Fluorine removing agent for industrial wastewater and method for preparing the same

Abstract

The application belongs to the technical field of sewage treatment and specifically relates to a defluorination agent for industrial sewage and a preparation method thereof. The defluorination agent for industrial sewage is prepared from the following raw materials in parts by weight: 3-7 parts of sodium carboxymethyl cellulose, 20-25 parts of modified attapulgite dispersion liquid, 30-35 parts of polyaluminum solution, 10-15 parts of hydroxyapatite nano dispersion liquid, 1-3 parts of chitosan quaternary ammonium salt, 0.5-2 parts of ferric ammonium sulfate, 1-3 parts of potassium sodium tartrate, 1-3 parts of modified nano magnesium oxide, 2-4 parts of modified biochar, 1-3 parts of Fe / Al modified kaolin material and 70-90 parts of deionized water. The application has excellent stability and can quickly and efficiently remove fluorides in industrial sewage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment, and particularly relates to a defluorination agent for industrial sewage and a preparation method thereof. BACKGROUND

[0002] Defluorination agents are mainly divided into two categories: solid and liquid. Their characteristics and applicable scenarios are different. Solid defluorination agents can be used as filter materials in adsorption filters to achieve integration of adsorption and filtration, and the process has high integration degree. However, the solid defluorination agents have many drawbacks, such as slow dissolution rate, which cannot play a defluorination effect in time when a large amount of industrial sewage needs to be treated in an emergency; and uneven dispersion, which easily leads to incomplete defluorination in some local areas and affects the overall water quality. Although liquid defluorination agents are convenient to use and can quickly react with industrial sewage, their stability is poor, and the effective components are prone to degradation during storage, which easily leads to precipitation and stratification, resulting in a significant decrease in defluorination performance.

[0003] Chinese Patent CN120794124A discloses a defluorination agent for mine water, a preparation method and application thereof. The preparation method comprises the following steps: adding aluminum salt, calcium salt, magnesium salt and iron salt into water and stirring, then adding a chelating agent, a hydroxyl carboxylic acid compound and a dispersant, heating to 40-60 DEG C and stirring and dispersing, and keeping warm. The defluorination agent is in liquid form and contains a large amount of aluminum salt, calcium salt, magnesium salt and iron salt, and its high efficiency depends on the long-chain porous structure formed by chelation. During storage, the defluorination agent is prone to agglomeration and other phenomena, and has poor chemical stability and storage stability.

[0004] Therefore, it is urgent to develop a defluorination agent for deep treatment of fluoride in industrial sewage, which has high stability and high efficiency. SUMMARY

[0005] The application aims to provide a defluorination agent for industrial sewage, which has excellent stability and can quickly and efficiently remove fluoride in industrial sewage. The application also provides a preparation method of the defluorination agent for industrial sewage.

[0006] The defluorination agent for industrial sewage comprises the following raw materials in the following proportions by weight: 3-7 parts of sodium carboxymethyl cellulose, 20-25 parts of modified attapulgite dispersion liquid, 30-35 parts of polyaluminum solution, 10-15 parts of hydroxyapatite nano dispersion liquid, 1-3 parts of chitosan quaternary ammonium salt, 0.5-2 parts of ferric ammonium sulfate, 1-3 parts of potassium sodium tartrate, 1-3 parts of modified nano magnesium oxide, 2-4 parts of modified biochar, 1-3 parts of Fe / Al modified kaolin material, and 70-90 parts of deionized water.

[0007] The solid content of the modified attapulgite dispersion liquid is 20-30%, the mass concentration of the polyaluminum solution is 8-12%, and the solid content of the hydroxyapatite nano dispersion liquid is 10-15%.

[0008] The preparation method of the modified attapulgite dispersion liquid is that: attapulgite is crushed, soaked in a sulfuric acid solution, washed, dried to obtain acidified attapulgite; the acidified attapulgite is mixed with a cetyltrimethylammonium bromide solution and then stirred and reacted, filtered to obtain modified attapulgite, and the modified attapulgite is dispersed in deionized water at a high speed to obtain the modified attapulgite dispersion liquid; wherein the crushed attapulgite has a mesh size of 300-500 mesh, the mass concentration of the sulfuric acid solution is 8-12%, the ratio of the attapulgite to the sulfuric acid solution is 1:4-8, the attapulgite is measured in grams, and the sulfuric acid solution is measured in milliliters; the soaking temperature is 60-80℃, the soaking time is 3-5h, the mass concentration of the cetyltrimethylammonium bromide solution is 5-10%, the mass ratio of the acidified attapulgite to the cetyltrimethylammonium bromide solution is 1:3-5, the stirring and reaction temperature is 40-60℃, the stirring and reaction time is 2-4h, the high-speed dispersion speed is 5000-8000r / min, and the high-speed dispersion time is 30-60min.

[0009] The preparation method of the hydroxyapatite nano dispersion liquid is that: calcium chloride and diammonium hydrogen phosphate are dissolved in deionized water, ammonia water is added to adjust the pH value under stirring, and then hydrothermal reaction is performed, the mixture is cooled, centrifuged, and washed to obtain nano hydroxyapatite; deionized water is added to the nano hydroxyapatite, and then sodium hexametaphosphate is added and ultrasonic dispersed to obtain the hydroxyapatite nano dispersion liquid; wherein the molar ratio of calcium chloride to diammonium hydrogen phosphate is 5:2.5-3.5; during the preparation of the nano hydroxyapatite, the ratio of calcium chloride to deionized water is 1:40-60, the calcium chloride is measured in grams, and the deionized water is measured in milliliters; the pH value is adjusted to 10-11, the hydrothermal reaction temperature is 150-180℃, the hydrothermal reaction time is 12-24h, the addition amount of sodium hexametaphosphate is 0.5-1.0% of the mass of the nano hydroxyapatite, the ultrasonic dispersion frequency is 40-60kHz, and the ultrasonic dispersion time is 40-80min.

[0010] The preparation method of the modified nano magnesium oxide comprises the following steps: dissolving a rare earth salt and a ligand in deionized water to obtain a rare earth complex solution; adding nano magnesium oxide into anhydrous ethanol, and performing ultrasonic dispersion to obtain a nano magnesium oxide suspension; then, adding the rare earth complex solution into the nano magnesium oxide suspension, and performing constant temperature stirring, centrifugal washing, drying, and grinding into powder to obtain the modified nano magnesium oxide; wherein, the molar ratio of the rare earth salt to the ligand is 1:2-3, the mass ratio of the rare earth salt to the deionized water is 1:50-100, the rare earth salt is lanthanum nitrate or cerium sulfate, and the ligand is citric acid; the concentration of the nano magnesium oxide suspension is 5-10 g / L; the ratio of the nano magnesium oxide in the nano magnesium oxide suspension to the rare earth complex solution is 1:10-20, wherein the nano magnesium oxide is measured in g, and the rare earth complex solution is measured in mL; the ultrasonic dispersion power is 300-500 W, and the ultrasonic dispersion time is 20-30 min; the constant temperature stirring temperature is 50-70 ℃, the constant temperature stirring speed is 200-300 rpm, and the constant temperature stirring time is 1-2 h; the centrifugal speed is 3000-5000 rpm, the centrifugal time is 10-15 min; and the drying temperature is 80-120 ℃, and the drying time is 2-4 h.

[0011] The preparation method of the modified biochar comprises the following steps: adding granular biochar into a nitric acid solution, soaking to obtain activated biochar, then adding the activated biochar into a pyrrole solution for impregnation, adding a FeCl3 solution dropwise for polymerization reaction, and then performing high-temperature treatment in an ammonia atmosphere, and sequentially washing with dilute hydrochloric acid and distilled water, drying to obtain the modified biochar; wherein, the concentration of the nitric acid solution is 15-20 wt.%; the ratio of the biochar to the nitric acid solution is 1:10-15, the biochar is measured in g, and the nitric acid solution is measured in mL; the soaking temperature is 15-20 ℃, and the soaking time is 10-12 h; the concentration of the pyrrole solution is 5-20 g / L; the mass ratio of the activated biochar to the pyrrole solution is 1:3-5; the impregnation temperature is 10-20 ℃, and the impregnation time is 15-20 h; the ratio of the activated biochar to the FeCl3 solution is 1:20-30, the activated biochar is measured in g, and the FeCl3 solution is measured in mL; the concentration of the FeCl3 solution is 14-16 g / L; the polymerization reaction temperature is 10-12 ℃, and the polymerization reaction time is 20-22 h; the high-temperature treatment temperature is 800-900 ℃, and the high-temperature treatment time is 2-3 h; the drying temperature is 100-110 ℃, and the drying time is 10-12 h.

