A process for treating acidic wastewater from smelting industry

Abstract

The present invention relates to the technical field of acid sewage treatment, and discloses a smelting industry acid sewage treatment process, comprising the following steps: adding an alkaline substance to the smelting industry acid sewage, adjusting the sewage pH value to be neutral, standing for 10 30 minutes, filtering, and collecting a filtrate and a precipitate A; adding a composite adsorbent to the filtrate, vibrating for 30 40 minutes, adding a polyacrylamide flocculant, continuing to shake for 10 20 minutes, filtering, and obtaining a precipitate B and a supernatant; Precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered and detected for reuse. The diatomaceous earth loaded with porous carbon has a double-layer porous structure, has a large adsorption capacity, and can adsorb heavy metal ions and organic impurities in sewage; an amphoteric small molecule functional reagent is grafted on the surface of the diatomaceous earth composite, and can be electrostatically bonded with the acidic anions and metal cation impurities in sewage, and a collaborative porous structure is formed to complete directional adsorption and fixation.

Description

Technical Field

[0001] The invention relates to the technical field of acidic wastewater treatment, in particular to a smelting industry acidic wastewater treatment process. Background Art

[0002] The main sources of acidic wastewater in the smelting industry are flue gas washing in the smelting section, the flue gas recovery acid production section, and the electrolytic liquid purification section. The acidic wastewater generated by these three sections will produce a large amount of wastewater. The pH value of the wastewater is lower than 1.0, indicating that it is strongly acidic, and the concentrations of elements such as As, Cu and Hg are seriously exceeded. By improving the production process and treating and reusing the acidic wastewater, it has both environmental and economic benefits, and has therefore been studied and applied by many companies.

[0003] Adding diatomaceous earth adsorbent to acidic wastewater from the smelting industry can effectively adsorb impurities such as metal ions in the wastewater. However, the adsorption capacity of diatomaceous earth adsorbent is low, the adsorption rate is slow, and it is easy to be saturated, resulting in low wastewater treatment efficiency; and the inorganic impurities in diatomaceous earth are easy to fall off, affecting the wastewater treatment effect. Summary of the Invention

[0004] The invention provides a process for treating acidic wastewater from the smelting industry, which solves the shortcomings of poor treatment effect and low efficiency of acidic wastewater from the smelting industry.

[0005] The technical solution of the present invention:

[0006] A process for treating acidic wastewater from a smelting industry comprises the following steps:

[0007] S1. Add an alkaline substance to the acidic wastewater from the smelting industry, adjust the pH value of the wastewater to neutral, let it stand for 10-30 minutes, filter, and collect the filtrate and precipitate A;

[0008] S2. The composite adsorbent was added to the filtrate, shaken for 30-40 minutes, and then a polyacrylamide flocculant was added. The mixture was shaken for 10-20 minutes and filtered to obtain a precipitate B and a supernatant.

[0009] S3. Precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered and reused;

[0010] The composite adsorbent is obtained by reacting a modified diatomaceous earth composite, β-cyclodextrin, and a cross-linking agent;

[0011] The modified diatomaceous earth composite is obtained by reacting tetraethylenepentamine with ethylenediaminetetraacetic acid and then mixing with the diatomaceous earth composite;

[0012] The diatomaceous earth composite is obtained by mixing diatomaceous earth and a carbon precursor, calcining them at high temperature, and then reacting them with epichlorohydrin.

[0013] Furthermore, the alkaline substance is selected from any one of calcium carbonate, lime milk, and magnesium oxide.

[0014] Furthermore, the polyacrylamide flocculant is prepared by mixing amphoteric polyacrylamide and deionized water in a dosage ratio of (30-40) g: (40-55) mL.

[0015] Furthermore, the carbon precursor is tobacco powder.

[0016] Furthermore, the cross-linking agent is ethylenediaminetetraacetic acid.

[0017] Furthermore, the composite adsorbent is specifically prepared by the following steps:

[0018] A1. Add the carbon precursor to ethanol and stir evenly. Add citric acid and diatomaceous earth and stir the mixture at 65-75°C for 25-35 minutes. Filter, wash, dry, place in a tube furnace, add 5 mL of potassium hydroxide for activation, stir evenly, carbonize at 750-850°C for 1-2 hours, cool to room temperature, remove, wash, and dry to obtain modified diatomaceous earth.

[0019] A2. Add modified diatomaceous earth and epichlorohydrin to deionized water, stir evenly, add 45-55% by mass of sodium hydroxide solution, stir and react at 75-85° C. for 10-15 minutes, filter, wash and dry to obtain a diatomaceous earth composite;

[0020] A3. Add tetraethylenepentamine to deionized water, stir evenly, add ethylenediaminetetraacetic acid, heat to 70-90°C, stir and react at a rate of 550-650 r / min for 25-35 minutes, heat to 100-110°C, continue the reaction, and cool to room temperature to obtain an amphiphilic small molecule functional reagent;

[0021] A4. Add the diatomaceous earth composite to deionized water and stir evenly. Add an amphiphilic small molecule functional reagent and a 45-55% by mass sodium hydroxide solution. Stir and react at 60-70° C. for 25-35 minutes. Filter, wash, and dry to obtain a modified diatomaceous earth composite.

