Hot galvanizing waste residue pickling waste liquid treatment method and chloride ion adsorbent preparation method

Abstract

The invention relates to the technical field of wastewater treatment, and particularly discloses a hot galvanizing waste residue pickling waste liquid treatment method and a chloride ion adsorbent preparation method. The hot galvanizing waste residue pickling waste liquid treatment method comprises the following steps: adding a chloride ion adsorbent into waste residue pickling waste liquid with the pH value of 3-4, and stirring and mixing to obtain mixed liquid; adding sodium alginate into the mixed solution, stirring and mixing, filtering, and adjusting the pH value of the filtrate to 6-7 by using caustic alkali to obtain the treated waste residue pickling waste liquid; the preparation method of the chloride ion adsorbent comprises the following steps: stirring and mixing the amino silane coupling agent and the water, then adding the aluminum-magnesium hydrotalcite, stirring and mixing, aging, washing, drying and grinding to obtain the chloride ion adsorbent. The hot galvanizing waste residue pickling waste liquid treatment method can effectively remove chloride ions and ferrous ions in the waste residue pickling waste liquid, and is high in safety and suitable for large-scale popularization.

Description

Technical Field

[0001] The present application relates to the technical field of wastewater treatment, and more specifically, to a method for treating hot-dip galvanizing waste slag pickling waste liquid and a method for preparing a chloride ion adsorbent. Background Art

[0002] Hot-dip galvanizing, also known as hot-dip galvanizing or hot-dip galvanizing, is an effective way to prevent metal corrosion. It mainly uses hot-dip plating technology to immerse the rusted steel parts in molten zinc liquid at about 500°C, so that a zinc layer adheres to the surface of the steel parts, thereby achieving the purpose of corrosion protection.

[0003] In the hot-dip galvanizing process, the key step of the rust removal process of the plated parts is usually pickling with hydrochloric acid. Therefore, a large amount of pickling waste liquid containing divalent iron will be produced after pickling. Domestic enterprises using hot-dip galvanizing technology usually use quicklime to neutralize the waste acid and its pickling waste liquid before discharge. Not only neutralization equipment is required, but also alkaline chemical raw materials for waste acid neutralization treatment need to be purchased to ensure that the acidic wastewater reaches the pH value specified in the discharge standard.

[0004] However, neutralization of waste acid will produce a certain amount of useless waste residue pickling waste liquid, the main component of which is calcium chloride. Calcium chloride and ferrous chloride are both water-soluble substances, which will inevitably cause a large amount of chloride ion emissions and cause serious "chlorine poisoning" to the environment. Summary of the invention

[0005] In order to improve the removal rate of chloride ions in waste slag pickling waste liquid, the present application provides a method for treating hot-dip galvanizing waste slag pickling waste liquid and a method for preparing a chloride ion adsorbent.

[0006] In the first aspect, the present application provides a method for treating hot-dip galvanizing waste slag pickling waste liquid, which adopts the following technical scheme: a method for treating hot-dip galvanizing waste slag pickling waste liquid, comprising the following steps: S1: adding a chloride ion adsorbent to a waste residue pickling waste liquid having a pH value of 3 to 4, stirring and mixing, and obtaining a mixed liquid; S2: adding sodium alginate to the mixed solution, stirring and mixing, filtering, and adjusting the pH value of the filtrate to 6-7 with caustic soda to obtain a treated waste residue pickling waste liquid; The preparation method of the chloride ion adsorbent is as follows: firstly, the aminosilane coupling agent and water are stirred and mixed, then aluminum magnesium hydrotalcite is added, stirred and mixed, aged, washed with water, dried, and ground to obtain the chloride ion adsorbent.

[0007] After the pickling waste liquid is treated with quicklime, the waste residue with a pH value of 3 to 4 is obtained. The pickling waste liquid contains a large amount of chloride ions and divalent iron ions.

