One-step process for purification and organic modification of attapulgite

Abstract

The application discloses a one-step process for purification and organic modification of attapulgite. The one-step process for purification and organic modification of attapulgite comprises the following steps: step 1, performing preliminary purification on attapulgite raw ore to obtain a preliminary purified attapulgite suspension; and step 2, performing organic modification and further purification on the preliminary purified attapulgite suspension. The one-step process for purification and organic modification of attapulgite can complete the purification and organic modification of attapulgite in one step, and has the advantages of simple process, low water consumption, low cost, less wastewater, less environmental pollution and conformity to the green industrial production advocated by the country.

Description

Technical Field

[0001] This invention relates to the field of attapulgite processing technology, and in particular to a one-step process for attapulgite purification and organic modification. Background Technology

[0002] Attapulgite is a naturally occurring silicate mineral rich in magnesium and aluminum. Mineralogically, it belongs to the attapulgite group, and its theoretical chemical formula is Mg5Si8O. 20 (OH)₂(OH₂)·4H₂O. Attapulgite's structure consists of two layers of silicon-oxygen tetrahedra and one layer of magnesium-oxygen octahedra. The cation sites in the octahedra are mainly filled with magnesium ions, while the corner positions are occupied by cations. The tetrahedra are distributed on the same plane and interconnected through three corner vertices, forming two-dimensional extended bands. Each crystal unit contains eight water molecules, four of which coordinate with magnesium ions to form water of crystallization; the other four exist in a free state, bound within the structural channels. Hydroxyl groups also exist within the structure.

[0003] Attapulgite, a chain-layered mineral, possesses a nanorod-like crystal morphology and regular one-dimensional nanopores. Its unique structure endows it with properties such as adsorption, rheology, and carrier activity. Due to its unique physicochemical properties and enormous potential application value, attapulgite has been applied in many fields, including adsorption, catalysis, energy storage, filling, biomedicine, and agriculture.

[0004] Before preparing or utilizing organic attapulgite, purification and impurity removal are necessary to improve its grade. Currently, the purification and organic modification of attapulgite are carried out separately by two different companies or on two different production lines. This inevitably leads to a lack of unified control over purification and organic modification, resulting in low resource utilization, unsatisfactory quality of raw materials for modification, high procurement costs, and an inability to improve the production efficiency and quality of organic attapulgite products.

[0005] Therefore, in order to overcome the shortcomings of the existing technology, especially to improve resource utilization efficiency, increase the production efficiency and quality of organic attapulgite, and reduce production costs, it is urgent to provide a method for preparing organic attapulgite, so as to obtain organic attapulgite with excellent performance. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides a one-step process for the purification and organic modification of attapulgite.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a one-step process for the purification and organic modification of attapulgite, comprising the following steps:

[0008] Step 1: Perform preliminary purification on the raw attapulgite ore to obtain a preliminary purified attapulgite suspension.

[0009] Step 2: Organic modification and further purification of the preliminarily purified attapulgite suspension.

[0010] In a second aspect, the present invention provides an organic attapulgite, which is prepared according to the method of the first aspect.

[0011] The beneficial effects of the one-step process for attapulgite purification and organic modification of the present invention include:

[0012] (1) This invention integrates the purification and organic modification steps of attapulgite through wet modification process, and completes the purification and organic modification of attapulgite in one step. The process is simple, consumes less water, has low cost, generates less wastewater, and causes less environmental pollution, which is in line with the green industrialization production advocated by the state.

[0013] (2) In the process of organic modification of attapulgite, the present invention not only improves the organic modification efficiency of attapulgite compared with the traditional organic modification process, but also further improves the purity of attapulgite.

[0014] (3) The organic attapulgite obtained by the present invention has good oleophilicity. Its contact angle can reach more than 48° compared with the 14° of the purified attapulgite, which is more than 100% and even 240%.

[0015] (4) The organic attapulgite obtained by the present invention has good dispersibility in the organic phase and its performance is adjustable. By selecting a suitable organic modifier, organic attapulgite products that meet different needs can be prepared. Attached Figure Description

[0016] Figure 1 The XRD pattern and mineral composition standard card of raw attapulgite ore are shown;

[0017] Figure 2 The XRD patterns of conventionally purified attapulgite in Comparative Example 2 and the organic attapulgite prepared in Examples 1-4 are shown.

[0018] Figure 3 The XRD patterns of the organic attapulgite prepared after treatment with different amounts of hydrochloric acid in Comparative Example 3 are shown.

