Composite bio-based wastewater treatment agent and wastewater treatment method

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a composite bio-based wastewater treatment agent and a wastewater treatment method.The composite bio-based wastewater treatment agent is applied to treatment of industrial wastewater, heavy metal ions in the industrial wastewater can be efficiently removed, and organic pollutants can be efficiently adsorbed and catalytically degraded; the negative influence of the industrial wastewater on the environment is reduced, the water quality is improved, heavy metal resources are recycled, and harmless and resourceful treatment of the industrial wastewater is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular 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 wastewater it produces has become a severe challenge to environmental protection. Industrial wastewater is a liquid waste with extremely complex composition, which contains a large number of harmful substances, such as organic pollutants, heavy metal ions, suspended particles and various toxic chemicals. These pollutants are in extremely high concentrations and have significant ecological risks and potential long-term hazards. Once industrial wastewater is discharged directly without effective treatment, it will cause a devastating blow to the aquatic ecosystem. What is more serious is that these harmful substances will pose a long-term threat to human health through drinking water, crops and other channels, and may cause various chronic diseases and genetic diseases. Therefore, the development and application of efficient and economical sewage treatment methods are crucial to achieving sustainable development and improving the utilization rate of water resources.

[0003] At present, the main methods for removing impurities from sewage include ion exchange, membrane filtration, chemical precipitation, adsorption, electrolysis, advanced oxidation and reverse osmosis. Adsorption is a method of removing impurities from wastewater using solid adsorbents. The advantages of this method mainly include fast reaction process, high adsorption efficiency, and convenient and simple operating facilities. 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 grounds biochar and its preparation method and application, which comprises pyrolyzing coffee grounds and then reacting with H 2 O 2 The solution is mixed and modified to obtain coffee grounds biochar. Although the preparation method of the above-mentioned technical adsorbent is simple and low-cost, its application effect is slightly poor, especially the adsorption rate of wastewater with complex components is low, and the biochar needs to be further improved. Summary of the invention

[0005] In view of the deficiencies of the prior art, the object 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 a good treatment effect when treating wastewater with complex components.

[0006] In order to achieve the above object, 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. Preparation of titanium dioxide / biochar composite carrier

[0009] Tetrabutyl titanate and ethanol are mixed evenly, and then straw powder is added thereto, stirred and dispersed evenly, followed by adding deionized water, stirring and reacting for 2-4 hours, centrifuged, and the centrifuged product is dried and calcined in a nitrogen atmosphere to obtain a titanium dioxide / biochar composite carrier.

[0010] In this step, the straw is first cut into 3 cm long branches, and then ground 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, and 600°C can be selected; the calcination time is 2-3h, for example, 2h, 2.5h, and 3h can be selected, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] In this step, titanium dioxide particles are loaded on biochar and titanium dioxide is used to photocatalytically degrade organic pollutants, thereby improving the biochar's ability to treat wastewater and solving the problem of titanium dioxide particles easily agglomerating in water, which leads to a decrease in photocatalytic performance.

[0014] S2. Preparation of amino-modified composite carrier

[0015] The titanium dioxide / biochar composite carrier is dispersed in an ethanol aqueous solution, and then an aminosilane coupling agent is added thereto, stirred for 1-3 hours, and then filtered, washed, and dried to obtain an amino-modified composite carrier.

[0016] In this step, the mass ratio of the titanium dioxide / biochar composite carrier and the aminosilane 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 also applicable.

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

[0018] In this step, the titanium dioxide / biochar composite carrier is treated with an aminosilane coupling agent to introduce amino groups on the surface of the titanium dioxide / biochar composite carrier, which is beneficial to the subsequent reaction.

[0019] S3. Preparation of polyethyleneimine modified composite carrier

[0020] The amino-modified composite carrier is dispersed in deionized water, and then polyethyleneimine and glutaraldehyde are added thereto, the pH of the solution is adjusted to 9-12, and the solution is heated and stirred for reaction. After the reaction is completed, the solution is filtered, washed, and dried 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, and 80°C can be selected; the time of the heating and stirring reaction is 3-5h, for example, 3h, 3.5h, 4h, 4.5h, and 5h can be selected, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] In this step, polyethyleneimine is grafted onto the composite carrier through the reaction of amino groups and aldehyde groups. Polyethyleneimine is a high molecular compound containing a large number of amino groups on the molecular chain. The amino molecules 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, thereby enhancing the adsorption capacity of the wastewater treatment agent.

[0024] S4. Preparation of composite bio-based wastewater treatment agent

[0025] The polyethyleneimine modified composite carrier is dispersed in DMF, EDC and NHS are added, stirred evenly, and then 2,2'-bipyridine-3,3'-dicarboxylic acid is added, and the reaction is stirred at room temperature for 6-12 hours. After the reaction is completed, the composite bio-based wastewater treatment agent is obtained by filtering, washing and drying.

[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, EDC and NHS are used to activate the carboxyl group in 2,2'-bipyridine-3,3'-dicarboxylic acid, and then the amino group that does not participate in the reaction in the polyethyleneimine-modified composite carrier reacts chemically with the carboxyl group in 2,2'-bipyridine-3,3'-dicarboxylic acid 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 synergistically work with titanium dioxide particles to photocatalytically degrade organic matter in the wastewater.

[0028] The present invention also provides a wastewater treatment method, which uses the composite bio-based wastewater treatment agent to treat wastewater at a feed 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, which 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, recycle heavy metal resources, and achieve harmless and resource-based treatment of industrial wastewater.