[0008] By adopting the above technical scheme, aminosilane is hydrolyzed and polycondensed to form a polymer, which can form a gel adsorbed on the surface of aluminum-magnesium hydrotalcite after aging and other treatments, thereby obtaining a chloride ion adsorbent containing amino gel. On the one hand, the gel in the chloride ion adsorbent has a large number of micropores and a high surface area, which can adsorb a large amount of chloride ions, effectively reducing the content of chloride ions in the waste residue pickling waste liquid. On the other hand, in the waste residue pickling waste liquid with a pH value of 3 to 4, the amino groups in the chloride ion adsorbent can be ionized to form ammonium ions, and the ammonium ions interact with the chloride ions, thereby adsorbing the chloride ions in the chloride ion adsorbent, which is conducive to further improving the removal rate of chloride ions in the waste residue pickling waste liquid. Then, after the filtrate is neutralized with caustic soda, the treated waste residue pickling waste liquid can reach the pH value specified in the emission standard.

[0009] Therefore, the present application adopts chloride ion adsorbent to treat the waste liquid of waste slag pickling, which can not only reduce the chloride ion content in the waste liquid of waste slag pickling, but also reduce the use of caustic soda during the neutralization of the filtrate, effectively improving the environmental protection and safety of the hot-dip galvanizing waste liquid pickling treatment method, and is suitable for large-scale production.

[0010] Preferably, in the preparation method of the chloride ion adsorbent, the weight ratio of aluminum-magnesium hydrotalcite, aminosilane coupling agent and water is 1:(0.025-0.055):(3-6).

[0011] By adopting the above technical scheme, aluminum-magnesium hydrotalcite with a layered structure is used as a carrier, and the weight ratio of aminosilane to aluminum-magnesium hydrotalcite is controlled, so that the interlayer ions of the aluminum-magnesium hydrotalcite are easily exchanged with the chloride ions and divalent iron ions in the waste residue pickling waste liquid, and the removal rate of chloride ions and divalent iron ions in the waste residue pickling waste liquid can be effectively improved.

[0012] Preferably, the aminosilane is one or both of 3-aminopropylmethyldimethoxysilane and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane.

[0013] By adopting the above technical solution, the above type of aminosilane has a good hydrolysis rate, the formed gel has many active sites, and has a good chloride ion removal efficiency.

[0014] Preferably, the aminosilane is composed of 3-aminopropylmethyldimethoxysilane and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane mixed in a weight ratio of 1:(0.45-0.65).

[0015] By adopting the above technical scheme, two aminosilanes are selected for hydrolysis polymerization to form a dense three-dimensional network structure gel, which has good acid and alkali resistance and is beneficial to improving the application range of the chloride ion adsorbent in waste slag pickling waste liquid with different pH values.

[0016] Preferably, the preparation method of the chloride ion adsorbent is: firstly, the aminosilane coupling agent and water are stirred and mixed, and then aluminum magnesium hydrotalcite and non-ionic water-soluble cellulose ether are added, stirred and mixed, aged, washed with water, dried, and ground to obtain the chloride ion adsorbent; The weight ratio of the aluminum-magnesium hydrotalcite, the aminosilane coupling agent, the water-soluble nonionic cellulose ether and water is 1:(0.025-0.055):(0.01-0.015):(3-6).

[0017] By adopting the above technical scheme, the non-ionic water-soluble cellulose ether has good suspension stability, which can improve the dispersion stability of the obtained chloride ion adsorbent in the waste residue pickling waste liquid, and is beneficial to improving the removal rate of chloride ions and divalent iron ions in the waste residue pickling waste liquid.

[0018] Preferably, the water-soluble nonionic cellulose ether is methyl hydroxyethyl cellulose or hydroxyethyl cellulose.

[0019] Preferably, the hydroxyethyl cellulose has a molar substitution degree of 1.8 to 2.0, a pH value of 6.0 to 8.5, and a viscosity of 5 to 60,000 mPa·s.

[0020] By adopting the above technical scheme, methyl hydroxyethyl cellulose and hydroxyethyl cellulose have good water solubility, which is conducive to the full dispersion of aluminum-magnesium hydrotalcite in the aminosilane polymer, so that the gel is evenly distributed on the surface of the aluminum-magnesium hydrotalcite, which is conducive to improving the adsorption efficiency of the chloride ion adsorbent.

[0021] Preferably, the dosage of the chloride ion adsorbent in the waste residue pickling waste liquid with a pH value of 3 to 4 is 0.6 to 1.8 g / L.