[0019] Figure 4 The surface contact angle test results of attapulgite in Comparative Example 2 and organic attapulgite in Examples 1-4 are shown in the figure.

[0020] Figure 5 The surface contact angle test results of the organic attapulgite prepared after treatment with different amounts of hydrochloric acid in Comparative Example 3 are shown. Detailed Implementation

[0021] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0022] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0023] In traditional processes, the purification and organic modification of attapulgite are separated. For example, the purification process of attapulgite may include: crushing the raw attapulgite ore, dispersing it into a slurry, adding an appropriate amount of dispersant, separating impurities from the slurry by sedimentation or centrifugation, dehydrating, drying, and pulverizing to obtain purified attapulgite powder. The organic modification process of attapulgite may include: hydrating the purified attapulgite powder in water, adding a modifier, reacting through stirring, separating, drying, and pulverizing to obtain organic attapulgite.

[0024] The purification and organic modification processes of attapulgite both require a large amount of water and repeated separation, drying, and crushing steps, thus increasing time and economic costs. Due to the high viscosity and colloidal nature of attapulgite, dehydration and drying are quite difficult. During the dehydration process, flocculants are often added to reduce the viscosity of the slurry or high-speed centrifugation is used to achieve separation from water while maintaining the original mineral properties (laboratory). At the same time, the use of flocculants also affects the organic modification effect of attapulgite.

[0025] Therefore, it is necessary to improve the purification and organic modification processes of attapulgite to eliminate the aforementioned unfavorable factors such as unnecessary cost increases and changes in the surface properties of attapulgite caused by flocculants, thus completing further organic modification of attapulgite. The key lies in how to seamlessly integrate the purification and organic modification processes and control the production process parameters to obtain high-quality organic attapulgite.

[0026] To achieve the above objectives, in a first aspect, the present invention provides a one-step process for the purification and organic modification of attapulgite, which mainly includes the following steps:

[0027] Step 1: Perform preliminary purification on the raw attapulgite ore to obtain a preliminary purified attapulgite suspension.

[0028] Preferably, the attapulgite ore originates from Linze, Gansu Province. Linze boasts vast reserves of attapulgite ore, but the overall grade of the ore is relatively low, primarily containing impurities such as quartz, dolomite, and muscovite. Therefore, understanding how to purify and organically modify the ore to obtain high-purity, highly hydrophobic, and well-dispersible organic attapulgite is of guiding significance for the modification of attapulgite.

[0029] In a preferred embodiment of the present invention, before step 1, the process may further include: pretreatment of the attapulgite ore, preferably including drying.

[0030] Studies have shown that attapulgite ore, when in contact with water under dry conditions, is more readily hydrated than attapulgite ore. Preferably, the attapulgite ore is dried at 50–120°C, and more preferably at 60–100°C.

[0031] In a preferred embodiment of the present invention, step 1 may include the following sub-steps:

[0032] Step 1-1: Soak the raw attapulgite ore in water, stir and let it stand, adding a dispersant before and / or during stirring.

[0033] Specifically, attapulgite is fibrous in microscopic form and has (110) cleavage parallel to the fiber axis. It is easily dispersed in water and highly polar solvents, forming a disordered fibrous suspension system.

[0034] Studies have shown that when the mass concentration of attapulgite ore is below 0.1:100, water consumption is high and product production efficiency is low; when the mass concentration is above 50:100, the time required for full dispersion and hydration is longer. Therefore, preferably, the mass ratio of attapulgite ore to water is (0.1-50):100, more preferably (1-35):100, and even more preferably (5-20):100.

[0035] Preferably, the attapulgite ore is soaked in water for a predetermined time, then stirred and allowed to stand.

[0036] Research has shown that when the predetermined time is 2 to 48 hours, preferably 10 to 30 hours, and more preferably 20 to 24 hours, the above-mentioned amount of attapulgite ore can be in full contact with water without consuming too much time.

[0037] Specifically, stirring allows the attapulgite ore to come into full contact with water, accelerating the dispersion speed and saving operation time. Studies have found that when the stirring time is less than 0.5 hours, the attapulgite ore is dispersed in water but not fully hydrated, affecting subsequent operations; when the reaction time is greater than 4 hours, the attapulgite ore is fully hydrated, but the time is long, increasing labor and equipment usage costs. Therefore, the preferred stirring time is 0.5 to 4 hours, more preferably 1 to 2 hours.

[0038] After being stirred for the aforementioned period, the attapulgite ore disperses in water in a fibrous manner, forming a network structure. Mineral impurities often contained in attapulgite, such as quartz and dolomite, are deposited in the lower layers due to their higher specific gravity.

