A method for preparing a defluorinating agent and a method for treating fluoride-containing boric acid wastewater

Abstract

This invention discloses a method for preparing a defluorinating agent and a method for treating fluoroboric acid-containing wastewater. The preparation method of the defluorinating agent involves: mixing and dissolving aluminum salt, iron salt, and rare earth metal salt solutions to obtain a mixed metal salt solution; slowly adding sodium carbonate solution dropwise to the mixed metal salt solution to adjust the solution to acidity; reacting with stirring to obtain a ternary metal salt solution; mixing the ternary metal salt solution with a *Ulva lactuca* polysaccharide solution; adjusting the solution to weak alkalinity; and reacting under heating conditions to obtain the defluorinating agent. The method for treating fluoroboric acid-containing wastewater involves: adjusting the pH of the wastewater to weak alkalinity; adding the aforementioned defluorinating agent; reacting to decompose fluoroboric acid and simultaneously removing fluoride ions; then adding a flocculant for flocculation; and allowing the solution to settle. The alkaline defluorinating agent of this invention can make the defluorination reaction tank neutral to slightly alkaline, allowing fluoroboric acid to be further decomposed into boric acid and fluoride ions, resulting in sufficient degradation of fluoroboric acid. This invention can deeply remove fluoride and fluoroboric acid that is difficult to remove through coagulation and sedimentation from wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing a wastewater treatment agent and a method for treating wastewater. BACKGROUND

[0002] Fluorine is a widely used chemical raw material in modern industry, often in the form of hydrofluoric acid for various cleaning processes. In addition, as a stable compound, fluoroboric acid (HBF4) is widely used in the electronics and electroplating industries due to its stable performance and fast deposition rate. For example, in the production process of semiconductors, fluoroboric acid is often used for the surface cleaning of silicon; in the electroplating industry, fluoroboric acid can be used not only for cleaning before metal surface and alloy electroplating, but also as an important component of electroplating solution; in the electrolytic industry, fluoroboric acid can be used for the electrolytic refining of aluminum, as a stabilizer for diazonium salts, etc. In recent years, with the rapid development of industry, the amount of fluoroboric acid-containing wastewater has increased. Since fluoroboric acid has strong toxicity, excessive exposure of fluoroboric acid salt will be toxic to humans and animals, causing increasingly serious environmental pollution, so the fluoroboric acid-containing wastewater generated in industry needs to be thoroughly and effectively removed.

[0003] However, there is still a large gap in the research on the advanced treatment of fluoroboric acid wastewater. Patent CN105600977A discloses a method for treating fluoroboric acid wastewater generated in an etching process, which realizes the removal of fluorine through steps such as "neutralization - first supernatant separation - lime reaction - second supernatant separation - coagulation - third supernatant separation". This method only removes the fluorine ion to below 15 ppm, which cannot meet the current fluorine emission standard (The Surface Water Environmental Quality Standard (GB 3838-2002) stipulates that the fluorine content of surface water I, II, III class should be less than 1.0 mg / L, and the fluorine content of surface water IV, V class should be less than 1.5 mg / L.). At the same time, after the dissociation of fluoroboric acid into boric acid in this method, the boric acid is not further removed, and a large amount of boron elements are contained in the drainage, causing further harm to the environment. Patent CN102336460B provides a hydrolysis agent for treating fluoroboric acid-containing wastewater and its application, which reduces the fluoroboric acid concentration to below 10 mg / L by using aluminum salt and cerium salt. Similarly, the boric acid generated after the hydrolysis of fluoroboric acid is not further treated, causing further harm to the environment. Therefore, in the current treatment methods for fluoroboric acid wastewater, the removal of fluorine elements is mainly concerned, and the removal of boron elements is ignored. Therefore, it is crucial to develop a new advanced treatment method for fluoroboric acid-containing wastewater.

[0004] Currently, there are the following problems in the treatment of fluoroboric acid wastewater: (1) fluoroboric acid wastewater contains various fluorine and boron compounds, including tetrafluoroboric acid (HBF4), boron trifluoride (BF3), boric acid (H3BO3), fluoroboric acid ion (BF4 - ) and so on. Unlike fluorine ions, BF4 -It is difficult to remove fluoride, fluoroboric acid, boric acid and other substances by calcium salt precipitation method, and it is difficult to remove them by reaction with aluminum and iron flocculants, so a treatment method for removing fluoride, fluoroboric acid, boric acid and other substances needs to be developed.(2) In the currently disclosed fluoroboric acid wastewater treatment method, the concentration of fluorine ions and fluoroboric acid cannot be reduced to below 1.5 mg / L, and there is a problem that fluoroboric acid wastewater is difficult to remove deeply, so a deep treatment method needs to be developed to fill this research gap.(3) In the currently disclosed fluoroboric acid wastewater treatment method, fluoroboric acid can be hydrolyzed into fluorine ions and boric acid, but the generated boric acid is often ignored and cannot be effectively removed, and the exposure of excessive boric acid will be toxic to humans and animals and plants, causing more serious environmental hazards, so after removing fluoroboric acid and fluoride, a process section for effectively removing boric acid needs to be developed. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of a defluorination agent with good defluorination and boric acid removal effect.

[0006] The second purpose of the present application is to provide a method for treating fluorine-containing fluoroboric acid wastewater.

[0007] Technical scheme: The preparation method of the defluorination agent comprises the following steps:

[0008] (A1) A mixed metal salt solution is obtained by mixing and dissolving aluminum salt, iron salt and rare earth metal salt solution, sodium carbonate solution is slowly dropped into the mixed metal salt solution, the solution is adjusted to be acidic, and the reaction is carried out by stirring to obtain a ternary metal salt solution;

[0009] (A2) The stone oyster polysaccharide solution is obtained by dissolving the stone oyster polysaccharide, the ternary metal salt solution is mixed with the stone oyster polysaccharide solution, the solution is adjusted to be weakly alkaline, and the reaction is carried out under heating conditions to obtain a ternary metal modified stone oyster polysaccharide solution with aluminum-iron-rare earth metal cross-linking ligand, that is, the defluorination agent is prepared.