[0012] The preparation method of the Fe / Al modified kaolin material comprises the following steps:

[0013] (A) dissolving iron nitrate and aluminum isopropoxide into anhydrous ethanol, adding ammonia water dropwise to adjust pH, and performing constant temperature stirring to obtain a Fe / Al sol;

[0014] (B) The kaolin is added into anhydrous ethanol, ultrasonic dispersion is carried out to obtain a suspension, the suspension is added into the Fe / Al sol, stirring is carried out, and then standing, drying, calcination and grinding are carried out to obtain the Fe / Al modified kaolin material.

[0015] In step (A), the molar ratio of iron in the ferric nitrate and aluminum in the aluminum isopropoxide is 7-9:1-3; the ratio of the ferric nitrate to the anhydrous ethanol is 1:10-14, the ferric nitrate is measured in g, and the anhydrous ethanol is measured in mL; the pH is 8.0-9.5; the temperature of the constant temperature stirring is 40-60 DEG C; and the time of the constant temperature stirring is 2-4h.

[0016] In step (B), the ratio of the kaolin to the anhydrous ethanol is 1:10-15, the kaolin is measured in g, and the anhydrous ethanol is measured in mL; the volume ratio of the suspension to the Fe / Al sol is 3-5:1; the stirring time is 2-4h; the standing time is 4-6h; the drying temperature is 80-100 DEG C; the drying time is 12-24h; the calcination temperature is 400-500 DEG C; and the calcination time is 3-5h.

[0017] The preparation method of the defluorination agent for industrial wastewater provided by the application comprises the following steps:

[0018] (1) The sodium carboxymethyl cellulose, the chitosan quaternary ammonium salt, the potassium sodium tartrate and the ferric ammonium sulfate are sequentially added into the deionized water, and stirring is carried out to obtain a base solution;

[0019] (2) The modified nano magnesium oxide, the modified biochar and the Fe / Al modified kaolin material are sequentially added into the base solution, and stirring is carried out until the components are uniformly dispersed;

[0020] (3) The polyaluminum solution, the modified attapulgite dispersion liquid and the hydroxyapatite nano dispersion liquid are sequentially added, and continuous stirring is carried out to obtain the defluorination agent for industrial wastewater.

[0021] In step (1), the stirring time is 30-60min.

[0022] In steps (1)-(3), the stirring speed is 200-300r / min, and the stirring temperature is 20-30 DEG C; the addition of each component is carried out in the stirring state.

[0023] The action mechanism of the application is as follows:

[0024] 1、The application selects modified attapulgite dispersion liquid, Fe / Al modified kaolin material, modified biochar, modified nano magnesium oxide and other different forms of components, which are complementary in space, realize spontaneous assembly through force gradient, build stable flocculation framework, and then superimpose the rapid precipitation of polyaluminum solution and ferric ammonium sulfate, ion exchange of hydroxyapatite, surface complexation of Fe / Al modified kaolin material and modified nano magnesium oxide, electrostatic adsorption of modified attapulgite and modified biochar and other action mechanisms, so that all-round defluorination from physical interception to chemical fixation is realized.

[0025] (1) The modified attapulgite is modified by using cetyltrimethylammonium bromide to organicize attapulgite, so that the surface of attapulgite is changed from negative to positive, and the number of surface hydroxyl groups is increased by acidification, so that hydrogen bond action can be formed with F - , and the defluorination rate is further improved. The modified attapulgite can be interpenetrated with the modified biochar and the Fe / Al modified kaolin material to prevent interlayer stacking and form a stable three-dimensional structure, so that the active sites are exposed and the capture capacity of F - is enhanced by electrostatic attraction superposition effect. The modified attapulgite can also form hydrophobic interaction with the hydrophobic skeleton of chitosan quaternary ammonium salt, and the positive groups of the two can synergistically adsorb negatively charged fluorine-containing particles, so that the flocculation structure is more compact, and at the same time, as a physical skeleton, it supports the formation of a three-dimensional network flocculation.

[0026] (2) The modified nano magnesium oxide is loaded with rare earth ions on the surface of nano magnesium oxide through the bridging of citric acid ligand, changes the surface charge of magnesium oxide, and improves the hydrophilicity of magnesium oxide surface. Strong coordination chelation is formed with F - , and as a ligand, one end of citric acid is complexed with rare earth ions, and the other end is combined with the surface of MgO through hydrogen bond or physical adsorption, forming an organic-inorganic composite layer to play a role of steric hindrance, solving the problem of nano magnesium oxide particle agglomeration, keeping higher specific surface area and more active sites. At the same time, the modification of nano magnesium oxide will cause a local alkaline environment, which can promote the formation of hydroxyl polymer products with strong electric neutralization and bridging ability of polyaluminum salt, and enhance the deprotonation of the surface functional groups of other adsorbents such as modified biochar, and improve its adsorption performance.

[0027] (3) The modified biochar has a rich specific surface area, by introducing nitrogen sites and further nitrogen doping and carbon matrix reconstruction in an ammonia atmosphere, a carbon / graphene composite structure rich in nitrogen doping is formed, specific adsorption sites are enriched, charge transfer is accelerated, and electrostatic adsorption of F - is improved. Because the biochar has a rich pore structure, it can load modified nano magnesium oxide and other small particles, and the sp 2The carbon network is coupled with the interface to form a close interface, and the positive charges contained in the modified biochar form a positive potential site cluster with the nano magnesium oxide and Fe / Al modified kaolin material. Through electrostatic attraction, the biochar-magnesium oxide-kaolin material ternary composite adsorbent is formed, which effectively promotes the adsorption capacity of F - . The modified biochar provides an attachment skeleton for colloids, enhances the flocculation density, and strengthens the flocculation skeleton.

[0028] (4) Kaolin has natural interlayer spacing, but the structure is single, the specific surface area is low, and the active site is insufficient. Fe / Al modified kaolin material is a material loaded with iron and aluminum active metal ions on the basis of not introducing other impurity metal ions; iron ions dominate high selectivity for fluorine capture, and aluminum ions form a cross-linked network through Al-O bonds, so that the layered structure of kaolin avoids agglomeration, and the hydroxyl groups of Al(OH)3 colloid supplement ion exchange sites, increase coordination chelation sites, and realize stable loading. Fe 3+ / Al 3+ and other cations form a multi-cation network to enhance the selectivity of F - ; Fe / Al modified kaolin material and modified attapulgite and modified biochar interlock to avoid agglomeration, form a positive potential site cluster and a charge transfer region, and the specific surface area is synergistically amplified; Fe / Al active sites on the Fe / Al modified kaolin material interact with polyaluminum solution, ferric ammonium sulfate and other components and residual hydrolysis products in the sewage to form a more dense composite colloid.

[0029] (5) Polyaluminum solution and ferric ammonium sulfate are flocculants. Polyaluminum hydrolysis forms Al(OH)3 amorphous colloid, which can adsorb fluorine-containing particles of different particle sizes and different charges, build a basic flocculation skeleton, and ferric ammonium sulfate hydrolysis generates Fe(OH)3 colloid with high density and strong coagulation force. The two form a Fe-Al composite flocculation system, which doubles the bridging capacity and settling speed, and the formation of Fe-O-Al chemical bond makes the colloid skeleton more stable. At the same time, through electrostatic neutralization and bridging effect, the adsorption capacity of fluorine-containing particles is enhanced.

[0030] (6) Hydroxyapatite nanodispersion is the core component of low-concentration fluoride deep purification. Its reaction specific surface area is large, and the hydroxyl groups in the crystal structure exchange with F - equally. The complex formed after adsorbing F - can combine with the flocculant colloid in the system through electrostatic attraction to form a flocculation that is easy to settle, and the speed of solid-liquid separation is strengthened.