[0039] Preferably, the settling time is 2 to 48 hours, more preferably 12 to 36 hours, and even more preferably 18 to 24 hours. After the attapulgite suspension has been settling for the above time, the attapulgite and mineral impurities can be clearly separated into layers, and most of the mineral impurities can be separated and removed without the need for filtration or centrifugation.

[0040] Specifically, due to its high surface activity, attapulgite easily agglomerates into clusters, reducing its dispersibility and limiting its applications. Simultaneously, mineral impurities do not readily bind with dispersants, and when the system viscosity decreases, quartz and dolomite easily separate under gravity and centrifugal force. Utilizing the viscosity-reducing effect of dispersants added to attapulgite suspensions is a crucial step in attapulgite purification. The effect of dispersants on attapulgite suspensions stems from the fact that the adsorption layer formed by the dispersant on the surface of the dispersed particles significantly alters the van der Waals repulsion, electrostatic repulsion, and steric hindrance repulsion energy of the dispersion system, resulting in a substantial increase in the total interparticle repulsion energy. This leads to independent movement between colloidal particles and a decrease in viscosity. Studies have shown that when the dispersant is selected from anionic dispersants, preferably phosphates, and more preferably sodium pyrophosphate and / or sodium hexametaphosphate, such as sodium hexametaphosphate, attapulgite can be uniformly dispersed in water.

[0041] Meanwhile, when the mass ratio of dispersant to water is less than 0.25:1000, the attapulgite cannot be uniformly dispersed due to the small amount of dispersant. When the mass ratio of dispersant to water is greater than 10:1000, the repulsive force between attapulgite particles in the system becomes dominant, and the particles are independent of each other; further increasing the amount of dispersant will not have a significant impact. Therefore, preferably, the mass ratio of dispersant to water is (0.25–10):1000, more preferably (0.3–5):1000, and even more preferably (0.5–2.5):1000.

[0042] Step 1-2: Add acid solution to the suspension from Step 1-1, stir, and let stand.

[0043] Specifically, acid treatment of attapulgite can remove some mineral impurities (such as carbonate impurities). Preferably, when the acid solution is an inorganic acid, more preferably a strong inorganic acid, and even more preferably at least one of sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid, such as hydrochloric acid, it can effectively dissolve carbonate impurities in attapulgite.

[0044] Specifically, when the mass ratio of solute to attapulgite ore in the acid solution is 0.05:10, the attapulgite fiber bundles deagglomerate, some acid-soluble mineral impurities (such as carbonate impurities) dissolve, the pores of the attapulgite are unblocked, and the specific surface area increases. As the mass (or concentration) of the acid increases, H... + Replacement of Mg in attapulgite octahedrons 2+ Al 3+ Fe 3+ Cation, H + The ionic radius of attapulgite is much smaller than that of metal ions, thus enhancing the surface activity of attapulgite. However, when the mass ratio of solute to attapulgite ore in the acid solution is greater than 5:10, a large amount of cations in the octahedrons and tetrahedra of attapulgite dissolve, leaving silica. Although this silica still retains the needle-like morphology and porous structure of attapulgite silicate minerals, its activity is low and its effective specific surface area is small. Therefore, preferably, the mass ratio of solute to attapulgite ore in the acid solution is (0.05-5):10, more preferably (0.5-3.2):10, and more preferably (0.7-1.5):10, wherein the concentration of the acid solution is 20-60%, preferably 30-45%, and more preferably 35-40%.

[0045] Specifically, the stirring time is 0.5 to 4 hours, preferably 1 to 2 hours; and / or the settling time is 2 to 48 hours, preferably 18 to 24 hours, which can increase the specific surface area of ​​attapulgite.

[0046] Steps 1-3: Post-process the suspension from Step 1-2.

[0047] Specifically, steps 1-3 may include:

[0048] Step 1-3-1: Centrifuge the suspension from Step 1-2 at high speed and wash the precipitate after centrifugation.

[0049] Since hydrogen ions in the acid, acting as cations, are adsorbed onto the negatively charged surface of attapulgite, occupying negatively charged adsorption sites, hydrogen ions can be removed by high-speed centrifugation and washing, thus improving the adsorption effect of the organic modifier. Preferably, the high-speed centrifugation speed is 1000–6000 r / min for 3–20 min, more preferably 2500–5000 r / min for 5–12 min, and even more preferably 3000–4000 r / min for 8–10 min. Steps 1-3-1 are repeated multiple times until the resulting suspension is neutral, further enhancing the adsorption effect of the organic modifier.

