A composite bio-based wastewater treatment agent and a wastewater treatment method

Abstract

The present invention relates to the technical field of wastewater treatment, and particularly relates to a composite bio-based wastewater treatment agent and a wastewater treatment method. The composite bio-based wastewater treatment agent provided by the present invention, when applied to the treatment of industrial wastewater, can efficiently remove heavy metal ions in industrial wastewater, adsorb and catalytically degrade organic pollutants, reduce the negative impact of industrial wastewater on the environment, improve water quality, recover heavy metal resources, and realize the harmless and resource-based treatment of industrial wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and particularly relates to a composite bio-based wastewater treatment agent and a wastewater treatment method. Background Art

[0002] Industrial production is an important pillar of modern social and economic development, but the industrial sewage it generates has become a severe challenge to environmental protection. Industrial sewage is an extremely complex liquid waste containing a large number of harmful substances, such as organic pollutants, heavy metal ions, suspended particles, and various toxic chemical substances. These pollutants have extremely high concentrations, with significant ecological risks and potential long-term hazards. Once directly discharged without effective treatment, industrial wastewater will cause devastating blows to the water ecosystem. More seriously, these harmful substances will pose long-term threats to human health through drinking water, crops, etc., and may trigger various chronic diseases and genetic diseases. Therefore, the development and application of efficient and economical sewage treatment methods are crucial for achieving sustainable development and improving water resource utilization.

[0003] At present, the main methods for removing impurities in sewage include ion exchange, membrane filtration, chemical precipitation, adsorption, electrolysis, advanced oxidation, and reverse osmosis, etc. Adsorption is a method that uses solid adsorbents to remove impurities in wastewater. The advantages of this method mainly include fast reaction process speed, high adsorption efficiency, convenient and simple operation facilities, etc. Therefore, more and more people use this method to remove heavy metal impurities in wastewater.

[0004] For example, patent document CN202111466024.2 discloses a coffee residue biochar and its preparation method and application. By pyrolyzing coffee residues and then mixing and modifying them with H2O2 solution, coffee residue biochar is obtained. Although the preparation method of the above-mentioned technical adsorbent is simple and the cost is low, its application effect is slightly poor, especially the adsorption rate for wastewater with complex components is low, and the biochar needs to be further improved. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a composite bio-based wastewater treatment agent and a wastewater treatment method. The composite bio-based wastewater treatment agent provided by the present invention has good treatment effects when treating wastewater with complex components.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The present invention provides a composite bio-based wastewater treatment agent, and the preparation method of the composite bio-based wastewater treatment agent is as follows:

[0008] S1. Prepare a titanium dioxide / biochar composite carrier

[0009] Mix tetrabutyl titanate and ethanol evenly, then add straw powder thereto, stir and disperse evenly, subsequently add deionized water, stir and react for 2 - 4 h, carry out centrifugal separation, dry the centrifuged product, and calcine it in a nitrogen atmosphere to obtain a titanium dioxide / biochar composite support.

[0010] In this step, first cut the straw into branches with a length of 3 cm, and then grind it through a 100 - mesh sieve to obtain straw powder.

[0011] In this step, the mass ratio of tetrabutyl titanate, ethanol, straw powder and deionized water is 4 - 8:60 - 80:10 - 15:8 - 12.

[0012] In this step, the calcination temperature is 450 - 600 °C, for example, 450 °C, 500 °C, 550 °C, 600 °C can be selected; the calcination time is 2 - 3 h, for example, 2 h, 2.5 h, 3 h can be selected, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0013] In this step, by loading titanium dioxide particles on biochar, the titanium dioxide is used to photocatalytically degrade organic pollutants, thereby improving the sewage treatment ability of biochar, and at the same time solving the problem that titanium dioxide particles are prone to agglomeration in water, resulting in a decline in photocatalytic performance.

[0014] S2. Prepare an amino - modified composite support

[0015] Disperse the titanium dioxide / biochar composite support in an ethanol - aqueous solution, then add an amino - silane coupling agent thereto, stir for 1 - 3 h, and then filter, wash and dry to obtain an amino - modified composite support.

[0016] In this step, the mass ratio of the titanium dioxide / biochar composite support to the amino - silane coupling agent is 10 - 15:1 - 3. In some embodiments of the present invention, for example, 10:1, 10:2, 10:3, 12:1, 12:2, 12:3, 15:1, 15:2, 15:3 can be selected, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0017] Specifically, the amino - silane coupling agent is selected from γ - aminopropyltrimethoxysilane, γ - aminopropyltriethoxysilane or N - β(aminoethyl)-γ - aminopropylmethyldiethoxysilane.