[0022] By adopting the above technical scheme, the chloride ion adsorbent of the present application has a high adsorption rate of chloride ions and divalent iron ions, and waste slag pickling waste liquid can be treated with a small amount of chloride ion adsorbent, which has good economic benefits.

[0023] In a second aspect, the present application provides a method for preparing a chloride ion adsorbent, using the following technical solution: A method for preparing a chloride ion adsorbent comprises the following steps: After the aminosilane and water are stirred and mixed, aluminum magnesium hydrotalcite is added, stirred and mixed, aged, washed with water, dried, and ground to obtain a chloride ion adsorbent; The weight ratio of the aluminum-magnesium hydrotalcite, the aminosilane coupling agent and water is 1:(0.025-0.055):(3-6).

[0024] Aminosilane can be polymerized to form gel after hydrolysis. By adopting the above technical scheme and controlling the weight ratio of aluminum-magnesium hydrotalcite, aminosilane coupling agent and water, the aluminum-magnesium hydrotalcite not only retains the interlayer structure, but also can adsorb gel with amino active sites on its surface, has good adsorption for chloride ions and divalent iron ions in waste residue pickling waste liquid, and has good removal rate of chloride ions and divalent iron ions.

[0025] Preferably, the preparation method of the chloride ion adsorbent comprises the following steps: Firstly, the aminosilane coupling agent and water are stirred and mixed, and then aluminum magnesium hydrotalcite and water-soluble nonionic cellulose ether are added, stirred and mixed, aged, washed with water, dried, and ground to obtain a chloride ion adsorbent.

[0026] The weight ratio of the aluminum-magnesium hydrotalcite, the aminosilane coupling agent, the water-soluble nonionic cellulose ether and water is 1:(0.025-0.055):(0.01-0.015):(3-6).

[0027] By adopting the above technical scheme, the water-soluble nonionic cellulose ether has good suspension stability, which is conducive to obtaining aluminum-magnesium hydrotalcite with gel uniformly adsorbed on the surface, and can effectively improve the adsorption rate of chloride ions and divalent iron ions by the chloride ion adsorbent.

[0028] In summary, this application has the following beneficial effects: 1. First, limestone is used to adjust the pH value of the pickling waste liquid, and then a chloride ion adsorbent is used to treat the waste slag pickling waste liquid, which can not only reduce the content of chloride ions and divalent iron ions in the waste slag pickling waste liquid, but also reduce the use of a large amount of alkaline chemical raw materials, effectively avoid the heat release of the strong acid and strong alkali neutralization reaction, and improve the environmental protection and safety of the hot-dip galvanizing waste slag pickling waste liquid treatment method; 2. In the present application, aluminum-magnesium hydrotalcite with a layered structure is used as a carrier, and aminosilane is used as a gel raw material to prepare a chloride ion adsorbent with an interlayer structure and amino active sites, which has a high divalent iron adsorption rate and chloride ion adsorption rate, and has a wide range of applicability in the field of water treatment. DETAILED DESCRIPTION

[0029] The present application is further described in detail below with reference to the embodiments.

[0030] The raw materials used in the examples of the present application are commercially available unless otherwise specified below.

[0031] Aluminum-magnesium hydrotalcite, magnesium-aluminum molar ratio 2.25g / Al, active ingredient content 99%, average particle size ≤1.0; Hydroxyethyl cellulose, molar substitution degree of 1.8 to 2.0, pH value of 6.0 to 8.5, viscosity of 5 to 60,000 mPa·s; Sodium carboxymethyl cellulose, model 9032-42-2, purchased from Shanghai Hongzhuang Chemical Technology Co., Ltd.; Sodium alginate, sodium alginate ≥50%, sodium sulfate <40%, sodium hexametaphosphate <10%, pH value 6.0~8.0.

[0032] Preparation Example Preparation Example 1 A chloride ion adsorbent, the raw materials and their corresponding weights (g) are shown in the following table.

[0033] The preparation method of the above chloride ion adsorbent is: firstly, the aminosilane coupling agent and water are stirred and mixed at 800r / min for 30min, then aluminum magnesium hydrotalcite is added, stirred and mixed for 60min, aged for 24h, washed with water, dried, and ground to obtain the chloride ion adsorbent.