[0010] In step (A1), the molar ratio of aluminum, rare earth metal and iron in the ternary metal salt solution is 6-8:2-4:1.

[0011] In step (A1), the pH value of the solution is 2-3, and the concentration of the sodium carbonate solution is 0.5-1 mol / L.

[0012] In step (A1), the aluminum salt is at least one of polyaluminum chloride and polyaluminum sulfate; the iron salt is at least one of polyaluminum ferric chloride, polyaluminum ferric sulfate and polyferric chloride; and the rare earth metal salt is at least one of lanthanum chloride, cerium chloride, neodymium chloride, yttrium chloride and scandium chloride.

[0013] In step (A2), the volume ratio of the ternary metal salt solution to the stone oyster polysaccharide solution is 1:2-3.

[0014] In step (A2), the pH value of the solution is 7-9; preferably, a 10% NaOH solution is added to adjust the pH value.

[0015] In step (A2), the concentration of the Ulva pertusa polysaccharide solution is 1-2 g / L.

[0016] In step (A2), the heating temperature is 60-80°C; the stirring rate is 150-200 rpm; and the reaction time is 2-4 h.

[0017] In step (A2), the method for treating fluorine-containing boric acid wastewater by using the defluorination agent prepared by the above method comprises the following steps:

[0018] (B1) adjusting the fluorine-containing boric acid wastewater to be treated to be weakly alkaline;

[0019] (B2) adding the defluorination agent to decompose fluoroboric acid and remove fluoride ions synchronously through reaction;

[0020] (B3) adding a flocculating agent to the wastewater after defluorination to perform flocculation, and then standing and settling.

[0021] In step (B1), the pH value in the adjusting tank is adjusted to 7-8; preferably, a 30% NaOH solution is added to adjust the pH value.

[0022] In step (B2), the defluorination agent is added in an amount of 500-2000 ppm, and the reaction time is 20-30 min.

[0023] In step (B3), the pH value of the solution is adjusted to 6.5-7.5; preferably, a 30% NaOH solution is added to the flocculation tank to adjust the pH value.

[0024] In step (B3), the supernatant obtained after standing and settling is introduced into the defluorination and deboronization resin for adsorption; preferably, the supernatant is introduced into a defluorination and deboronization resin tower for adsorption; the adsorption time is preferably 15-20 h; after the resin is completely saturated, the fluoride ion concentration, fluoroboric acid concentration and boric acid concentration of the effluent are determined.

[0025] The defluorination and deboronization resin is prepared by the following steps:

[0026] (C1) dissolving cellulose and performing ultrasonic dispersion to form a viscous cellulose suspension;

[0027] (C2) mixing the cellulose suspension with an ammonium persulfate solution to perform a reaction under heating to obtain a carboxylated cellulose solution, and performing centrifugation, washing and drying to form a carboxylated cellulose matrix;

[0028] (C3) mixing and dissolving carboxylated cellulose and hexamino benzene (3 hydrochloride) in a solvent to form a viscous carboxylated cellulose-hexamino benzene suspension; adding 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N,N-diisopropyl ethylamine as condensing agents into the carboxylated cellulose-hexamino benzene suspension respectively, and adding 1-hydroxybenzotriazole as an activating agent, and performing condensation reaction and functional group activation under stirring; after the reaction is completed, centrifugation and washing are performed to obtain amino-functionalized cellulose-based balls;

[0029] (C4) adding methanol, gluconic acid solution and rare earth metal salt solution into the amino-functionalized cellulose-based balls, mixing thoroughly, adjusting the solution to be acidic, and performing reaction under heating to obtain rare earth metal-amino polyol chelate resin balls.

[0030] In step (C2), the volume ratio of the cellulose suspension to the ammonium persulfate solution is 0.6-1; the reaction temperature is 60-80°C; the time is 12-20h; and the stirring rate is 300-500rpm.

[0031] In step (C2), the obtained carboxylated cellulose solution is cooled by ice water bath before centrifugation.

[0032] In step (C3), the mass ratio of carboxylated cellulose to hexamino benzene (3 hydrochloride) is 1:1-2; the mass ratio of the carboxylated cellulose-hexamino benzene suspension to 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride is 100-150:1;

[0033] The mass ratio of the carboxylated cellulose-hexamino benzene suspension to N,N-diisopropyl ethylamine is 100-150:1; and the mass ratio of the carboxylated cellulose-hexamino benzene suspension to 1-hydroxybenzotriazole is 100-150:1.

[0034] In step (C3), the reaction temperature is room temperature, the reaction time is 12-24h, and the stirring rate is 300-500rpm.

[0035] In step (C4), the heating temperature is 60-80°C; and the solution pH is 2-5.

[0036] In step (C4), the volume ratio of the amino-functionalized cellulose-based balls, methanol, gluconic acid solution and lanthanum chloride solution is 2-5:0.5-1:1-2:1.

[0037] In step (C4), the obtained rare earth metal@amino polyol chelating resin is packed into a column and passed through the column with ethanol / water solution and deionized water respectively. The column passing rate is set to 2-3 BV. After centrifugation, the resin is freeze-dried under vacuum to form the fluorine-free boron chelating resin of the present invention, namely, rare earth metal@amino polyol chelating resin.

[0038] When the supernatant is introduced into the boron and fluoride removal resin for adsorption saturation, it needs to be regenerated. The regeneration method is as follows: first, elute with 2%-5% hydrochloric acid solution at a rate of 2-3 BV, and then regenerate with 2%-5% liquid alkali solution at a rate of 2-3 BV.

[0039] Invention Principle: Ulva polysaccharide contains numerous -OH and -COOH active sites. The -COOH groups provide conjugated coordination sites for metal ions. Aluminum ions, iron ions, and rare earth metal ions can form Al-O / Fe-O / MO structures through metal hydrolysis, and can also form octahedral metal conjugated structures with the -COOH groups in Ulva polysaccharide, namely AlO6 / FeO6 / MO6, as shown in the following structural formulas, where M represents a rare earth metal. This forms a stable gel network, allowing for the efficient removal of fluoride ions in wastewater through specific adsorption, ion exchange, complexation precipitation, and net trapping. Furthermore, the polyhydroxyl groups in Ulva polysaccharide can bind to other fluoride and boron pollutants in wastewater (such as tetrafluoroboric acid (HBF4) and boric acid (H3BO3)) through hydrogen bonds and van der Waals forces, achieving a synergistic removal of multiple pollutants.

