Activated carbon adsorbent for industrial sewage treatment and preparation method thereof

Abstract

The invention discloses an activated carbon adsorbent for industrial sewage treatment and a preparation method thereof, and relates to the technical field of sewage treatment. The method comprises the following steps: 1) adding activated carbon into a phosphoric acid solution for dipping treatment to obtain pretreated activated carbon; 2) adding the pretreated activated carbon into a sucrose solution, carrying out hydrothermal reaction, and activating with potassium hydroxide to obtain modified activated carbon; 2, dispersing the modified activated carbon in deionized water, adding the modified polyacrylamide, and stirring for 1-2 hours; adding sodium alginate and an EDC-NHS cross-linking agent, and stirring for 18 to 24 hours; dropwise adding an aqueous solution of calcium nitrate, and standing; and washing, freeze-drying, grinding and sieving to obtain the activated carbon adsorbent. The activated carbon adsorbent prepared by the invention has good purification capacity on cyanogen-containing industrial wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically to an activated carbon adsorbent for industrial sewage treatment and a preparation method thereof. Background Technique

[0002] The sewage treatment project is a key link in environmental protection; among them, industrial wastewater, due to its complex composition and high toxicity, poses a serious threat to the ecological environment and human health. Among them, electroplating wastewater, as typical industrial sewage, not only contains high concentrations of heavy metal ions (such as nickel, copper, zinc, chromium and other metal ions), but also often contains complexing agents such as cyanides and EDTA. These substances will form stable complexes with heavy metals, significantly reducing the removal efficiency of traditional adsorbents. For example, although common activated carbon has a certain adsorption capacity for single metal ions, in actual electroplating wastewater, cyanides and organic substances also compete for active sites, which will inhibit the removal rate of heavy metal ions such as chromium. In addition, the surface chemical properties of activated carbon are single, the adsorption capacity for specific pollutants (such as cyanides) is limited, and it is easy to be saturated in high-concentration wastewater, with poor regeneration performance, making it difficult to meet the requirements of high efficiency and economy in industrial wastewater treatment.

[0003] In summary, to solve the above problems, it is of practical value to prepare an activated carbon adsorbent for industrial sewage treatment. Summary of the Invention

[0004] The purpose of the present invention is to provide an activated carbon adsorbent for industrial sewage treatment and a preparation method thereof to solve the problems raised in the above background technique.

[0005] To solve the above technical problems, the present invention provides the following technical solutions: A preparation method of an activated carbon adsorbent for industrial sewage treatment includes the following steps: Step 1: 1) Add activated carbon to a phosphoric acid solution for impregnation treatment to obtain pretreated activated carbon; 2) Add the pretreated activated carbon to a sucrose solution, carry out hydrothermal reaction and potassium hydroxide activation to obtain modified activated carbon; Step 2: Disperse the modified activated carbon in deionized water, add modified polyacrylamide, and stir for 1-2 hours; add sodium alginate and an EDC-NHS crosslinking agent, and stir for 18-24 hours; dropwise add an aqueous solution of calcium nitrate, and let it stand; wash, freeze-dry, grind and sieve to obtain the activated carbon adsorbent.

[0006] Preferably, the activated carbon adsorbent includes the following raw materials: by weight, 20-30 parts of modified activated carbon, 30-35 parts of modified polyacrylamide, 10-15 parts of sodium alginate, 0.8-1.2 parts of EDC-NHS crosslinking agent, and 0.1-0.2 parts of calcium nitrate.

[0007] Preferably, the activated carbon is coconut shell activated carbon with a particle size of 40 - 60 mesh; the specific surface area is 950 - 1200 m² / g; During the impregnation treatment, the ratio of the activated carbon to the phosphoric acid solution is 1 - 2:10; the concentration of the phosphoric acid solution is 10 - 15 wt%, and the treatment temperature is 40 - 60 °C.

