An adsorbent for treating high-concentration industrial wastewater and its preparation method

Abstract

This invention discloses an adsorbent for treating high-concentration industrial wastewater and its preparation method. First, chitosan is used to treat zeolite powder, coating the surface of the zeolite powder with chitosan. After calcination, the chitosan forms porous biochar on the surface of the zeolite powder, increasing the specific surface area of ​​the zeolite powder and thus improving the adsorption performance of the adsorbent for pollutants. Then, polyethyleneimine is used to modify the biochar-supported zeolite powder. Polyethyleneimine is a three-dimensional network polymer compound; grafting it onto the biochar-supported zeolite powder facilitates the subsequent loading of titanium dioxide and lanthanum hydroxide. Simultaneously, the polyethyleneimine molecule contains a large number of amino groups, exhibiting excellent adsorption capacity for pollutants in wastewater, further improving the adsorption performance of the adsorbent.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an adsorbent for treating high-concentration industrial wastewater and its preparation method. Background Technology

[0002] The development of industrialization has led to an increase in the discharge of industrial wastewater, polluting water bodies and soil and directly affecting the hygiene of human drinking water. Therefore, the treatment of industrial wastewater has become a hot topic of concern and research. Currently, the main methods used to treat heavy metal ions in wastewater include chemical precipitation, ion exchange, electrolysis, membrane separation, and adsorption. Among these, adsorption utilizes adsorbents to adsorb one or more heavy metal ions in water, and then achieves separation and enrichment of heavy metals through desorption. Adsorption has received widespread attention due to its advantages of high adsorption efficiency, wide availability of materials, and simple operation.

[0003] Traditional adsorbents suffer from drawbacks such as small adsorption capacity and secondary pollution. Therefore, the preparation of a new type of highly efficient and environmentally friendly adsorbent is imperative. For example, Chinese patent document CN201810297336.7 discloses an adsorbent for industrial wastewater treatment and its preparation method. Using cottonseed hulls and expanded vermiculite as main raw materials, an adsorbent for industrial wastewater treatment is prepared at a low cost. Cottonseed hulls contain lignin, crude protein, and other components, and their molecular structure contains groups that are easily chemically modified. Modification treatment improves the adsorption capacity of cottonseed hulls. Modified cottonseed hull powder and expanded vermiculite are mixed and subjected to microwave oxidation treatment to form a surface-activated composite powder with abundant pore structure. Finally, functionalization modification with fatty alcohol ether phosphate and 3-mercaptopropyltrimethoxysilane further enhances the adsorption performance of the product. The prepared adsorbent has strong adsorption capacity, good industrial wastewater treatment effect, and good regenerability. However, its effect is not ideal when treating complex and high-concentration industrial wastewater, and further improvement is still needed. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide an adsorbent for treating high-concentration industrial wastewater and its preparation method. The prepared adsorbent still has good treatment effect when treating industrial wastewater with complex composition and high concentration.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing an adsorbent for treating high-concentration industrial wastewater includes the following steps:

[0007] S1. Chitosan is added to an acetic acid solution and stirred to dissolve. Then zeolite powder is added to the solution, heated and stirred, and then filtered, washed, dried, calcined and ground to obtain biochar-supported zeolite powder.

[0008] S2. Add biochar-supported zeolite powder to deionized water, adjust the pH of the solution to 9-12, then add polyethyleneimine and epichlorohydrin, stir the reaction, and after the reaction is complete, filter, wash and dry to obtain modified zeolite powder.

[0009] S3. The modified zeolite powder is ultrasonically dispersed in deionized water, and then tetrabutyl titanate, lanthanum nitrate and ammonia are added. After stirring evenly, the mixture is refluxed. After the reaction is completed, the mixture is filtered, washed and dried to obtain the adsorbent.

[0010] Preferably, in step S1, the mass ratio of chitosan, acetic acid solution and zeolite powder is 3-6:100:5-10.

[0011] Preferably, in step S1, the heating and stirring temperature is 50-70℃, the heating and stirring time is 2-3 hours, and the stirring speed is 400-600 r / min.

[0012] Preferably, in step S2, the mass ratio of biochar-supported zeolite powder, polyethyleneimine, and epichlorohydrin is 8-10:4-6:3-5.

[0013] Preferably, in step S2, the temperature of the stirring reaction is 60-80℃, and the stirring reaction time is 2-4h.

[0014] Preferably, in step S3, the mass ratio of modified zeolite powder, tetrabutyl titanate, lanthanum nitrate, and ammonia is 8-12:10-15:2-4:20-30.

