A purification treatment method for industrial acidic wastewater

Abstract

The present invention relates to the technical field of wastewater treatment, and specifically to a method for purifying industrial acidic wastewater. The method comprises the following steps: selecting solid waste powder fly ash, biomaterial chitosan, and renewable attapulgite as raw materials, mixing them with bentonite, sodium silicate, and deionized water to form granules to prepare a spherical purification adsorbent; adopting a method of co-precipitating ascorbic acid and nano-FeS on the attapulgite to obtain pretreated attapulgite, and then grafting an amine polymer containing a carboxyl group to prepare a composite attapulgite; and modifying the chitosan by first cross-linking the chitosan with glutaraldehyde, then reacting the chitosan with epichlorohydrin under alkaline conditions to introduce an epoxy group, and utilizing the epoxy group to react with the amine polymer containing a carboxyl group to prepare a modified chitosan. The modified chitosan is prepared by increasing the bonding strength between the raw materials of the purification adsorbent, reducing the amount of sediment, and synergistically improving the adsorption effect of the adsorbent, thereby improving the adsorption effect of the pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and specifically to a purification treatment method for industrial acidic wastewater. Background Art

[0002] Mining activities, exposure of open-pit veins, etc. will generate acidic wastewater. Since acidic wastewater has a low pH value and contains a large number of heavy metal ions such as copper, nickel, mercury, cadmium, lead, and chromium, direct discharge will cause water body acidification, damage the self-purification function of water, and at the same time poison the soil and vegetation, affecting the sustainable development of the production area.

[0003] The existing treatment methods for mine acidic wastewater mainly include the neutralization method, the sulfide precipitation method, and the microbial method. However, most of the existing methods have high treatment costs, low efficiency, and are prone to problems such as secondary pollution. Summary of the Invention

[0004] The purpose of the present invention is to provide a purification treatment method for industrial acidic wastewater to solve the problems in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A purification treatment method for industrial acidic wastewater includes the following steps:

[0007] S1: Put alkaline agents into industrial acidic wastewater, stir, stand, and filter to obtain pretreated waste liquid;

[0008] S2: Mix fly ash, composite attapulgite, modified chitosan, bentonite, sodium silicate, and deionized water, granulate and cure to obtain a purification adsorbent;

[0009] S3: Put the purification adsorbent into the pretreated waste liquid, stir intermittently and filter to obtain treated waste liquid.

[0010] Further, the alkaline agents are one or a combination of calcium oxide, calcium hydroxide, sodium hydroxide, sodium carbonate, and sodium bicarbonate.

[0011] Further, the pH of the industrial acidic wastewater is 1 - 5, and the pH of the pretreated waste liquid is 6 - 8.

[0012] Further, the mass-volume ratio of the purification adsorbent to the pretreated waste liquid is 8g:10L.

[0013] Further, the working conditions of intermittent stirring are: stir for 10 - 20 min after feeding, and stir for 10 min every 1 h until adsorption is completed.

[0014] Furthermore, the raw material composition of the purification adsorbent is as follows: 27-37 parts of fly ash, 13-25 parts of composite attapulgite, 3-10 parts of modified chitosan, 2-5 parts of bentonite, 1-3 parts of sodium silicate, and 3-8 parts of deionized water.

[0015] By optimizing the component ratio of the purification adsorbent, a non-fired purification adsorbent that can be recycled, is green and environmentally friendly, and has strong heavy metal adsorption capacity is prepared. When purifying industrial acidic wastewater, it can effectively improve the heavy metal ion pollution situation of the acidic wastewater and achieve the water purification effect.

[0016] Fly ash, a solid waste powder, chitosan, a biological raw material, and renewable attapulgite are selected as raw materials, and are mixed with bentonite, sodium silicate, and deionized water to prepare a spherical purification adsorbent, which meets the current green production requirements. By controlling the component ratio, the structural stability of the purification adsorbent is greatly improved, thereby enhancing its adsorption capacity for heavy metal ions and pollutants, and achieving the purpose of solid waste resource utilization.