[0008] Preferably, the preparation method of the modified activated carbon is as follows: 2.1) Add the pretreated activated carbon into the sucrose solution, carry out hydrothermal reaction at 150 - 180 °C for 10 - 20 hours, wash and dry to obtain hydrothermally treated activated carbon; 2.2) Mix the hydrothermally treated activated carbon with potassium hydroxide, in a microwave reactor, set the power at 600 - 900 W and heat up to 600 - 650 °C for the first microwave activation for 10 - 20 minutes, then continue to heat up to 800 - 850 °C for the second microwave activation for 20 - 40 minutes, wash and dry to obtain the modified activated carbon.

[0009] Preferably, the concentration of the sucrose solution is 0.1 - 0.15 g / L; the solute is sucrose and iron-based tannic acid with a mass ratio of 8 - 9:1 - 2, and the solution is deionized water.

[0010] Preferably, the preparation method of the iron-based tannic acid is as follows: 2.1.1) Add tannic acid into deionized water to obtain a solution with a concentration of 50 - 60 g / L; adjust the pH to 3 - 4, add the EDC-NHS crosslinking agent; add L-cysteine methyl ester hydrochloride, heat up to 60 - 65 °C and react for 2 - 3 hours; wash and dry to obtain mercapto-functionalized tannic acid; 2.1.2) Add the mercapto-functionalized tannic acid into deionized water, add ferric nitrate and copper nitrate, stir evenly, remove water to obtain iron-based tannic acid.

[0011] Preferably, in the raw materials of the mercapto-functionalized tannic acid, the mass ratio of tannic acid, EDC-NHS crosslinking agent, and L-cysteine methyl ester hydrochloride is 10:1.5 - 2:2; in the raw materials of the iron-based tannic acid, the mass ratio of mercapto-functionalized tannic acid, ferric nitrate, and copper nitrate is 2:0.4 - 0.6:0.4 - 0.6.

[0012] Preferably, the preparation method of the modified polyacrylamide is as follows: Add polyacrylamide, dibutyltin dilaurate, isocyanatoethyl methacrylate, and hydroquinone into DMF, under a nitrogen atmosphere, react at 60 - 70 °C for 4 - 6 hours, add ether for precipitation, wash and dry to obtain methacrylic acid-based polyacrylamide; Add the methacrylic acid-based polyacrylamide into tetrahydrofuran, add a photoinitiator, 4-mercapto-N,N,N-trimethylanilinium chloride, and N-(2-mercaptopropionyl)-glycine and stir evenly; under ultraviolet light, stir for 4 - 6 hours, wash and dry to obtain the modified polyacrylamide.

[0013] Preferably, in the raw materials of the methacrylic acid-based polyacrylamide, the mass ratio of polyacrylamide to isocyanatoethyl methacrylate is 10:1.5-2.5; in the raw materials of the modified polyacrylamide, the mass ratio of methacrylic acid-based polyacrylamide, 4-mercapto-N,N,N-trimethylanilinium chloride, and N-(2-mercaptopropionyl)-glycine is 10:1-1.5:0.5-0.8.

[0014] An activated carbon adsorbent prepared by a preparation method of an activated carbon adsorbent for industrial sewage treatment.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: Based on activated carbon, combined with organic adsorbents such as polyacrylamide and sodium alginate, a composite activated carbon adsorbent is formed, effectively improving the removal efficiency of pollutants such as metal ions in industrial sewage containing cyanide, etc.; it is not only applicable to cyanide-containing wastewater, but also can efficiently remove heavy metals such as nickel, copper, and zinc, and has broad industrial application prospects.

[0016] In the scheme, the use of modified activated carbon effectively improves the adsorption efficiency. Using coconut shell activated carbon as the basis, it is pre-treated with a phosphoric acid solution to obtain pre-treated activated carbon. In this process, without affecting the internal pores, the interfacial active groups are improved, providing a basis for the subsequent formation of hydrothermal carbon on its surface. Then, the pre-treated activated carbon is added to a sucrose solution for hydrothermal treatment, and then activated with potassium hydroxide to form hydrothermal carbon on the surface of the coconut shell activated carbon.