[0050] Step 1-3-2: Centrifuge the suspension formed by precipitation in step 1-3-1 at low speed to obtain a preliminarily purified attapulgite suspension.

[0051] Preferably, the low-speed centrifugation speed is 500-4000 r / min for 3-15 min, more preferably 1000-3000 r / min for 4-10 min, and even more preferably 1200-1800 r / min for 5-8 min.

[0052] In this invention, since the attapulgite in the suspension is fibrous, within the above-mentioned centrifugation parameter range, the attapulgite can be separated from mineral impurities sufficiently and effectively. The lower precipitate after centrifugation is discarded, and the upper layer is a suspension with a high content of attapulgite.

[0053] In a preferred embodiment of the present invention, before steps 1-3, the process may further include: sonicating the suspension obtained in steps 1-2.

[0054] Specifically, ultrasonic dispersion breaks up the aggregated attapulgite and mineral impurities, allowing the mineral impurities encased within the attapulgite to be released, thus improving the separation degree of attapulgite and mineral impurities. Preferably, the ultrasonic power is 200W to 800W, more preferably 400W to 600W, and / or the ultrasonic time is 0.5 to 4 hours, more preferably 2 to 3 hours, so that the attapulgite and mineral impurities can be well dispersed.

[0055] Step 2: Organic modification and further purification of the preliminarily purified attapulgite suspension.

[0056] As shown in step 1 above, in the preliminary purification process of attapulgite, after removing some mineral impurities, there is no need for subsequent steps such as adding flocculants, separation, drying, and pulverizing to obtain purified attapulgite. Simultaneously, in the organic modification process, the step of rehydrating the purified attapulgite powder in water is omitted; organic modification can be carried out in the original suspension. Furthermore, the organic modifier in this process has both modifying and further purifying effects on attapulgite. This integration of the purification and organic modification processes effectively avoids steps such as separation, drying, and pulverizing, and eliminates the need for secondary water use, achieving a one-step preparation process for organic attapulgite, shortening the time, reducing economic costs, and improving the purity of attapulgite.

[0057] It is worth noting that this technology not only reduces costs by eliminating the use of flocculants, but more importantly, it avoids the impact of flocculants on the surface properties of attapulgite, reduces the efficiency and effectiveness of organic modifiers, and affects product quality; at the same time, it further improves the purity of organic attapulgite.

[0058] In a preferred embodiment of the present invention, step 2 may include:

[0059] Step 2-1: Add an organic modifier to the preliminarily purified attapulgite suspension and stir.

[0060] In a preferred embodiment of the present invention, the organic modifier is a cationic modifier, preferably a quaternary ammonium salt surfactant, and more preferably at least one of dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyldimethylbenzylammonium chloride, octadecyltrimethylammonium chloride, octadecyldimethylbenzylammonium chloride, or bis(octadecyldimethylammonium chloride).

[0061] In this invention, a cationic modifier is used to modify attapulgite. Because the cationic modifier has a long carbon chain, this long chain reduces the surface polarity of attapulgite, resulting in highly dispersible attapulgite in the organic phase. Simultaneously, since the attapulgite surface carries a negative charge, the cationic modifier can easily bind to the attapulgite surface to achieve its modifying effect. At this point, the attapulgite surface is organically modified, exhibiting good hydrophobic properties, agglomerating and suspending in the aqueous system, and effectively separating from other associated minerals. This further purifies the attapulgite; the content of attapulgite obtained through conventional purification is 57.4%, while the content of attapulgite in this invention is 68.6%.

[0062] Specifically, when the mass ratio of attapulgite ore to organic modifier is less than 10:0.5, the amount of modifier that binds to the attapulgite is limited, resulting in poor dispersibility of the modified attapulgite in the organic phase. When the mass ratio is greater than 10:5, the organic modifier becomes saturated on the surface of the attapulgite, and excess organic modifier is adsorbed onto the first layer of modifier, with the polar end extending out, which also reduces the dispersibility of the organic attapulgite in the organic phase. Furthermore, the consumption of organic modifier is high, leading to high costs and hindering industrial production. Therefore, the mass ratio of attapulgite ore to organic modifier is 10:(0.5-5), preferably 10:(1.5-3.5).

[0063] Specifically, the stirring time is 0.5–5 hours, preferably 1–3 hours. As stirring proceeds, the organic modifier is rapidly dispersed in the reaction system, avoiding excessive local concentrations and accelerating the organic modification process.

[0064] Step 2-2: Post-process the suspension from Step 2-1 to obtain organic attapulgite.

[0065] Preferably, the post-processing includes centrifugation or filtration, more preferably centrifugation, and drying.