[0022] A5. Add β-cyclodextrin, a cross-linking agent, polyethylene glycol 200, and sodium dihydrogen phosphate to deionized water, stir evenly, place in an 80-120°C oil bath and stir for 1-2 hours, add the modified diatomaceous earth composite, continue stirring and reacting for 30-35 minutes, place in an oven at 150-160°C and heat to react for 8-12 hours, cool to room temperature, remove, grind, place in deionized water, wash with water, filter, and dry to obtain a composite adsorbent.

[0023] Furthermore, during the above-mentioned A1 reaction process, diatomaceous earth is mixed with a carbon precursor, and the carbon precursor tobacco powder is dissolved in the organic solvent ethanol. The hydroxyl and carboxyl groups contained in the carbon precursor tobacco powder can chemically react with the carboxyl groups in citric acid, and citric acid as a linker can react with the hydroxyl groups on the surface of the diatomaceous earth to achieve the deposition of the carbon precursor on the surface of the diatomaceous earth. Potassium hydroxide is used as an activator and carbonization treatment is carried out at a temperature of 750-850°C. The carbon precursor tobacco powder is decomposed by heat to form a dense carbon layer on the surface of the diatomaceous earth, and the potassium hydroxide molecules decompose to form pores on the surface of the carbon layer, thereby achieving the synthesis of porous carbon materials on the surface of the diatomaceous earth.

[0024] Furthermore, in the above-mentioned A2 reaction process, sodium hydroxide is used as a catalyst to enable the hydroxyl groups on the surface of the modified diatomaceous earth to undergo a ring-opening reaction with the epoxy groups in epichlorohydrin at 80°C, thereby achieving the grafting of epichlorohydrin on the surface of the modified diatomaceous earth, which serves as a reaction site with the amphiphilic small molecule functional reagent. The hydroxyl groups generated by the epoxy ring opening can also complex with metal ions in the sewage, thereby increasing the removal efficiency of metal ions.

[0025] Furthermore, in the above reaction process A3, the mass ratio of tetraethylenepentamine to ethylenediaminetetraacetic acid is controlled to be 10:7, and the secondary amine of tetraethylenepentamine can react with one of the carboxyl groups of ethylenediaminetetraacetic acid to form an amphoteric small molecule functional reagent.

[0026] Furthermore, during the above-mentioned reaction A4, the chlorine atom of epichlorohydrin in the diatomite composite can undergo a substitution reaction with the primary amine group of tetraethylenepentamine in the amphiphilic small molecule functional reagent, so that the amphiphilic small molecule functional reagent is grafted onto the surface of the diatomite composite to form a modified diatomite composite.

[0027] Furthermore, in the above-mentioned A5 reaction process, polyethylene glycol 200 is used as a dispersant to promote the dissolution of β-cyclodextrin in deionized water, and sodium dihydrogen phosphate is used as a catalyst, so that the hydroxyl groups on the surface of β-cyclodextrin can react with the carboxyl groups in the cross-linking agent ethylenediaminetetraacetic acid to form a cross-linked network structure resin, and the functional groups contained in the amphiphilic small molecule functional reagent in the modified diatomaceous earth composite can also react with the carboxyl and hydroxyl groups of the cross-linked network structure resin, so that the modified diatomaceous earth composite is embedded in the cross-linked network structure resin.

[0028] Furthermore, in step A1, the ratio of the carbon precursor, ethanol, citric acid, diatomaceous earth, and potassium hydroxide is (4-6) g: (45-55) mL: (0.1-0.3) g: (1.6-2) g: (5-7) mL.

[0029] Furthermore, in step A2, the modified diatomaceous earth, epichlorohydrin, deionized water, and sodium hydroxide solution are used in a ratio of (1-1.4) g: (10-20) mL: (15-25) mL: (5-7) mL.

[0030] Furthermore, in step A3, the ratio of tetraethylenepentamine, deionized water, and ethylenediaminetetraacetic acid is (8-12) g: (8-12) mL: (6-8) g.

[0031] Furthermore, in step A4, the dosage ratio of the diatomaceous earth composite, deionized water, amphoteric small molecule functional reagent, and sodium hydroxide solution is (1.6-2) g: (25-35) mL: (8-12) g: (0.2-0.4) mL.

[0032] Furthermore, in step A5, the amount ratio of the β-cyclodextrin, cross-linking agent, polyethylene glycol 200, sodium dihydrogen phosphate, deionized water, and modified diatomaceous earth composite is (3-5) g: (5-7) g: (0.3-0.7) g: (2.5-2.7) g: (15-25) mL: (2-3) g.

[0033] Furthermore, the diatomaceous earth has a particle size of 2-5 microns and a pore size of 100-150 nanometers.

[0034] The present invention has the following beneficial effects:

[0035] (1) In the technical solution of the present invention, diatomaceous earth is used as an adsorbent to adsorb impurities such as heavy metal ions in sewage. A porous carbon material is synthesized on the surface of the diatomaceous earth. The excellent adsorption performance of the porous carbon can adsorb and fix impurities that are easy to fall off in the diatomaceous earth, thereby preventing them from falling into the sewage during sewage treatment and affecting the treatment effect. The diatomaceous earth loaded with porous carbon has a double-layer porous structure and a large adsorption capacity. It can adsorb heavy metal ions and organic impurities in sewage and complete the removal of metal ions in sewage. Epichlorohydrin is grafted on the surface of the diatomaceous earth loaded with porous carbon as a reaction site with amphoteric small molecule functional reagents, and can adsorb acidic substances in sewage. The hydroxyl groups generated by the epoxy ring opening can also complex with metal ions in sewage, thereby increasing the removal efficiency of metal ions.