[0017] Among them, the treatment of loading hydrothermal carbon on the surface of activated carbon will affect the specific surface area of the original coconut shell activated carbon; however, after modification, it can effectively improve the acidic functional groups, increase the surface active sites, and effectively improve the application in actual industrial sewage. First, the hydrothermal carbon is composed of a sucrose solution of specific sucrose and iron-based tannic acid. Compared with a single sucrose aqueous solution, the introduction of iron-based tannic acid has the following advantages: First, it partially decomposes under hydrothermal conditions, and the released carboxyl and phenolic hydroxyl groups can be grafted onto the surface of activated carbon, directly increasing the density of acidic functional groups (such as —COOH, —OH), enhancing the electrostatic adsorption or coordination ability for polar pollutants, and promoting the pollutant removal rate; Second, the coordination structure formed by iron ions and tannic acid may form tiny iron oxide nanoparticles during the hydrothermal process, which are loaded on the hydrothermal carbon layer, providing additional adsorption sites; and it contains sulfur elements, and the two can promote the removal of chromium and inhibit the influence of cyanide. Third, it can stabilize the intermediate product of sucrose carbonization, avoid the disordered carbon deposition generated by the single hydrothermal treatment of high-concentration sucrose, and inhibit the blockage of the original pores of coconut shell activated carbon. It should be noted that: the concentration of the sucrose solution and the introduction amount of iron-based tannic acid need to be limited, otherwise there will be an antagonistic effect.

[0018] Among them, potassium hydroxide activation can partially etch the hydrothermal carbon layer, reopen the covered micropores, alleviate the loss of specific surface area, selectively remove unstable oxygen-containing groups, and retain acidic groups such as carboxyl groups at the same time.

[0019] In the solution, natural polymer sodium alginate and modified polyacrylamide are further crosslinked, effectively improving the mechanical properties and stability of the activated carbon adsorbent, and further enhancing the selective adsorption ability for pollutants. At the same time, in the solution, polyacrylamide is further modified, and 4-mercapto-N,N,N-trimethylanilinium chloride and N-(2-mercaptopropionyl)-glycine are grafted onto its chain segment, effectively improving the adsorption efficiency. Among them, the sulfur-containing group has excellent high affinity for soft acid-type metals such as Cd²⁺, Hg²⁺, etc., which can improve metal removal; while the betaine structure has a quaternary ammonium cation, which can adsorb anionic pollutants (such as cyanide CN⁻) through electrostatic interaction, effectively improving the inhibition of cyanide; at the same time, it can adapt to a wide range of pH environments and improve stability; the introduction of N-(2-mercaptopropionyl)-glycine, on the one hand, has an affinity with EDTA introduced in common electroplating wastewater, which can improve the influence of this substance on the metal ion removal rate; the grafting of the two chain segments can preferentially compete for the adsorption of metal ions, destroy the influence of substances such as cyanide complexes and EDTA, and thus synergistically improve the adsorption and removal of metal ions.

[0020] In addition, the crosslinking network of sodium alginate and modified polyacrylamide can inhibit the aggregation of activated carbon particles and maintain the mesoporous structure of the composite material; ensure the smooth diffusion channel of heavy metal ions. Therefore, the activated carbon adsorbent can achieve a triple synergistic mechanism of physical adsorption (activated carbon) + chemical chelation (PAM graft) + ion exchange (SA), enabling it to exhibit efficient and stable pollutant removal ability in complex industrial wastewater. Specific implementation mode

