Process for treating acidic sewage in smelting industry

Abstract

The invention relates to the technical field of acidic sewage treatment, and discloses a smelting industry acidic sewage treatment process which comprises the following steps: adding an alkaline substance into smelting industry acidic sewage, adjusting the pH value of the sewage to be neutral, standing for 10-30 minutes, filtering, and collecting filtrate and precipitate A; adding a composite adsorbent into the filtrate, oscillating for 30-40 minutes, adding a polyacrylamide flocculant, continuously oscillating for 10-20 minutes, and filtering to obtain a precipitate B and supernate; and mixing and recovering the precipitate A and the precipitate B, and recovering, detecting and reusing the supernate. The diatomite loaded with porous carbon has a double-layer porous structure, has relatively large adsorption capacity, and can adsorb heavy metal ions and organic impurities in sewage; the amphoteric small molecular functional reagent is grafted on the surface of the diatomite compound, and can be electrostatically combined with acidic anions and metal cation impurities in sewage to cooperate with a porous structure to complete directional adsorption fixation.

Description

Technical Field

[0001] The present invention relates to the technical field of acid sewage treatment, and specifically to a sewage treatment process for acid sewage in the smelting industry. Background Art

[0002] The main sources of acid sewage in the smelting industry are flue gas washing in the smelting section, acid production from flue gas recovery, and electrolytic purification section. The acid sewage and wastewater generated in these three sections will produce a large amount of sewage. The pH value of the sewage is lower than 1.0, showing strong acidity, and the concentrations of elements such as As, Cu, and Hg seriously exceed the standard. Treating and reusing the acid sewage by improving the production process has dual environmental and economic benefits, so it has been studied and applied by many enterprises.

[0003] Adding diatomite adsorbent to the acid sewage in the smelting industry can effectively adsorb impurities such as metal ions in the sewage. However, the diatomite adsorbent has a low adsorption capacity, a slow adsorption rate, and is easily saturated by adsorption, resulting in low sewage treatment efficiency; and the inorganic impurities in the diatomite are easily detached, affecting the sewage treatment effect. Summary of the Invention

[0004] The present invention provides a sewage treatment process for acid sewage in the smelting industry, which solves the problems of poor sewage treatment effect and low efficiency in the smelting industry.

[0005] The technical solution of the present invention:

[0006] A sewage treatment process for acid sewage in the smelting industry includes the following steps:

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

[0008] S2. Add a composite adsorbent to the filtrate, oscillate for 30 - 40 minutes, then add a polyacrylamide flocculant, continue to oscillate for 10 - 20 minutes, filter, and obtain precipitate B and supernatant;

[0009] S3. Mix and recycle precipitate A and precipitate B, and recycle and reuse the supernatant;

[0010] The composite adsorbent is obtained by reacting a modified diatomite complex, β - cyclodextrin, and a cross - linker;

[0011] The modified diatomite complex is obtained by reacting tetraethylenepentamine with ethylenediaminetetraacetic acid and then mixing with the diatomite complex;

[0012] The diatomite complex is obtained by mixing diatomite with a carbon precursor, calcining at high temperature, and then reacting with epichlorohydrin.

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

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

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

[0016] Further, the cross - linker is ethylenediaminetetraacetic acid.

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

[0018] A1. Add the carbon precursor to ethanol, stir evenly, add citric acid and diatomite, stir and react at 65 - 75 °C for 25 - 35 minutes, filter, wash, dry, place it 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, take out, wash and dry to obtain modified diatomite;

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

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

[0021] A4. Add the diatomite composite to deionized water, stir evenly, add the amphoteric small - molecule functional reagent and a sodium hydroxide solution with a mass fraction of 45 - 55%, stir and react at 60 - 70 °C for 25 - 35 minutes, filter, wash and dry to obtain a modified diatomite composite;

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

[0023] Further, in the above A1 reaction process, diatomaceous earth is mixed with a carbon precursor. 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 undergo chemical reactions with the carboxyl groups in citric acid, and citric acid, as a linking agent, can react with the hydroxyl groups on the surface of diatomaceous earth, enabling the carbon precursor to deposit on the surface of 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 decomposes upon heating, forming a dense carbon layer on the surface of diatomaceous earth, and the potassium hydroxide molecules decompose, forming pores on the surface of the carbon layer, thus realizing the synthesis of a porous carbon material on the surface of diatomaceous earth.