[0036] (2) In the technical solution of the present invention, tetraethylenepentamine reacts with ethylenediaminetetraacetic acid to form an amphoteric small molecule functional reagent, which is grafted onto the surface of the diatomaceous earth composite to form a modified diatomaceous earth composite. The amphoteric small molecule functional reagent carries a positively charged amino group and a negatively charged carboxyl group, and can electrostatically bind to the acidic anions and metal cation impurities in the sewage, and cooperate with the porous structure to directionally adsorb and fix the acidic anions and metal cation impurities in the sewage in the modified diatomaceous earth composite, thereby avoiding the double-layer porous structure of the modified diatomaceous earth composite to adsorb more water molecules, occupy the pore capacity, and affect the sewage treatment efficiency.

[0037] (3) In the technical solution of the present invention, in the composite adsorbent, the modified diatomaceous earth complex is embedded in the β-cyclodextrin cross-linked resin. On the one hand, the modified diatomaceous earth complex gives the β-cyclodextrin cross-linked resin amphiphilicity, and the negatively charged carboxyl groups can complex with metal ions in sewage, adsorbing and fixing heavy metal ions in sewage in the composite adsorbent. On the other hand, the heavy metals consume the anionic groups of the composite adsorbent, causing the composite adsorbent to be unbalanced in potential. The remaining amino groups of the composite adsorbent show a positive charge, which can then combine with the negatively charged sludge particles, causing the sludge particles to aggregate and settle, thereby effectively removing sludge and heavy metal particles.

[0038] (4) In the technical solution of the present invention, the cavity structure and hydroxyl groups contained in the β-cyclodextrin cross-linked resin in the composite adsorbent can adsorb metal impurities in sewage, and the modified diatomaceous earth composite serves as the skeleton structure of the β-cyclodextrin cross-linked resin, thereby increasing the interaction force between the β-cyclodextrin cross-linked resins and avoiding the small interaction force between the β-cyclodextrin cross-linked resins, which affects the treatment efficiency.

[0039] (5) In the technical solution of the present invention, alkaline substances are added to the acidic wastewater from the smelting industry to adjust the pH value of the wastewater to make it close to neutral, and some heavy metals are prompted to form insoluble precipitates, which is beneficial to subsequent treatment. In addition, polyacrylamide flocculant is added to the treated wastewater. The positive charge it carries can neutralize the small sludge particles carrying negative charges in the wastewater. It has strong adsorption and bridging capabilities, causing them to agglomerate into larger particles, thereby adsorbing and removing the small sludge particles in the wastewater, thereby completing the treatment of the wastewater. DETAILED DESCRIPTION

[0040] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] The raw materials used in the embodiments of the present invention are as follows:

[0042] Ethylenediaminetetraacetic acid (Shanghai Maclean Co., Ltd.).

[0043] Diatomaceous earth: The particle size of diatomaceous earth is 2-5 microns, and the pore size is 100-150 nanometers, Jinan Shanzheng Trading Co., Ltd.

[0044] Citric acid: Shanghai Zhenzhun Biotechnology Co., Ltd.

[0045] Tetraethylenepentamine, epichlorohydrin: analytical grade, Aladdin Co., Ltd.

[0046] β-Cyclodextrin: mass fraction 98%, Sinopharm Chemical Reagent Co., Ltd.

[0047] Polyethylene glycol 200: Hai'an Petrochemical Plant, Jiangsu Province, mass fraction 99%.

[0048] Sodium dihydrogen phosphate: purity 99%, Hubei Handafei Biotechnology Co., Ltd.

[0049] The alkaline substance is selected from any one of calcium carbonate, lime milk and magnesium oxide.

[0050] Calcium carbonate: purity 99%, Shanghai Lianmai Bioengineering Co., Ltd.

[0051] Lime milk: purity 95%, Shanghai Yiji Biological Co., Ltd.

[0052] Magnesium oxide: Beijing Aomijiade Pharmaceutical Technology Co., Ltd.

[0053] Example 1

[0054] A process for treating acidic wastewater from a smelting industry, characterized by comprising the following steps:

[0055] S1. Add an alkaline substance to the acidic wastewater from the smelting industry to adjust the pH value of the wastewater to neutral, let it stand for 30 minutes, filter, and collect the filtrate and precipitate A;

[0056] S2. The composite adsorbent was added to the filtrate, shaken for 30-40 minutes, and then a polyacrylamide flocculant was added. The mixture was shaken for 10-20 minutes and filtered to obtain a precipitate B and a supernatant.

[0057] S3. Precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered and reused.