[0031] (7) The chitosan quaternary ammonium salt is a cationic organic polymer flocculant, which captures and connects the destabilized particles through electrostatic neutralization and bridging effect. The positive groups thereof are electrostatically crosslinked with the flocculant colloid, the long-chain molecules are entangled with the colloid skeleton, a three-dimensional network skeleton is formed, and the mechanical strength of the floe is enhanced. The hydrophobic skeleton thereof forms van der Waals force with the hydrophobic long chains on the surface of the modified attapulgite, and the positive groups synergistically adsorb the negative fluorine-containing particles, so that the combination inside the floe is more compact.

[0032] (8) The sodium carboxymethyl cellulose provides a unified stable dispersion environment for all components through the triple effects of electrostatic, hydration film and thickening, avoids the plugging of active sites caused by agglomeration. The sodium carboxymethyl cellulose can adjust the viscosity of the system, avoid the rapid settlement of the adsorbent, and ensure that the fluorine removal agent is uniformly mixed with the sewage; the -COO - groups on the molecular chain of the sodium carboxymethyl cellulose form hydrogen bonds with the hydroxyl groups on the surface of the nanoparticles, avoid particle agglomeration through electrostatic repulsion and steric hindrance effect; the sodium carboxymethyl cellulose hydration film prevents the interlayer stacking of kaolin materials and the agglomeration of attapulgite, maintains the unobstructed micropore-mesopore channel, and ensures that the active sites are fully exposed. The sodium carboxymethyl cellulose molecular chain serves as an auxiliary skeleton, and enhances the continuity of the floe through bridging effect.

[0033] (9) The potassium sodium tartrate forms a water-soluble complex with metal ions in the system, prevents premature hydrolysis to form a precipitate, and ensures that the active ingredients can diffuse to all parts of the water body, efficiently capture F - , and at the same time stabilizes the pH environment of the system, maintains the stability of the system and the effective active components, and ensures deep fluorine removal.

[0034] 2. The present application determines the feeding sequence by exploring the process of the fluorine removal agent, solves the problems of component failure and uneven dispersion caused by disordered mixing through the logic of "first constructing a stable base, then introducing active components, and finally strengthening dispersion and synergy", improves the storage stability, ensures the synergistic efficiency of each component, and stably meets the standard requirements of deep fluorine removal of industrial wastewater.

[0035] (1) First, add sodium carboxymethyl cellulose, chitosan quaternary ammonium salt, potassium sodium tartrate and ferric ammonium sulfate in deionized water in sequence to construct a dispersion-stable base:

[0036] The addition of sodium carboxymethyl cellulose increases the viscosity of the aqueous phase, and at the same time, the dispersion system is constructed through the hydration film effect and steric hindrance effect; after the addition of chitosan quaternary ammonium salt, it is fully dissolved in the neutral dispersion system, and the molecular chain is free to stretch, and the subsequent coordination with the flocculant can exert the best electrostatic crosslinking and hydrogen bonding effect; the potassium sodium tartrate as a complexing stabilizer and pH buffer agent, chelates interfering ions in advance, stabilizes the system environment; the addition of ferric ammonium sulfate as a flocculant, uniformly dispersed to form a stable system, and the subsequent coordination with polyaluminum can form a uniform Fe-Al composite colloid, and strengthen the flocculation effect.

[0037] (2) Then, modified nano magnesium oxide, modified biochar and Fe / Al modified kaolin material are added in sequence to introduce active components:

[0038] The modified nano magnesium oxide, modified biochar and Fe / Al modified kaolin material are added in sequence into the stable dispersion system constructed, in the buffer network formed by sodium carboxymethyl cellulose and chitosan quaternary ammonium salt, and under the protection of potassium sodium tartrate, each active component can be slowly and uniformly dispersed, the active sites are fully exposed, a uniform and stable suspension is formed, and mutual adsorption and agglomeration between different adsorbents due to charge difference is avoided.

[0039] (3) Finally, polyaluminum solution, modified attapulgite dispersion liquid and hydroxyapatite nano dispersion liquid are added in sequence to realize flocculation and deep fluorine removal:

[0040] After the polyaluminum solution is added, potassium sodium tartrate will immediately complex part of Al 3+ , control the hydrolysis rate, and part of the polyaluminum hydrolysis forms Al(OH)3 colloid, which is uniformly dispersed in the system to form multiple high-activity fluorine removal reaction points; after the modified attapulgite dispersion liquid is added, the modified attapulgite serves as a flocculation skeleton to form a three-dimensional network flocculation with the colloid, thereby improving the flocculation density and settling speed; finally, the hydroxyapatite nano dispersion liquid is added, which can avoid being wrapped and buried by the formed flocculation network and precipitate, so that it is uniformly dispersed in the stable flocculation system to play an ion exchange role and capture residual low-concentration F - , and at the same time, it can be adsorbed on the formed flocculation skeleton, which not only ensures deep fluorine removal activity, but also avoids the loss of nanoparticles.

[0041] The beneficial effects of the present application are as follows:

[0042] (1) The components selected in the present application have a synergistic effect, cover complexation adsorption, coagulation precipitation, ion exchange and other fluorine removal mechanisms, and can efficiently remove fluorides, and through the adsorption, coagulation and ion exchange and complexation of the components, the fluorides in industrial wastewater can be quickly and deeply removed. Experimental data show that after the fluorine removal agent of the present application is used to treat industrial wastewater with a fluoride concentration higher than 20 mg / L, the fluoride concentration can be stably reduced to below 1 mg / L, which is far below the national discharge standard.

[0043] (2) By reasonably selecting raw materials and optimizing the preparation process, the present application can effectively prevent the fluorine removal agent from precipitating and stratifying, improve its chemical stability and storage stability, and the prepared fluorine removal agent has excellent chemical stability and storage stability. Tests show that after being stored at room temperature for 12 months or at high temperature (40℃) and low temperature (5℃) for 3 months, the fluorine removal effect of the fluorine removal agent is stable, and no precipitation or stratification occurs, which can ensure that the performance is reliable and stable during actual application and transportation, and can adapt to different storage and use environments.

[0044] (3) The defluorination agent of the present application is in liquid form, convenient to use, can be quickly mixed with industrial wastewater, improve the treatment efficiency, reduce the operation difficulty and labor intensity. In the actual industrial wastewater treatment, the dosage of the defluorination agent can be accurately controlled according to the flow and fluoride concentration of the industrial wastewater, and automatic and efficient treatment can be realized.

[0045] (4) Most of the raw materials selected by the present application are natural or degradable substances, which will not produce secondary pollution in the preparation and use process, and meet the environmental protection requirements. At the same time, the defluorination agent of the present application can effectively reduce the harm of fluoride in industrial wastewater to the environment, protect the surrounding ecological environment, and has environmental friendliness. DETAILED DESCRIPTION

[0046] The present application is further described below in conjunction with examples.

[0047] Example 1

[0048] The defluorination agent for industrial wastewater is prepared from the following raw materials in parts by weight: 3 parts of sodium carboxymethyl cellulose, 20 parts of modified attapulgite dispersion liquid, 30 parts of polyaluminum solution, 10 parts of hydroxyapatite nano dispersion liquid, 1 part of chitosan quaternary ammonium salt, 0.5 part of ferric ammonium sulfate, 1 part of potassium sodium tartrate, 2 parts of modified nano magnesium oxide, 2 parts of modified biochar, 2 parts of Fe / Al modified kaolin material, and 70 parts of deionized water.

[0049] The preparation method of the modified attapulgite dispersion liquid is as follows:

[0050] Grind 1000g of attapulgite to 300 mesh, put it into 4000mL of 12% sulfuric acid solution, soak at 60℃ for 5h, then wash with deionized water until neutral, dry to obtain acidized attapulgite; mix 1000g of acidized attapulgite with 4000g of 8% hexadecyltrimethylammonium bromide solution, stir at 60℃ for 2h, filter after reaction, obtain modified attapulgite, add deionized water to the modified attapulgite, disperse at a speed of 5000r / min for 60min, obtain modified attapulgite dispersion liquid with a solid content of 20%.