[0015] Preferably, in step S3, the mass fraction of ammonia is 20-30%.

[0016] Preferably, in step S3, the reflux reaction temperature is 50-60℃ and the reflux reaction time is 8-12h.

[0017] The present invention provides an adsorbent prepared by the above preparation method.

[0018] The present invention also provides the application of the above-mentioned adsorbent in the treatment of high-concentration industrial wastewater.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) In this invention, chitosan is first used to treat zeolite powder, coating the surface of the zeolite powder with chitosan. After calcination, the chitosan forms porous biochar on the surface of the zeolite powder, increasing the specific surface area of ​​the zeolite powder and thus improving the adsorption performance of the adsorbent for pollutants. Then, polyethyleneimine is used to modify the biochar-supported zeolite powder. Polyethyleneimine is a three-dimensional network polymer compound. Grafting it onto the biochar-supported zeolite powder is beneficial for the subsequent loading of titanium dioxide and lanthanum hydroxide. At the same time, polyethyleneimine molecules contain a large number of amino groups, which have good adsorption capacity for pollutants in wastewater, further improving the adsorption performance of the adsorbent.

[0021] (2) In this invention, titanium dioxide and lanthanum hydroxide are loaded onto the surface of the modified zeolite powder by reflux reaction of tetrabutyl titanate, lanthanum nitrate, ammonia and modified zeolite powder. Lanthanum hydroxide can adsorb organic pollutants and heavy metal ions in wastewater. At the same time, lanthanum hydroxide can also act as a catalyst for the photocatalytic degradation of organic matter by titanium dioxide. The synergistic effect of lanthanum hydroxide and titanium dioxide improves the adsorbent's ability to treat organic pollutants in industrial wastewater. Detailed Implementation

[0022] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0023] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0024] The chitosan used in this invention was purchased from Jiangsu Caiwei Biotechnology Co., Ltd., CAS No.: 9012-76-4;

[0025] The particle size of zeolite powder is 100-200 mesh;

[0026] The relative molecular mass of polyethyleneimine is 2000.

[0027] Example 1

[0028] A method for preparing an adsorbent for treating high-concentration industrial wastewater includes the following steps:

[0029] S1. Add 3g of chitosan to 100g of 3wt% acetic acid solution, stir to dissolve, then add 5g of zeolite powder, heat and stir at 50℃ for 3h at a stirring speed of 500r / min, then filter, wash and dry, calcine at 400℃ for 2h in a nitrogen atmosphere, and grind through 200 mesh to obtain biochar-supported zeolite powder.

[0030] S2. Add 8g of biochar-supported zeolite powder to 150g of deionized water, adjust the pH of the solution to 9, then add 4g of polyethyleneimine and 3g of epichlorohydrin, stir and react at 60℃ for 4h. After the reaction is complete, filter, wash and dry to obtain modified zeolite powder.

[0031] S3. Disperse 8g of modified zeolite powder ultrasonically in 150g of deionized water, then add 10g of tetrabutyl titanate, 2g of lanthanum nitrate and 20g of 25wt% ammonia water. After stirring evenly, reflux reaction is carried out at a temperature of 50℃ for 8h. After the reaction is completed, filter, wash and dry to obtain the adsorbent.

[0032] Example 2

[0033] A method for preparing an adsorbent for treating high-concentration industrial wastewater includes the following steps:

[0034] S1. Add 5g of chitosan to 100g of 3wt% acetic acid solution, stir to dissolve, then add 8g of zeolite powder, heat and stir at 70℃ for 2h at a stirring speed of 600r / min, then filter, wash and dry, calcine at 400℃ for 2h under nitrogen atmosphere, grind through 200 mesh to obtain biochar-supported zeolite powder.

[0035] S2. Add 10g of biochar-supported zeolite powder to 150g of deionized water, adjust the pH of the solution to 9, then add 5g of polyethyleneimine and 4g of epichlorohydrin, stir and react at 80℃ for 2h. After the reaction is complete, filter, wash and dry to obtain modified zeolite powder.

[0036] S3. Disperse 10g of modified zeolite powder ultrasonically in 150g of deionized water, then add 12g of tetrabutyl titanate, 3g of lanthanum nitrate and 30g of 25wt% ammonia water. After stirring evenly, reflux the mixture at 60℃ for 10h. After the reaction is complete, filter, wash and dry to obtain the adsorbent.