[0058] The composite adsorbent is specifically prepared by the following steps:

[0059] A1. 4 g of tobacco powder was added to 45 mL of ethanol and stirred. 0.1 g of citric acid and 1.6 g of diatomaceous earth were added and stirred at 65 ° C for 25 minutes. The mixture was filtered, washed, dried, placed in a tube furnace, and activated by adding 5 mL of potassium hydroxide. The mixture was stirred and carbonized at 750 ° C for 1 hour. The mixture was cooled to room temperature, taken out, washed 3 times with deionized water, and dried in a 70 ° C oven for 10 minutes to obtain modified diatomaceous earth.

[0060] A2. Add 1 g of modified diatomaceous earth and 10 mL of epichlorohydrin to 15 mL of deionized water, stir evenly, add 5 mL of 45% sodium hydroxide solution, stir and react at 75°C for 10 minutes, filter, wash with deionized water three times, and dry in an oven at 50°C for 10 minutes to obtain a diatomaceous earth composite;

[0061] A3. Add 8 g of tetraethylenepentamine to 8 mL of deionized water, stir evenly, add 6 g of ethylenediaminetetraacetic acid, heat to 70-90 ° C, stir and react at a rate of 550-650 r / min for 25-35 minutes, heat to 100-110 ° C, continue the reaction, and cool to room temperature to obtain an amphiphilic small molecule functional reagent;

[0062] A4. Add 1.6 g of the diatomaceous earth composite to 25 mL of deionized water and stir evenly. Add 8 g of the amphiphilic small molecule functional reagent and 0.2 mL of a 45% sodium hydroxide solution by mass. Stir and react at 60°C for 25 minutes. Filter, wash with deionized water three times, and dry in an oven at 60°C for 10 minutes to obtain a modified diatomaceous earth composite.

[0063] A5. Add 3 g of β-cyclodextrin, 5 g of ethylenediaminetetraacetic acid, 0.3 g of polyethylene glycol 200, and 2.5 g of sodium dihydrogen phosphate to 15 mL of deionized water, stir evenly, place in an 80 ° C oil bath and stir for 2 hours, add 2 g of modified diatomaceous earth composite, continue stirring and react for 30 minutes, place in a 150 ° C oven and heat to react for 8 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water, filter, and dry at 65 ° C for 1 hour to obtain a composite adsorbent.

[0064] Example 2

[0065] A process for treating acidic wastewater from a smelting industry, characterized by comprising the following steps:

[0066] S1. Add an alkaline substance to the acidic wastewater from the smelting industry to adjust the pH value of the wastewater to neutral, let it stand for 20 minutes, filter, and collect the filtrate and precipitate A;

[0067] S2. The composite adsorbent was added to the filtrate, shaken for 35 minutes, and then a polyacrylamide flocculant was added. The mixture was shaken for 15 minutes and filtered to obtain a precipitate B and a supernatant.

[0068] S3. Precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered and reused.

[0069] The composite adsorbent is specifically prepared by the following steps:

[0070] A1. 5 g of tobacco powder was added to 50 mL of ethanol and stirred. 0.2 g of citric acid and 1.8 g of diatomaceous earth were added and stirred at 70 ° C for 30 minutes. The mixture was filtered, washed, dried, placed in a tube furnace, and activated by adding 6 mL of potassium hydroxide. The mixture was stirred and carbonized at 800 ° C for 1.5 hours. The mixture was cooled to room temperature, taken out, washed 3 times with deionized water, and dried in a 70 ° C oven for 10 minutes to obtain modified diatomaceous earth.

[0071] A2. Add 1.2 g of modified diatomaceous earth and 15 mL of epichlorohydrin to 20 mL of deionized water, stir evenly, add 6 mL of 50% sodium hydroxide solution, stir and react at 80° C. for 13 minutes, filter, wash with deionized water three times, and dry in an oven at 50° C. for 10 minutes to obtain a diatomaceous earth composite.

[0072] A3. Add 10 g of tetraethylenepentamine to 10 mL of deionized water, stir evenly, add 7 g of ethylenediaminetetraacetic acid, heat to 80° C., stir and react at a rate of 600 r / min for 30 minutes, heat to 105° C., continue the reaction, and cool to room temperature to obtain an amphiphilic small molecule functional reagent;

[0073] A4. Add 1.8 g of the diatomaceous earth composite to 30 mL of deionized water and stir evenly. Add 10 g of an amphoteric small molecule functional reagent and 0.3 mL of a 50% sodium hydroxide solution by mass. Stir and react at 65°C for 30 minutes. Filter, wash with deionized water three times, and dry in an oven at 60°C for 10 minutes to obtain a modified diatomaceous earth composite.

[0074] A5. Add 4 g of β-cyclodextrin, 6 g of ethylenediaminetetraacetic acid, 0.5 g of polyethylene glycol 200, and 2.6 g of sodium dihydrogen phosphate to 20 mL of deionized water, stir evenly, place in a 100 ° C oil bath and stir for 1.5 hours, add 2.5 g of modified diatomaceous earth composite, continue stirring and react for 33 minutes, place in a 155 ° C oven and heat to react for 10 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water, filter, and dry at 65 ° C for 1-5 hours to obtain a composite adsorbent.