[0017] Furthermore, the preparation of the composite attapulgite includes the following steps:

[0018] 1) Under a nitrogen atmosphere, mix a sodium sulfide solution and attapulgite, stir for 1-2 h, add a mixed solution of ascorbic acid and deionized water, add a ferrous sulfate solution, ultrasonically stir for 15-20 min, filter and freeze-dry to obtain pretreated attapulgite;

[0019] 2) Mix the pretreated attapulgite, deionized water, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and a carboxyl-containing amine polymer, heat to 70-80 °C and keep warm for 2-3 h to obtain the composite attapulgite.

[0020] In order to improve the adsorption and purification capacity of attapulgite and improve its uniformity of dispersion in the purification adsorbent, pretreated attapulgite is obtained by the method of coprecipitation of ascorbic acid and nano-FeS on attapulgite, and then a carboxyl-containing amine polymer is grafted using the polyhydroxy structure of ascorbic acid. The carboxyl-containing amine polymer is a Bronsted acid proton buffer polyamine that is resistant to acids and bases, which can greatly improve the stability of the purification adsorbent and its adsorption capacity for heavy metal ions such as cadmium, lead, and chromium.

[0021] Furthermore, the preparation of the modified chitosan includes the following steps:

[0022] (1) Mix chitosan, methanol, and a glutaraldehyde solution, keep warm in a water bath at 53-57 °C for 5-6 h, wash and dry to obtain crosslinked chitosan; mix the crosslinked chitosan, a NaOH solution, and epichlorohydrin, oscillate in a water bath at 38-42 °C for 3-4 h, and wash to neutrality to obtain epoxy chitosan;

[0023] (3) Mix the amine polymer containing carboxyl group and NaOH solution, add epoxy chitosan, oscillate in a water bath at 68 - 72 °C for 5 - 6 h, wash and dry to obtain modified chitosan.

[0024] Chitosan is selected as the binder. To improve the water solubility and stability of chitosan, chitosan is modified. First, chitosan is cross-linked and modified with glutaraldehyde, and then reacted with epichlorohydrin under alkaline conditions to introduce epoxy groups. The epoxy groups react with the amine polymer containing carboxyl group to prepare modified chitosan, which has a composite effect on fly ash, composite attapulgite and bentonite, improves the bonding strength between the raw materials of the purification adsorbent, reduces the sediment volume, and simultaneously synergistically improves the adsorption effect of the adsorbent on pollutants.

[0025] Furthermore, the mass ratio of the amine polymer containing carboxyl group to epoxy chitosan is: 0.8:1.

[0026] Furthermore, the preparation of the amine polymer containing carboxyl group includes the following steps:

[0027] Under a nitrogen atmosphere, mix 2-(trifluoromethyl)acrylic acid, methanol, trimethylolpropane trimethacrylate, 4-vinyl aniline, and azobisisobutyronitrile, keep warm at 68 - 72 °C for 22 - 24 h, filter, wash and grind to obtain the amine polymer containing carboxyl group.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] The present invention provides a method for purifying and treating industrial acidic wastewater. By optimizing the component ratio of the used purification adsorbent, a non-fired purification adsorbent that can be recycled, is green and environmentally friendly, and has high heavy metal adsorption capacity is prepared. When used for purifying industrial acidic wastewater, it can effectively improve the pollution situation of acidic wastewater.

[0030] In the present invention, fly ash as solid waste powder, chitosan as biological raw material, and renewable attapulgite are selected as raw materials, and are mixed with bentonite, sodium silicate, and deionized water to granulate to prepare a spherical purification adsorbent, which meets the requirements of green production. By controlling the component ratio, the structural stability of the adsorbent is improved, thereby improving its adsorption capacity for heavy metal ions and pollutants, and achieving the purpose of solid waste resource utilization and wastewater treatment.