[0066] The filtration method can be either atmospheric pressure filtration or pressurized filtration, with pressurized filtration being preferred to reduce filtration time.

[0067] When the centrifugation speed is 2000-7000 r / min and the centrifugation time is 3-10 min, preferably 4000-6000 r / min and the centrifugation time is 4-7 min, and more preferably 4500-5500 r / min and the centrifugation time is 5-6 min, organic attapulgite can be effectively separated.

[0068] The drying temperature is 40–120℃, preferably 60–80℃.

[0069] Optionally, the organic attapulgite is dried and then crushed through a 200-mesh sieve, with the maximum particle size of the crushed product being less than 75 micrometers.

[0070] In this invention, unlike the impurities contained in sepiolite, Linze attapulgite contains muscovite, which is difficult to remove. Compared with traditional purification methods, a one-step organic modification method is used. The organic modifier not only organically modifies the attapulgite but also removes the muscovite to a certain extent. Furthermore, acid is added for purification in this invention, which effectively removes impurities and improves the organic modification effect.

[0071] In a second aspect, the present invention provides an organic attapulgite, which is prepared according to the method of the first aspect.

[0072] In this invention, organic attapulgite exhibits (110), (040), (121), (231) and (161) diffraction peaks at 2θ of 8.32°, 19.74°, 20.86°, 26.58° and 35.31°.

[0073] More preferably, the contact angle of organic attapulgite can reach more than 48° compared to the contact angle of purified attapulgite of 14°, which is an increase of more than 100%, or even 240%.

[0074] The present invention will be further described below through specific embodiments. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of protection of the present invention.

[0075] Example

[0076] Example 1

[0077] Weigh 100g of attapulgite ore dried at 60℃ for 24h, soak it in 2L of water for 24h to obtain an attapulgite ore suspension;

[0078] Add 1g of sodium hexametaphosphate to the suspension, stir for 1 hour, let stand for 24 hours, pour off the upper suspension and discard the precipitate.

[0079] Add 8.3 mL of 36% hydrochloric acid (density 1.18 g / mL), stir for 1 h, and let stand for 24 h;

[0080] The suspension was sonicated for 2 hours and centrifuged at 4000 rpm for 10 minutes. The precipitate was then washed and the suspension was brought to a neutral state.

[0081] Centrifuge the suspension at 1000 rpm for 5 min, discard the lower precipitate, and keep the upper suspension.

[0082] Weigh 15% of the mass of attapulgite ore and dissolve it in 200 mL of water. Then add it to the attapulgite suspension and continue stirring for 1 hour to obtain an organic attapulgite suspension.

[0083] The suspension was centrifuged at 5000 rpm for 5 min to separate the organic attapulgite; the organic attapulgite was dried at 60℃, pulverized, and passed through a 200-mesh sieve to obtain the organic attapulgite sample.

[0084] Example 2

[0085] Weigh 100g of attapulgite ore dried at 60℃ for 24h, soak it in 2L of water for 24h to obtain an attapulgite ore suspension;

[0086] Add 2g of sodium hexametaphosphate to the suspension, stir for 1 hour, let stand for 24 hours, pour off the upper suspension and discard the precipitate;

[0087] Add 8.3 mL of 36% hydrochloric acid, stir for 1 hour, and let stand for 24 hours;

[0088] The suspension was sonicated for 3 hours and centrifuged at 4000 rpm for 10 minutes. The precipitate was then washed and the suspension was brought to a neutral state.

[0089] Centrifuge the suspension at 1500 rpm for 5 min, discard the lower precipitate, and keep the upper suspension.

[0090] Weigh out 30% of the mass of the raw attapulgite ore, dissolve it in 200 mL of water, then add it to the attapulgite suspension and continue stirring for 1 h to obtain an organic attapulgite suspension.

[0091] The suspension was centrifuged at 5000 rpm for 5 min to separate the organic attapulgite; the organic attapulgite was dried at 60℃, pulverized, and passed through a 200-mesh sieve to obtain the organic attapulgite sample.

[0092] Example 3

[0093] Weigh 100g of attapulgite ore dried at 60℃ for 24h, soak it in 2L of water for 24h to obtain an attapulgite ore suspension;

[0094] Add 2g of sodium hexametaphosphate to the suspension, stir for 1 hour, let stand for 24 hours, pour off the upper suspension and discard the precipitate;

[0095] Add 12.6 mL of 36% hydrochloric acid, stir for 1 hour, and let stand for 24 hours;

[0096] The suspension was sonicated for 3 hours and centrifuged at 4000 rpm for 10 minutes. The precipitate was then washed and the suspension was brought to a neutral state.