[0075] Example 3

[0076] A process for treating acidic wastewater from a smelting industry, characterized by comprising the following steps:

[0077] S1. Add an alkaline substance to the acidic wastewater from the smelting industry to adjust the pH value of the wastewater to neutral, let it stand for 30 minutes, filter, and collect the filtrate and precipitate A;

[0078] S2. The composite adsorbent was added to the filtrate, shaken for 40 minutes, and then a polyacrylamide flocculant was added. The mixture was shaken for 20 minutes and filtered to obtain a precipitate B and a supernatant.

[0079] S3. Precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered and reused.

[0080] The composite adsorbent is specifically prepared by the following steps:

[0081] A1. 6 g of tobacco powder was added to 55 mL of ethanol and stirred. 0.3 g of citric acid and 2 g of diatomaceous earth were added and stirred at 75 ° C for 35 minutes. The mixture was filtered, washed, dried, placed in a tube furnace, and activated by adding 7 mL of potassium hydroxide. The mixture was stirred and carbonized at 850 ° C for 2 hours. The mixture was cooled to room temperature, taken out, washed 3 times with deionized water, and dried in a 70 ° C oven for 10 minutes to obtain modified diatomaceous earth.

[0082] A2. Add 1.4 g of modified diatomaceous earth and 20 mL of epichlorohydrin to 25 mL of deionized water, stir evenly, add 7 mL of 55% sodium hydroxide solution, stir and react at 85° C. for 15 minutes, filter, wash with deionized water three times, and dry in an oven at 50° C. for 10 minutes to obtain a diatomaceous earth composite.

[0083] A3. Add 12 g of tetraethylenepentamine to 12 mL of deionized water, stir evenly, add 8 g of ethylenediaminetetraacetic acid, heat to 90 ° C, stir and react at a rate of 650 r / min for 35 minutes, heat to 110 ° C, continue the reaction, and cool to room temperature to obtain an amphiphilic small molecule functional reagent;

[0084] A4. Add 2 g of diatomaceous earth composite to 35 mL of deionized water and stir evenly. Add 12 g of amphoteric small molecule functional reagent and 0.4 mL of 55% sodium hydroxide solution. Stir and react at 70°C for 35 minutes. Filter, wash with deionized water three times, and dry in an oven at 60°C for 10 minutes to obtain a modified diatomaceous earth composite.

[0085] A5. Add 5 g of β-cyclodextrin, 7 g of ethylenediaminetetraacetic acid, 0.7 g of polyethylene glycol 200, and 2.67 g of sodium dihydrogen phosphate to 25 mL of deionized water, stir evenly, place in a 120 ° C oil bath and stir for 2 hours, add 3 g of modified diatomaceous earth composite, continue stirring and react for 35 minutes, place in a 160 ° C oven and heat to react for 12 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water, filter, and dry at 65 ° C for 2 hours to obtain a composite adsorbent.

[0086] Comparative Example 1

[0087] A process for treating acidic wastewater from a smelting industry, characterized by comprising the following steps:

[0088] S1. Add an alkaline substance to the acidic wastewater from the smelting industry to adjust the pH value of the wastewater to neutral, let it stand for 30 minutes, filter, and collect the filtrate and precipitate A;

[0089] S2. The composite adsorbent was added to the filtrate, shaken for 40 minutes, and then a polyacrylamide flocculant was added. The mixture was shaken for 20 minutes and filtered to obtain a precipitate B and a supernatant.

[0090] S3. Precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered and reused.

[0091] The composite adsorbent is specifically prepared by the following steps:

[0092] A1. Add 1.4 g of diatomaceous earth and 20 mL of epichlorohydrin to 25 mL of deionized water, stir evenly, add 7 mL of 55% sodium hydroxide solution, stir and react at 85°C for 15 minutes, filter, wash with deionized water three times, and dry in an oven at 50°C for 10 minutes to obtain a diatomaceous earth composite;

[0093] A2. Add 12 g of tetraethylenepentamine to 12 mL of deionized water, stir evenly, add 8 g of ethylenediaminetetraacetic acid, heat to 90 ° C, stir and react at a rate of 650 r / min for 35 minutes, heat to 110 ° C, continue the reaction, and cool to room temperature to obtain an amphiphilic small molecule functional reagent;

[0094] A3. Add 2 g of diatomaceous earth composite to 35 mL of deionized water, stir evenly, add 12 g of amphoteric small molecule functional reagent and 0.4 mL of 55% sodium hydroxide solution, stir and react at 70 ° C for 35 minutes, filter, wash with deionized water three times, and dry in a 60 ° C oven for 10 minutes to obtain a modified diatomaceous earth composite;

[0095] A4. Add 5 g of β-cyclodextrin, 7 g of ethylenediaminetetraacetic acid, 0.7 g of polyethylene glycol 200, and 2.67 g of sodium dihydrogen phosphate to 25 mL of deionized water, stir evenly, place in a 120 ° C oil bath and stir for 2 hours, add 3 g of modified diatomaceous earth composite, continue stirring and react for 35 minutes, place in a 160 ° C oven and heat to react for 12 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water, filter, and dry at 65 ° C for 2 hours to obtain a composite adsorbent.

[0096] Comparative Example 2

[0097] A process for treating acidic wastewater from a smelting industry, characterized by comprising the following steps:

[0098] S1. Add an alkaline substance to the acidic wastewater from the smelting industry to adjust the pH value of the wastewater to neutral, let it stand for 30 minutes, filter, and collect the filtrate and precipitate A;

[0099] S2. The composite adsorbent was added to the filtrate, shaken for 40 minutes, and then a polyacrylamide flocculant was added. The mixture was shaken for 20 minutes and filtered to obtain a precipitate B and a supernatant.