[0051] The preparation method of the hydroxyapatite nano dispersion liquid is as follows:

[0052] Dissolve 1000 g of calcium chloride and diammonium hydrogen phosphate in 50 L of deionized water, the molar ratio of calcium chloride and diammonium hydrogen phosphate is 5:3, slowly add ammonia water to adjust the pH value to 10 under stirring, then carry out hydrothermal reaction at 150℃ for 24 h, after the reaction, cool, centrifugal separation, washing, to obtain nano-hydroxyapatite; add deionized water to 1000 g of nano-hydroxyapatite, then add 10 g of sodium hexametaphosphate, ultrasonic dispersion for 80 min at a frequency of 40 kHz, to prepare a hydroxyapatite nano-dispersion with a solid content of 10%.

[0053] The preparation method of modified nano-magnesium oxide is as follows:

[0054] Dissolve 1000 g of lanthanum nitrate and citric acid in 100 kg of deionized water, the molar ratio of lanthanum nitrate and citric acid is 1:2, to obtain a rare earth complex solution; add 1000 g of nano-magnesium oxide to anhydrous ethanol, ultrasonic dispersion for 30 min at a power of 300 W, to obtain a nano-magnesium oxide suspension with a concentration of 5 g / L; then add 1.5 L of the rare earth complex solution to 20 L of the nano-magnesium oxide suspension, constant temperature stirring at a temperature of 70℃ and a speed of 200 rpm for 2 h, centrifugal separation at 3000 rpm for 15 min, washing, drying at 100℃ for 3 h, grinding into powder, to prepare modified nano-magnesium oxide.

[0055] The preparation method of modified biochar is as follows:

[0056] Add 1000 g of granular biochar to 10 L of a 20 wt.% nitric acid solution, soak at a temperature of 15℃ for 12 h to obtain activated biochar, then add 1000 g of the activated biochar to 4000 g of a pyrrole solution with a concentration of 15 g / L, impregnate at 10℃ for 20 h, add 25 L of a FeCl3 solution with a concentration of 15 g / L dropwise, carry out polymerization reaction at a temperature of 10℃ for 20 h, then treat at a high temperature of 850℃ for 2 h in an ammonia atmosphere, wash with dilute hydrochloric acid and distilled water in sequence, dry at 105℃ for 12 h, to obtain modified biochar.

[0057] The preparation method of Fe / Al modified kaolin material is as follows:

[0058] Dissolve 1000 g of ferric nitrate and aluminum isopropoxide in 12 L of anhydrous ethanol, the molar ratio of iron in ferric nitrate and aluminum in aluminum isopropoxide is 8:2, add ammonia water dropwise to adjust the pH to 8.0, constant temperature stirring at 60℃ for 2 h to obtain Fe / Al sol; add 1000 g of kaolin to 15 L of anhydrous ethanol, ultrasonic dispersion to obtain a suspension, then add 5 L of the suspension to 1 L of the Fe / Al sol, stirring for 2 h, then stand for 6 h, dry at 90℃ for 18 h, calcine at 500℃ for 3 h, grind into powder, to prepare Fe / Al modified kaolin material.

[0059] The preparation method of the defluorination agent for industrial wastewater comprises the following steps:

[0060] Deionized water is added into a reaction kettle, stirring is started, the stirring speed is 200 r / min, the stirring temperature is 30 DEG C, sodium carboxymethyl cellulose, chitosan quaternary ammonium salt, potassium sodium tartrate and ferric ammonium sulfate are sequentially added, stirring is conducted for 30 min to prepare a base solution, modified nano magnesium oxide, modified biochar and Fe / Al modified kaolin material are sequentially added into the base solution, and stirring is conducted until the mixture is uniformly dispersed; then, 10% polyaluminum solution is added, and stirring is conducted for 10 min; then, modified attapulgite dispersion liquid is added, and stirring is conducted for 10 min; finally, hydroxyapatite nano dispersion liquid is added, and stirring is continued for 40 min to prepare the defluorination agent for industrial wastewater.

[0061] Example 2

[0062] The defluorination agent for industrial wastewater is prepared from the following raw materials in parts by weight: 5 parts of sodium carboxymethyl cellulose, 25 parts of modified attapulgite dispersion liquid, 35 parts of polyaluminum solution, 12 parts of hydroxyapatite nano dispersion liquid, 2 parts of chitosan quaternary ammonium salt, 1.2 parts of ferric ammonium sulfate, 2 parts of potassium sodium tartrate, 1 part of modified nano magnesium oxide, 3 parts of modified biochar, 1 part of Fe / Al modified kaolin material and 80 parts of deionized water.

[0063] The preparation method of the modified attapulgite dispersion liquid is as follows:

[0064] 1000 g of attapulgite is crushed to 400 mesh, is placed into 6000 mL of 10% sulfuric acid solution, is soaked at 70 DEG C for 4 h, is then washed with deionized water until neutral, and is dried to obtain acidified attapulgite; 1000 g of the acidified attapulgite is mixed with 5000 g of 5% cetyltrimethylammonium bromide solution, is stirred at 40 DEG C for 4 h, is filtered after the reaction is completed, and is dispersed in deionized water at a speed of 6000 r / min for 50 min to prepare modified attapulgite dispersion liquid with a solid content of 25%.

[0065] The preparation method of the hydroxyapatite nano dispersion liquid is as follows:

[0066] 1000 g of calcium chloride and 1000 g of diammonium hydrogen phosphate are dissolved in 60 L of deionized water, the molar ratio of calcium chloride to diammonium hydrogen phosphate is 5:3.5, ammonia water is slowly added under stirring to adjust the pH value to 10.5, and then hydrothermal reaction is conducted at 160 DEG C for 18 h, after the reaction is completed, the mixture is cooled, is centrifuged and washed to obtain nano hydroxyapatite; 1000 g of the nano hydroxyapatite is added with deionized water, 5 g of sodium hexametaphosphate is further added, and ultrasonic dispersion is conducted at a frequency of 50 kHz for 60 min to prepare hydroxyapatite nano dispersion liquid with a solid content of 12%.

[0067] The preparation method of the modified nano-magnesium oxide is as follows:

[0068] 1000g of lanthanum nitrate and citric acid are dissolved in 50kg of deionized water, the molar ratio of lanthanum nitrate to citric acid is 1:3, and a rare earth complex solution is obtained; 1000g of nano-magnesium oxide is added to anhydrous ethanol, ultrasonic dispersion is carried out for 25min under a power of 400W, and a nano-magnesium oxide suspension with a concentration of 5g / L is obtained; then 2L of the rare earth complex solution is added dropwise to 20L of the nano-magnesium oxide suspension, constant temperature stirring is carried out at a temperature of 60℃ and a speed of 300rpm for 1h, centrifugation is carried out at 4000rpm for 12min, washing is carried out, drying is carried out at 120℃ for 2h, and grinding into powder is carried out, and the modified nano-magnesium oxide is prepared.

[0069] The preparation method of the modified biochar is as follows:

[0070] 1000g of granular biochar is added to 15L of a nitric acid solution with a concentration of 15wt.%, and after soaking at a temperature of 20℃ for 10h, activated biochar is obtained; then 1000g of the activated biochar is added to 3000g of a pyrrole solution with a concentration of 10g / L, and impregnation is carried out at 20℃ for 15h; then 20L of a FeCl3 solution with a concentration of 15g / L is added dropwise, and polymerization reaction is carried out at a temperature of 10℃ for 22h; then high-temperature treatment is carried out at 800℃ for 3h in an ammonia atmosphere, washing is carried out with dilute hydrochloric acid and distilled water in sequence, and drying is carried out at 110℃ for 10h, and the modified biochar is obtained.

[0071] The preparation method of the Fe / Al modified kaolin material is as follows:

[0072] 1000g of ferric nitrate and aluminum isopropoxide are dissolved in 10L of anhydrous ethanol according to a molar ratio of iron in ferric nitrate to aluminum in aluminum isopropoxide of 7:3, ammonia water is added dropwise to adjust the pH to 9.0, and Fe / Al sol is obtained by constant temperature stirring at 50℃ for 3h; 1000g of kaolin is added to 10L of anhydrous ethanol to obtain a suspension, 3L of the suspension is added to 1L of the Fe / Al sol, stirring is carried out for 2h, and then standing is carried out for 5h; drying is carried out at 95℃ for 18h, calcination is carried out at 450℃ for 4h, and grinding into powder is carried out, and the Fe / Al modified kaolin material is prepared.