[0040]

[0041]

[0042] The chelating resin of the present invention achieves amino functionalization through the condensation reaction of carboxylated cellulose and hexaaminobenzene (3-hydrochloride). Compared with the long-chain polyamines commonly used for amino functionalization, hexaaminobenzene (hydrochloride) with benzene ring contains conjugated π bonds, thereby enhancing the molecular stability and reactivity of the condensate, making it less prone to chain scission and more likely to undergo amino substitution reactions.

[0043] The chelating resin is loaded with polyhydroxyl groups through a reaction with gluconic acid. Boric acid (H3BO3) is a Lewis acid that can coordinate bonds to form B(OH)4 in water. - Therefore, under neutral or weakly alkaline conditions, i.e., pH 7-9, the B(OH)3 and B(OH)4 in the wastewater... - These substances can combine with the cis-dihydroxy functional groups on the functional groups in the form of hydrogen bonds, and undergo a complexation reaction, thereby efficiently removing boron-containing compounds from wastewater.

[0044] The chelating resin is simultaneously loaded with rare earth metals because the amino-functionalized cellulose spheres of this invention contain two types of amine groups, primary and secondary amines (i.e., primary and secondary amine groups). Rare earth metals can coordinate with primary and secondary amine groups. The nitrogen of the primary and secondary amine groups shares electron pairs with the rare earth metals to form metal complexes, resulting in rare earth adsorption (MN coordinate bond, where M is a rare earth metal element). When rare earth metals are loaded, fluoride ions in wastewater can combine with rare earth metal ions on the functional groups through electrostatic adsorption or ionic bonds, thereby further removing fluoride and achieving ultra-low concentration fluoride removal.

[0045] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0046] (1) Under a pH of 7-9, the defluorinating agent of the present invention can promote the deprotonation of -COOH under weakly alkaline conditions, thereby enhancing the formation of cross-linked coordination structures such as AlO6 / FeO6 / MO6. On the other hand, the alkaline defluorinating agent can make the defluorination reaction tank neutral to alkaline. Fluoroboric acid that is not completely decomposed in the hydrolysis tank can be further decomposed into boric acid and fluoride ions in the defluorination reaction tank under alkaline conditions. Fluoroboric acid can be fully degraded after passing through the hydrolysis tank and the defluorination reaction tank. (2) The conjugated coordination of Ulva polysaccharide and metal ions can form closed gel flocs with multiple cross-linked ligand regions, achieving strong adsorption and netting of pollutants, thereby encapsulating pollutants in the gel flocs, inhibiting the secondary release of fluoride compounds, and avoiding the re-dissolution of pollutants. (3) In addition to the conjugated ligands, the defluorinating agent prepared in the present invention also contains a small amount of free metal ions, and free Al 3+ / Fe 3+ / M 3+ Metal ions can promote floc growth through metal hydrolysis, complexation precipitation, etc., making the formed flocs denser, greatly improving settling performance, and avoiding problems such as the floating of fluoride-containing sludge; (4) The fluoride-removing boron chelating resin is loaded with polyhydroxyl groups and rare earth metals at the same time, which can remove boron-containing compounds and fluoride ions in wastewater at the same time. At the same time, the pH of the wastewater entering the resin tower is in a neutral to alkaline state, which is conducive to the complexation reaction of boron-containing compounds and hydroxyl groups, which are combined in the form of hydrogen bonds and undergo dehydrogenation reaction. The removed hydrogen ions can further reduce the pH during the reaction process. When the reaction pH drops to a neutral to weakly acidic state, it is conducive to the electrostatic adsorption and chemical bonding of fluoride ions and rare earth metals, resulting in the reaction always occurring in the forward direction. (5) Using the fluoride removal agent and fluoride-removing boron chelating resin of the present invention to treat wastewater can deeply remove fluoride and fluoroboric acid that is difficult to remove by coagulation and sedimentation. Attached Figure Description

[0047] Figure 1 This is a diagram illustrating the preparation mechanism of the rare earth metal@amino polyol chelating resin of the present invention. Detailed Implementation

[0048] The present invention will now be described in further detail.

[0049] Example 1

[0050] A method for preparing a highly efficient defluorinating agent includes the following steps:

[0051] (1) A ternary mixed metal salt solution was prepared using aluminum chloride hexahydrate (AlCl3·6H2O), ferric chloride hexahydrate (FeCl3·6H2O), and lanthanum chloride heptahydrate (LaCl3·7H2O) as precursors. Specifically, 10g of aluminum chloride hexahydrate (AlCl3·6H2O), 1.6g of ferric chloride hexahydrate (FeCl3·6H2O), and 6.6g of lanthanum chloride heptahydrate (LaCl3·7H2O) were dissolved in 400mL of deionized water. Then, 1mol / L Na2CO3 solution was slowly added dropwise to the mixed metal salt solution to fully chelate the mixture. The pH of the solution was adjusted to 2.5, and the solution was stirred at room temperature for 2 hours at a stirring speed of 200rpm. The solution was then diluted to 500mL to obtain a ternary metal salt solution with an aluminum-lanthanum-iron molar ratio of 7:3:1.

[0052] (2) Dissolve 1g of Ulva polysaccharide in 1L of deionized water to prepare a Ulva polysaccharide solution with a concentration of 1g / L. Mix the ternary metal salt solution obtained in step (1) with the Ulva polysaccharide solution at a volume ratio of 1:2.5. Add 10% NaOH solution dropwise at 70℃ and 150rpm to adjust the pH to 8.0. Set the reaction time to 2h to obtain the high-efficiency defluorination agent of the present invention.