[0024] Further, in the above A2 reaction process, sodium hydroxide is used as a catalyst. At 80 °C, the hydroxyl groups on the surface of the modified diatomaceous earth can undergo a ring-opening reaction with the epoxy groups in epichlorohydrin, enabling epichlorohydrin to graft onto the surface of the modified diatomaceous earth, serving as a reaction site for reacting with the amphoteric small molecule functional reagent. Moreover, the hydroxyl groups generated by the epoxy ring-opening can also complex with metal ions in the sewage, increasing the removal efficiency of metal ions.

[0025] Further, in the above A3 reaction process, the mass ratio of tetraethylenepentamine to ethylenediaminetetraacetic acid is controlled to be 10:7. 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] Further, in the above A4 reaction process, the chlorine atoms of epichlorohydrin in the diatomaceous earth composite can undergo a substitution reaction with the primary amino groups of tetraethylenepentamine in the amphoteric small molecule functional reagent, enabling the amphoteric small molecule functional reagent to graft onto the surface of the diatomaceous earth composite, forming a modified diatomaceous earth composite.

[0027] Further, in the above A5 reaction process, polyethylene glycol 200 is used as a dispersant to promote the dissolution of β-cyclodextrin in deionized water. Sodium dihydrogen phosphate is used as a catalyst, enabling the hydroxyl groups on the surface of β-cyclodextrin to react with the carboxyl groups in the cross-linking agent ethylenediaminetetraacetic acid to form a cross-linked network structure resin. Moreover, the functional groups contained in the amphoteric 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, enabling the modified diatomaceous earth composite to be embedded in the cross-linked network structure resin.

[0028] Further, in step A1, the dosage 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] Further, in step A2, the dosage ratio of the modified diatomaceous earth, epichlorohydrin, deionized water, and sodium hydroxide solution is (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, amphiphilic 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 micrometers and a pore size of 100-150 nanometers.

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

[0035] (1) In the technical scheme 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 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 remove metal ions in sewage. Epichlorohydrin is grafted on the surface of the diatomaceous earth loaded with porous carbon as a reaction site with a zwitterionic small molecule functional reagent, 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 a zwitterionic small molecule functional reagent, which is grafted onto the surface of the diatomite composite to form a modified diatomite composite. The zwitterionic small molecule functional reagent carries a positively charged amino group and a negatively charged carboxyl group, and can electrostatically bind to acidic anions and metal cation impurities in sewage, and cooperate with the porous structure to directionally adsorb and fix the acidic anions and metal cation impurities in sewage in the modified diatomite composite, thereby preventing the double-layer porous structure of the modified diatomite composite from adsorbing more water molecules, occupying the pore capacity, and affecting 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, and adsorb and fix the 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, and can then combine with the negatively charged sludge particles, causing the sludge particles to aggregate and settle, thereby effectively removing the sludge and heavy metal particles.

[0038] (4) In the technical solution of the present invention, in the composite adsorbent, the cavity structure and hydroxyl groups contained in the β-cyclodextrin cross-linked resin can adsorb metal impurities in sewage, and the modified diatomaceous earth composite serves as the skeleton structure of the β-cyclodextrin cross-linked resin, which increases the interaction force between the β-cyclodextrin cross-linked resins and avoids 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 flocculants are added to the treated wastewater. The positive charge carried by polyacrylamide flocculants 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 described embodiments 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 creative work are 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 Factory, Jiangsu Province, mass fraction 99%.