[0097] Centrifuge the suspension at 1500 rpm for 5 min, discard the lower precipitate, and keep the upper suspension.

[0098] Weigh out 30% of the mass of the raw attapulgite ore, dissolve it in 200 mL of water, then add it to the attapulgite suspension and continue stirring for 1 h to obtain an organic attapulgite suspension.

[0099] The suspension was centrifuged at 5000 rpm for 5 min to separate the organic attapulgite; the organic attapulgite was dried at 60℃, pulverized, and passed through a 200-mesh sieve to obtain the organic attapulgite sample.

[0100] Example 4

[0101] Weigh 100g of attapulgite ore dried at 60℃ for 24h, soak it in 2L of water for 24h to obtain an attapulgite ore suspension;

[0102] Add 1g of sodium hexametaphosphate to the suspension, stir for 1 hour, let stand for 24 hours, pour off the upper suspension and discard the precipitate;

[0103] Add 8.3 mL of 36% hydrochloric acid, stir for 1 hour, and let stand for 24 hours;

[0104] The suspension was sonicated for 3 hours and centrifuged at 4000 rpm for 10 minutes. The precipitate was then washed and the suspension was brought to a neutral state.

[0105] Centrifuge the suspension at 1500 rpm for 5 min, discard the lower precipitate, and keep the upper suspension.

[0106] Weigh 30% of the mass of attapulgite ore and dissolve it in 200 mL of water. Then add it to the attapulgite suspension and continue stirring for 1 h to obtain an organic attapulgite suspension.

[0107] The suspension was centrifuged at 5000 rpm for 5 min to separate the organic attapulgite; the organic attapulgite was dried at 60℃, pulverized, and passed through a 200-mesh sieve to obtain the organic attapulgite sample.

[0108] Comparative Example

[0109] Comparative Example 1

[0110] Raw attapulgite ore that has not undergone purification or organic modification.

[0111] Comparative Example 2

[0112] Weigh 100g of attapulgite ore dried at 60℃ for 24h, soak it in 2L of water for 24h to obtain an attapulgite ore suspension;

[0113] Add 1g of sodium hexametaphosphate to the suspension, stir for 1 hour, let stand for 24 hours, pour off the upper suspension and discard the precipitate.

[0114] Add 8.3 mL of 36% hydrochloric acid, stir for 1 hour, and let stand for 24 hours;

[0115] The suspension was sonicated for 2 hours and centrifuged at 4000 rpm for 10 minutes. The precipitate was then washed and the suspension was brought to a neutral state.

[0116] The suspension was centrifuged at 1000 rpm for 5 min, the lower precipitate was discarded, and the upper suspension was centrifuged at 5000 rpm for 5 min to separate the purified attapulgite. The purified attapulgite was then dried and pulverized to obtain the conventionally purified sample.

[0117] Comparative Example 3

[0118] Weigh 100g each of three groups of attapulgite ore dried at 60℃ for 24h, disperse them in 2L of water, and let stand for 24h to obtain an attapulgite ore suspension.

[0119] Add 1g of sodium hexametaphosphate to the suspension, stir for 1 hour, let stand for 24 hours, pour off the upper suspension and discard the precipitate;

[0120] Add 20 mL, 27.8 mL and 35.0 mL of 36% hydrochloric acid respectively, stir for 1 h and let stand for 24 h;

[0121] The suspension was sonicated for 3 hours and centrifuged at 6000 rpm for 2 minutes. The precipitate was then washed and the suspension was brought to a neutral state.

[0122] Weigh 16.7% of the mass of attapulgite ore and dissolve it in 300 mL of water. Then add it to the attapulgite suspension and continue stirring for 1 h to obtain an organic attapulgite suspension.

[0123] The suspension was centrifuged at 5000 rpm for 5 min to separate the organic attapulgite; the organic attapulgite was dried at 60℃, pulverized, and passed through a 200-mesh sieve to obtain organic attapulgite samples (a, 35.0 mL of hydrochloric acid; b, 27.8 mL of hydrochloric acid; c, 20.0 mL of hydrochloric acid).

[0124] Experimental Example

[0125] Experimental Example 1: XRD Analysis

[0126] Using a German-made Bruker D8 Advance X-ray powder diffractometer (Cu target K) α The sample was analyzed under the conditions of λ = 0.15406 nm, step width = 0.02, working voltage 40 kV, and working current 40 mA.