[0100] S3. Precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered and reused.

[0101] The composite adsorbent is specifically prepared by the following steps:

[0102] A1. 6 g of tobacco powder was added to 55 mL of ethanol and stirred. 0.3 g of citric acid and 2 g of diatomaceous earth were added and stirred at 75 ° C for 35 minutes. The mixture was filtered, washed, dried, placed in a tube furnace, and activated by adding 7 mL of potassium hydroxide. The mixture was stirred and carbonized at 850 ° C for 2 hours. The mixture was cooled to room temperature, taken out, washed 3 times with deionized water, and dried in a 70 ° C oven for 10 minutes to obtain modified diatomaceous earth.

[0103] A2. Add 12 g of tetraethylenepentamine to 12 mL of deionized water, stir evenly, add 8 g of ethylenediaminetetraacetic acid, heat to 90 ° C, stir and react at a rate of 650 r / min for 35 minutes, heat to 110 ° C, continue the reaction, and cool to room temperature to obtain an amphiphilic small molecule functional reagent;

[0104] A3. Add 2 g of modified diatomaceous earth to 35 mL of deionized water, stir evenly, add 12 g of amphoteric small molecule functional reagent and 0.4 mL of 55% sodium hydroxide solution, stir and react at 70 ° C for 35 minutes, filter, wash with deionized water three times, and dry in a 60 ° C oven for 10 minutes to obtain a modified diatomaceous earth composite;

[0105] A4. Add 5 g of β-cyclodextrin, 7 g of ethylenediaminetetraacetic acid, 0.7 g of polyethylene glycol 200, and 2.67 g of sodium dihydrogen phosphate to 25 mL of deionized water, stir evenly, place in a 120 ° C oil bath and stir for 2 hours, add 3 g of modified diatomaceous earth composite, continue stirring and react for 35 minutes, place in a 160 ° C oven and heat to react for 12 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water, filter, and dry at 65 ° C for 2 hours to obtain a composite adsorbent.

[0106] Comparative Example 3

[0107] A process for treating acidic wastewater from a smelting industry, characterized by comprising the following steps:

[0108] S1. Add an alkaline substance to the acidic wastewater from the smelting industry to adjust the pH value of the wastewater to neutral, let it stand for 30 minutes, filter, and collect the filtrate and precipitate A;

[0109] S2. The composite adsorbent was added to the filtrate, shaken for 40 minutes, and then a polyacrylamide flocculant was added. The mixture was shaken for 20 minutes and filtered to obtain a precipitate B and a supernatant.

[0110] S3. Precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered and reused.

[0111] The composite adsorbent is specifically prepared by the following steps:

[0112] A1. 6 g of tobacco powder was added to 55 mL of ethanol and stirred. 0.3 g of citric acid and 2 g of diatomaceous earth were added and stirred at 75 ° C for 35 minutes. The mixture was filtered, washed, dried, placed in a tube furnace, and activated by adding 7 mL of potassium hydroxide. The mixture was stirred and carbonized at 850 ° C for 2 hours. The mixture was cooled to room temperature, taken out, washed 3 times with deionized water, and dried in a 70 ° C oven for 10 minutes to obtain modified diatomaceous earth.

[0113] A2. Add 1.4 g of modified diatomaceous earth and 20 mL of epichlorohydrin to 25 mL of deionized water, stir evenly, add 7 mL of 55% sodium hydroxide solution, stir and react at 85° C. for 15 minutes, filter, wash with deionized water three times, and dry in an oven at 50° C. for 10 minutes to obtain a diatomaceous earth composite.

[0114] A3. Add 5 g of β-cyclodextrin, 7 g of ethylenediaminetetraacetic acid, 0.7 g of polyethylene glycol 200, and 2.67 g of sodium dihydrogen phosphate to 25 mL of deionized water, stir evenly, place in a 120 ° C oil bath and stir for 2 hours, add 3 g of diatomaceous earth complex, continue stirring and react for 35 minutes, place in a 160 ° C oven and heat to react for 12 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water, filter, and dry at 65 ° C for 2 hours to obtain a composite adsorbent.

[0115] Comparative Example 4

[0116] A process for treating acidic wastewater from a smelting industry, characterized by comprising the following steps:

[0117] S1. Add an alkaline substance to the acidic wastewater from the smelting industry to adjust the pH value of the wastewater to neutral, let it stand for 30 minutes, filter, and collect the filtrate and precipitate A;

[0118] S2. The composite adsorbent was added to the filtrate, shaken for 40 minutes, and then a polyacrylamide flocculant was added. The mixture was shaken for 20 minutes and filtered to obtain a precipitate B and a supernatant.

[0119] S3. Precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered and reused.

[0120] The composite adsorbent is specifically prepared by the following steps:

[0121] A1. 6 g of tobacco powder was added to 55 mL of ethanol and stirred. 0.3 g of citric acid and 2 g of diatomaceous earth were added and stirred at 75 ° C for 35 minutes. The mixture was filtered, washed, dried, placed in a tube furnace, and activated by adding 7 mL of potassium hydroxide. The mixture was stirred and carbonized at 850 ° C for 2 hours. The mixture was cooled to room temperature, taken out, washed 3 times with deionized water, and dried in a 70 ° C oven for 10 minutes to obtain modified diatomaceous earth.