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

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

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

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

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

[0053] Example 1

[0054] A smelting industrial acidic sewage treatment process, characterized in that it comprises the following steps:

[0055] S1. Add the basic substance to the smelting industrial acidic sewage, adjust the pH value of the sewage to neutral, let it stand for 30 minutes, filter, and collect the filtrate and precipitate A;

[0056] S2. Add the composite adsorbent to the filtrate, oscillate for 30 - 40 minutes, then add polyacrylamide flocculant, continue to oscillate for 10 - 20 minutes, filter, to obtain precipitate B and supernatant;

[0057] S3. Mix and recycle precipitate A and precipitate B, and recycle and reuse the supernatant.

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

[0059] A1. Add 4g of tobacco powder to 45mL of ethanol, stir evenly, add 0.1g of citric acid and 1.6g of diatomite, stir and react at 65°C for 25 minutes, filter, wash, dry, place it in a tube furnace, add 5mL of potassium hydroxide for activation, stir evenly, carbonize at 750°C for 1 hour, cool to room temperature, take out, wash 3 times with deionized water, and dry in an oven at 70°C for 10 minutes to obtain modified diatomite;

[0060] A2. Add 1g of modified diatomite and 10mL of epichlorohydrin to 15mL of deionized water, stir evenly, add 5mL of sodium hydroxide solution with a mass fraction of 45%, stir and react at 75°C for 10 minutes, filter, wash 3 times with deionized water, and dry in an oven at 50°C for 10 minutes to obtain diatomite composite;

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

[0062] A4. Add 1.6 g of diatomite composite to 25 mL of deionized water, stir evenly, add 8 g of amphoteric small molecule functional reagent and 0.2 mL of sodium hydroxide solution with a mass fraction of 45%, stir and react at 60 °C for 25 minutes, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 10 minutes to obtain a modified diatomite 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 oil bath at 80 °C and stir for 2 hours, add 2 g of modified diatomite composite, continue to stir and react for 30 minutes, place in an oven at 150 °C and heat - react for 8 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water and filter by suction, and dry at 65 °C for 1 hour to obtain a composite adsorbent.

[0064] Example 2

[0065] A smelting industrial acidic sewage treatment process, characterized by comprising the following steps:

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

[0067] S2. Add the composite adsorbent to the filtrate, oscillate for 35 minutes, then add a polyacrylamide flocculant, continue to oscillate for 15 minutes, filter to obtain precipitate B and supernatant;

[0068] S3. Mix and recycle precipitate A and precipitate B, and recycle and reuse the supernatant.

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

[0070] A1. Add 5 g of tobacco powder to 50 mL of ethanol, stir evenly, add 0.2 g of citric acid and 1.8 g of diatomite, stir and react at 70 °C for 30 minutes, filter, wash, dry, place in a tubular furnace, add 6 mL of potassium hydroxide for activation, then stir evenly, carbonize at 800 °C for 1.5 hours, cool to room temperature, take out, wash with deionized water 3 times, and dry in an oven at 70 °C for 10 minutes to obtain modified diatomite;

[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 sodium hydroxide solution with a mass fraction of 50%, stir and react at 80 °C for 13 minutes, filter, wash with deionized water 3 times, and dry in an oven at 50 °C for 10 minutes to obtain 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 up to 80 °C, stir and react at a rate of 600 r / min for 30 minutes, heat up to 105 °C, continue to react, and cool to room temperature to obtain an amphoteric small molecule functional reagent;

[0073] A4. Add 1.8 g of diatomaceous earth composite to 30 mL of deionized water, stir evenly, add 10 g of amphoteric small molecule functional reagent and 0.3 mL of sodium hydroxide solution with a mass fraction of 50%, stir and react at 65 °C for 30 minutes, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 10 minutes to obtain 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 an oil bath at 100 °C and stir for 1.5 hours, add 2.5 g of modified diatomaceous earth composite, continue to stir and react for 33 minutes, place in an oven at 155 °C and heat and react for 10 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water and filter by suction, and dry at 65 °C for 1 - 5 hours to obtain a composite adsorbent.