[0031] To improve the adsorption and purification capacity of attapulgite and its uniform dispersion in the adsorbent, ascorbic acid and nano-FeS were co-precipitated on attapulgite to obtain pretreated attapulgite. The polyhydroxy structure of ascorbic acid was then used to graft a carboxyl-containing amine polymer. The carboxyl-containing amine polymer, prepared by polymerizing 2-(trifluoromethyl)acrylic acid as a functional monomer for proton storage with the amino monomer 4-vinylaniline and the cross-linking agent trimethylolpropane trimethacrylate, is an acid- and alkali-resistant Brønsted acid proton-buffered polyamine, which significantly improves the stability of the purification adsorbent and its adsorption capacity for heavy metal ions such as cadmium, lead, and chromium.

[0032] In the present invention, chitosan is selected as a binder. In order to improve the water solubility and stability of chitosan, the chitosan is modified. First, the chitosan is cross-linked with glutaraldehyde, and then reacted with epichlorohydrin under alkaline conditions to introduce epoxy groups. The epoxy groups are reacted with amine polymers containing carboxyl groups to prepare modified chitosan. The modified chitosan has a composite effect on fly ash, composite attapulgite and bentonite, improves the bonding strength between the purification adsorbent raw materials, reduces the amount of sediment, and synergistically improves the adsorption effect of the adsorbent, thereby improving the adsorption effect of the pollutants. DETAILED DESCRIPTION

[0033] The following will provide a clear and complete description of the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, and back, such directional indications are only used to explain a specific posture, such as the relative position relationship between components, the movement status, etc. If the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions between the various embodiments may be combined with each other, but they must be based on the premise that they can be implemented by ordinary technicians in this field. If the combination of technical solutions is mutually inconsistent or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0035] The technical solutions of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely used to explain the present invention and are not intended to limit the present invention.

[0036] Example 1: A method for purifying industrial acidic wastewater, comprising the following steps:

[0037] S1: adding alkaline reagent into industrial acidic wastewater, stirring, standing, and filtering to obtain pretreated waste liquid;

[0038] The alkaline agent is calcium oxide; the pH of the industrial acidic wastewater is 1, and the pH of the pretreated wastewater is 6;

[0039] S2: mixing fly ash, composite attapulgite, modified chitosan, bentonite, sodium silicate, and deionized water, granulating, and curing to obtain a purification adsorbent;

[0040] The raw material composition of the purification adsorbent is as follows: 27 parts of fly ash, 13 parts of composite attapulgite, 3 parts of modified chitosan, 2 parts of bentonite, 1 part of sodium silicate, and 3 parts of deionized water.

[0041] The working conditions for curing are: let it stand for 6 hours, heat it up to 65℃ and keep it for 2 hours, heat it up to 95℃ and keep it for 2 hours, heat it up to 115℃ and keep it for 2 hours, and cool it down to 25℃.

[0042] The preparation of the composite attapulgite comprises the following steps:

[0043] 1) Under a nitrogen atmosphere, 100 mL of a 1 mol / L sodium sulfide solution and 2 g of attapulgite were mixed and stirred for 1 hour. A mixture of 0.25 g of ascorbic acid and 250 mL of deionized water was added, followed by 100 mL of a 1 mol / L ferrous sulfate solution. The mixture was ultrasonically stirred for 15 minutes, filtered, and freeze-dried to obtain pretreated attapulgite.

[0044] 2) 8.4 g of pretreated attapulgite, 100 mL of deionized water, 1.8 g of carbodiimide hydrochloride, 0.9 g of N-hydroxysuccinimide, and 3.7 g of a carboxyl-containing amine polymer were mixed, and the mixture was heated to 70° C. and maintained for 3 h to obtain a composite attapulgite.