[0034] Preparation Examples 2-3 A chloride ion adsorbent, which is different from Preparation Example 1 in that its raw materials and their corresponding weights (g) are shown in the following table.

[0035] Preparation Examples 4 to 6 A chloride ion adsorbent, which is different from Preparation Example 1 in that the aminosilane coupling agent and its corresponding weight (g) are shown in the following table.

[0036] Preparation Examples 7 to 10 A chloride ion adsorbent, which is different from Preparation Example 1 in that it also includes water-soluble cellulose ether, and the weight (g) of the water-soluble cellulose ether is shown in the following table.

[0037] The preparation method of the above-mentioned chloride ion adsorbent is: firstly, the aminosilane coupling agent and water are stirred and mixed at 800r / min for 30min, then aluminum magnesium hydrotalcite and water-soluble cellulose ether are added, stirred and mixed at 60°C for 60min, aged for 24h, washed with water, dried, and ground to obtain the chloride ion adsorbent.

[0038] Preparation Example 11 A chloride ion adsorbent is different from Preparation Example 1 in that an equal weight of aminosilane coupling agent is used to replace aluminum-magnesium hydrotalcite.

[0039] The preparation method of the chloride ion adsorbent is as follows: the aminosilane coupling agent and water are stirred and mixed at 800 r / min for 90 minutes, aged for 24 hours, washed with water, dried, and ground to obtain the chloride ion adsorbent.

[0040] Preparation Example 12 A chloride ion adsorbent is aluminum-magnesium hydrotalcite. Example

[0041] Example 1 A method for treating hot-dip galvanizing waste slag pickling waste liquid comprises the following steps: S1: adding a chloride ion adsorbent to a waste residue pickling waste liquid having a pH value of 3, stirring and mixing at room temperature (20-25° C.) for 90 minutes to obtain a mixed solution; S2: adding sodium alginate to the mixed solution, stirring and mixing for 60 minutes, settling for 180 minutes, filtering, adjusting the pH value of the filtrate to 6-7 with caustic soda, aerating, settling for 120 minutes, filtering, and obtaining the treated waste residue pickling waste liquid.

[0042] In the embodiment of the present application, the chloride ion adsorbent is the chloride ion adsorbent prepared in Preparation Example 1; The dosage of chloride ion adsorbent in the waste pickling waste liquid with a pH value of 3 is 1.5 g / L; The dosage of sodium alginate in the waste residue pickling waste liquid with a pH value of 3 is 0.15 g / L.

[0043] The caustic soda is sodium hydroxide; The aeration volume is 18Q and the time is 5h.

[0044] Embodiments 2 to 10 A method for treating hot-dip galvanizing waste slag pickling waste liquid is different from Example 1 in that, in S1, the chloride ion adsorbent is the chloride ion adsorbent prepared in the following table. Example Preparation Example Example 1 Preparation Example 1 Example 2 Preparation Example 2 Example 3 Preparation Example 3 Example 4 Preparation Example 4 Example 5 Preparation Example 5 Example 6 Preparation Example 6 Example 7 Preparation Example 7 Example 8 Preparation Example 8 Example 9 Preparation Example 9 Example 10 Preparation Example 10

[0045] Embodiment 11 A method for treating hot-dip galvanizing waste slag pickling waste liquid is different from Example 1 in that, in S1, the amount of chloride ion adsorbent added to the waste slag pickling waste liquid with a pH value of 3 is 0.6 g / L.

[0046] Example 12 A method for treating hot-dip galvanizing waste slag pickling waste liquid is different from Example 1 in that, in S1, the pH value of the waste slag pickling waste liquid is 4, and the amount of the chloride ion adsorbent in the waste slag pickling waste liquid with a pH value of 4 is 1.8 g / L.

[0047] Comparative Example Comparative Example 1 A method for treating hot-dip galvanizing waste slag pickling waste liquid is different from Example 1 in that, in S1, the chloride ion adsorbent is the chloride ion adsorbent prepared in Preparation Example 11.