[0073] The preparation method of the defluorination agent for industrial wastewater, comprising the following steps:

[0074] In the reaction kettle, add deionized water, open the stirring, stirring speed is 250 r / min, stirring temperature is 25℃, add sodium carboxymethyl cellulose, chitosan quaternary ammonium salt, potassium sodium tartrate and ferric ammonium sulfate in turn, stirring for 45 min to prepare the base solution, then add modified nano magnesium oxide, modified biochar and Fe / Al modified kaolin materials to the base solution in turn, stirring until dispersed uniformly; then add 10% polyaluminum solution, stirring for 12 min; then add modified attapulgite dispersion liquid, stirring for 12 min; finally add hydroxyapatite nano dispersion liquid, continue stirring for 60 min to prepare the defluorination agent for industrial wastewater.

[0075] Example 3

[0076] The defluorination agent for industrial wastewater is made of the following raw materials in parts by weight: sodium carboxymethyl cellulose 7 parts, modified attapulgite dispersion liquid 25 parts, polyaluminum solution 35 parts, hydroxyapatite nano dispersion liquid 15 parts, chitosan quaternary ammonium salt 3 parts, ferric ammonium sulfate 2 parts, potassium sodium tartrate 3 parts, modified nano magnesium oxide 3 parts, modified biochar 4 parts, Fe / Al modified kaolin material 3 parts, and deionized water 90 parts.

[0077] The preparation method of the modified attapulgite dispersion liquid is as follows:

[0078] Grind 1000g attapulgite to 500 mesh, immerse in 8000mL 8% sulfuric acid solution at 80℃ for 3h, then wash with deionized water until neutral, dry to obtain acidified attapulgite; mix 1000g acidified attapulgite with 3000g 10% cetyltrimethylammonium bromide solution, stir at 50℃ for 3h, filter after reaction, obtain modified attapulgite, add deionized water to the modified attapulgite, high-speed dispersion at 6500r / min for 40min to obtain modified attapulgite dispersion liquid with solid content of 30%.

[0079] The preparation method of the hydroxyapatite nano dispersion liquid is as follows:

[0080] Dissolve 1000g calcium chloride and 3000g diammonium hydrogen phosphate in 40L deionized water, the molar ratio of calcium chloride to diammonium hydrogen phosphate is 5:3, slowly add ammonia water under stirring to adjust the pH value to 11, perform hydrothermal reaction at 180℃ for 12h, after reaction, cool, centrifugal separation, wash to obtain nano hydroxyapatite; add deionized water to 1000g nano hydroxyapatite, then add 10g sodium hexametaphosphate, ultrasonic dispersion at 60kHz for 40min to obtain hydroxyapatite nano dispersion liquid with solid content of 15%.

[0081] The preparation method of the modified nano magnesium oxide is as follows:

[0082] Lanthanum nitrate 1000 g and citric acid were dissolved in 75 kg deionized water, the molar ratio of lanthanum nitrate to citric acid was 1:3, to obtain a rare earth complex solution; 1000 g of nano-magnesium oxide was added to anhydrous ethanol, and ultrasonic dispersion was carried out for 20 min under a power of 500 W to obtain a nano-magnesium oxide suspension with a concentration of 7 g / L; then 1.4 L of the rare earth complex solution was added dropwise into 20 L of the nano-magnesium oxide suspension, and constant temperature stirring was carried out at a temperature of 55℃ and a speed of 250 rpm for 1.5 h, followed by centrifugation at 5000 rpm for 10 min, washing, drying at 100℃ for 3 h, and grinding into powder to obtain modified nano-magnesium oxide.

[0083] The preparation method of the modified biochar is as follows:

[0084] 1000 g of granular biochar was added to 10 L of a 20 wt.% nitric acid solution, and after soaking at a temperature of 18℃ for 11 h, activated biochar was obtained, then 1000 g of the activated biochar was added to 4000 g of a pyrrole solution with a concentration of 10 g / L, and impregnated at 15℃ for 20 h, then 20 L of a FeCl3 solution with a concentration of 15 g / L was added dropwise, and a polymerization reaction was carried out at a temperature of 12℃ for 20 h, then high-temperature treatment was carried out at 900℃ for 2 h under an ammonia atmosphere, and then washing was carried out with dilute hydrochloric acid and distilled water, and drying was carried out at 105℃ for 11 h to obtain modified biochar.

[0085] The preparation method of the Fe / Al modified kaolin material is as follows:

[0086] 1000 g of ferric nitrate and 1000 g of aluminum isopropoxide were dissolved in 14 L of anhydrous ethanol according to a molar ratio of iron in ferric nitrate to aluminum in aluminum isopropoxide of 7:3, ammonia water was added dropwise to adjust the pH to 9.5, and Fe / Al sol was obtained by constant temperature stirring at 60℃ for 4 h; 1000 g of kaolin was added to 15 L of anhydrous ethanol, and a suspension was obtained by ultrasonic dispersion, then 6 L of the suspension was added to 2 L of the Fe / Al sol, stirring was carried out for 3 h, and then standing was carried out for 4 h, drying was carried out at 80℃ for 24 h, calcination was carried out at 400℃ for 5 h, and grinding into powder to obtain a Fe / Al modified kaolin material.

[0087] The preparation method of the defluorination agent for industrial wastewater includes the following steps:

[0088] In the reaction kettle, add deionized water, open the stirring, stirring speed is 300 r / min, stirring temperature is 20℃, add sodium carboxymethyl cellulose, chitosan quaternary ammonium salt, potassium sodium tartrate and ferric ammonium sulfate in turn, stirring for 60 min to prepare the base solution, then add modified nano magnesium oxide, modified biochar and Fe / Al modified kaolin materials to the base solution in turn, stirring until dispersed uniformly; then add 12% polyaluminum solution, stirring for 15 min; then add modified attapulgite dispersion liquid, stirring for 15 min; finally add hydroxyapatite nano dispersion liquid, continue stirring for 80 min to prepare the defluorination agent for industrial wastewater.

[0089] Example 4

[0090] The defluorination agent for industrial wastewater is prepared from the following raw materials: sodium carboxymethyl cellulose 4 parts, modified attapulgite dispersion liquid 22 parts, polyaluminum solution 32 parts, hydroxyapatite nano dispersion liquid 11 parts, chitosan quaternary ammonium salt 1.5 parts, ferric ammonium sulfate 1 part, potassium sodium tartrate 1.5 parts, modified nano magnesium oxide 2 parts, modified biochar 2.5 parts, Fe / Al modified kaolin material 2 parts, and deionized water 75 parts.

[0091] The preparation method of the modified attapulgite dispersion liquid is as follows:

[0092] Grind 1000g attapulgite to 300 mesh, immerse it in 6000mL 9% sulfuric acid solution at 65℃ for 4.5h, then wash it with deionized water until it is neutral, and dry it to obtain acidified attapulgite; mix 1000g acidified attapulgite with 3000g 10% cetyltrimethylammonium bromide solution, stir at 45℃ for 3h, filter after the reaction is completed, add deionized water to the modified attapulgite, and disperse it at 7000r / min for 35min to obtain a modified attapulgite dispersion liquid with a solid content of 22%.

[0093] The preparation method of the hydroxyapatite nano dispersion liquid is as follows:

[0094] Dissolve 1000g calcium chloride and 60L deionized water diammonium hydrogen phosphate in 60L deionized water, the molar ratio of calcium chloride to diammonium hydrogen phosphate is 5:2.5, slowly add ammonia water under stirring to adjust the pH value to 10, and perform hydrothermal reaction at 170℃ for 14h, after the reaction is completed, cool, centrifuge, wash, and obtain nano hydroxyapatite; add deionized water to 1000g nano hydroxyapatite, then add 6g sodium hexametaphosphate, and ultrasonic disperse at 50kHz for 50min to obtain a hydroxyapatite nano dispersion liquid with a solid content of 14%.