[0018] In this step, by treating the titanium dioxide / biochar composite support with an amino - silane coupling agent, an amino group is introduced on the surface of the titanium dioxide / biochar composite support, which is beneficial to the subsequent reaction.

[0019] S3. Prepare a polyethyleneimine - modified composite support

[0020] Disperse the amino-modified composite carrier in deionized water, then add polyethyleneimine and glutaraldehyde thereto, adjust the pH of the solution to 9 - 12, heat and stir for reaction. After the reaction is completed, filter, wash, and dry to obtain the polyethyleneimine-modified composite carrier.

[0021] In this step, the mass ratio of the amino-modified composite carrier, polyethyleneimine, and glutaraldehyde is 10 - 15:4 - 8:3 - 6.

[0022] In this step, the temperature of the heating and stirring reaction is 60 - 80 °C. For example, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C can be selected; the time of the heating and stirring reaction is 3 - 5 h. For example, 3 h, 3.5 h, 4 h, 4.5 h, 5 h can be selected, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0023] In this step, through the reaction of amino and aldehyde groups, polyethyleneimine is grafted onto the composite carrier. Polyethyleneimine is a high molecular compound, and there are a large number of amino groups on the molecular chain. Amino molecules have strong polarity, which improves the dispersion ability of the composite carrier in water. At the same time, amino also has extremely strong coordination and bonding abilities, which can effectively adsorb heavy metals and organic pollutants in wastewater and enhance the adsorption ability of the wastewater treatment agent.

[0024] S4. Prepare the composite bio-based wastewater treatment agent

[0025] Disperse the polyethyleneimine-modified composite carrier in DMF, add EDC and NHS, stir evenly, then add 2,2'-bipyridine-3,3'-dicarboxylic acid, and stir for reaction at room temperature for 6 - 12 h. After the reaction is completed, filter, wash, and dry to obtain the composite bio-based wastewater treatment agent.

[0026] In this step, the mass ratio of the polyethyleneimine-modified composite carrier, 2,2'-bipyridine-3,3'-dicarboxylic acid, EDC, and NHS is 10 - 15:3 - 5:0.5 - 1:0.5 - 1.

[0027] In this step, the carboxyl group in 2,2'-bipyridine-3,3'-dicarboxylic acid is activated by EDC and NHS, and then a chemical reaction occurs between the unreacted amino group in the polyethyleneimine-modified composite carrier and the carboxyl group in 2,2'-bipyridine-3,3'-dicarboxylic acid to obtain the composite bio-based wastewater treatment agent. The pyridine structure in the composite bio-based wastewater treatment agent can adsorb metal ions and organic pollutants. When the pyridine structure adsorbs metal ions, it will have a photocatalytic effect and cooperate with titanium dioxide particles to photocatalytically degrade the organic matter in wastewater.

[0028] The present invention also provides a wastewater treatment method, in which the above-mentioned composite bio-based wastewater treatment agent is used to treat wastewater according to a feeding amount of 0.5 - 1 g per liter of wastewater.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention provides a composite bio-based wastewater treatment agent. When it is applied to the treatment of industrial wastewater, it can efficiently remove heavy metal ions in industrial wastewater, adsorb and catalytically degrade organic pollutants, reduce the negative impact of industrial wastewater on the environment, improve water quality, recover heavy metal resources, and achieve harmless and resource-based treatment of industrial wastewater.

[0031] (2) In the present invention, titanium dioxide particles are loaded on biochar, and the titanium dioxide is used to photocatalytically degrade organic pollutants, thereby improving the sewage treatment capacity of biochar. At the same time, the problem that titanium dioxide particles are prone to agglomeration in water, resulting in a decline in photocatalytic performance, is solved.

[0032] (3) In the present invention, polyethyleneimine is grafted onto the composite carrier. Polyethyleneimine is a high-molecular compound, and a large number of amino groups are contained in its molecular chain. The amino groups have strong polarity, which improves the dispersion ability of the composite carrier in water. At the same time, the amino groups also have extremely strong coordination and bonding abilities, which can effectively adsorb heavy metals and organic pollutants in wastewater, enhancing the adsorption ability of the wastewater treatment agent. At the same time, the high-molecular network structure of polyethyleneimine increases the specific surface area of the amino-modified composite carrier, further enhancing the adsorption ability of the wastewater treatment agent and also facilitating the subsequent loading of 2,2'-bipyridine-3,3'-dicarboxylic acid.