[0053] Example 2

[0054] A method for preparing a highly efficient defluorinating agent includes the following steps:

[0055] (1) A ternary mixed metal salt solution was prepared using aluminum chloride hexahydrate (AlCl3·6H2O), ferric chloride hexahydrate (FeCl3·6H2O), and lanthanum chloride heptahydrate (LaCl3·7H2O) as precursors. Specifically, 10g of aluminum chloride hexahydrate (AlCl3·6H2O), 1.6g of ferric chloride hexahydrate (FeCl3·6H2O), and 6.6g of lanthanum chloride heptahydrate (LaCl3·7H2O) were dissolved in 400mL of deionized water. Then, 1mol / L Na2CO3 solution was slowly added dropwise to the mixed metal salt solution to fully chelate the mixture. The pH of the solution was adjusted to 2, and the solution was stirred at room temperature for 2h at a stirring speed of 200rpm. The solution was then diluted to 500mL to obtain a ternary metal salt solution with an aluminum-lanthanum-iron molar ratio of 7:3:1.

[0056] (2) Dissolve 1g of Ulva polysaccharide in 1L of deionized water to prepare a Ulva polysaccharide solution with a concentration of 1g / L. Mix the ternary metal salt solution obtained in step (1) with the Ulva polysaccharide solution at a volume ratio of 1:2.5. Add 10% NaOH solution dropwise at 60℃ and 150rpm to adjust the pH to 8.0. Set the reaction time to 2h to obtain the high-efficiency defluorination agent of the present invention.

[0057] Example 3

[0058] A method for preparing a highly efficient defluorinating agent includes the following steps:

[0059] (1) A ternary mixed metal salt solution was prepared using aluminum chloride hexahydrate (AlCl3·6H2O), ferric chloride hexahydrate (FeCl3·6H2O), and lanthanum chloride heptahydrate (LaCl3·7H2O) as precursors. Specifically, 10g of aluminum chloride hexahydrate (AlCl3·6H2O), 1.6g of ferric chloride hexahydrate (FeCl3·6H2O), and 6.6g of lanthanum chloride heptahydrate (LaCl3·7H2O) were dissolved in 400mL of deionized water. Then, 1mol / L Na2CO3 solution was slowly added dropwise to the mixed metal salt solution to fully chelate the mixture. The pH of the solution was adjusted to 3, and the solution was stirred at room temperature for 2h at a stirring speed of 300rpm. The solution was then diluted to 500mL to obtain a ternary metal salt solution with an aluminum-lanthanum-iron molar ratio of 7:3:1.

[0060] (2) Dissolve 1g of Ulva polysaccharide in 1L of deionized water to prepare a Ulva polysaccharide solution with a concentration of 1g / L. Mix the ternary metal salt solution obtained in step (1) with the Ulva polysaccharide solution at a volume ratio of 1:2.5. Add 10% NaOH solution dropwise at 80℃ and 200rpm to adjust the pH to 8.0. Set the reaction time to 2h to obtain the high-efficiency defluorination agent of the present invention.

[0061] Example 4

[0062] A method for preparing a fluoride-removing boron resin includes the following steps:

[0063] (1) Dissolve 10g of cellulose in 100mL of deionized water and place it in an ultrasonic reactor. The reaction time is 30min to form a viscous cellulose suspension.

[0064] (2) Add the cellulose suspension formed in step (1) and 1 mol / L ammonium persulfate solution (APS) to a 500 mL three-necked flask to oxidize cellulose. The volume ratio is set to 1:1. Stir at 60 °C for 12 h at a stirring rate of 300 rpm to form a carboxylated cellulose solution.

[0065] (3) After the reaction is complete, the carboxylated cellulose solution is placed in an ice-water bath to cool down, centrifuged at 4500 rpm, the supernatant is discarded, and washed with deionized water. The centrifugation-washing steps are repeated 3 times, and then the carboxylated cellulose matrix is ​​formed by vacuum freeze drying.

[0066] (4) The carboxylated cellulose formed in step (3) is mixed with hexaaminobenzene (3 hydrochloride) at a mass ratio of 1:2 and dissolved in 100 mL of deionized water. The mixture is then placed in an ultrasonic reactor and ultrasonically treated for 30 min to form a viscous carboxylated cellulose-hexaaminobenzene suspension.

[0067] (5) Add 5 mM 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCl) and 5 mM N,N-diisopropylethylamine (DIPEA) as condensing agents and 5 mM 1-hydroxybenzotriazole (HOBt) as activating agent to carboxylated cellulose-hexaaminobenzene suspension respectively to carry out condensation reaction and functional group activation. Stir the reaction at room temperature for 24 h at a stirring rate of 300 rpm.

[0068] (6) After the reaction is complete, centrifuge at 4500 rpm and wash with deionized water 3 times to form amino-functionalized cellulose spheres.

[0069] (7) Place 200 mL of the amino-functionalized cellulose spheres obtained in step (6) into a 500 mL three-necked flask, and add 50 mL of methanol, 100 mL of 1 mol / L gluconic acid solution and 100 mL of 0.5 mol / L lanthanum chloride solution to it. Mix thoroughly, adjust the reaction temperature to 60 °C, the reaction pH to 2.5, and stir and reflux at 150 rpm for 24 h.

[0070] (8) After the reaction is completed, cool to room temperature, pack the resin balls obtained in step (7) into a column, pass them through the column three times with ethanol / water solution and deionized water in a volume ratio of 1:1, set the column pass rate to 2 BV, then centrifuge at 4500 rpm, and freeze dry under vacuum to form the fluorine-free boron chelating resin, namely La@amino polyol chelating resin, as described in this invention.

[0071] The preparation mechanism of the rare earth metal@amino polyol chelating resin of this invention is as follows: Figure 1 As shown.

[0072] Example 5

[0073] A method for preparing a fluoride-removing boron resin includes the following steps:

[0074] (1) Dissolve 10g of cellulose in 100mL of deionized water and place it in an ultrasonic reactor. The reaction time is 30min to form a viscous cellulose suspension.