[0095] The preparation method of the modified nano magnesium oxide is as follows:

[0096] La(NO3)3 1000 g and citric acid were dissolved in 80 kg deionized water, the molar ratio of La(NO3)3 to citric acid was 1:2.5, to obtain a rare earth complex solution; 1000 g of nano-magnesium oxide was added to anhydrous ethanol, and ultrasonic dispersion was carried out for 25 min under a power of 400 W to obtain a nano-magnesium oxide suspension with a concentration of 10 g / L; then 2 L of the rare earth complex solution was added dropwise to 20 L of the nano-magnesium oxide suspension, and constant temperature stirring was carried out at a temperature of 50℃ and a speed of 300 rpm for 1 h, followed by centrifugation at 4000 rpm for 12 min, washing, drying at 80℃ for 4 h, and grinding into powder to obtain modified nano-magnesium oxide.

[0097] The preparation method of the modified biochar is as follows:

[0098] 1000 g of granular biochar was added to 15 L of a nitric acid solution with a concentration of 15 wt.%, and after soaking at a temperature of 15℃ for 12 h, activated biochar was obtained, then 1000 g of the activated biochar was added to 5000 g of a pyrrole solution with a concentration of 20 g / L, and impregnated at 10℃ for 20 h, then 30 L of an FeCl3 solution with a concentration of 14 g / L was added dropwise, and a polymerization reaction was carried out at a temperature of 11℃ for 21 h, then high-temperature treatment was carried out at 850℃ for 2 h in an ammonia atmosphere, and then washing was carried out with dilute hydrochloric acid and distilled water, and drying was carried out at 100℃ for 12 h to obtain modified biochar.

[0099] The preparation method of the Fe / Al modified kaolin material is as follows:

[0100] 1000 g of iron nitrate and aluminum isopropoxide were dissolved in 10 L of anhydrous ethanol according to a molar ratio of iron in the iron nitrate to aluminum in the aluminum isopropoxide of 9:1, ammonia water was added dropwise to adjust the pH to 8.0, and Fe / Al sol was obtained by constant temperature stirring at 40℃ for 4 h; 1000 g of kaolin was added to 12 L of anhydrous ethanol, and a suspension was obtained by ultrasonic dispersion, then 4 L of the suspension was added to 1 L of the Fe / Al sol, stirring was carried out for 2 h, and then standing was carried out for 6 h, drying was carried out at 85℃ for 18 h, calcination was carried out at 500℃ for 3 h, and grinding into powder to obtain a Fe / Al modified kaolin material.

[0101] The preparation method of the defluorination agent for industrial wastewater includes the following steps:

[0102] In the reaction kettle, add deionized water, open the stirring, stirring speed is 220r / min, stirring temperature is 20℃, add sodium carboxymethyl cellulose, chitosan quaternary ammonium salt, potassium sodium tartrate and ferric ammonium sulfate in turn, stirring for 35min to prepare the base solution, then add modified nano magnesium oxide, modified biochar and Fe / Al modified kaolin materials to the base solution in turn, stirring until dispersed uniformly; then add 10% polyaluminum solution, stirring for 11min; then add modified attapulgite dispersion liquid, stirring for 11min; finally add hydroxyapatite nano dispersion liquid, continue stirring for 50min to prepare the defluorination agent for industrial wastewater.

[0103] Example 5

[0104] The defluorination agent for industrial wastewater is made of the following raw materials in weight ratio: sodium carboxymethyl cellulose 6 parts, modified attapulgite dispersion liquid 24 parts, polyaluminum solution 34 parts, hydroxyapatite nano dispersion liquid 14 parts, chitosan quaternary ammonium salt 2.5 parts, ferric ammonium sulfate 1.8 parts, potassium sodium tartrate 2.5 parts, modified nano magnesium oxide 2.5 parts, modified biochar 3 parts, Fe / Al modified kaolin material 2.5 parts, and deionized water 85 parts.

[0105] The preparation method of modified attapulgite dispersion liquid is as follows:

[0106] Grind 1000g attapulgite to 400 mesh, put it into 5000mL 10% sulfuric acid solution, soak at 75℃ for 3.5h, then wash with deionized water until neutral, dry to obtain acidified attapulgite; mix 1000g acidified attapulgite with 4000g 9% cetyltrimethylammonium bromide solution, stir at 60℃ for 2.5h, filter after the reaction is completed, add deionized water to the modified attapulgite, high-speed dispersion at 8000r / min for 30min to prepare modified attapulgite dispersion liquid with solid content of 28%.

[0107] The preparation method of hydroxyapatite nano dispersion liquid is as follows:

[0108] Dissolve 1000g calcium chloride and 50L deionized water diammonium hydrogen phosphate in 50L deionized water, the molar ratio of calcium chloride and diammonium hydrogen phosphate is 5:3, slowly add ammonia water under stirring condition to adjust the pH value to 11, carry out hydrothermal reaction at 160℃ for 20h, after the reaction is completed, cool, centrifugal separation, wash to obtain nano hydroxyapatite; add deionized water to 1000g nano hydroxyapatite, then add 5g sodium hexametaphosphate, ultrasonic dispersion at 60kHz frequency for 45min to prepare hydroxyapatite nano dispersion liquid with solid content of 11%.

[0109] The preparation method of modified nano magnesium oxide is as follows:

[0110] Ce(SO4)1000g and citric acid were dissolved in 80kg deionized water, the molar ratio of Ce(SO4) to citric acid was 1:2, to obtain a rare earth complex solution; 1000g of nano-magnesium oxide was added to anhydrous ethanol, and ultrasonic dispersion was carried out for 30min under a power of 400W to obtain a nano-magnesium oxide suspension with a concentration of 8g / L; then 2.4L of the rare earth complex solution was added dropwise to 20L of the nano-magnesium oxide suspension, and constant temperature stirring was carried out at a temperature of 60℃ and a speed of 300rpm for 1.5h, followed by centrifugation at 5000rpm for 12min, washing, drying at 100℃ for 3h, and grinding into powder to obtain modified nano-magnesium oxide.

[0111] The preparation method of the modified biochar is as follows:

[0112] 1000g of granular biochar was added to 12L of a nitric acid solution with a concentration of 18wt.%, and after soaking at a temperature of 18℃ for 12h, activated biochar was obtained, then 1000g of the activated biochar was added to 4000g of a pyrrole solution with a concentration of 5g / L, and impregnation was carried out at 15℃ for 17h, then 20L of an FeCl3 solution with a concentration of 16g / L was added dropwise, and polymerization reaction was carried out at a temperature of 10℃ for 20h, then high-temperature treatment was carried out at 800℃ for 2.5h under an ammonia atmosphere, and then washing was carried out with dilute hydrochloric acid and distilled water in sequence, and drying was carried out at 105℃ for 12h to obtain modified biochar.

[0113] The preparation method of the Fe / Al modified kaolin material is as follows:

[0114] 1000g of ferric nitrate and aluminum isopropoxide were dissolved in 12L of anhydrous ethanol according to a molar ratio of iron in ferric nitrate to aluminum in aluminum isopropoxide of 7:3, ammonia water was added dropwise to adjust the pH to 9.0, and Fe / Al sol was obtained by constant temperature stirring at 50℃ for 3h; 1000g of kaolin was added to 12L of anhydrous ethanol, and a suspension was obtained by ultrasonic dispersion, then 5L of the suspension was added to 1L of the Fe / Al sol, stirring was carried out for 4h, and then standing was carried out for 5h, drying was carried out at 100℃ for 12h, calcination was carried out at 450℃ for 4h, and grinding into powder to obtain the Fe / Al modified kaolin material.

[0115] The preparation method of the defluorination agent for industrial wastewater, comprising the following steps:

[0116] Into a reaction kettle, deionized water was added, stirring was started with a stirring speed of 280 r / min and a stirring temperature of 25℃, sodium carboxymethyl cellulose, chitosan quaternary ammonium salt, potassium sodium tartrate and ferric ammonium sulfate were sequentially added, and stirring was continued for 55 min to obtain a base solution. Then, modified nano magnesium oxide, modified biochar and Fe / Al modified kaolin were sequentially added to the base solution and stirred until uniformly dispersed. Then, a polyaluminum solution with a mass concentration of 8% was added, and stirring was continued for 13 min. Then, a modified palygorskite dispersion liquid was added, and stirring was continued for 13 min. Finally, a hydroxyapatite nano dispersion liquid was added, and stirring was continued for 70 min to obtain a defluorination agent for industrial wastewater.