[0037] Example 3

[0038] A method for preparing an adsorbent for treating high-concentration industrial wastewater includes the following steps:

[0039] S1. Add 6g of chitosan to 100g of 3wt% acetic acid solution and stir to dissolve. Then add 10g of zeolite powder and heat and stir at 60℃ for 3h at a stirring speed of 400r / min. After filtration, washing and drying, calcine at 400℃ for 2h under nitrogen atmosphere and grind through 200 mesh to obtain biochar-supported zeolite powder.

[0040] S2. Add 10g of biochar-supported zeolite powder to 150g of deionized water, adjust the pH of the solution to 12, then add 6g of polyethyleneimine and 5g of epichlorohydrin, stir and react at 70℃ for 3h. After the reaction is complete, filter, wash and dry to obtain modified zeolite powder.

[0041] S3. Disperse 12g of modified zeolite powder ultrasonically in 150g of deionized water, then add 15g of tetrabutyl titanate, 4g of lanthanum nitrate and 30g of 25wt% ammonia water. After stirring evenly, reflux the mixture at 60℃ for 12h. After the reaction is complete, filter, wash and dry to obtain the adsorbent.

[0042] Example 4

[0043] A method for preparing an adsorbent for treating high-concentration industrial wastewater includes the following steps:

[0044] S1. Add 5g of chitosan to 100g of 3wt% acetic acid solution, stir to dissolve, then add 10g of zeolite powder, heat and stir at 60℃ for 2h at a stirring speed of 600r / min, then filter, wash and dry, calcine at 400℃ for 2h under nitrogen atmosphere, and grind through 200 mesh to obtain biochar-supported zeolite powder.

[0045] S2. Add 9g of biochar-supported zeolite powder to 150g of deionized water, adjust the pH of the solution to 12, then add 5g of polyethyleneimine and 5g of epichlorohydrin, stir and react at 70℃ for 4h. After the reaction is complete, filter, wash and dry to obtain modified zeolite powder.

[0046] S3. Disperse 10g of modified zeolite powder ultrasonically in 150g of deionized water, then add 15g of tetrabutyl titanate, 2.5g of lanthanum nitrate and 30g of 25wt% ammonia water. After stirring evenly, reflux the mixture at 60℃ for 10h. After the reaction is complete, filter, wash and dry to obtain the adsorbent.

[0047] Comparative Example 1

[0048] A method for preparing an adsorbent for treating high-concentration industrial wastewater includes the following steps:

[0049] S1. Add 10g of zeolite powder to 150g of deionized water, adjust the pH of the solution to 12, then add 6g of polyethyleneimine and 5g of epichlorohydrin, stir and react at 70℃ for 3h. After the reaction is complete, filter, wash and dry to obtain modified zeolite powder.

[0050] S2. Disperse 12g of modified zeolite powder ultrasonically in 150g of deionized water, then add 15g of tetrabutyl titanate, 4g of lanthanum nitrate and 30g of 25wt% ammonia water. After stirring evenly, reflux the mixture at 60℃ for 12 hours. After the reaction is complete, filter, wash and dry to obtain the adsorbent.

[0051] Comparative Example 2

[0052] A method for preparing an adsorbent for treating high-concentration industrial wastewater includes the following steps:

[0053] S1. Add 6g of chitosan to 100g of 3wt% acetic acid solution and stir to dissolve. Then add 10g of zeolite powder and heat and stir at 60℃ for 3h at a stirring speed of 400r / min. After filtration, washing and drying, calcine at 400℃ for 2h under nitrogen atmosphere and grind through 200 mesh to obtain biochar-supported zeolite powder.

[0054] S2. 12g of biochar-supported zeolite powder was ultrasonically dispersed in 150g of deionized water. Then, 15g of tetrabutyl titanate, 4g of lanthanum nitrate and 30g of 25wt% ammonia water were added. After stirring evenly, the mixture was refluxed at 60℃ for 12h. After the reaction was completed, the adsorbent was obtained by filtration, washing and drying.

[0055] Comparative Example 3

[0056] A method for preparing an adsorbent for treating high-concentration industrial wastewater includes the following steps:

[0057] S1. Add 6g of chitosan to 100g of 3wt% acetic acid solution and stir to dissolve. Then add 10g of zeolite powder and heat and stir at 60℃ for 3h at a stirring speed of 400r / min. After filtration, washing and drying, calcine at 400℃ for 2h under nitrogen atmosphere and grind through 200 mesh to obtain biochar-supported zeolite powder.