[0075] (2) Add the cellulose suspension formed in step (1) and 1 mol / L ammonium persulfate solution (APS) to a 500 mL three-necked flask to oxidize cellulose. The volume ratio is set to 1:1. Stir at 60 °C for 12 h at a stirring rate of 300 rpm to form a carboxylated cellulose solution.

[0076] (3) After the reaction is complete, the carboxylated cellulose solution is placed in an ice-water bath to cool down, centrifuged at 4500 rpm, the supernatant is discarded, and washed with deionized water. The centrifugation-washing steps are repeated 3 times, and then the carboxylated cellulose matrix is ​​formed by vacuum freeze drying.

[0077] (4) The carboxylated cellulose formed in step (3) is mixed with hexaaminobenzene (3 hydrochloride) at a mass ratio of 1:2 and dissolved in 100 mL of deionized water. The mixture is then placed in an ultrasonic reactor and ultrasonically treated for 30 min to form a viscous carboxylated cellulose-hexaaminobenzene suspension.

[0078] (5) Add 5 mM 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCl) and 5 mM N,N-diisopropylethylamine (DIPEA) as condensing agents and 5 mM 1-hydroxybenzotriazole (HOBt) as activating agent to carboxylated cellulose-hexaaminobenzene suspension respectively to carry out condensation reaction and functional group activation. Stir the reaction at room temperature for 24 h at a stirring rate of 300 rpm.

[0079] (6) After the reaction is complete, centrifuge at 4500 rpm and wash with deionized water 3 times to form amino-functionalized cellulose spheres.

[0080] (7) Place 200 mL of the amino-functionalized cellulose spheres obtained in step (6) into a 500 mL three-necked flask, and add 50 mL of methanol, 100 mL of 1 mol / L gluconic acid solution and 100 mL of 0.5 mol / L lanthanum chloride solution to it. Mix thoroughly, adjust the reaction temperature to 60 °C, the reaction pH to 2, and stir and reflux at 150 rpm for 24 h.

[0081] (8) After the reaction is completed, cool to room temperature, pack the resin balls obtained in step (7) into a column, pass them through the column with ethanol / water solution and deionized water in a volume ratio of 1:1, set the column pass rate to 2 BV, centrifuge at 4500 rpm, and freeze dry under vacuum to form the fluorine-free boron chelating resin, namely La@amino polyol chelating resin, as described in this invention.

[0082] Example 6

[0083] A method for preparing a fluoride-removing boron resin includes the following steps:

[0084] (1) Dissolve 10g of cellulose in 100mL of deionized water and place it in an ultrasonic reactor. The reaction time is 30min to form a viscous cellulose suspension.

[0085] (2) Add the cellulose suspension formed in step (1) and 1 mol / L ammonium persulfate solution (APS) to a 500 mL three-necked flask to oxidize cellulose. The volume ratio is set to 1:1. Stir at 60 °C for 12 h at a stirring rate of 300 rpm to form a carboxylated cellulose solution.

[0086] (3) After the reaction is complete, the carboxylated cellulose solution is placed in an ice-water bath to cool down, centrifuged at 4500 rpm, the supernatant is discarded, and washed with deionized water. The centrifugation-washing steps are repeated 3 times, and then the carboxylated cellulose matrix is ​​formed by vacuum freeze drying.

[0087] (4) The carboxylated cellulose formed in step (3) is mixed with hexaaminobenzene (3 hydrochloride) at a mass ratio of 1:2 and dissolved in 100 mL of deionized water. The mixture is then placed in an ultrasonic reactor and ultrasonically treated for 30 min to form a viscous carboxylated cellulose-hexaaminobenzene suspension.

[0088] (5) Add 5 mM 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCl) and 5 mM N,N-diisopropylethylamine (DIPEA) as condensing agents and 5 mM 1-hydroxybenzotriazole (HOBt) as activating agent to carboxylated cellulose-hexaaminobenzene suspension respectively to carry out condensation reaction and functional group activation. Stir the reaction at room temperature for 24 h at a stirring rate of 300 rpm.

[0089] (6) After the reaction is complete, centrifuge at 4500 rpm and wash with deionized water 3 times to form amino-functionalized cellulose spheres.

[0090] (7) Place 200 mL of the amino-functionalized cellulose spheres obtained in step (6) into a 500 mL three-necked flask, and add 50 mL of methanol, 100 mL of 1 mol / L gluconic acid solution and 100 mL of 0.5 mol / L lanthanum chloride solution to it. Mix thoroughly, adjust the reaction temperature to 60 °C, the reaction pH to 5, and stir and reflux at 150 rpm for 24 h.

[0091] (8) After the reaction is completed, cool to room temperature, pack the resin balls obtained in step (7) into a column, pass them through the column three times with ethanol / water solution and deionized water in a volume ratio of 1:1, and set the column pass rate to 3 BV. Then centrifuge at 4500 rpm and freeze dry under vacuum to form the fluorine-free boron chelating resin, namely La@amino polyol chelating resin, as described in this invention.

[0092] Example 7

[0093] The defluorinating agent prepared in Example 1 and the defluorinating boron resin prepared in Example 4 were applied to the wastewater containing fluoroboric acid from a semiconductor factory in Wuxi. The concentration of fluoroboric acid was 150 ppm, the concentration of boric acid was 40 ppm, the concentration of fluoride ions was 20 ppm, and the pH was 2.37.

[0094] A method for treating the above-mentioned fluorinated boric acid wastewater includes the following steps:

[0095] (1) The fluoroboric acid-containing wastewater is collected through the raw water pipeline and enters the wastewater collection tank. The water quality and quantity are uniformly mixed by the agitator in the tank, and then it flows into the fluoroboric acid hydrolysis tank by gravity.

[0096] (2) In the fluoroboric acid hydrolysis tank, 30% NaOH by mass fraction is added to adjust the pH value of the tank to 7.5 by liquid alkali dosing pump. After reacting for 30 minutes, the solution flows by gravity to the defluorination reaction tank.

[0097] (3) In the defluorination reaction tank, 1500ppm of defluorination agent is added to it through the defluorination agent dosing metering pump, and after stirring and reacting for 30 minutes, it flows into the flocculation tank by gravity.