[0117] Comparative Example 1

[0118] The preparation method was the same as that in Example 5, except that the modified palygorskite dispersion liquid was not added.

[0119] Comparative Example 2

[0120] The preparation method was the same as that in Example 5, except that the modified palygorskite dispersion liquid was replaced by a palygorskite dispersion liquid. The preparation method of the palygorskite dispersion liquid was as follows: palygorskite was ground to 400 mesh, deionized water was added, and high-speed dispersion was carried out at a speed of 8000 r / min for 30 min to obtain a palygorskite dispersion liquid with a solid content of 28%.

[0121] Comparative Example 3

[0122] The preparation method was the same as that in Example 5, except that the hydroxyapatite nano dispersion liquid was not added.

[0123] Comparative Example 4

[0124] The preparation method was the same as that in Example 5, except that the modified nano magnesium oxide was not added.

[0125] Comparative Example 5

[0126] The preparation method was the same as that in Example 5, except that the modified nano magnesium oxide was replaced by nano magnesium oxide.

[0127] Comparative Example 6

[0128] The preparation method was the same as that in Example 5, except that the modified biochar was not added.

[0129] Comparative Example 7

[0130] The preparation method was the same as that in Example 5, except that the modified biochar was replaced by biochar.

[0131] Comparative Example 8

[0132] The preparation method was the same as that in Example 5, except that the Fe / Al modified kaolin was not added.

[0133] Comparative Example 9

[0134] The preparation method is the same as that of Example 5, except that the Fe / Al modified kaolin material is replaced by kaolin.

[0135] Comparative Example 10

[0136] The preparation method is the same as that of Example 5, except that no potassium sodium tartrate is added.

[0137] Comparative Example 11

[0138] The preparation method is the same as that of Example 5, except that no ferric ammonium sulfate is added.

[0139] Comparative Example 12

[0140] The preparation method is the same as that of Example 5, except that no sodium carboxymethyl cellulose is added.

[0141] Comparative Example 13

[0142] The preparation method is the same as that of Example 5, except that no chitosan quaternary ammonium salt is added.

[0143] Comparative Example 14

[0144] The raw materials of the fluoride removal agent for industrial wastewater are the same as those of Example 5.

[0145] The preparation method of the fluoride removal agent for industrial wastewater comprises the following steps:

[0146] Deionized water is added to a reaction kettle, stirring is started, the stirring speed is 280 r / min, the stirring temperature is 25°C, sodium carboxymethyl cellulose, chitosan quaternary ammonium salt, potassium sodium tartrate, ferric ammonium sulfate, modified nano magnesium oxide, modified biochar, Fe / Al modified kaolin material, 8% polyaluminum solution, modified attapulgite dispersion, and hydroxyapatite nano dispersion are added, stirring is carried out for 151 min, and the fluoride removal agent for industrial wastewater is prepared.

[0147] The product performance test is as follows:

[0148] 1. Fluoride removal effect test of the fluoride removal agent

[0149] 1000 mL of industrial wastewater with different fluoride concentrations are taken respectively, the fluoride removal agent prepared in Example 1 is added, 3 mL of polyacrylamide with a concentration of 1‰ is added, stirring is carried out for 10 min, and then standing and precipitation is carried out for 1 h, the concentration of fluoride in the supernatant is detected, and the test results are shown in Table 1.

[0150] Table 1 Fluoride removal effect of the fluoride removal agent prepared in Example 1

[0151]

[0152] From Table 1, it can be seen that the fluoride removal agent prepared in Example 1 can effectively reduce the fluoride concentration in industrial wastewater to below 1 mg / L, which is far below the specified concentration of the national discharge standard, indicating that the fluoride removal agent prepared in the application can effectively remove fluoride in industrial wastewater and significantly reduce the fluoride concentration.

[0153] 2. Stability test of the fluoride removal agent

[0154] The fluoride removal agents prepared in Examples 1-5 were respectively stored at room temperature (25°C) for 12 months, at high temperature (40°C) for 3 months, and at low temperature (5°C) for 3 months. 1000 mL of the same industrial wastewater containing fluoride was taken, and an equal amount of the fluoride removal agent before storage and the fluoride removal agent after storage was added for treatment (1‰ concentration of polyacrylamide 3 mL was additionally added during treatment). The removal rate of fluoride by the fluoride removal agent before storage and the fluoride removal agent after storage was measured, and the fluoride removal retention rate was calculated.

[0155] Fluoride removal retention rate = fluoride removal rate after storage / fluoride removal rate before storage x 100%.

[0156] The test results are shown in Table 2.

[0157] Table 2. Fluoride removal retention rate of the fluoride removal agent prepared in Examples 1-5

[0158]

[0159] From Table 2, it can be seen that the fluoride removal agent prepared in the application has a fluoride removal retention rate of more than 95.1% after being stored at room temperature for 12 months, a fluoride removal retention rate of more than 91.8% after being stored at high temperature (40°C) for 3 months, and a fluoride removal retention rate of more than 95.0% after being stored at low temperature (5°C) for 3 months. It is observed that the fluoride removal agent prepared in the application does not have precipitation or stratification after long-term storage. It is indicated that the fluoride removal agent prepared in the application has excellent storage stability.

[0160] 3. Comparison of fluoride removal effect and stability of the fluoride removal agents prepared in Example 5 and Comparative Examples 1-14

[0161] Fluoride removal effect test: 1000 mL of the same industrial wastewater containing fluoride was taken, and the fluoride removal agents prepared in Example 5 and Comparative Examples 1-14 were added, and 3 mL of 1‰ concentration of polyacrylamide was added. After stirring for 10 min, the supernatant was detected after standing for 1 h.

[0162] Stability test: the fluoride removal agents prepared from example 5 and comparative examples 1-14 were respectively stored at room temperature (25℃) for 12 months, at high temperature (40℃) for 3 months, and at low temperature (5℃) for 3 months. 1000 mL of the same fluoride-containing industrial wastewater was taken, and an equal amount of the fluoride removal agent before storage and the fluoride removal agent after storage was added respectively for treatment (1‰ concentration of polyacrylamide 3 mL was additionally added during treatment). The removal rates of fluoride removal agents before and after storage were measured, and the fluoride removal retention rate was calculated.

[0163] The determination results are shown in Table 3.

[0164] Table 3: Fluoride removal effect and stability results of the fluoride removal agents prepared from example 5 and comparative examples 1-14

[0165]

[0166] As can be seen from Table 3, compared with example 5, the fluoride removal effect of the fluoride removal agents prepared from comparative examples 1-13 all decreased significantly, indicating that the addition of modified attapulgite dispersion, hydroxyapatite nano dispersion, modified nano magnesium oxide, modified biochar, Fe / Al modified kaolin material, potassium sodium tartrate and ferric ammonium sulfate in the present application can effectively improve the fluoride removal effect. At the same time, the stability of the fluoride removal agents prepared from comparative examples 1-13 also decreased to different degrees, indicating that the components in the present application can synergistically build high stability of the fluoride removal agent. The addition of unmodified attapulgite dispersion, nano magnesium oxide, biochar and kaolin in comparative example 2, comparative example 5, comparative example 7 and comparative example 9 will not only lead to the decrease of the fluoride removal effect of the fluoride removal agent, but also reduce the stability of the system, and easy to appear agglomeration and sedimentation during storage. The results of comparative example 1 and comparative example 13 show that the lack of any one of the raw materials of modified attapulgite dispersion and chitosan quaternary ammonium salt cannot synergistically adsorb negatively charged fluoride-containing particles, resulting in the decrease of the fluoride removal capacity. The lack of modified nano magnesium oxide in comparative example 4, the lack of modified biochar in comparative example 6 and the lack of Fe / Al modified kaolin material in comparative example 8 cannot form a ternary composite adsorbent of biochar-magnesium oxide-kaolin material, resulting in the decrease of the adsorption capacity of F⁻. The lack of potassium sodium tartrate in comparative example 10 and the lack of sodium carboxymethyl cellulose in comparative example 12 will lead to the decrease of the stability of the fluoride removal agent and the significant decrease of the fluoride removal performance, indicating that the addition of potassium sodium tartrate and sodium carboxymethyl cellulose in the present application can significantly improve the stability of the fluoride removal agent, ensure the stable play of the fluoride removal performance and prolong the storage period of the product. The fluoride removal effect and stability of the fluoride removal agent prepared from comparative example 14 without following the feeding sequence of the present application are significantly reduced, indicating that the present application adjusts the process of the fluoride removal agent, explores the feeding sequence, solves the problems of component failure and uneven dispersion caused by disordered mixing through the logic of “first constructing a stable base, then introducing active components, and finally strengthening dispersion and synergy”, and can significantly improve the stability of the fluoride removal agent and fully play the fluoride removal performance.