[0045] The preparation of the modified chitosan comprises the following steps:

[0046] (1) Mix 1 g of chitosan, 30 mL of methanol, and 6 mL of 10% glutaraldehyde solution, keep it in a 53°C water bath for 6 h, wash it, and dry it to obtain cross-linked chitosan; mix 1 g of cross-linked chitosan, 30 mL of 1 mol / L NaOH solution, and 4 mL of epichlorohydrin, shake it in a 38°C water bath for 4 h, and wash it until it is neutral to obtain epoxy chitosan;

[0047] (3) 0.8 g of an amine polymer containing a carboxyl group and 30 mL of 1 mol / L NaOH solution were mixed, 1 g of epoxy chitosan was added, and the mixture was shaken in a water bath at 68 °C for 6 h, washed, and dried to obtain modified chitosan;

[0048] The preparation of the carboxyl-containing amine polymer comprises the following steps:

[0049] Under nitrogen atmosphere, 0.5 mmol 2-(trifluoromethyl)acrylic acid, 5 mL methanol, 0.5 mmol trimethylolpropane trimethacrylate, 2 mmol 4-vinylaniline, and 50 mg azobisisobutyronitrile were mixed and kept at 68°C for 24 h. The mixture was filtered, washed, and ground to obtain an amine polymer containing carboxyl groups.

[0050] S3: adding the purification adsorbent to the pre-treated waste liquid, stirring and filtering intermittently to obtain the treated waste liquid;

[0051] The mass volume ratio of the purified adsorbent to the pretreated waste liquid is 8 g:10 L;

[0052] The working conditions of intermittent stirring are: stirring for 10 minutes after adding the materials, and stirring for 10 minutes every hour until the adsorption is completed.

[0053] Example 2: A method for purifying industrial acidic wastewater, comprising the following steps:

[0054] S1: adding alkaline reagent into industrial acidic wastewater, stirring, standing, and filtering to obtain pretreated waste liquid;

[0055] The alkaline agent is calcium oxide; the pH of the industrial acidic wastewater is 3, and the pH of the pretreated wastewater is 7;

[0056] S2: mixing fly ash, composite attapulgite, modified chitosan, bentonite, sodium silicate, and deionized water, granulating, and curing to obtain a purification adsorbent;

[0057] The raw material composition of the purification adsorbent is as follows: 32 parts of fly ash, 19 parts of composite attapulgite, 7 parts of modified chitosan, 3 parts of bentonite, 2 parts of sodium silicate, and 5 parts of deionized water.

[0058] The working conditions for curing are: let it stand for 6 hours, heat it up to 65℃ and keep it for 2 hours, heat it up to 95℃ and keep it for 2 hours, heat it up to 115℃ and keep it for 2 hours, and cool it down to 25℃.

[0059] The preparation of the composite attapulgite comprises the following steps:

[0060] 1) Under a nitrogen atmosphere, 100 mL of 1 mol / L sodium sulfide solution and 2 g of attapulgite were mixed and stirred for 1.5 h. A mixture of 0.25 g of ascorbic acid and 250 mL of deionized water was added, followed by 100 mL of 1 mol / L ferrous sulfate solution. The mixture was ultrasonically stirred for 18 min, filtered, and freeze-dried to obtain pretreated attapulgite.

[0061] 2) Mix 8.4 g of pretreated attapulgite, 100 mL of deionized water, 1.8 g of carbodiimide hydrochloride, 0.9 g of N-hydroxysuccinimide, and 3.7 g of amine polymer containing carboxyl group, heat up to 75 °C and keep warm for 2.5 h to obtain composite attapulgite;

[0062] The preparation of the modified chitosan includes the following steps:

[0063] (1) Mix 1 g of chitosan, 30 mL of methanol, and 6 mL of 10% glutaraldehyde solution by mass concentration, keep warm in a water bath at 55 °C for 5.5 h, wash and dry to obtain cross-linked chitosan; mix 1 g of cross-linked chitosan, 30 mL of 1 mol / L NaOH solution, and 4 mL of epichlorohydrin, oscillate in a water bath at 40 °C for 3.5 h, wash until neutral to obtain epoxy chitosan;

[0064] (3) Mix 0.8 g of amine polymer containing carboxyl group and 30 mL of 1 mol / L NaOH solution, add 1 g of epoxy chitosan, oscillate in a water bath at 70 °C for 5.5 h, wash and dry to obtain modified chitosan;