[0127] XRD analysis was performed on the organic attapulgite prepared in Examples 1-4 and Comparative Examples 1-3, and the raw attapulgite ore in Comparative Example 1. The results are as follows: Figure 1-3 As shown.

[0128] Figure 1 XRD pattern and mineral composition standard card of raw attapulgite ore for Comparative Example 1;

[0129] Figure 2 XRD patterns of conventionally purified attapulgite in Comparative Example 2 and the organic attapulgite prepared in Examples 1-4;

[0130] Figure 3 The image shows the XRD pattern of the organic attapulgite prepared after treatment with different amounts of hydrochloric acid in Comparative Example 3.

[0131] from Figure 1 As can be seen, the main minerals present in this mine are attapulgite, quartz, dolomite, and muscovite. The content of each mineral is calculated according to standard SY / T 5163—2010 (X-ray diffraction analysis method for clay and non-clay minerals in sedimentary rocks), as shown in Table 1.

[0132] Table 1. Mineral composition and content in Examples 1, 2, 4 and Comparative Examples 1-3

[0133]

[0134] The XRD patterns of organic attapulgite obtained by the one-step purification and organic modification method of this invention and conventionally purified attapulgite are shown below. Figure 2 ,from Figure 2 As can be seen, organic modification did not change the crystal structure of attapulgite, but mainly achieved surface modification of attapulgite.

[0135] The composition and content of Examples 1, 2, 4 and Comparative Examples 2-3 were calculated based on the XRD results and are shown in Table 1. As can be seen from Table 1, compared with Comparative Example 1, in Comparative Example 2, quartz and dolomite were basically removed after traditional purification, while muscovite was essentially not separated and removed; however, Example 4 effectively removed muscovite.

[0136] The X-ray diffraction patterns of the organic attapulgite prepared in Examples 1-4 conform to the standard card pattern of attapulgite. The organic attapulgite has (110), (040), (121), (231) and (161) crystal plane diffraction peaks at 2θ of 8.32°, 19.74°, 20.86°, 26.58° and 35.31°. The impurity minerals dolomite and quartz are effectively removed, while the removal of muscovite is different.

[0137] Comparing Examples 1 and 4, it was found that the sample in Example 4 not only had the lowest content of impurity minerals such as quartz, but also a significantly reduced content of muscovite, which is difficult to separate from attapulgite. This result indicates that increasing the amount of organic modifier during the organic modification process can remove some muscovite minerals that cannot be separated during traditional purification processes.

[0138] A comparison of Examples 2 and 4 revealed that the dolomite content in Example 2 was significantly higher than that in Example 4, indicating that the type of organic modifier can also affect the removal effect of impurity minerals. This may be because organic modifiers with longer chain lengths have better hydrophobicity, and the hydrophobicity of attapulgite increases after adsorbing the organic modifier, thereby improving the degree of separation from muscovite and quartz.

[0139] In Comparative Example 3, XRD results showed that the amount of acid used had varying effects on the removal of impurity minerals. Dolomite was effectively removed in all three groups with different amounts of hydrochloric acid. However, the removal effect on quartz and muscovite was best at a hydrochloric acid volume of 27.8 mL, not at the maximum hydrochloric acid volume (35.0 mL). This is because while higher hydrochloric acid volumes can effectively separate impurity minerals, the greater the amount of hydrochloric acid used, the more hydrogen ions are adsorbed on the surface of the attapulgite particles. This affects the adsorption of the cationic organic modifier on the attapulgite surface, weakening the organic modification effect and reducing the separation effect between organic attapulgite and impurity minerals.

[0140] Experiment Example 2: Surface Contact Angle Test

[0141] The contact angle of the sample was measured using a Shanghai Zhongchen JC200D contact angle measuring instrument. The powder sample was pressed into a tablet under a pressure of 15 MPa and held for 1 minute. Water was then dropped onto the surface of the sample tablet, and the contact angle was measured.

[0142] The surface contact angles of the organic attapulgite prepared in Examples 1-4 and the purified attapulgite in Comparative Example 2 were tested, and the results are as follows: Figure 4 As shown.

[0143] Depend on Figure 4 It can be seen that the contact angle of purified attapulgite is relatively small, only 14°.

[0144] The contact angle of the organic attapulgite prepared in Example 1 increased from 14° of the purified attapulgite to 33° of the organic attapulgite, indicating enhanced surface hydrophobicity.

[0145] The contact angle of the organic attapulgite prepared in Example 2 increased from 14° of the purified attapulgite to 43° of the organic attapulgite, which is larger than the contact angle in Example 1. This indicates that the increased amount of organic modifier improved the hydrophobicity of the attapulgite surface.