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] It should be noted that the following parts are by weight, and the relevant raw materials are all commercially available; there are no special restrictions on the purchasing manufacturers of all raw materials involved in the present invention. Exemplarily, it includes: in the following examples, the activated carbon is coconut shell activated carbon, with a particle size of 40 to 60 mesh; the specific surface area is 950 to 1200 m² / g; polyacrylamide, with a molecular weight of 10 million; the purity of sodium alginate is 99%, and the brand is Hengtian. The CAS number of L-cysteine methyl ester hydrochloride is 18598-63-5; the CAS number of isocyanatoethyl methacrylate is 30674-80-7; the CAS number of 4-mercapto-N,N,N-trimethylbenzenaminium chloride is 856357-47-6; the CAS number of N-(2-mercaptopropionyl)-glycine is 1953-02-2.

[0023] The preparation method of iron-based tannic acid is as follows: 2.1.1) Add 10 parts of tannic acid to deionized water to obtain a solution with a concentration of 50 g / L; adjust the pH to 3.8, add 1.8 parts of EDC-NHS cross-linking agent (EDC and NHS with a mass ratio of 1:1); add 2 parts of L-cysteine methyl ester hydrochloride, and raise the temperature to 60 °C and react for 2 hours; wash and dry to obtain mercapto-tannic acid; 2.1.2) Add 2 parts of mercapto-tannic acid to 18 parts of deionized water, add 0.6 part of ferric nitrate and 0.4 part of copper nitrate, stir evenly, remove water to obtain iron-based tannic acid.

[0024] The preparation method of modified polyacrylamide is as follows: Add 10 parts of polyacrylamide, 0.1 part of dibutyltin dilaurate, 2.1 parts of isocyanatoethyl methacrylate, and 0.2 part of hydroquinone to 40 parts of DMF. Under a nitrogen atmosphere, react at 65 °C for 4 hours, add ether to precipitate, wash and dry to obtain methacrylic acid-based polyacrylamide; Add 10 parts of methacrylic acid-based polyacrylamide to tetrahydrofuran, add 0.2 part of photoinitiator 2959, 1.2 parts of 4-mercapto-N,N,N-trimethylbenzenaminium chloride, and 0.7 part of N-(2-mercaptopropionyl)-glycine and stir evenly; under ultraviolet light, stir for 6 hours, wash and dry to obtain modified polyacrylamide.

[0025] Example 1: A preparation method of an activated carbon adsorbent for industrial sewage treatment, comprising the following steps: Step 1: 1) Add activated carbon into a 10 wt% phosphoric acid solution with a mass ratio of 2:10; impregnate at 50 °C for 4 hours, wash and dry to obtain pretreated activated carbon; 2) Preparation of modified activated carbon: 2.1) Add the pretreated activated carbon into a sucrose solution, perform hydrothermal reaction at 160 °C for 18 hours, wash and dry to obtain hydrothermally treated activated carbon; 2.2) Mix the hydrothermally treated activated carbon with potassium hydroxide at a mass ratio of 1:1, in a microwave reactor, set the power to 600 W and heat up to 600 °C for the first microwave activation for 10 minutes, continue to heat up to 800 °C for the second microwave activation for 40 minutes, wash and dry to obtain modified activated carbon; Among them, the concentration of the sucrose solution is 0.11 g / L; the solute is sucrose and iron-based tannic acid with a mass ratio of 9:2, and the solution is deionized water; Step 2: Disperse 28 parts of modified activated carbon in deionized water, add 32 parts of modified polyacrylamide, and stir for 1 hour; add 10 parts of sodium alginate and 0.8 part of EDC-NHS crosslinking agent (EDC and NHS with a mass ratio of 1:1), and stir for 24 hours; dropwise add a 1 wt% calcium nitrate aqueous solution containing 0.1 part of calcium nitrate, and let it stand for 15 minutes; wash, freeze-dry, grind and sieve to obtain the activated carbon adsorbent.

