The results are as Figure 4 shown, as Figure 4 can be seen, using potassium hydroxide (2 mol / L) to desorb and regenerate the material after adsorbing Congo red in this example, the effect of using the desorbed material to adsorb Congo red again is relatively stable. After 4 cycles of regeneration, the decolorization rate of Congo red reaches 62.17%.

[0061] Example 3: In this example, the sepiolite-based decolorization material prepared in Example 1 was used to decolorize actual dye wastewater. The actual wastewater was taken from the production wastewater of a clothing washing company in Ganzhou, Jiangxi. The pH was 6.56 and the chromaticity was 90. The dosage of the decolorizing agent was 0.4 g / L, the reaction time was 20 min, the reaction temperature was 25 °C, and the rotation speed of the constant temperature magnetic stirrer was 150 rpm.

[0062] In this example, the determination of chromaticity was carried out with reference to "Determination of Chromaticity in Water - Dilution Multiple Method" (HJ 1182 - 2021). The chromaticity of the treated wastewater was 9.

[0063] The above describes the main technical features, basic principles and related advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary specific embodiments, and can be implemented in other specific forms without departing from the concept or basic features of the present invention. Therefore, from any point of view, the above specific embodiments should be regarded as exemplary and non - restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

[0064] In addition, it should be understood that although this specification is described in accordance with various embodiments, not every embodiment only includes an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A preparation method of a sepiolite-based decolorizing material, characterized in that, It includes the following steps: S1. Immerse natural sepiolite in an activator, activate it under ultrasonic assistance, centrifuge it, filter off the supernatant, and wash it until neutral; S2. Mix and stir the product obtained in step S1 with a modifier; S3. While performing step S2, add the prepared pH regulator to adjust the pH; S4. Age the product obtained in step S3; S5. Filter, wash, dry, grind, and sieve the product obtained in step S4.

2. The preparation method of a sepiolite-based decolorizing material according to claim 1, characterized in that, In step S1, the activator is hydrochloric acid; the activation is to mix natural sepiolite and the activator at a solid-liquid ratio of 1:75 g / mL to 1:85 g / mL, and activate it for 20 min to 30 min under the assistance of an ultrasonic power of 100 W; the centrifugation time is 8 min to 15 min, and the rotation speed is 4000 rpm; after suction filtration, wash it with pure water until neutral.

3. The preparation method of a sepiolite-based decolorizing material according to claim 2, characterized in that, The concentration of the activator is 0.1 mol / L. The activator is prepared by diluting concentrated hydrochloric acid with pure water at normal temperature and pressure; the solid-liquid ratio of the natural sepiolite to the activator is 1:80 g / mL; the activation time is 25 min, and the centrifugation time is 10 min.

4. The preparation method of a sepiolite-based decolorizing material according to claim 1, characterized in that, In step S2, add the modifier to the product obtained in step S1 at a solid-liquid ratio of 1:15 g / mL to 1:20 g / mL; the modifier is a mixed solution of magnesium chloride and aluminum chloride; the mixing and stirring are carried out under the condition of uniform stirring in a constant-temperature magnetic stirrer, and the mixing and stirring time is 8 min to 15 min.

5. The preparation method of a sepiolite-based decolorizing material according to claim 4, characterized in that, The solid-liquid ratio of the product obtained in step S1 to the modifier is 1:16 g / mL; the mixing and stirring time is 10 min, and the rotation speed is 150 rpm; the modifier is prepared by using magnesium chloride hexahydrate and aluminum chloride hexahydrate as raw materials, respectively preparing 0.1 mol / L solutions, and then mixing them at a volume ratio of the magnesium chloride solution to the aluminum chloride solution of 3:1; mix and stir at normal temperature and pressure for 8 min to 15 min to obtain.

6. The preparation method of a sepiolite-based decolorizing material according to claim 1, characterized in that, In step S3, dropwise add the pH regulator to adjust the pH range to 9 - 10; the concentration of the pH regulator is 0.1 mol / L to 0.15 mol / L; the pH regulator is prepared by dissolving solid sodium hydroxide in pure water at normal temperature and pressure.

7. The preparation method of a sepiolite-based decolorization material according to claim 1, characterized in that In step S4, the aging is carried out under the condition of uniform oscillation in a constant-temperature water bath oscillator, the aging temperature is 60 °C, the aging time is 10 h to 14 h, and the rotation speed of uniform oscillation is 150 rpm.

8. The preparation method of a sepiolite-based decolorizing material according to claim 1, characterized in that, In step S5, the washing is to wash with pure water until neutral, the drying is carried out in a constant-temperature drying oven, the drying temperature is 100 °C, the grinding is carried out with an agate mortar, and the sieving is through a combined sieve of 100 mesh and 200 mesh, and take the material on the 200-mesh sieve.

9. A sepiolite-based decolorizing material, characterized in that, This sepiolite-based decolorizing material is prepared by using the preparation method of a sepiolite-based decolorizing material described in any one of claims 1 - 8.

10. Use of the sepiolite-based decolorizing material as described in claim 9, characterized in that, This sepiolite-based decolorizing material is applied to the adsorption treatment of industrial wastewater.

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