[0122] A2. Add 1.4 g of modified diatomaceous earth and 20 mL of epichlorohydrin to 25 mL of deionized water, stir evenly, add 7 mL of 55% sodium hydroxide solution, stir and react at 85° C. for 15 minutes, filter, wash with deionized water three times, and dry in an oven at 50° C. for 10 minutes to obtain a diatomaceous earth composite.

[0123] A3. Add 12 g of tetraethylenepentamine to 12 mL of deionized water, stir evenly, add 8 g of ethylenediaminetetraacetic acid, heat to 90 ° C, stir and react at a rate of 650 r / min for 35 minutes, heat to 110 ° C, continue the reaction, and cool to room temperature to obtain an amphiphilic small molecule functional reagent;

[0124] A4. Add 2 g of diatomaceous earth composite to 35 mL of deionized water and stir evenly. Add 12 g of amphoteric small molecule functional reagent and 0.4 mL of 55% sodium hydroxide solution. Stir and react at 70°C for 35 minutes. Filter, wash with deionized water three times, and dry in an oven at 60°C for 10 minutes to obtain a composite adsorbent.

[0125] The performance of the composite adsorbents prepared in Examples 1-3 and Comparative Examples 1-4 in treating acidic wastewater from the smelting industry was tested.

[0126] The smelting industrial acid wastewater of the present invention has a heavy metal content of 5.7 g / L, a sludge content of 200 g / L, a CODcr of 82 (mg / L), and a pH of 1.2.

[0127] According to the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" (GB18918-2002), the supernatants of Examples 1-3 and Comparative Examples 1-4 were tested;

[0128] Metal ion detection in the supernatant: The metal ions in the supernatant were detected using the "Method for the Examination of Sludge from Municipal Wastewater Treatment Plants (CJT221-2005)". After digestion, the metal ion content in the supernatant was determined using flame atomic spectrophotometry and inductively coupled plasma atomic emission spectrometry, and the metal removal rate (%) was calculated.

[0129] Detect the pH value in the supernatant: Take a dry pH test paper, use a clean glass rod or tweezers to dip a small amount of sewage to be tested, drop it on the test paper, and then compare it with the standard colorimetric card and record the pH value; as shown in Table 1 below.

[0130] Table 1 Performance test of composite adsorbents prepared in Examples 1-3 and Comparative Examples 1-4

[0131]

[0132] As can be seen from the data in Table 1, the modified fusible polytetrafluoroethylene prepared in Examples 1-3 has good mechanical properties and lubricity, and nano-silicon dioxide has good coating performance on fusible polytetrafluoroethylene. In Comparative Example 1, modified diatomaceous earth is replaced with diatomaceous earth, and the prepared composite adsorbent treats smelting industrial acidic sewage. The supernatant is tested, and its metal ion removal rate decreases, and CODcr does not meet the emission standards, proving that porous carbon materials are synthesized on the surface of diatomaceous earth. The excellent adsorption performance of porous carbon can adsorb and fix impurities that are easy to fall off in diatomaceous earth, avoid falling into sewage during sewage treatment, and affect the treatment effect. The diatomaceous earth formed by loading porous carbon has a double-layer porous structure, has a large adsorption capacity, and can adsorb heavy metal ions and organic impurities in sewage.

[0133] In Comparative Example 2, the diatomaceous earth composite was replaced with a composite adsorbent prepared by modified diatomaceous earth to treat acidic wastewater from the smelting industry. The supernatant was tested and the metal ion removal rate decreased, and the CODcr and pH values ​​did not meet the standards. This proves that epichlorohydrin is grafted onto the surface of diatomaceous earth loaded with porous carbon, serving as a reaction site with amphiphilic small molecule functional reagents, and can adsorb acidic substances in the wastewater. The hydroxyl groups generated by the epoxy ring opening can also complex with metal ions in the wastewater, thereby increasing the removal efficiency of metal ions.

[0134] In Comparative Example 3, the modified diatomaceous earth composite was replaced with a diatomaceous earth composite mixture, and the prepared composite adsorbent was used to treat acidic wastewater from the smelting industry. The supernatant was tested, and its metal ion removal rate and sludge removal rate decreased, and the CODcr and pH values ​​did not meet the standards. This shows that the amphiphilic small molecule functional reagent is grafted on the surface of the diatomaceous earth composite, carrying positively charged amino groups and negatively charged carboxyl groups, and can be electrostatically bonded with acidic anions and metal cation impurities in the sewage. The porous structure cooperates to directionally adsorb and fix the acidic anions and metal cation impurities in the sewage in the modified diatomaceous earth composite, and shows a positive charge, and can then combine with negatively charged sludge particles, causing the sludge particles to aggregate and settle.

[0135] In Comparative Example 4, no β-cyclodextrin or cross-linking agent ethylenediaminetetraacetic acid was added, and the prepared composite adsorbent was used to treat acidic wastewater from the smelting industry. The supernatant was tested and its metal ion removal rate decreased, and the CODcr did not meet the standard, proving that the cavity structure and hydroxyl groups contained in the β-cyclodextrin cross-linked resin can adsorb metal impurities and organic impurities in the wastewater.