[0026] Example 2: A preparation method of an activated carbon adsorbent for industrial sewage treatment, comprising the following steps: Step 1: 1) Add activated carbon into a 10 wt% phosphoric acid solution with a mass ratio of 2:10; impregnate at 50 °C for 4 hours, wash and dry to obtain pretreated activated carbon; 2) Preparation of modified activated carbon: 2.1) Add the pretreated activated carbon into a sucrose solution, perform hydrothermal reaction at 160 °C for 18 hours, wash and dry to obtain hydrothermally treated activated carbon; 2.2) Mix the hydrothermally treated activated carbon with potassium hydroxide at a mass ratio of 1:1, in a microwave reactor, set the power to 600 W and heat up to 600 °C for the first microwave activation for 10 minutes, continue to heat up to 800 °C for the second microwave activation for 40 minutes, wash and dry to obtain modified activated carbon; Among them, the concentration of the sucrose solution is 0.1 g / L; the solute is sucrose and iron-based tannic acid with a mass ratio of 8:2, and the solution is deionized water; Step 2: Disperse 20 parts of modified activated carbon in deionized water, add 30 parts of modified polyacrylamide, and stir for 1 hour; add 10 parts of sodium alginate and 0.8 part of EDC-NHS crosslinking agent (EDC and NHS with a mass ratio of 1:1), and stir for 24 hours; dropwise add a 1 wt% calcium nitrate aqueous solution containing 0.1 part of calcium nitrate, and let it stand for 15 minutes; wash, freeze-dry, grind and sieve to obtain the activated carbon adsorbent.

[0027] Example 3: A preparation method of an activated carbon adsorbent for industrial sewage treatment, comprising the following steps: Step 1: 1) Add activated carbon to a phosphoric acid solution with a concentration of 10 wt%, and the mass ratio is 2:10; impregnate at 50 °C for 4 hours, wash and dry; obtain pretreated activated carbon; 2) Preparation of modified activated carbon: 2.1) Add the pretreated activated carbon to a sucrose solution, and carry out hydrothermal reaction at 160 °C for 18 hours, wash and dry to obtain hydrothermally treated activated carbon; 2.2) Mix the hydrothermally treated activated carbon with potassium hydroxide in a mass ratio of 1:1, in a microwave reactor, set the power to 600 W and heat up to 600 °C for the first microwave activation for 10 minutes, continue to heat up to 800 °C for the second microwave activation for 40 minutes, wash and dry to obtain modified activated carbon; Among them, the concentration of the sucrose solution is 0.15 g / L; the solute is sucrose and iron-based tannic acid with a mass ratio of 9:1, and the solution is deionized water; Step 2: Disperse 30 parts of the modified activated carbon in deionized water, add 35 parts of modified polyacrylamide, and stir for 1 hour; add 15 parts of sodium alginate and 1.2 parts of EDC-NHS cross-linking agent (EDC and NHS with a mass ratio of 1:1), and stir for 24 hours; dropwise add a calcium nitrate aqueous solution with a concentration of 2 wt% containing 0.2 parts of calcium nitrate, and let stand for 15 minutes; wash, freeze-dry, grind and sieve to obtain the activated carbon adsorbent.

[0028] Comparative Example 1: Replace the modified activated carbon with pretreated activated carbon; the rest is the same as in Example 1; the specific differences are as follows: Step 1: Add activated carbon to a phosphoric acid solution with a concentration of 10 wt%, and the mass ratio is 2:10; impregnate at 50 °C for 4 hours, wash and dry; obtain pretreated activated carbon; Step 2: Disperse 28 parts of the pretreated activated carbon in deionized water, add 32 parts of modified polyacrylamide, and stir for 1 hour; add 10 parts of sodium alginate and 0.8 parts of EDC-NHS cross-linking agent (EDC and NHS with a mass ratio of 1:1), and stir for 24 hours; dropwise add a calcium nitrate aqueous solution with a concentration of 1 wt% containing 0.1 parts of calcium nitrate, and let stand for 15 minutes; wash, freeze-dry, grind and sieve to obtain the activated carbon adsorbent.