[0167] 4. Comparison of fluoride removal effect and stability of the fluoride removal agent prepared in Example 5 and commercially available fluoride removal agents

[0168] Fluoride removal effect test: 1000 mL of the same fluoride-containing industrial wastewater was taken, and equal amounts of the fluoride removal agent prepared in Example 5, commercially available liquid fluoride removal agent 1 and commercially available liquid fluoride removal agent 2 were added, respectively. Then, 3 mL of polyacrylamide with a concentration of 1 ‰ was added, and after stirring for 10 min, the supernatant was detected after standing for 1 h.

[0169] Stability test: the fluoride removal agent prepared in Example 5, commercially available liquid fluoride removal agent 1 and commercially available liquid fluoride removal agent 2 were stored at room temperature (25℃) for 12 months, at high temperature (40℃) for 3 months and at low temperature (5℃) for 3 months, respectively. 1000 mL of the same fluoride-containing industrial wastewater was taken, and equal amounts of the fluoride removal agent before storage and the fluoride removal agent after storage were added for treatment (3 mL of polyacrylamide with a concentration of 1 ‰ was additionally added during the treatment), the removal rates of fluoride removal agents before and after storage were determined, and the fluoride removal retention rates were calculated.

[0170] The determination results are shown in Table 4.

[0171] Table 4 Fluoride removal effect and stability results of the fluoride removal agent prepared in Example 5, commercially available liquid fluoride removal agent 1 and commercially available liquid fluoride removal agent 2

[0172]

[0173] As can be seen from Table 4, compared with commercially available liquid fluoride removal agents, the fluoride concentration in the supernatant after treating the industrial wastewater with the fluoride removal agent of the present application is significantly reduced, and the fluoride removal retention rate is significantly increased. After long-term storage, it is observed that the commercially available liquid fluoride removal agents all have precipitation and stratification phenomenon, while the fluoride removal agent of the present application does not have precipitation and stratification phenomenon. Therefore, compared with commercially available liquid fluoride removal agents, the fluoride removal agent of the present application has a significant fluoride removal effect and excellent stability.

Claims

1. A defluoridating agent for industrial wastewater, characterized in that... It is made from the following raw materials in parts by weight: 3-7 parts sodium carboxymethyl cellulose, 20-25 parts modified attapulgite dispersion, 30-35 parts polyaluminum solution, 10-15 parts hydroxyapatite nano dispersion, 1-3 parts chitosan quaternary ammonium salt, 0.5-2 parts ferric ammonium sulfate, 1-3 parts potassium sodium tartrate, 1-3 parts modified nano magnesium oxide, 2-4 parts modified biochar, 1-3 parts Fe / Al modified kaolin material, and 70-90 parts deionized water; The modified nano-magnesium oxide is prepared by dissolving rare earth salts and ligands in deionized water to obtain a rare earth complex solution; adding nano-magnesium oxide to anhydrous ethanol and ultrasonically dispersing it to obtain a nano-magnesium oxide suspension; then adding the rare earth complex solution dropwise to the nano-magnesium oxide suspension, stirring at a constant temperature, centrifuging and washing, drying, and grinding into powder to obtain modified nano-magnesium oxide. The modified biochar is prepared by adding granular biochar to a nitric acid solution and soaking it to obtain activated biochar. Then, the activated biochar is added to a pyrrole solution for impregnation, FeCl3 solution is added dropwise to carry out a polymerization reaction, and then it is treated at high temperature under an ammonia atmosphere. It is then washed with dilute hydrochloric acid and distilled water in sequence and dried to obtain modified biochar. The method for preparing modified attapulgite dispersion is as follows: attapulgite is crushed, soaked in sulfuric acid solution, washed, and dried to obtain acidified attapulgite; then the acidified attapulgite is mixed with hexadecyltrimethylammonium bromide solution, stirred and reacted, filtered to obtain modified attapulgite; deionized water is added to the modified attapulgite and dispersed at high speed to obtain modified attapulgite dispersion.

2. The defluoridating agent for industrial wastewater according to claim 1, characterized in that... The solid content of the modified attapulgite dispersion is 20-30%, the mass concentration of the polyaluminum solution is 8-12%, and the solid content of the hydroxyapatite nano-dispersion is 10-15%.

3. The defluoridating agent for industrial wastewater according to claim 1, characterized in that... The preparation method of hydroxyapatite nano-dispersion is to dissolve calcium chloride and diammonium hydrogen phosphate in deionized water, add ammonia water to adjust the pH value under stirring, carry out hydrothermal reaction, cool, centrifuge, and wash to obtain nano-hydroxyapatite; add deionized water to nano-hydroxyapatite, then add sodium hexametaphosphate, and disperse by ultrasonication to obtain hydroxyapatite nano-dispersion.

4. The defluoridating agent for industrial wastewater according to claim 1, characterized in that... The molar ratio of rare earth salt to ligand is 1:2-3, the mass ratio of rare earth salt to deionized water is 1:50-100, the rare earth salt is lanthanum nitrate or cerium sulfate, and the ligand is citric acid; the concentration of the nano magnesium oxide suspension is 5-10 g / L; the ratio of nano magnesium oxide to rare earth complex solution in the nano magnesium oxide suspension is 1:10-20, where nano magnesium oxide is expressed in g and rare earth complex solution is expressed in mL.

5. The defluoridating agent for industrial wastewater according to claim 1, characterized in that... The concentration of nitric acid solution is 15-20 wt.%; the ratio of biochar to nitric acid solution is 1:10-15, with biochar measured in g and nitric acid solution measured in mL; the soaking temperature is 15-20℃, and the soaking time is 10-12 h; the concentration of pyrrole solution is 5-20 g / L; the mass ratio of activated biochar to pyrrole solution is 1:3-5; the impregnation temperature is 10-20℃, and the impregnation time is 15-20 h; the ratio of activated biochar to FeCl3 solution is 1:20-30, with activated biochar measured in g and FeCl3 solution measured in mL; the concentration of FeCl3 solution is 14-16 g / L; the polymerization reaction temperature is 10-12℃, and the polymerization reaction time is 20-22 h; the high-temperature treatment temperature is 800-900℃, and the high-temperature treatment time is 2-3 h; the drying temperature is 100-110℃, and the drying time is 10-12 h.

6. The defluorinating agent for industrial wastewater according to claim 1, characterized in that... The preparation method of Fe / Al modified kaolin material includes the following steps: (A) Dissolve ferric nitrate and aluminum isopropoxide in anhydrous ethanol, add ammonia to adjust the pH, and stir at a constant temperature to obtain Fe / Al sol; (B) Kaolin was added to anhydrous ethanol and ultrasonically dispersed to obtain a suspension. The suspension was then added to Fe / Al sol, stirred, allowed to stand, dried, calcined, and ground to obtain Fe / Al modified kaolin material.

7. A method for preparing a defluorinating agent for industrial wastewater according to any one of claims 1-6, characterized in that... Includes the following steps: (1) Sodium carboxymethyl cellulose, chitosan quaternary ammonium salt, potassium sodium tartrate and ferric ammonium sulfate were added to deionized water in sequence and stirred to prepare a base solution; (2) Add modified nano-magnesium oxide, modified biochar and Fe / Al modified kaolin material to the base solution in sequence, and stir until evenly dispersed; (3) Then add polyaluminum solution, modified attapulgite dispersion and hydroxyapatite nano dispersion in sequence, and stir continuously to obtain defluorinating agent for industrial wastewater.

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