[0098] (4) In the flocculation tank, acid and alkali are added to the flocculation tank by sulfuric acid dosing pump and liquid alkali dosing pump to adjust the pH of the wastewater in the tank to 7.5. At the same time, 5ppm 1‰ PAM is added to the flocculation tank to carry out flocculation reaction. After flocculation for 30 minutes, the wastewater enters the sedimentation tank.

[0099] (5) After settling in the sedimentation tank for 60 min, the supernatant was taken and the concentration of fluoroboric acid was measured to be 0.1 ppm, the concentration of fluoride was 1.48 ppm, and the SS of the effluent was 125 mg / L.

[0100] (6) The effluent from the sedimentation tank enters the defluorination and boron resin tower filled with 100ml of resin from top to bottom. The inner diameter of the defluorination and boron resin tower is 2cm, the height is 150cm, the flow rate through the column is 5BV, and after running for 20h, it enters the discharge tank. The concentration of fluoroboric acid in the discharge tank is measured to be 0.06ppm, the concentration of fluorine is 0.43ppm, and the concentration of boron is 0.2ppm.

[0101] Example 8

[0102] The defluorinating agent prepared in Example 1 and the defluorinating boron resin prepared in Example 4 were applied to the wastewater containing fluoroboric acid from an electroplating plant in Jiangsu Province. The concentration of fluoroboric acid was 125 ppm, the concentration of boric acid was 62 ppm, the concentration of fluoride ions was 15 ppm, and the pH was 2.63.

[0103] A method for treating the above-mentioned fluorinated boric acid wastewater includes the following steps:

[0104] (1) The fluoroboric acid-containing wastewater is collected through the raw water pipeline and enters the wastewater collection tank. The water quality and quantity are uniformly mixed by the agitator in the tank, and then it flows into the fluoroboric acid hydrolysis tank by gravity.

[0105] (2) In the fluoroboric acid hydrolysis tank, 30% NaOH by mass fraction is added to adjust the pH value of the tank to 7.5 by liquid alkali dosing pump. After reacting for 30 minutes, the solution flows by gravity to the defluorination reaction tank.

[0106] (3) In the defluorination reaction tank, 1200ppm of defluorination agent is added to it through the defluorination agent dosing metering pump, and after stirring and reacting for 30 minutes, it flows into the flocculation tank by gravity.

[0107] (4) In the flocculation tank, acid and alkali are added to the flocculation tank by sulfuric acid dosing pump and liquid alkali dosing pump to adjust the pH of the wastewater in the tank to 7.5. At the same time, 5ppm 1‰ PAM is added to the flocculation tank to carry out flocculation reaction. After flocculation for 30 minutes, the wastewater enters the sedimentation tank.

[0108] (5) After settling in the sedimentation tank for 60 min, the supernatant was taken and the concentration of fluoroboric acid was measured to be 0.13 ppm, the concentration of fluoride was 1.39 ppm, and the SS of the effluent was 134 mg / L.

[0109] (6) The effluent from the sedimentation tank enters the defluorination and boron resin tower filled with 100ml of resin from top to bottom. The inner diameter of the defluorination and boron resin tower is 2cm, the height is 150cm, the flow velocity through the column is 5BV, and after running for 20h, it enters the discharge tank. The concentration of fluoroboric acid in the discharge tank is measured to be 0.08ppm, the concentration of fluorine is 0.48ppm, and the concentration of boron is 0.5ppm.

[0110] Example 9

[0111] The defluorinating agent prepared in Example 2 and the defluorinating boron resin prepared in Example 4 were applied to the wastewater containing fluoroboric acid from a semiconductor factory in Wuxi. The concentration of fluoroboric acid was 150 ppm, the concentration of boric acid was 40 ppm, the concentration of fluoride ions was 20 ppm, and the pH was 2.37.

[0112] A method for treating the above-mentioned fluorinated boric acid wastewater includes the following steps:

[0113] (1) The fluoroboric acid-containing wastewater is collected through the raw water pipeline and enters the wastewater collection tank. The water quality and quantity are uniformly mixed by the agitator in the tank, and then it flows into the fluoroboric acid hydrolysis tank by gravity.

[0114] (2) In the fluoroboric acid hydrolysis tank, 30% NaOH by mass fraction is added to adjust the pH value of the tank to 7.5 by liquid alkali dosing pump. After reacting for 30 minutes, the solution flows by gravity to the defluorination reaction tank.

[0115] (3) In the defluorination reaction tank, 1500ppm of defluorination agent is added to it through the defluorination agent dosing metering pump, and after stirring and reacting for 30 minutes, it flows into the flocculation tank by gravity.

[0116] (4) In the flocculation tank, acid and alkali are added to the flocculation tank by sulfuric acid dosing pump and liquid alkali dosing pump to adjust the pH of the wastewater in the tank to 7.5. At the same time, 5ppm 1‰ PAM is added to the flocculation tank to carry out flocculation reaction. After flocculation for 30 minutes, the wastewater enters the sedimentation tank.

[0117] (5) After settling in the sedimentation tank for 60 min, the supernatant was taken and the concentration of fluoroboric acid was measured to be 0.12 ppm, the concentration of fluoride was 1.42 ppm, and the SS of the effluent was 137 mg / L.

[0118] (6) The effluent from the sedimentation tank enters the defluorination and boron resin tower filled with 100ml of resin from top to bottom. The inner diameter of the defluorination and boron resin tower is 2cm, the height is 150cm, the flow rate through the column is 5BV, and after running for 20h, it enters the discharge tank. The concentration of fluoroboric acid in the discharge tank is measured to be 0.05ppm, the concentration of fluorine is 0.52ppm, and the concentration of boron is 0.26ppm.

[0119] Example 10

[0120] The defluorinating agent prepared in Example 1 and the defluorinating boron resin prepared in Example 5 were applied to the wastewater containing fluoroboric acid from a semiconductor factory in Wuxi. The concentration of fluoroboric acid was 150 ppm, the concentration of boric acid was 40 ppm, the concentration of fluoride ions was 20 ppm, and the pH was 2.37.