[0029] Comparative Example 2: The solute of the sucrose solution is single sucrose; the rest is the same as in Example 1; the specific differences are as follows: Step 1: 1) Add activated carbon into a phosphoric acid solution with a concentration of 10 wt%, and the mass ratio is 2:10; impregnate at 50 °C for 4 hours, wash and dry; obtain pretreated activated carbon; 2) Preparation of modified activated carbon: 2.1) Add the pretreated activated carbon into a sucrose solution, carry out hydrothermal reaction at 160 °C for 18 hours, wash and dry to obtain hydrothermally treated activated carbon; 2.2) Mix the hydrothermally treated activated carbon with potassium hydroxide in a mass ratio of 1:1, in a microwave reactor, set the power to 600 W and heat up to 600 °C for the first microwave activation for 10 minutes, continue to heat up to 800 °C for the second microwave activation for 40 minutes, wash and dry to obtain modified activated carbon; Among them, the concentration of the sucrose solution is 0.11 g / L; the solute is sucrose, and the solution is deionized water; Step 2: Disperse 28 parts of modified activated carbon in deionized water, add 32 parts of modified polyacrylamide, and stir for 1 hour; add 10 parts of sodium alginate and 0.8 part of EDC-NHS crosslinking agent (EDC and NHS with a mass ratio of 1:1), and stir for 24 hours; dropwise add a 1 wt% calcium nitrate aqueous solution containing 0.1 part of calcium nitrate, and let stand for 15 minutes; wash, freeze-dry, grind and sieve to obtain an activated carbon adsorbent.

[0030] Comparative Example 3: Increase the concentration of the sucrose solution; the rest is the same as Example 1; the specific differences are as follows: Step 1: 1) Add activated carbon into a phosphoric acid solution with a concentration of 10 wt%, and the mass ratio is 2:10; impregnate at 50 °C for 4 hours, wash and dry; obtain pretreated activated carbon; 2) Preparation of modified activated carbon: 2.1) Add the pretreated activated carbon into a sucrose solution, carry out hydrothermal reaction at 160 °C for 18 hours, wash and dry to obtain hydrothermally treated activated carbon; 2.2) Mix the hydrothermally treated activated carbon with potassium hydroxide in a mass ratio of 1:1, in a microwave reactor, set the power to 600 W and heat up to 600 °C for the first microwave activation for 10 minutes, continue to heat up to 800 °C for the second microwave activation for 40 minutes, wash and dry to obtain modified activated carbon; Among them, the concentration of the sucrose solution is 0.22 g / L; the solute is sucrose and iron-based tannic acid with a mass ratio of 9:2, and the solution is deionized water; Step 2: Disperse 28 parts of modified activated carbon in deionized water, add 32 parts of modified polyacrylamide, and stir for 1 hour; add 10 parts of sodium alginate and 0.8 part of EDC-NHS crosslinking agent (EDC and NHS with a mass ratio of 1:1), and stir for 24 hours; dropwise add a 1 wt% calcium nitrate aqueous solution containing 0.1 part of calcium nitrate, and let stand for 15 minutes; wash, freeze-dry, grind and sieve to obtain an activated carbon adsorbent.