[0065] The preparation of the amine polymer containing carboxyl group includes the following steps:

[0066] Under a nitrogen atmosphere, mix 0.5 mmol of 2-(trifluoromethyl)acrylic acid, 5 mL of methanol, 0.5 mmol of trimethylolpropane trimethacrylate, 2 mmol of 4-vinyl aniline, and 50 mg of azobisisobutyronitrile, keep warm at 70 °C for 23 h, filter, wash, and grind to obtain an amine polymer containing carboxyl group;

[0067] S3: Put the purification adsorbent into the pretreated waste liquid, stir intermittently and filter to obtain the treated waste liquid;

[0068] The mass-volume ratio of the purification adsorbent to the pretreated waste liquid is 8 g:10 L;

[0069] The working conditions of intermittent stirring are: stir for 15 min after feeding, and stir for 10 min every 1 h until adsorption is completed.

[0070] Example 3: A method for purifying and treating industrial acidic wastewater includes the following steps:

[0071] S1: Put the alkaline agent into the industrial acidic wastewater, stir, stand, and filter to obtain the pretreated waste liquid;

[0072] The alkaline agent is calcium oxide; the pH of the industrial acidic wastewater is 5, and the pH of the pretreated waste liquid is 8;

[0073] S2: Mix fly ash, composite attapulgite, modified chitosan, bentonite, sodium silicate, and deionized water, granulate and cure to obtain a purification adsorbent;

[0074] By weight, the raw material composition of the purification adsorbent is: 37 parts of fly ash, 25 parts of composite attapulgite, 10 parts of modified chitosan, 5 parts of bentonite, 3 parts of sodium silicate, and 8 parts of deionized water;

[0075] The working conditions for curing are: standing for 6 h, heating to 65 °C and maintaining for 2 h, heating to 95 °C and maintaining for 2 h, heating to 115 °C and maintaining for 2 h, and cooling to 25 °C;

[0076] The preparation of the composite attapulgite includes the following steps:

[0077] 1) Under a nitrogen atmosphere, mix 100 mL of 1 mol / L sodium sulfide solution and 2 g of attapulgite, stir for 2 h, add a mixture of 0.25 g of ascorbic acid and 250 mL of deionized water, add 100 mL of 1 mol / L ferrous sulfate solution, ultrasonically stir for 20 min, filter and freeze-dry to obtain pretreated attapulgite;

[0078] 2) Mix 8.4 g of pretreated attapulgite, 100 mL of deionized water, 1.8 g of carbodiimide hydrochloride, 0.9 g of N-hydroxysuccinimide, and 3.7 g of amine polymer containing carboxyl group, heat to 80 °C and keep warm for 2 h to obtain composite attapulgite;

[0079] The preparation of the modified chitosan includes the following steps:

[0080] (1) Mix 1 g of chitosan, 30 mL of methanol, and 6 mL of 10% glutaraldehyde solution by mass, keep warm in a water bath at 57 °C for 5 h, wash and dry to obtain crosslinked chitosan; mix 1 g of crosslinked chitosan, 30 mL of 1 mol / L NaOH solution, and 4 mL of epichlorohydrin, oscillate in a water bath at 42 °C for 3 h, wash to neutrality to obtain epoxy chitosan;

[0081] (3) Mix 0.8 g of amine polymer containing carboxyl group and 30 mL of 1 mol / L NaOH solution, add 1 g of epoxy chitosan, oscillate in a water bath at 72 °C for 5 h, wash and dry to obtain modified chitosan;

[0082] The preparation of the amine polymer containing carboxyl group includes the following steps:

[0083] Under nitrogen atmosphere, 0.5 mmol 2-(trifluoromethyl)acrylic acid, 5 mL methanol, 0.5 mmol trimethylolpropane trimethacrylate, 2 mmol 4-vinylaniline, and 50 mg azobisisobutyronitrile were mixed and kept at 72°C for 22 h. The mixture was filtered, washed, and ground to obtain an amine polymer containing carboxyl groups.