[0136] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0137] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A process for treating acidic wastewater from a smelting industry, characterized in that: The following steps are involved: S1. Add an alkaline substance to the acidic wastewater from the smelting industry, adjust the pH value of the wastewater to neutral, let it stand for 10-30 minutes, filter, and collect the filtrate and precipitate A; S2. The composite adsorbent was added to the filtrate, shaken for 30-40 minutes, and then a polyacrylamide flocculant was added. The mixture was shaken for 10-20 minutes and filtered to obtain a precipitate B and a supernatant. S3. The precipitate A and precipitate B are mixed and recovered, and the supernatant is recovered for detection and reuse; The composite adsorbent is obtained by reacting a modified diatomaceous earth composite, β-cyclodextrin, and a cross-linking agent; The modified diatomaceous earth composite is obtained by reacting tetraethylenepentamine with ethylenediaminetetraacetic acid and then mixing with the diatomaceous earth composite; The diatomaceous earth composite is obtained by mixing diatomaceous earth and a carbon precursor, calcining them at high temperature, and then reacting them with epichlorohydrin; The composite adsorbent is specifically prepared by the following steps: A1. Add the carbon precursor to ethanol and stir evenly. Add citric acid and diatomaceous earth and stir the mixture at 65-75°C for 25-35 minutes. Filter, wash, dry, place in a tube furnace, add 5 mL of potassium hydroxide for activation, stir evenly, carbonize at 750-850°C for 1-2 hours, cool to room temperature, remove, wash, and dry to obtain modified diatomaceous earth. A2. Add modified diatomaceous earth and epichlorohydrin to deionized water, stir evenly, add 45-55% by mass sodium hydroxide solution, stir and react at 75-85° C. for 10-15 minutes, filter, wash, and dry to obtain a diatomaceous earth composite; A3. Add tetraethylenepentamine to deionized water, stir evenly, add ethylenediaminetetraacetic acid, heat to 70-90°C, stir and react at a rate of 550-650 r / min for 25-35 minutes, heat to 100-110°C, continue the reaction, and cool to room temperature to obtain an amphiphilic small molecule functional reagent; A4. Add the diatomaceous earth composite to deionized water and stir evenly. Add an amphiphilic small molecule functional reagent and a 45-55% by mass sodium hydroxide solution. Stir and react at 60-70° C. for 25-35 minutes. Filter, wash, and dry to obtain a modified diatomaceous earth composite. A5. Add β-cyclodextrin, a cross-linking agent, polyethylene glycol 200, and sodium dihydrogen phosphate to deionized water, stir evenly, place in an 80-120°C oil bath and stir for 1-2 hours, add the modified diatomaceous earth composite, continue stirring and reacting for 30-35 minutes, place in an oven at 150-160°C and heat to react for 8-12 hours, cool to room temperature, remove, grind, place in deionized water, wash with water, filter, and dry to obtain a composite adsorbent.

2. A smelting industry acid wastewater treatment process according to claim 1, characterized in that: In step A1, the ratio of the carbon precursor, ethanol, citric acid, diatomaceous earth, and potassium hydroxide is (4-6) g: (45-55) mL: (0.1-0.3) g: (1.6-2) g: (5-7) mL.

3. A smelting industry acid wastewater treatment process according to claim 1, characterized in that: In step A2, the modified diatomaceous earth, epichlorohydrin, deionized water, and sodium hydroxide solution are used in a ratio of (1-1.4) g: (10-20) mL: (15-25) mL: (5-7) mL.

4. A smelting industry acid wastewater treatment process according to claim 1, characterized in that: In step A3, the ratio of tetraethylenepentamine, deionized water, and ethylenediaminetetraacetic acid is (8-12) g: (8-12) mL: (6-8) g.

5. A smelting industry acid wastewater treatment process according to claim 1, characterized in that: In step A4, the ratio of the diatomaceous earth composite, deionized water, amphoteric small molecule functional reagent, and sodium hydroxide solution is (1.6-2) g: (25-35) mL: (8-12) g: (0.2-0.4) mL.

6. A smelting industry acid wastewater treatment process according to claim 1, characterized in that: In step A5, the ratio of the amount of β-cyclodextrin, cross-linking agent, polyethylene glycol 200, sodium dihydrogen phosphate, deionized water, and modified diatomaceous earth composite is (3-5) g: (5-7) g: (0.3-0.7) g: (2.5-2.7) g: (15-25) mL: (2-3) g.

7. A smelting industry acid wastewater treatment process according to claim 1, characterized in that: The alkaline substance is selected from any one of calcium carbonate, lime milk, and magnesium oxide.

8. A process for treating acidic wastewater from a smelting industry according to claim 1, characterized in that: The polyacrylamide flocculant is prepared by mixing amphoteric polyacrylamide and deionized water in a dosage ratio of (30-40) g: (40-55) mL.

9. A process for treating acidic wastewater from a smelting industry according to claim 1, characterized in that: The cross-linking agent is ethylenediaminetetraacetic acid; the carbon precursor is tobacco powder.

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