[0075] Example 3

[0076] A smelting industrial acid sewage treatment process, characterized in that it includes the following steps:

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

[0078] S2. Add the composite adsorbent to the filtrate, oscillate for 40 minutes, then add a polyacrylamide flocculant, continue to oscillate for 20 minutes, filter, and obtain precipitate B and supernatant;

[0079] S3. Mix and recycle precipitate A and precipitate B, and recycle and reuse the supernatant.

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

[0081] A1. Add 6 g of tobacco powder to 55 mL of ethanol, stir evenly, add 0.3 g of citric acid and 2 g of diatomite, stir and react at 75 °C for 35 minutes, filter, wash, dry, place in a tube furnace, add 7 mL of potassium hydroxide for activation, stir evenly, carbonize at 850 °C for 2 hours, cool to room temperature, take out, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 minutes to obtain modified diatomite;

[0082] A2. Add 1.4 g of modified diatomite and 20 mL of epichlorohydrin to 25 mL of deionized water, stir evenly, add 7 mL of sodium hydroxide solution with a mass fraction of 55%, stir and react at 85 °C for 15 minutes, filter, wash 3 times with deionized water, and dry in an oven at 50 °C for 10 minutes to obtain a diatomite 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 to react, and cool to room temperature to obtain an amphoteric small molecule functional reagent;

[0084] A4. Add 2 g of diatomite composite to 35 mL of deionized water, stir evenly, add 12 g of amphoteric small molecule functional reagent and 0.4 mL of sodium hydroxide solution with a mass fraction of 55%, stir and react at 70 °C for 35 minutes, filter, wash 3 times with deionized water, and dry in an oven at 60 °C for 10 minutes to obtain a modified diatomite 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 an oil bath at 120 °C and stir for 2 hours, add 3 g of modified diatomite composite, continue to stir and react for 35 minutes, place in an oven at 160 °C and heat and react for 12 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water and filter by suction, and dry at 65 °C for 2 hours to obtain a composite adsorbent.

[0086] Comparative Example 1

[0087] A smelting industrial acidic sewage treatment process, characterized by comprising the following steps:

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

[0089] S2. Add the composite adsorbent to the filtrate, oscillate for 40 minutes, add a polyacrylamide flocculant, continue to oscillate for 20 minutes, filter, and obtain precipitate B and supernatant;

[0090] S3. The 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 diatomite and 20 mL of epichlorohydrin to 25 mL of deionized water, stir evenly, add 7 mL of sodium hydroxide solution with a mass fraction of 55%, stir and react at 85 °C for 15 minutes, filter, wash with deionized water 3 times, and dry in an oven at 50 °C for 10 minutes to obtain a diatomite 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 to react, and cool to room temperature to obtain an amphoteric small molecule functional reagent;

[0094] A3. Add 2 g of the diatomite composite to 35 mL of deionized water, stir evenly, add 12 g of the amphoteric small molecule functional reagent and 0.4 mL of sodium hydroxide solution with a mass fraction of 55%, stir and react at 70 °C for 35 minutes, filter, wash with deionized water 3 times, and dry in an oven at 60 °C for 10 minutes to obtain a modified diatomite 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 an oil bath at 120 °C and stir for 2 hours, add 3 g of the modified diatomite composite, continue to stir and react for 35 minutes, place in an oven at 160 °C and heat and react for 12 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water and filter by suction, and dry at 65 °C for 2 hours to obtain the composite adsorbent.

[0096] Comparative Example 2

[0097] A smelting industrial acid sewage treatment process, characterized in that it includes the following steps:

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

[0099] S2. Add the composite adsorbent to the filtrate, oscillate for 40 minutes, then add a polyacrylamide flocculant, continue to oscillate for 20 minutes, and filter to obtain precipitate B and a supernatant;

[0100] S3. The 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. Add 6 g of tobacco powder to 55 mL of ethanol, stir evenly, add 0.3 g of citric acid and 2 g of diatomite, stir and react at 75 °C for 35 minutes, filter, wash, dry, place in a tube furnace, add 7 mL of potassium hydroxide for activation, stir evenly, carbonize at 850 °C for 2 hours, cool to room temperature, take out, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 minutes to obtain modified diatomite;