[0084] S3: adding the purification adsorbent to the pre-treated waste liquid, stirring and filtering intermittently to obtain the treated waste liquid;

[0085] The mass volume ratio of the purified adsorbent to the pretreated waste liquid is 8 g:10 L;

[0086] The working conditions of intermittent stirring are: stirring for 20 minutes after adding the materials, and stirring for 10 minutes every hour until the adsorption is completed.

[0087] Comparative Example 1: Taking Example 3 as the control group, attapulgite was used to replace the composite attapulgite, and the other processes were normal.

[0088] Comparative Example 2: Taking Example 3 as the control group, chitosan was used to replace the modified chitosan, and the other processes were normal.

[0089] Comparative Example 3: Example 3 was used as a control group, in which no amine polymer containing a carboxyl group was prepared, and other processes were normal.

[0090] Sources of raw materials used (for demonstration purposes only):

[0091] Fly ash (3µm): Main components are: by mass fraction, silicon dioxide 51.5%, aluminum oxide 26.8%, calcium oxide 5.5%, iron oxide 4.5%, magnesium oxide 0.1%; bentonite (5µm, 99%): Hubei Kewode Chemical Co., Ltd.; attapulgite M62688: Shanghai Myrel Biochemical Technology Co., Ltd.; ascorbic acid A103533, ferrous sulfate F116338, carbodiimide hydrochloride E106172, N-hydroxysuccinimide N164062, chitosan C105802, glutaraldehyde G105905, epichlorohydrin E108182, 2-(trifluoromethyl)acrylic acid T109983, trimethylolpropane trimethacrylate T131641, 4-vinylaniline A151485, azobisisobutyronitrile A434183: Aladdin reagent; calcium oxide, methanol, sodium silicate, sodium sulfide, NaOH, analytical grade: Sinopharm reagents.

[0092] Performance testing:

[0093] The purification agent was subjected to five cycles of wastewater treatment, and then its adsorption capacity for cadmium and chromium ions was tested:

[0094] Prepare 100mL 100mg / LCr 6+The test solution is used as wastewater to test the adsorption capacity for chromium ions; prepare 100 mL of 100 mg / L Cd 2+ The test solution is used as wastewater to test the adsorption capacity for cadmium ions; the removal rate D is (A0 - Ai) / A0 × 100%, where A0 is the initial concentration and Ai is the concentration after adsorption; the obtained results are shown in Table 1;

[0095] Table 1

[0096]

[0097] The present invention provides a purification treatment method for industrial acidic wastewater. By optimizing the component ratio of the used purification adsorbent, a non-fired purification adsorbent that can be recycled, is green and environmentally friendly, and has high heavy metal adsorption capacity is prepared, which can effectively improve the pollution situation of acidic wastewater when used for purifying industrial acidic wastewater.

[0098] Comparing Example 3 with Comparative Example 1 and Comparative Example 3, it can be seen that in order to improve the adsorption and purification capacity of attapulgite and its uniform dispersion in the adsorbent, a method of co-precipitation of ascorbic acid and nano-FeS on attapulgite is used to obtain pretreated attapulgite, and then using the polyhydroxy structure of ascorbic acid, an amine polymer containing a carboxyl group is grafted. The amine polymer containing a carboxyl group uses 2-(trifluoromethyl)acrylic acid as a functional monomer for storing protons, and polymerizes with the amino monomer 4-vinyl aniline and the cross-linking agent trimethylolpropane trimethacrylate. The prepared amine polymer containing a carboxyl group is a Bronsted acid proton buffer polyamine resistant to acids and bases, which greatly improves the stability of the purification adsorbent and its adsorption capacity for heavy metal ions such as mercury, lead, and chromium.