[0121] A method for treating the above-mentioned fluorinated boric acid wastewater includes the following steps:

[0122] (1) The fluoroboric acid-containing wastewater is collected through the raw water pipeline and enters the wastewater collection tank. The water quality and quantity are uniformly mixed by the agitator in the tank, and then it flows into the fluoroboric acid hydrolysis tank by gravity.

[0123] (2) In the fluoroboric acid hydrolysis tank, 30% NaOH by mass fraction is added to adjust the pH value of the tank to 7.5 by liquid alkali dosing pump. After reacting for 30 minutes, the solution flows by gravity to the defluorination reaction tank.

[0124] (3) In the defluorination reaction tank, 1500ppm of defluorination agent is added to it through the defluorination agent dosing metering pump, and after stirring and reacting for 30 minutes, it flows into the flocculation tank by gravity.

[0125] (4) In the flocculation tank, acid and alkali are added to the flocculation tank by sulfuric acid dosing pump and liquid alkali dosing pump to adjust the pH of the wastewater in the tank to 7.5. At the same time, 5ppm 1‰ PAM is added to the flocculation tank to carry out flocculation reaction. After flocculation for 30 minutes, the wastewater enters the sedimentation tank.

[0126] (5) After settling in the sedimentation tank for 60 min, the supernatant was taken and the concentration of fluoroboric acid was measured to be 0.16 ppm, the concentration of fluoride was 1.38 ppm, and the SS of the effluent was 152 mg / L.

[0127] (6) The effluent from the sedimentation tank enters the defluorination and boron resin tower filled with 100ml of resin from top to bottom. The inner diameter of the defluorination and boron resin tower is 2cm, the height is 150cm, the flow rate through the column is 5BV, and after running for 20h, it enters the discharge tank. The concentration of fluoroboric acid in the discharge tank is measured to be 0.07ppm, the concentration of fluorine is 0.46ppm, and the concentration of boron is 0.4ppm.

[0128] Comparative Example 1

[0129] The method for treating fluoride-containing boric acid wastewater in Comparative Example 1 is basically the same as that in Example 7. The difference is that the defluorinating agent used in Comparative Example 1 is a ternary metal salt solution with an aluminum-iron-lanthanum molar ratio of 7:3:1 prepared in step (1) of Example 1, instead of using Ulva polysaccharide for cross-linking.

[0130] In step (5), the concentration of fluoroboric acid in the supernatant was measured to be 0.75 ppm, the concentration of fluoride was 7.53 ppm, and the SS in the effluent was 482 mg / L; in step (6), the concentration of fluoroboric acid in the discharge tank was measured to be 0.58 ppm, the concentration of fluoride was 5.25 ppm, and the concentration of boron was 1.28 ppm.

[0131] Comparison of Example 1 and Example 7 shows that when Ulva polysaccharide is used for cross-linking coordination, the treatment effect is better. Under the same dosage, the defluorination efficiency is increased by 24.1%, the boron removal efficiency is increased by 2.7%, and the sedimentation effect is better, with the effluent SS reduced by 74.07%.

[0132] Comparative Example 2

[0133] The method for treating fluoride-containing boric acid wastewater in Comparative Example 2 is basically the same as that in Example 7, the difference is that the molar ratio of aluminum-lanthanum-iron in the high-efficiency defluorinating agent used in Comparative Example 2 is 7:1:3.

[0134] In step (5), the concentration of fluoroboric acid in the supernatant was measured to be 0.53 ppm, the concentration of fluoride was 4.67 ppm, and the SS in the effluent was 326 mg / L. In step (6), the concentration of fluoroboric acid in the discharge tank was measured to be 0.35 ppm, the concentration of fluoride was 2.72 ppm, and the concentration of boron was 0.84 ppm.

[0135] Comparing Comparative Example 2 with Example 7, it can be seen that the treatment effect is better when the aluminum-lanthanum-iron molar ratio is 7:3:1. Under the same dosage, the defluorination efficiency is increased by 11.45%, the boron removal efficiency is increased by 1.6%, and the sedimentation effect is better, with the effluent SS reduced by 61.66%.

[0136] Comparative Example 3

[0137] The method for treating fluoride-containing boric acid wastewater in Comparative Example 3 is basically the same as that in Example 7, except that Comparative Example 3 does not use the fluoride-removing boric acid resin tower prepared in this invention.

[0138] In step (5), the concentration of fluoroboric acid was measured to be 0.13 ppm, the concentration of fluoride was 1.49 ppm, the concentration of boron was 38 ppm, and the SS in the effluent was 130 mg / L.

[0139] Comparison of Example 3 and Example 7 shows that when the fluoride-removing boron resin tower prepared by the present invention is used, the boride removal effect is greatly improved, and the boron removal efficiency is increased by 94.5%.

[0140] Comparative Example 4

[0141] The method for treating fluoroboric acid-containing wastewater in Comparative Example 4 is basically the same as that in Example 7, except that the resin used in Comparative Example 4 is not loaded with rare earth metals.

[0142] In step (5), the concentration of fluoroboric acid in the supernatant was measured to be 0.12 ppm, the concentration of fluoride was 1.47 ppm, and the SS in the effluent was 135 mg / L. In step (6), the concentration of fluoroboric acid in the discharge tank was measured to be 0.07 ppm, the concentration of fluoride was 1.45 ppm, and the concentration of boron was 0.4 ppm.

[0143] By comparing Comparative Example 4 and Example 7, it can be seen that when the resin tower is filled with the fluoride-removing boron chelating resin of the present invention, ultra-low fluoride concentration emissions can be achieved, and the fluoride removal efficiency is improved by 5.1%.

[0144] Comparative Example 5

[0145] The method for treating fluoroboric acid-containing wastewater in Comparative Example 5 is basically the same as that in Example 7, except that the resin used in Comparative Example 5 is not loaded with polyhydroxyl groups.

[0146] In step (5), the concentration of fluoroboric acid in the supernatant was measured to be 0.13 ppm, the concentration of fluoride was 1.45 ppm, and the SS in the effluent was 129 mg / L; in step (6), the concentration of fluoroboric acid in the discharge tank was measured to be 0.08 ppm, the concentration of fluoride was 0.45 ppm, and the concentration of boron was 35 ppm.