[0048] Comparative Example 2 A method for treating hot-dip galvanizing waste slag pickling waste liquid, which is different from Example 1 in that in S1, the chloride ion adsorbent is the chloride ion adsorbent prepared in Preparation Example 12 Comparative Example 3 A method for treating hot-dip galvanizing waste slag pickling waste liquid is different from Example 1 in that, in S1, a chloride ion adsorbent is added to the waste slag pickling waste liquid with a pH value of 5.

[0049] Performance Testing The slag pickling waste liquid treated by the hot-dip galvanizing slag pickling waste liquid treatment method of Examples 1 to 12 and Comparative Examples 1 to 3 was tested for chloride ion removal rate and iron concentration, and the testing method was as follows: Chloride ion removal rate: Refer to GB / T 11896-1989 to detect the chloride ion concentration, and calculate the chloride ion removal rate according to the following formula: Chloride ion removal rate = (chloride ion concentration in the waste residue pickling waste liquid in S1 - chloride ion concentration in the treated waste residue pickling waste liquid in S2) / chloride ion concentration in the waste residue pickling waste liquid in S1; Iron concentration: Tested in accordance with GB13456-2012 “Emission Standards of Water Pollutants from Iron and Steel Industry”.

[0050] The test results are shown in the following table.

[0051] According to the provisions of my country's GB13456-2012 "Water Pollutant Emission Standards for the Iron and Steel Industry", the limit for total iron in water pollutant emissions from the steel industry is 10 mg / L.

[0052] By analyzing the data in the above table, it can be seen that the iron content of the waste slag pickling waste liquid treated by the hot-dip galvanizing waste slag pickling waste liquid treatment method of Examples 1 to 12 is as low as 0.15 to 0.66 mg / L, which meets the requirements of GB13456-2012 Iron and Steel Industry Water Pollutant Emission Standard.

[0053] The chloride ion removal rate of the waste slag pickling waste liquid treated in Examples 1, 4, and 5 is as high as 88.00-90.00%, and the chloride ion removal rate of the waste slag pickling waste liquid treated in Example 6 is as low as 84.30%. This shows that in the hot-dip galvanizing waste slag pickling waste liquid treatment method of the present application, the chloride ion adsorbent prepared by using 3-aminopropylmethyldimethoxysilane and / or N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane can improve the chloride ion removal rate of the waste slag pickling waste liquid.

[0054] The chloride ion removal rate of the waste residue pickling waste liquid treated in Examples 1, 8 and 9 is as high as 90.00-91.60%, and the chloride ion removal rate of the waste residue pickling waste liquid treated in Example 10 is as low as 83.60%. This shows that in the hot-dip galvanizing waste residue pickling waste liquid treatment method of the present application, the chloride ion adsorbent prepared by the water-soluble non-ionic cellulose ether can improve the chloride ion removal rate of the waste residue pickling waste liquid.

[0055] Compared with the waste slag pickling waste liquid treated in Example 1, the chloride ion removal rate of the waste slag pickling waste liquid treated in Example 11 is significantly reduced, but the chloride ion removal rate of the waste slag pickling waste liquid treated in Example 12 is slightly increased. This shows that in the hot-dip galvanizing waste slag pickling waste liquid treatment method of the present application, increasing the amount of chloride ion adsorbent can improve the chloride ion removal rate of the waste slag pickling waste liquid. However, when the amount of chloride ion adsorbent is 1.5g / L and 1.8g / L, the difference in the removal rate of chloride ions is not obvious, so when the amount of chloride ion adsorbent in the pickling waste liquid is 0.6-1.8g / L, it can have both good chloride ion removal rate and economic benefits.

[0056] Compared with the waste slag pickling waste liquid treated in Example 1, the chloride ion removal rate of the waste slag pickling waste liquid treated in Comparative Examples 1 and 2 is relatively reduced by 23.78-31.00%. This shows that in the hot-dip galvanizing waste slag pickling waste liquid treatment method of the present application, aluminum-magnesium hydrotalcite is used as a carrier to adsorb the polymer after the hydrolysis of the aminosilane coupling agent, and the chloride ion adsorbent finally prepared can improve the chloride ion removal rate of the waste slag pickling waste liquid.