[0146] The contact angle of the organic attapulgite prepared in Example 3 increased from 14° in the purified attapulgite to 38° in the organic attapulgite, which was smaller than the contact angle in Example 2. This indicates that the large amount of hydrochloric acid used will affect the adsorption of the organic modifier on the surface of the attapulgite, reduce the effect of organic modification, and weaken the surface hydrophobicity.

[0147] The contact angle of the organic attapulgite prepared in Example 4 increased from 14° in the purified attapulgite to 48° in the organic attapulgite, and the surface hydrophobicity was enhanced compared to that in Examples 1, 2, and 3. Given that the modifier octadecyltrimethylammonium chloride in Example 4 has stronger hydrophobicity than hexadecyltrimethylammonium chloride in Example 2, and considering the increased amount of modifier compared to Example 1, the results indicate that the stronger the hydrophobicity of the modifier, and the more moderately the amount used, the stronger the hydrophobicity of the resulting organic attapulgite.

[0148] The contact angles of the three organic attapulgite samples prepared in Comparative Example 3 were characterized, and the results are as follows: Figure 5 As shown.

[0149] The results showed that the contact angle of the organic attapulgite decreased with increasing hydrochloric acid dosage. Therefore, the amount of hydrochloric acid used can be considered from two aspects: the removal of impurity minerals and the organic modification effect. Higher hydrochloric acid dosage is more beneficial for impurity mineral removal, but it also leads to more hydrogen ions adsorbed on the surface of the attapulgite particles, affecting the adsorption of cationic organic modifiers on the particle surface and weakening the organic modification effect. Therefore, a one-step method was developed that reduced the amount of hydrochloric acid used through preliminary purification and further purification via organication, ensuring both high purification rate and effective organic modification.

[0150] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the present invention, and all such modifications and improvements fall within the scope of the present invention.

Claims

1. A one-step process for purifying and organically modifying attapulgite, characterized in that, Includes the following steps: Step 1: Perform preliminary purification on the raw attapulgite ore to obtain a preliminary purified attapulgite suspension. Step 2: Modify and further purify the preliminarily purified attapulgite suspension obtained in Step 1. Step 1 is: Step 1-1: Soak the raw attapulgite ore in water, stir and let it stand, adding a dispersant before and / or during stirring. Step 1-2: Add acid solution to the suspension from Step 1-1, stir, and let stand. Steps 1-3: Post-process the suspension from Step 1-2. In step 1-1, the dispersant is selected from anionic dispersants, specifically phosphates, and the mass ratio of the dispersant to water is (0.25~10):1000; In steps 1-2, the acid solution is an inorganic strong acid, and the mass ratio of the solute to the attapulgite ore in the acid solution is (0.05~5):

10. Steps 1-3 are as follows: Step 1-3-1: Centrifuge the suspension from Step 1-2 at a high speed of 1000-6000 r / min, and wash the precipitate after centrifugation. Step 1-3-2: Centrifuge the suspension from Step 1-3-1 at a low speed of 500-4000 r / min to obtain a preliminarily purified attapulgite suspension. Step 2 is: Step 2-1: Add an organic modifier to the preliminarily purified attapulgite suspension and stir; the organic modifier is at least one of dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyldimethylbenzylammonium chloride, octadecyltrimethylammonium chloride, octadecyldimethylbenzylammonium chloride, or dioctadecyldimethylammonium chloride; the mass ratio of attapulgite ore to organic modifier is 10:(1.5~3.5); Step 2-2: Post-process the suspension from Step 2-1 to obtain organic attapulgite.

2. The one-step process for attapulgite purification and organic modification according to claim 1, characterized in that, In step 1-1, the dispersant is sodium pyrophosphate and / or sodium hexametaphosphate; In steps 1-2, the acid solution is at least one of sulfuric acid, hydrochloric acid, and nitric acid.

3. The one-step process for attapulgite purification and organic modification according to claim 1, characterized in that, In step 1-3-1, the high-speed centrifugation speed is 2500~5000 r / min; and / or In step 1-3-2, the speed of low-speed centrifugation is 1000~3000 r / min.

4. The one-step process for attapulgite purification and organic modification according to claim 1, characterized in that, Before steps 1-3, the process also includes: sonicating the suspension from steps 1-2.

5. The one-step process for attapulgite purification and organic modification according to claim 1, characterized in that, Before step 1, the process also includes: pretreatment of the attapulgite ore.

6. The one-step process for attapulgite purification and organic modification according to claim 5, characterized in that, The pretreatment includes drying.

Images