[0033] (4) In the present invention, 2,2'-bipyridine-3,3'-dicarboxylic acid is grafted onto the polyethyleneimine-modified composite carrier to obtain a composite bio-based wastewater treatment agent. The pyridine structure in the composite bio-based wastewater treatment agent can adsorb metal ions and organic pollutants. When the pyridine structure adsorbs metal ions, it will have a photocatalytic effect and cooperate with titanium dioxide particles to photocatalytically degrade the organic matter in wastewater. Description of the Drawings

[0034] Figure 1 It is a test result diagram of the removal rates of various impurities after treating wastewater in different groups. Detailed Embodiments

[0035] The following further details the present invention through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0036] It should be noted that unless otherwise specified, the chemical reagents involved in the present invention are all purchased through commercial channels.

[0037] In the embodiments of the present invention, the straw powder used is wheat straw powder with a mesh number of 100; the polyethyleneimine has a relative molecular mass of 3000 and is purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.; the CAS number of 2,2'-bipyridine-3,3'-dicarboxylic acid is 4433-01-6, and it is purchased from Guangdong Fangxin Biotechnology Co., Ltd.

[0038] Example 1

[0039] A preparation method of a composite bio-based wastewater treatment agent includes the following steps:

[0040] S1. Mix 4 g of tetrabutyl titanate and 60 g of ethanol evenly, then add 10 g of straw powder thereto, stir and disperse evenly, then add 8 g of deionized water, stir and react for 3 h, perform centrifugal separation, dry the centrifuged product, and calcine it in a nitrogen atmosphere at a calcination temperature of 450 °C for 3 h to obtain a titanium dioxide / biochar composite support;

[0041] S2. Disperse 10 g of the titanium dioxide / biochar composite support in 100 g of a 60 wt% ethanol aqueous solution, then add 1 g of γ-aminopropyltriethoxysilane thereto, stir for 3 h, then filter, wash, and dry to obtain an amino-modified composite support;

[0042] S3. Disperse 10 g of the amino-modified composite support in 150 g of deionized water, then add 4 g of polyethyleneimine and 3 g of glutaraldehyde thereto, adjust the pH of the solution to 10, heat and stir at 60 °C for 5 h, after the reaction is completed, filter, wash, and dry to obtain a polyethyleneimine-modified composite support;

[0043] S4. Disperse 10 g of the polyethyleneimine-modified composite support in 150 mL of DMF, add 0.5 g of EDC and 0.5 g of NHS, stir evenly, then add 3 g of 2,2'-bipyridine-3,3'-dicarboxylic acid, stir and react at room temperature for 6 h, after the reaction is completed, filter, wash, and dry to obtain the composite bio-based wastewater treatment agent.

[0044] Example 2

[0045] A preparation method of a composite bio-based wastewater treatment agent includes the following steps:

[0046] S1. Mix 8 g of tetrabutyl titanate and 80 g of ethanol evenly, then add 15 g of straw powder thereto, stir and disperse evenly, then add 12 g of deionized water, stir and react for 4 h, perform centrifugal separation, dry the centrifuged product, and calcine it in a nitrogen atmosphere at a calcination temperature of 450 °C for 3 h to obtain a titanium dioxide / biochar composite support;

[0047] S2. Disperse 15 g of the titanium dioxide / biochar composite support in 100 g of a 60 wt% ethanol aqueous solution, then add 3 g of γ-aminopropyltriethoxysilane thereto, stir for 3 h, and then filter, wash, and dry to obtain an amino-modified composite support;

[0048] S3. Disperse 15 g of the amino-modified composite support in 150 g of deionized water, then add 8 g of polyethyleneimine and 6 g of glutaraldehyde thereto, adjust the pH of the solution to 12, heat and stir at 80 °C for 3 h, and after the reaction is completed, filter, wash, and dry to obtain a polyethyleneimine-modified composite support;

[0049] S4. Disperse 15 g of the polyethyleneimine-modified composite support in 150 mL of DMF, add 1 g of EDC and 1 g of NHS, stir evenly, then add 5 g of 2,2'-bipyridine-3,3'-dicarboxylic acid, and stir at room temperature for 12 h. After the reaction is completed, filter, wash, and dry to obtain the composite bio-based wastewater treatment agent.