[0031] Comparative Example 4: Polyacrylamide is not modified; the rest is the same as Example 1; the specific differences are as follows: Step 1: 1) Add activated carbon to a 10 wt% phosphoric acid solution at a mass ratio of 2:10; immerse the mixture at 50°C for 4 hours, wash, and dry to obtain pretreated activated carbon; 2) Preparation of modified activated carbon: 2.1) Add the pretreated activated carbon to a sucrose solution, hydrothermally react at 160°C for 18 hours, wash, and dry to obtain hydrothermally activated carbon; 2.2) Mix the hydrothermally activated carbon with potassium hydroxide at a mass ratio of 1:1, heat the mixture to 600°C in a microwave reactor at a power of 600 W, perform a primary microwave activation for 10 minutes, then continue heating the mixture to 800°C for a secondary microwave activation for 40 minutes, wash, and dry to obtain modified activated carbon; The concentration of the sucrose solution is 0.11 g / L; the solute is sucrose and iron-based tannic acid in a mass ratio of 9:2, and the solution is deionized water; Step 2: Disperse 28 parts of modified activated carbon in deionized water, add 32 parts of polyacrylamide, and stir for 1 hour; add 10 parts of sodium alginate and 0.8 parts of EDC-NHS crosslinker (EDC and NHS with a mass ratio of 1:1), and stir for 24 hours; add a 1wt% calcium nitrate aqueous solution containing 0.1 parts of calcium nitrate, and let it stand for 15 minutes; wash, freeze-dry, grind and sieve to obtain an activated carbon adsorbent.

[0032] Performance test: The activated carbon adsorbent prepared in the examples and comparative examples was tested for performance; the following components were contained in industrial wastewater: 10.8 mg / LCr 6+ 、8.3mg / LNi 2+ , 4.5mg / L cyanide, 2.1mg / LEDTA; the amount of activated carbon adsorbent added was 0.5g, and the adsorption was stirred at room temperature for 300 minutes; the metal ion removal rate was tested; then 0.2mol / L NaOH aqueous solution was used for elution for 5 hours and then reused; after 5 cycles, Cr was tested again 6+ The removal rate of Cr 6+ The reduction rate is obtained by subtracting the removal rates; the obtained data are shown in the following table:

[0033] Conclusion: The data in the table above demonstrate that this application has produced an activated carbon adsorbent with excellent purification capabilities for metal ions in cyanide-containing industrial wastewater. The data from Comparative Examples 1 to 4 demonstrate that: The data from the unmodified activated carbon in Comparative Example 1 demonstrate that further hydrothermal carbon loading of the activated carbon effectively improves adsorption performance; the data from Comparative Example 2 demonstrate that the introduction of iron-based tannic acid effectively improves adsorption performance; Increasing the sucrose concentration in Comparative Example 3 increases pore blockage, leading to decreased performance; and the unmodified polyacrylamide in Comparative Example 4 lacks grafted thiol and quaternary ammonium groups, resulting in a weakened competitive adsorption capacity for cyanide and EDTA, and reduced adsorption performance.

[0034] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of an activated carbon adsorbent for industrial sewage treatment, characterized in that: It includes the following steps: Step 1: 1) Add activated carbon into phosphoric acid solution for impregnation treatment to obtain pretreated activated carbon; 2) Add the pretreated activated carbon into sucrose solution, carry out hydrothermal reaction and potassium hydroxide activation to obtain modified activated carbon; Step 2: Disperse the modified activated carbon in deionized water, add modified polyacrylamide and stir for 1 - 2 hours; add sodium alginate and EDC - NHS crosslinking agent and stir for 18 - 24 hours; dropwise add aqueous solution of calcium nitrate, let it stand; wash, freeze - dry, grind and sieve to obtain activated carbon adsorbent.

2. The preparation method of an activated carbon adsorbent for industrial sewage treatment according to claim 1, characterized in that: The activated carbon adsorbent includes the following raw materials: by weight, 20 - 30 parts of modified activated carbon, 30 - 35 parts of modified polyacrylamide, 10 - 15 parts of sodium alginate, 0.8 - 1.2 parts of EDC - NHS crosslinking agent, 0.1 - 0.2 parts of calcium nitrate.

3. The preparation method of an activated carbon adsorbent for industrial sewage treatment according to claim 1, characterized in that: The activated carbon is coconut shell activated carbon, with a particle size of 40 - 60 mesh; the specific surface area is 950 - 1200 m² / g; During the impregnation treatment process, the ratio of activated carbon to phosphoric acid solution is 1 - 2:10; the concentration of phosphoric acid solution is 10 - 15 wt%, and the treatment temperature is 40 - 60 °C.