[0147] By comparing Comparative Example 5 and Example 7, it can be seen that when the resin tower is filled with the fluoride-removing boron chelating resin of the present invention, the boride removal efficiency is greatly improved, and the boron removal efficiency is increased by 87%.

[0148] Comparative Example 6

[0149] The methods for treating fluoride-containing boric acid wastewater in Comparative Example 6 and Example 7 are basically the same, except that the temperature of step (7) in Example 2 is changed from 60°C to 20°C during the preparation of the resin used in Comparative Example 6.

[0150] In step (5), the concentration of fluoroboric acid in the supernatant was measured to be 0.15 ppm, the concentration of fluoride was 1.48 ppm, and the SS in the effluent was 152 mg / L; in step (6), the concentration of fluoroboric acid in the discharge tank was measured to be 0.09 ppm, the concentration of fluoride was 1.16 ppm, and the concentration of boron was 25 ppm.

[0151] By comparing Comparative Example 6 and Example 7, it can be seen that when the resin preparation temperature reaches 60-80°C instead of room temperature, the fluoride removal efficiency is increased by 3.65%, the boride removal efficiency is greatly improved, and the boron removal efficiency is increased by 62%.

[0152] The results of Examples 7, 8, 9, and 10 and Comparative Examples 1-6 are shown in Tables 1 and 2.

[0153] Table 1

[0154]

[0155] Table 2

[0156]

Claims

1. A fluorine-removed boron resin, characterized by, The defluorination boron resin is prepared by the following steps: (C1) dissolving cellulose and ultrasonic dispersion to form a viscous cellulose suspension; (C2) mixing the cellulose suspension with an ammonium persulfate solution, and reacting under heating to obtain a carboxylated cellulose solution, which is centrifuged, washed and dried to form a carboxylated cellulose matrix; (C3) mixing the carboxylated cellulose matrix with hexamino benzene (3 hydrochloride) to form a viscous carboxylated cellulose-hexamino benzene suspension in a solvent; adding 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N,N-diisopropyl ethylamine as condensing agents and 1-hydroxybenzotriazole as an activating agent into the carboxylated cellulose-hexamino benzene suspension respectively, and performing condensation reaction and functional group activation under stirring; centrifuging and washing after the reaction to obtain amino-functionalized cellulose-based balls; (C4) adding methanol, gluconic acid solution and rare earth metal salt solution into the amino-functionalized cellulose-based balls, mixing thoroughly, adjusting the solution to be acidic, and reacting under heating to obtain a rare earth metal-amino polyol chelate resin.

2. The fluorine-free boron resin according to claim 1, characterized by In step (C3), the mass ratio of the carboxylated cellulose matrix to hexamino benzene (3 hydrochloride) is 1:1-2; The mass ratio of the carboxylated cellulose-hexamino benzene suspension to 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride is 100-150:1; The mass ratio of the carboxylated cellulose-hexamino benzene suspension to N,N-diisopropyl ethylamine is 100-150:1; The mass ratio of the carboxylated cellulose-hexamino benzene suspension to 1-hydroxybenzotriazole is 100-150:

1.

3. A method of treating fluorine-containing boric acid waste water, characterized by, The method comprises the following steps: (B1) adjusting the to-be-treated fluorine-containing boric acid wastewater to be weakly alkaline; (B2) adding a defluorination agent, decomposing fluoroboric acid and simultaneously removing fluoride ions through reaction; (B3) adding a flocculating agent into the wastewater after defluorination to perform flocculation, and then standing and settling; introducing the supernatant obtained after standing and settling into the defluorination boron resin of claim 1 to perform treatment; In step (B2), the preparation method of the defluorination agent comprises the following steps: (A1) mixing and dissolving aluminum salt, iron salt and rare earth metal salt solution to obtain a mixed metal salt solution, slowly dropping sodium carbonate solution into the mixed metal salt solution, adjusting the solution to be acidic, and performing reaction through stirring to obtain a ternary metal salt solution; (A2) dissolving ulva polysaccharide to obtain an ulva polysaccharide solution, mixing the ternary metal salt solution with the ulva polysaccharide solution, adjusting the solution to be weakly alkaline, and performing reaction under heating to obtain a ternary metal modified ulva polysaccharide solution with aluminum-iron-rare earth metal crosslinking ligand, that is, the defluorination agent is prepared.

4. The method of treating fluoboric acid-containing wastewater according to claim 3, wherein In step (B2), the defluorination agent is added in an amount of 500-2000 ppm, and the reaction time is 20-30 min.

5. The method of treating fluoboric acid-containing wastewater according to claim 3, wherein In step (A1), the molar ratio of aluminum, rare earth metal and iron in the ternary metal salt solution is 6-8:2-4:

1.

6. The method of treating fluoboric acid-containing wastewater according to claim 3, wherein In step (A2), the volume ratio of the ternary metal salt solution to the ulva polysaccharide solution is 1:2-3.

7. The method of treating fluoboric acid-containing wastewater according to claim 3, wherein In step (A2), the pH value of the solution is 7-9.

8. The method of treating fluoboric acid-containing wastewater of claim 3, wherein, In step (A1), the pH value of the solution is 2-3.

9. The method of treating fluoboric acid-containing wastewater according to claim 3, wherein In step (A1), the aluminum salt is at least one of polyaluminum chloride, polyaluminum sulfate; the iron salt is at least one of polyaluminum ferric chloride, polyaluminum ferric sulfate, polyferric chloride; and the rare earth metal salt is at least one of lanthanum chloride, cerium chloride, neodymium chloride, yttrium chloride, scandium chloride. In step (A1), the aluminum salt is at least one of polyaluminum chloride, polyaluminum sulfate; the iron salt is at least one of polyaluminum ferric chloride, polyaluminum ferric sulfate, polyferric chloride; and the rare earth metal salt is at least one of lanthanum chloride, cerium chloride, neodymium chloride, yttrium chloride, scandium chloride.

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