[0050] Example 3

[0051] A preparation method of a composite bio-based wastewater treatment agent includes the following steps:

[0052] S1. Mix 6 g of tetrabutyl titanate and 80 g of ethanol evenly, then add 12 g of straw powder thereto, stir and disperse evenly, then add 10 g of deionized water, stir and react for 4 h, perform centrifugal separation, dry the centrifuged product, and calcine in a nitrogen atmosphere at a calcination temperature of 600 °C for 2 h to obtain the titanium dioxide / biochar composite support;

[0053] S2. Disperse 12 g of the titanium dioxide / biochar composite support in 100 g of a 60 wt% ethanol aqueous solution, then add 2 g of γ-aminopropyltriethoxysilane thereto, stir for 3 h, and then filter, wash, and dry to obtain an amino-modified composite support;

[0054] S3. Disperse 12 g of the amino-modified composite support in 150 g of deionized water, then add 6 g of polyethyleneimine and 5 g of glutaraldehyde thereto, adjust the pH of the solution to 12, heat and stir at 60 °C for 5 h, and after the reaction is completed, filter, wash, and dry to obtain a polyethyleneimine-modified composite support;

[0055] S4. Disperse 12 g of the polyethyleneimine-modified composite support in 150 mL of DMF, add 0.8 g of EDC and 0.8 g of NHS, stir evenly, then add 4 g of 2,2'-bipyridine-3,3'-dicarboxylic acid, and stir at room temperature for 10 h. After the reaction is completed, filter, wash, and dry to obtain the composite bio-based wastewater treatment agent.

[0056] Comparative Example 1

[0057] A preparation method of a composite bio-based wastewater treatment agent comprises the following steps:

[0058] S1. Dry 10 g of straw powder, and then calcine it in a nitrogen atmosphere at a calcination temperature of 450 °C for 3 h to obtain biochar;

[0059] S2. Disperse 10 g of biochar in 100 g of 60 wt% ethanol aqueous solution, then add 1 g of γ-aminopropyltriethoxysilane thereto, stir for 3 h, and then filter, wash, and dry to obtain amino-modified biochar;

[0060] S3. Disperse 10 g of amino-modified biochar in 150 g of deionized water, then add 4 g of polyethyleneimine and 3 g of glutaraldehyde thereto, adjust the pH of the solution to 10, heat and stir the reaction at 60 °C for 5 h. After the reaction is completed, filter, wash, and dry to obtain polyethyleneimine-modified biochar;

[0061] S4. Disperse 10 g of polyethyleneimine-modified biochar in 150 mL of DMF, add 0.5 g of EDC and 0.5 g of NHS, stir evenly, then add 3 g of 2,2'-bipyridine-3,3'-dicarboxylic acid, stir the reaction at room temperature for 6 h. After the reaction is completed, filter, wash, and dry to obtain the composite bio-based wastewater treatment agent.

[0062] Compared with Example 1, in Comparative Example 1, the biochar was not treated with titanium dioxide loading.

[0063] Comparative Example 2

[0064] A preparation method of a composite bio-based wastewater treatment agent comprises the following steps:

[0065] S1. Mix 4 g of tetrabutyl titanate and 60 g of ethanol evenly, then add 10 g of straw powder thereto, stir and disperse evenly, then add 8 g of deionized water, stir the reaction for 3 h, perform centrifugal separation, dry the centrifuged product, and calcine it in a nitrogen atmosphere at a calcination temperature of 450 °C for 3 h to obtain a titanium dioxide / biochar composite support;

[0066] S2. Disperse 10 g of the titanium dioxide / biochar composite support in 100 g of 60 wt% ethanol aqueous solution, then add 1 g of γ-aminopropyltriethoxysilane thereto, stir for 3 h, and then filter, wash, and dry to obtain an amino-modified composite support;

[0067] S3. Disperse 10 g of the amino-modified composite support in 150 mL of DMF, add 0.5 g of EDC and 0.5 g of NHS, stir evenly, then add 3 g of 2,2'-bipyridine-3,3'-dicarboxylic acid, stir and react at room temperature for 6 h. After the reaction is completed, filter, wash, and dry to obtain the composite bio-based wastewater treatment agent.

[0068] Compared with Example 1, the amino-modified composite support in Comparative Example 2 did not graft polyethyleneimine.

[0069] Comparative Example 3

[0070] A preparation method of a composite bio-based wastewater treatment agent includes the following steps:

[0071] S1. Mix 4 g of tetrabutyl titanate and 60 g of ethanol evenly, then add 10 g of straw powder thereto, stir and disperse evenly, then add 8 g of deionized water, stir and react for 3 h, perform centrifugal separation, dry the centrifuged product, and calcine in a nitrogen atmosphere at a calcination temperature of 450 °C for 3 h to obtain a titanium dioxide / biochar composite support.

[0072] S2. Disperse 10 g of the titanium dioxide / biochar composite support in 100 g of a 60 wt% ethanol aqueous solution, then add 1 g of γ-aminopropyltriethoxysilane thereto, stir for 3 h, then filter, wash, and dry to obtain the amino-modified composite support.