[0058] S2. Add 10g of biochar-supported zeolite powder to 150g of deionized water, adjust the pH of the solution to 12, then add 6g of polyethyleneimine and 5g of epichlorohydrin, stir and react at 70℃ for 3h. After the reaction is complete, filter, wash and dry to obtain modified zeolite powder.

[0059] S3. Disperse 12g of modified zeolite powder ultrasonically in 150g of deionized water, then add 15g of tetrabutyl titanate and 30g of 25wt% ammonia water. After stirring evenly, reflux the mixture at 60℃ for 12 hours. After the reaction is complete, filter, wash and dry to obtain the adsorbent.

[0060] The adsorbents prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to high-concentration industrial wastewater treatment experiments. The specific steps are as follows: Simulated industrial wastewater was used, and 1000 mL of wastewater was prepared. The wastewater contained Cu... 2+ and Cd 2+ The concentrations of all pollutants were 1000 mg / L, and the concentration of methylene blue was 500 mg / L. Seven 250 mL Erlenmeyer flasks were used, and 100 mL of simulated industrial wastewater was added to each flask. Then, 1 g of the adsorbent prepared in Examples 1-4 and Comparative Examples 1-3 was added to each flask. The flasks were placed in a constant temperature shaker under natural light. The shaker temperature was set at 25℃, the rotation speed at 250 rpm, and the shaking time at 2 h. After shaking, the solution was filtered through a 0.22 μm microporous membrane. The concentrations of each pollutant in the solution were then measured. The average value of three tests was taken, and the removal rate was calculated. The experimental results are shown in Table 1.

[0061] Table 1

[0062] <![CDATA[Cu 2+ Removal rate (%) <![CDATA[Cd 2+ Removal rate (%) Methylene blue removal rate (%) Example 1 96.3 98.7 97.3 Example 2 97.2 99.3 97.8 Example 3 97.1 98.9 98.2 Example 4 96.9 99.0 97.4 Comparative Example 1 83.5 82.2 86.6 Comparative Example 2 76.4 71.8 80.9 Comparative Example 3 91.2 90.6 65.8

[0063] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for preparing an adsorbent for treating high-concentration industrial wastewater, characterized in that, Includes the following steps: S1. Chitosan is added to an acetic acid solution and stirred to dissolve. Then zeolite powder is added to the solution, heated and stirred, and then filtered, washed, dried, calcined and ground to obtain biochar-supported zeolite powder. S2. Add biochar-supported zeolite powder to deionized water, adjust the pH of the solution to 9-12, then add polyethyleneimine and epichlorohydrin, stir the reaction, and after the reaction is complete, filter, wash and dry to obtain modified zeolite powder. S3. The modified zeolite powder is ultrasonically dispersed in deionized water, and then tetrabutyl titanate, lanthanum nitrate and ammonia are added. After stirring evenly, the mixture is refluxed. After the reaction is completed, the mixture is filtered, washed and dried to obtain the adsorbent. In step S3, the mass ratio of modified zeolite powder, tetrabutyl titanate, lanthanum nitrate and ammonia is 8-12:10-15:2-4:20-30.

2. The method for preparing the adsorbent for treating high-concentration industrial wastewater according to claim 1, characterized in that, In step S1, the mass ratio of chitosan, acetic acid solution and zeolite powder is 3-6:100:5-10.

3. The method for preparing the adsorbent for treating high-concentration industrial wastewater according to claim 1, characterized in that, In step S1, the heating and stirring temperature is 50-70℃, the heating and stirring time is 2-3 hours, and the stirring speed is 400-600 r / min.

4. The method for preparing the adsorbent for treating high-concentration industrial wastewater according to claim 1, characterized in that, In step S2, the mass ratio of biochar-supported zeolite powder, polyethyleneimine, and epichlorohydrin is 8-10:4-6:3-5.

5. The method for preparing the adsorbent for treating high-concentration industrial wastewater according to claim 1, characterized in that, In step S2, the temperature of the stirring reaction is 60-80℃, and the stirring reaction time is 2-4h.

6. The method for preparing the adsorbent for treating high-concentration industrial wastewater according to claim 1, characterized in that, In step S3, the mass fraction of ammonia is 20-30%.

7. The method for preparing the adsorbent for treating high-concentration industrial wastewater according to claim 1, characterized in that, In step S3, the reflux reaction temperature is 50-60℃, and the reflux reaction time is 8-12h.

8. The adsorbent prepared by the preparation method according to any one of claims 1-7.

9. The application of the adsorbent as described in claim 8 in the treatment of high-concentration industrial wastewater.