[0099] Comparing Example 3 with Comparative Example 2 and Comparative Example 3, it can be seen that in the present invention, chitosan is selected as the binder. In order to improve the water solubility and stability of chitosan, chitosan is modified. First, chitosan is cross-linked and modified with glutaraldehyde, and then reacted with epichlorohydrin under alkaline conditions to introduce epoxy groups. The epoxy groups are used to react with the amine polymer containing a carboxyl group to prepare modified chitosan, which has a composite effect on fly ash, composite attapulgite, and bentonite, improves the bonding strength between the raw materials of the purification adsorbent, reduces the sediment volume, and simultaneously synergistically improves the adsorption effect on pollutants.

[0100] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. All equivalent structural transformations made using the description of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A purification treatment method for industrial acidic wastewater, characterized in that, It includes the following steps: S1: Put alkaline agents into industrial acidic wastewater, stir, stand still, and filter to obtain pretreated waste liquid; S2: Mix fly ash, composite attapulgite, modified chitosan, bentonite, sodium silicate, and deionized water, granulate and cure to obtain a purification adsorbent; S3: Put the purification adsorbent into the pretreated waste liquid, stir intermittently and filter to obtain the treated waste liquid; By weight, the raw material composition of the purification adsorbent is: 27 - 37 parts of fly ash, 13 - 25 parts of composite attapulgite, 3 - 10 parts of modified chitosan, 2 - 5 parts of bentonite, 1 - 3 parts of sodium silicate, and 3 - 8 parts of deionized water; The preparation of the composite attapulgite includes the following steps: 1) Under a nitrogen atmosphere, mix sodium sulfide solution and attapulgite, stir for 1 - 2 h, add a mixed solution of ascorbic acid and deionized water, add ferrous sulfate solution, stir ultrasonically for 15 - 20 min, filter and freeze-dry to obtain pretreated attapulgite; 2) Mix the pretreated attapulgite, deionized water, carbodiimide hydrochloride, N-hydroxysuccinimide, and a carboxyl-containing amine polymer, heat to 70 - 80 °C and keep warm for 2 - 3 h to obtain composite attapulgite; The preparation of the modified chitosan includes the following steps: (1) Mix chitosan, methanol, and glutaraldehyde solution, keep warm in a water bath at 53 - 57 °C for 5 - 6 h, wash and dry to obtain cross-linked chitosan; mix the cross-linked chitosan, NaOH solution, and epichlorohydrin, oscillate in a water bath at 38 - 42 °C for 3 - 4 h, wash to neutrality to obtain epoxy chitosan; (2) Mix a carboxyl-containing amine polymer and NaOH solution, add epoxy chitosan, oscillate in a water bath at 68 - 72 °C for 5 - 6 h, wash and dry to obtain modified chitosan.

2. The purification treatment method of industrial acidic wastewater according to claim 1, characterized in that, The alkaline agent is one or a combination of calcium oxide, calcium hydroxide, sodium hydroxide, sodium carbonate, and sodium bicarbonate.

3. The purification treatment method of industrial acidic wastewater according to claim 1, characterized in that, In step S1, the pH of the industrial acidic wastewater is 1 - 5, and the pH of the pretreated waste liquid is 6 - 8.

4. A purification treatment method for industrial acidic wastewater according to claim 1, characterized in that, The mass-volume ratio of the purification adsorbent to the pretreated waste liquid is 8 g:10 L.

5. A purification treatment method for industrial acidic wastewater according to claim 1, characterized in that, The working conditions of intermittent stirring are: stir for 10 - 20 min after feeding, and stir for 10 min every 1 h until adsorption is completed.

6. The purification treatment method for industrial acidic wastewater according to claim 1, wherein, In the preparation of modified chitosan, the mass ratio of the carboxyl-containing amine polymer to epoxy chitosan is 0.8:

1.

7. A purification treatment method for industrial acidic wastewater according to claim 1, characterized in that, The preparation of the carboxyl-containing amine polymer includes the following steps: Under a nitrogen atmosphere, mix 2-(trifluoromethyl)acrylic acid, methanol, trimethylolpropane trimethacrylate, 4-vinyl aniline, and azobisisobutyronitrile, keep warm at 68 - 72 °C for 22 - 24 h, filter, wash, and grind to obtain a carboxyl-containing amine polymer.

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