[0057] Compared with the waste slag pickling waste liquid treated in Example 1, the chloride ion removal rate of the waste slag pickling waste liquid treated in Comparative Example 3 is relatively reduced by 19.89%. This shows that in the hot-dip galvanizing waste slag pickling waste liquid treatment method of the present application, the chloride ion adsorbent has good adsorption activity in the waste slag pickling waste liquid with a pH value of 3 to 4, and has a good removal efficiency for chloride ions in the waste slag pickling waste liquid.

[0058] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for treating hot-dip galvanizing waste slag pickling waste liquid, characterized in that: The following steps are involved: S1: adding a chloride ion adsorbent to a waste residue pickling waste liquid having a pH value of 3 to 4, stirring and mixing, and obtaining a mixed liquid; S2: adding sodium alginate to the mixed solution, stirring and mixing, filtering, and adjusting the pH value of the filtrate to 6-7 with caustic soda to obtain a treated waste residue pickling waste liquid; The preparation method of the chloride ion adsorbent is as follows: firstly, the aminosilane coupling agent and water are stirred and mixed, then aluminum magnesium hydrotalcite is added, stirred and mixed, aged, washed with water, dried, and ground to obtain the chloride ion adsorbent.

2. The method for treating hot-dip galvanizing waste slag pickling waste liquid according to claim 1, characterized in that: In the preparation method of the chloride ion adsorbent, the weight ratio of aluminum-magnesium hydrotalcite, aminosilane coupling agent and water is 1:(0.025-0.055):(3-6).

3. The method for treating hot-dip galvanizing waste slag pickling waste liquid according to claim 1, characterized in that: The aminosilane is one or both of 3-aminopropylmethyldimethoxysilane and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane.

4. The method for treating hot-dip galvanizing waste slag pickling waste liquid according to claim 3, characterized in that: The aminosilane is composed of 3-aminopropylmethyldimethoxysilane and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane mixed in a weight ratio of 1:(0.45-0.65).

5. The chloride ion adsorbent according to claim 1, characterized in that: The preparation method of the chloride ion adsorbent is as follows: firstly, an aminosilane coupling agent and water are stirred and mixed, and then aluminum magnesium hydrotalcite and non-ionic water-soluble cellulose ether are added, stirred and mixed, aged, washed with water, dried, and ground to obtain the chloride ion adsorbent; The weight ratio of the aluminum-magnesium hydrotalcite, aminosilane coupling agent, nonionic water-soluble cellulose ether and water is 1:(0.025-0.055):(0.01-0.015):(3-6).

6. The chloride ion adsorbent according to claim 5, characterized in that: The nonionic water-soluble cellulose ether is methyl hydroxyethyl cellulose or hydroxyethyl cellulose.

7. The chloride ion adsorbent according to claim 5, characterized in that: The molar substitution degree of the hydroxyethyl cellulose is 1.8-2.0, the pH value is 6.0-8.5, and the viscosity is 5-60000 mpa·s.

8. The method for treating hot-dip galvanizing waste slag pickling waste liquid according to claim 1, characterized in that: The dosage of the chloride ion adsorbent in the waste residue pickling waste liquid with a pH value of 3 to 4 is 0.6 to 1.8 g / L.

9. A method for preparing a chloride ion adsorbent, characterized in that: The following steps are involved: After the aminosilane and water are stirred and mixed, aluminum magnesium hydrotalcite is added, stirred and mixed, aged, washed with water, dried, and ground to obtain a chloride ion adsorbent; The weight ratio of the aluminum-magnesium hydrotalcite, the aminosilane coupling agent and water is 1:(0.025-0.055):(3-6).

10. The method for preparing a chloride ion adsorbent according to claim 9, characterized in that: Firstly, the aminosilane coupling agent and water are stirred and mixed, and then aluminum magnesium hydrotalcite and non-ionic water-soluble cellulose ether are added, stirred and mixed, aged, washed with water, dried, and ground to obtain a chloride ion adsorbent; The weight ratio of the aluminum-magnesium hydrotalcite, the aminosilane coupling agent, the nonionic water-soluble cellulose ether and water is 1:(0.025-0.055):(0.01-0.015):(3-6).

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