4. The preparation method of an activated carbon adsorbent for industrial sewage treatment according to claim 1, characterized in that: The preparation method of the modified activated carbon is as follows: 2.1) Add the pretreated activated carbon into sucrose solution, carry out hydrothermal reaction at 150 - 180 °C for 10 - 20 hours, wash and dry to obtain hydrothermally treated activated carbon; 2.2) Mix the hydrothermally treated activated carbon with potassium hydroxide, in a microwave reactor, set the power of 600 - 900 W to heat up to 600 - 650 °C for the first - stage microwave activation for 10 - 20 minutes, then continue to heat up to 800 - 850 °C for the second - stage microwave activation for 20 - 40 minutes, wash and dry to obtain modified activated carbon.

5. The preparation method of an activated carbon adsorbent for industrial sewage treatment according to claim 4, characterized in that: The concentration of the sucrose solution is 0.1 - 0.15 g / L; the solute is sucrose and iron - based tannic acid with a mass ratio of 8 - 9:1 - 2, and the solution is deionized water.

6. The preparation method of an activated carbon adsorbent for industrial sewage treatment according to claim 5, characterized in that: The preparation method of the iron - based tannic acid is as follows: 2.1.1) Add tannic acid into deionized water to obtain a solution with a concentration of 50 - 60 g / L; adjust the pH = 3 - 4, add EDC - NHS crosslinking agent; add L - cysteine methyl ester hydrochloride, heat up to 60 - 65 °C and react for 2 - 3 hours; wash and dry to obtain mercapto - modified tannic acid; 2.1.2) Add the mercapto - modified tannic acid into deionized water, add ferric nitrate and copper nitrate, stir evenly, remove water to obtain iron - based tannic acid.

7. The preparation method of an activated carbon adsorbent for industrial sewage treatment according to claim 6, characterized in that: In the raw materials of the mercapto - modified tannic acid, the mass ratio of tannic acid, EDC - NHS crosslinking agent, and L - cysteine methyl ester hydrochloride is 10:1.5 - 2:2; in the raw materials of the iron - based tannic acid, the mass ratio of mercapto - modified tannic acid, ferric nitrate, and copper nitrate is 2:0.4 - 0.6:0.4 - 0.

6.

8. The preparation method of an activated carbon adsorbent for industrial sewage treatment according to claim 1, characterized in that: The preparation method of the modified polyacrylamide is as follows: Add polyacrylamide, dibutyltin dilaurate, isocyanatoethyl methacrylate, and hydroquinone into DMF, under a nitrogen atmosphere, react at 60 - 70 °C for 4 - 6 hours, add ether for precipitation, wash and dry to obtain methacrylic acid - based polyacrylamide; Add methacryloyl polyacrylamide to tetrahydrofuran, add a photoinitiator, 4-mercapto-N,N,N-trimethylanilinium chloride, and N-(2-mercaptopropionyl)-glycine, and stir evenly; under ultraviolet light, stir for 4 to 6 hours, wash and dry to obtain modified polyacrylamide.

9. The preparation method of an activated carbon adsorbent for industrial sewage treatment according to claim 8, characterized in that: In the raw materials of the methacryloyl polyacrylamide, the mass ratio of polyacrylamide to isocyanatoethyl methacrylate is 10:1.5 to 2.5; in the raw materials of the modified polyacrylamide, the mass ratio of methacryloyl polyacrylamide, 4-mercapto-N,N,N-trimethylanilinium chloride, and N-(2-mercaptopropionyl)-glycine is 10:1 to 1.5:0.5 to 0.

8.

10. An activated carbon adsorbent prepared by the preparation method of an activated carbon adsorbent for industrial sewage treatment according to any one of claims 1 to 9.

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