[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 to react, and cool to room temperature to obtain an amphoteric small molecule functional reagent;

[0104] A3. Add 2 g of modified diatomite to 35 mL of deionized water, stir evenly, add 12 g of amphoteric small molecule functional reagent and 0.4 mL of sodium hydroxide solution with a mass fraction of 55%, stir and react at 70 °C for 35 minutes, filter, wash 3 times with deionized water, and dry in an oven at 60 °C for 10 minutes to obtain a modified diatomite 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 an oil bath at 120 °C and stir for 2 hours, add 3 g of modified diatomite composite, continue to stir and react for 35 minutes, place in an oven at 160 °C and heat and react for 12 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water and filter by suction, and dry at 65 °C for 2 hours to obtain the composite adsorbent.

[0106] Comparative Example 3

[0107] A smelting industrial acidic sewage treatment process, characterized by comprising the following steps:

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

[0109] S2. Add the composite adsorbent to the filtrate, oscillate for 40 minutes, add a polyacrylamide flocculant, continue to oscillate for 20 minutes, filter, and obtain precipitate B and supernatant;

[0110] S3. Mix and recycle precipitate A and precipitate B, and recycle and reuse the supernatant.

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

[0112] A1. Add 6 g of tobacco powder to 55 mL of ethanol, stir evenly, add 0.3 g of citric acid and 2 g of diatomite, stir and react at 75 °C for 35 minutes, filter, wash, dry, place in a tube furnace, add 7 mL of potassium hydroxide for activation, stir evenly, carbonize at 850 °C for 2 hours, cool to room temperature, take out, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 minutes to obtain modified diatomite;

[0113] A2. Add 1.4 g of modified diatomite and 20 mL of epichlorohydrin to 25 mL of deionized water, stir evenly, add 7 mL of sodium hydroxide solution with a mass fraction of 55%, stir and react at 85 °C for 15 minutes, filter, wash 3 times with deionized water, and dry in an oven at 50 °C for 10 minutes to obtain diatomite 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 an oil bath at 120 °C and stir for 2 hours, add 3 g of diatomite composite, continue to stir and react for 35 minutes, place in an oven at 160 °C and heat and react for 12 hours, cool to room temperature, take out, grind, place in 500 mL of deionized water, wash with water and filter by suction, and dry at 65 °C for 2 hours to obtain the composite adsorbent.

[0115] Comparative Example 4

[0116] A smelting industrial acidic sewage treatment process, characterized by comprising the following steps:

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

[0118] S2. Add the composite adsorbent to the filtrate, oscillate for 40 minutes, add polyacrylamide flocculant, continue to oscillate for 20 minutes, filter, to obtain precipitate B and supernatant;

[0119] S3. Mix and recycle precipitate A and precipitate B, and recycle and reuse the supernatant.

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

[0121] A1. Add 6 g of tobacco powder to 55 mL of ethanol, stir evenly, add 0.3 g of citric acid and 2 g of diatomite, stir and react at 75 °C for 35 minutes. After filtration, washing, and drying, place it in a tube furnace, add 7 mL of potassium hydroxide for activation, stir evenly, carbonize at 850 °C for 2 hours, cool to room temperature, take out, wash 3 times with deionized water, and dry in an oven at 70 °C for 10 minutes to obtain modified diatomite;

[0122] A2. Add 1.4 g of modified diatomite and 20 mL of epichlorohydrin to 25 mL of deionized water, stir evenly, add 7 mL of sodium hydroxide solution with a mass fraction of 55%, stir and react at 85 °C for 15 minutes. After filtration, wash 3 times with deionized water, and dry in an oven at 50 °C for 10 minutes to obtain a diatomite 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 to react, and cool to room temperature to obtain an amphoteric small molecule functional reagent;

[0124] A4. Add 2 g of diatomite composite to 35 mL of deionized water, stir evenly, add 12 g of amphoteric small molecule functional reagent and 0.4 mL of sodium hydroxide solution with a mass fraction of 55%, stir and react at 70 °C for 35 minutes. After filtration, wash 3 times with deionized water, and dry in an oven at 60 °C for 10 minutes to obtain a composite adsorbent.