[0073] S3. Disperse 10 g of the amino-modified composite support in 150 g of deionized water, then add 4 g of polyethyleneimine and 3 g of glutaraldehyde thereto, adjust the pH of the solution to 10, heat and stir at 60 °C for 5 h. After the reaction is completed, filter, wash, and dry to obtain the composite bio-based wastewater treatment agent.

[0074] Compared with Example 1, Comparative Example 3 did not graft 2,2'-bipyridine-3,3'-dicarboxylic acid.

[0075] Perform wastewater treatment tests on the wastewater treatment agents prepared in Examples 1-3 and Comparative Examples 1-3. The specific steps are as follows:

[0076] Simulate chemical industrial sewage by configuring a wastewater solution in the laboratory. Configure 1 L of wastewater solution, and in the wastewater solution, there is Pb 2+ , Cu 2 + , Zn 2+The concentrations were all 200 mg / L, and the concentration of phenol was 100 mg / L. 1 g of the wastewater treatment agents prepared in Examples 1-3 and Comparative Examples 1-3 was added respectively, and the adsorption treatment was carried out at 25°C for 2 h. Then, the filtrate was obtained by filtration, and the concentrations of heavy metal ions and phenol in the filtrate were detected, and the removal rate was calculated. The removal rate = (initial concentration of pollutant - concentration of pollutant after adsorption) / initial concentration of pollutant × 100%. 3 parallel tests were set for each group, and the results were averaged. The test results are as Figure 1 shown. It can be seen from Figure 1 that compared with Comparative Examples 1-3, the wastewater treatment agents prepared in the examples of the present invention have good removal effects on both heavy metal ions and phenol.

[0077] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, based on the present invention, some modifications and improvements can be made. Therefore, any modification or improvement made without departing from the spirit of the present invention falls within the scope of protection of the present invention.

Claims

1. A composite bio-based wastewater treatment agent, characterized in that: The preparation method of the composite bio-based wastewater treatment agent is as follows: S1. Tetrabutyl titanate and ethanol are mixed uniformly, straw powder is added thereto, and the mixture is stirred and dispersed uniformly. Deionized water is then added, and the mixture is stirred and reacted for 2-4 hours. The mixture is centrifuged and dried, and calcined in a nitrogen atmosphere to obtain a titanium dioxide / biochar composite support. S2, dispersing the titanium dioxide / biochar composite support in an ethanol aqueous solution, then adding an aminosilane coupling agent thereto, stirring for 1-3 hours, and then filtering, washing, and drying to obtain an amino-modified composite support; S3, dispersing the amino-modified composite carrier in deionized water, then adding polyethyleneimine and glutaraldehyde thereto, adjusting the pH of the solution to 9-12, heating and stirring to react, and after the reaction is completed, filtering, washing, and drying to obtain a polyethyleneimine-modified composite carrier; S4. Disperse the polyethyleneimine modified composite carrier in DMF, add EDC and NHS, stir evenly, then add 2,2'-bipyridine-3,3'-dicarboxylic acid, stir and react at room temperature for 6-12 hours. After the reaction is completed, filter, wash and dry to obtain a composite bio-based wastewater treatment agent.

2. The composite bio-based wastewater treatment agent according to claim 1, characterized in that In step S1, the mass ratio of tetrabutyl titanate, ethanol, straw powder and deionized water is 4-8:60-80:10-15:8-12.

3. The composite bio-based wastewater treatment agent according to claim 1, characterized in that In step S1, the calcination temperature is 450-600° C., and the calcination time is 2-3 hours.

4. The composite bio-based wastewater treatment agent according to claim 1, characterized in that In step S2, the mass ratio of the titanium dioxide / biochar composite support to the aminosilane coupling agent is 10-15:1-3.

5. The composite bio-based wastewater treatment agent according to claim 1, characterized in that: In step S3, the mass ratio of the amino-modified composite carrier, polyethyleneimine and glutaraldehyde is 10-15:4-8:3-6.

6. The composite bio-based wastewater treatment agent according to claim 1, characterized in that: In step S3, the temperature for the heating and stirring reaction is 60-80° C., and the time for the heating and stirring reaction is 3-5 h.

7. The composite bio-based wastewater treatment agent according to claim 1, characterized in that In step S4, the mass ratio of the polyethyleneimine-modified composite support, 2,2'-bipyridine-3,3'-dicarboxylic acid, EDC and NHS is 10-15:3-5:0.5-1:0.5-1.

8. A wastewater treatment method, characterized in that: The wastewater is treated using the composite bio-based wastewater treatment agent according to any one of claims 1 to 7 at a feed rate of 0.5 to 1 g per liter of wastewater.

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