[0125] Now, perform performance tests on the composite adsorbents prepared in Examples 1-3 and Comparative Examples 1-4 for treating acidic sewage in the smelting industry.

[0126] In the acidic sewage of the smelting industry of the present invention, the heavy metal content is 5.7 g / L, the sludge content is 200 g / L, the CODcr is 82 (mg / L), and the pH is 1.2.

[0127] According to the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002), detect the supernatant of Examples 1-3 and Comparative Examples 1-4;

[0128] Detection of metal ions in the supernatant: Use the "Inspection Method for Sludge of Municipal Wastewater Treatment Plants (CJT221-2005)" to detect metal ions in the supernatant. After the supernatant is digested, use flame atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry to determine the content of metal ions in the supernatant, and calculate the metal removal rate (%);

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

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

[0131]

[0132] It can be seen from the data in Table 1 that the modified soluble polytetrafluoroethylene prepared in Examples 1-3 has good mechanical properties and lubricity, and nano-silica has good coating performance on soluble polytetrafluoroethylene. In Comparative Example 1, the modified diatomite was replaced with diatomite, and the composite adsorbent was used to treat the acidic sewage in the smelting industry. The supernatant was detected. The metal ion removal rate decreased, and the CODcr did not meet the discharge standard, which proved that porous carbon materials were synthesized on the surface of diatomite. The excellent adsorption performance of porous carbon could adsorb and fix the impurities that were easily shed in diatomite, preventing them from falling into the sewage during the sewage treatment process and affecting the treatment effect. Moreover, the diatomite loaded with porous carbon had a double-layer porous structure and a large adsorption capacity, and could adsorb heavy metal ions and organic impurities in the sewage.

[0133] In Comparative Example 2, the composite adsorbent prepared by replacing the diatomite composite with modified diatomite was used to treat the acidic sewage in the smelting industry. The supernatant was detected. The metal ion removal rate decreased, and the CODcr and pH value did not meet the standards, which proved that epichlorohydrin was grafted on the surface of the diatomite loaded with porous carbon as the reaction site with the amphoteric small molecule functional reagent, and could adsorb acidic substances in the sewage. Moreover, the hydroxyl groups generated by the ring-opening of epoxy could also complex with metal ions in the sewage, increasing the removal efficiency of metal ions.

[0134] In Comparative Example 3, the composite adsorbent prepared by mixing the modified diatomite composite with diatomite composite was used to treat the acidic sewage in the smelting industry. The supernatant was detected. The metal ion removal rate and sludge removal rate decreased, and the CODcr and pH value did not meet the standards, indicating that the amphoteric small molecule functional reagent was grafted on the surface of the diatomite composite, carrying positively charged amino groups and negatively charged carboxyl groups, and could electrostatically combine with 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 diatomite composite, and showed a positive charge, and then could combine with the negatively charged sludge particles, making the sludge particles aggregate and settle.

[0135] In Comparative Example 4, β-cyclodextrin and cross-linking agent ethylenediaminetetraacetic acid were not added. The prepared composite adsorbent was used to treat acidic sewage from the smelting industry, and the supernatant was detected. The removal rate of metal ions decreased, and the CODcr did not meet the standard, which proved that the cavity structure and hydroxyl groups contained in the β-cyclodextrin cross-linked resin could adsorb metal impurities and organic impurities in the sewage.

[0136] In the description of the specification, the descriptions with reference to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0137] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar ways to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should fall within the protection scope of the present invention.

Claims

1. A smelting industrial acidic sewage treatment process, characterized in that, It includes the following steps: S1. Add an alkaline substance to the acidic sewage in the smelting industry, adjust the pH value of the sewage to neutral, let it stand for 10 - 30 minutes, filter, and collect the filtrate and precipitate A; S2. Add the composite adsorbent to the filtrate, oscillate for 30 - 40 minutes, then add polyacrylamide flocculant, continue to oscillate for 10 - 20 minutes, filter, and obtain precipitate B and supernatant; S3. Mix and recycle precipitate A and precipitate B, and recycle and detect the supernatant for reuse; The composite adsorbent is obtained by reacting a modified diatomite complex, β - cyclodextrin, and a cross - linker; The modified diatomite complex is obtained by reacting tetraethylenepentamine with ethylenediaminetetraacetic acid and then mixing with the diatomite complex; The diatomite complex is obtained by mixing diatomite with a carbon precursor, calcining at high temperature, and then reacting with epichlorohydrin; 2. The acid wastewater treatment process for smelting industry according to claim 1, wherein The composite adsorbent is specifically prepared by the following steps: A1. Add the carbon precursor to ethanol, stir evenly, add citric acid and diatomite, stir and react 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, take out, wash and dry to obtain modified diatomite; A2. Add the modified diatomite and epichlorohydrin to deionized water, stir evenly, add a sodium hydroxide solution with a mass fraction of 45 - 55%, stir and react at 75 - 85 °C for 10 - 15 minutes, filter, wash, dry to obtain the diatomite complex; A3. Add tetraethylenepentamine to deionized water, stir evenly, add ethylenediaminetetraacetic acid, heat up to 70 - 90 °C, stir and react at a rate of 550 - 650 r / min for 25 - 35 minutes, heat up to 100 - 110 °C, continue to react, cool to room temperature to obtain an amphoteric small - molecule functional reagent; A4. Add the diatomite complex to deionized water, stir evenly, add the amphoteric small - molecule functional reagent and a sodium hydroxide solution with a mass fraction of 45 - 55%, stir and react at 60 - 70 °C for 25 - 35 minutes, filter, wash, dry to obtain the modified diatomite complex; A5. Add β - cyclodextrin, cross - linker, polyethylene glycol 200, and sodium dihydrogen phosphate to deionized water, stir evenly, place in an oil bath at 80 - 120 °C and stir for 1 - 2 hours, add the modified diatomite complex, continue to stir and react for 30 - 35 minutes, place in an oven at 150 - 160 °C and heat - react for 8 - 12 hours, cool to room temperature, take out, grind, place in deionized water, wash, filter by suction, dry to obtain the composite adsorbent.

3. The acid sewage treatment process for smelting industry according to claim 2, characterized in that, In step A1, the dosage ratio of the carbon precursor, ethanol, citric acid, diatomite, and potassium hydroxide is (4 - 6) g:(45 - 55) mL:(0.1 - 0.3) g:(1.6 - 2) g:(5 - 7) mL.

4. A smelting industrial acid sewage treatment process according to claim 2, characterized in that, In step A2, the dosage ratio of the modified diatomite, epichlorohydrin, deionized water, and sodium hydroxide solution is (1 - 1.4) g:(10 - 20) mL:(15 - 25) mL:(5 - 7) mL.

5. A smelting industrial acid sewage treatment process according to claim 2, characterized in that, In the step A3, the dosage ratio of tetraethylenepentamine, deionized water, and ethylenediaminetetraacetic acid is (8 - 12) g : (8 - 12) mL : (6 - 8) g.

6. A smelting industrial acid sewage treatment process according to claim 2, characterized in that, In the step A4, the dosage ratio of the diatomite 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.

7. A smelting industrial acid sewage treatment process according to claim 2, characterized in that, In the step A5, the dosage ratio of β - cyclodextrin, cross - linker, polyethylene glycol 200, sodium dihydrogen phosphate, deionized water, and modified diatomite composite is (3 - 5) g : (5 - 7) g : (0.3 - 0.7) g : (2.5 - 2.7) g : (15 - 25) mL : (2 - 3) g.

8. A smelting industrial acid sewage treatment process according to claim 1, characterized in that, The basic substance is selected from any one of calcium carbonate, lime milk, and magnesium oxide.

9. A smelting industrial acid sewage treatment process 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.

10. A smelting industrial acid sewage treatment process according to claim 1, characterized in that, The cross - linker is ethylenediaminetetraacetic acid; the carbon precursor is tobacco powder.

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