[0031] (2) The present invention loads titanium dioxide particles on biochar and utilizes titanium dioxide to photocatalytically degrade organic pollutants, thereby improving the biochar's ability to treat wastewater and solving the problem that titanium dioxide particles are easily agglomerated in water, resulting in a decrease in photocatalytic performance.

[0032] (3) The present invention grafts polyethyleneimine onto a composite carrier. Polyethyleneimine is a polymer compound containing a large number of amino groups on its molecular chain. The amino molecules 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, thereby enhancing the adsorption capacity of the wastewater treatment agent. At the same time, the polymer network structure of polyethyleneimine increases the specific surface area of ​​the amino-modified composite carrier, thereby enhancing the adsorption capacity of the wastewater treatment agent, and is also beneficial to the subsequent loading of 2,2'-bipyridine-3,3'-dicarboxylic acid.

[0033] (4) The present invention obtains a composite bio-based wastewater treatment agent by grafting 2,2'-bipyridine-3,3'-dicarboxylic acid onto a polyethyleneimine-modified composite carrier. 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 has a photocatalytic effect and synergistically acts with titanium dioxide particles to photocatalytically degrade organic matter in the wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a graph showing the test results of the removal rate of various impurities after wastewater treatment by different groups. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below 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 were purchased through commercial channels.

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

[0038] Example 1

[0039] A method for preparing a composite bio-based wastewater treatment agent comprises the following steps:

[0040] S1. 4 g of tetrabutyl titanate and 60 g of ethanol were mixed evenly, and then 10 g of straw powder was added thereto, stirred and dispersed evenly, and then 8 g of deionized water was added, stirred and reacted for 3 h, centrifuged, and the centrifuged product was dried and calcined in a nitrogen atmosphere at a calcination temperature of 450 ° C and a calcination time of 3 h to obtain a titanium dioxide / biochar composite carrier;

[0041] S2, dispersing 10 g of titanium dioxide / biochar composite carrier in 100 g of 60 wt% ethanol aqueous solution, then adding 1 g of γ-aminopropyltriethoxysilane thereto, stirring for 3 h, then filtering, washing, and drying to obtain an amino-modified composite carrier;

[0042] S3, dispersing 10g of the amino-modified composite carrier in 150g of deionized water, then adding 4g of polyethyleneimine and 3g of glutaraldehyde thereto, adjusting the pH of the solution to 10, heating and stirring the reaction at 60°C for 5h, and after the reaction is completed, filtering, washing and drying to obtain a polyethyleneimine-modified composite carrier;

[0043] S4. Disperse 10 g of the polyethyleneimine-modified composite carrier 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 a composite bio-based wastewater treatment agent.

[0044] Example 2

[0045] A method for preparing a composite bio-based wastewater treatment agent comprises the following steps:

[0046] S1. 8 g of tetrabutyl titanate and 80 g of ethanol were mixed evenly, and then 15 g of straw powder was added thereto, stirred and dispersed evenly, and then 12 g of deionized water was added, stirred and reacted for 4 h, centrifuged, and the centrifuged product was dried and calcined in a nitrogen atmosphere at a calcination temperature of 450 ° C and a calcination time of 3 h to obtain a titanium dioxide / biochar composite carrier;

[0047] S2, dispersing 15g of titanium dioxide / biochar composite carrier in 100g of 60wt% ethanol aqueous solution, then adding 3g of γ-aminopropyltriethoxysilane thereto, stirring for 3h, then filtering, washing and drying to obtain an amino-modified composite carrier;

[0048] S3, dispersing 15g of the amino-modified composite carrier in 150g of deionized water, then adding 8g of polyethyleneimine and 6g of glutaraldehyde thereto, adjusting the pH of the solution to 12, heating and stirring the reaction at 80°C for 3h, and after the reaction is completed, filtering, washing and drying to obtain a polyethyleneimine-modified composite carrier;

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

[0050] Example 3

[0051] A method for preparing a composite bio-based wastewater treatment agent comprises the following steps:

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

[0053] S2, dispersing 12 g of titanium dioxide / biochar composite carrier in 100 g of 60 wt% ethanol aqueous solution, then adding 2 g of γ-aminopropyltriethoxysilane thereto, stirring for 3 h, then filtering, washing, and drying to obtain an amino-modified composite carrier;

[0054] S3, dispersing 12g of the amino-modified composite carrier in 150g of deionized water, then adding 6g of polyethyleneimine and 5g of glutaraldehyde thereto, adjusting the pH of the solution to 12, heating and stirring the reaction at 60°C for 5h, and after the reaction is completed, filtering, washing and drying to obtain a polyethyleneimine-modified composite carrier;

[0055] S4. Disperse 12 g of the polyethyleneimine-modified composite carrier 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, stir and react at room temperature for 10 h. After the reaction is completed, filter, wash and dry to obtain a composite bio-based wastewater treatment agent.

[0056] Comparative Example 1

[0057] A method for preparing 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 temperature of 450° C. for 3 h to obtain biochar;

[0059] S2, dispersing 10 g of biochar in 100 g of 60 wt% ethanol aqueous solution, then adding 1 g of γ-aminopropyltriethoxysilane thereto, stirring for 3 h, then filtering, washing, and drying to obtain amino-modified biochar;

[0060] S3, dispersing 10g of amino-modified biochar in 150g of deionized water, then adding 4g of polyethyleneimine and 3g of glutaraldehyde thereto, adjusting the pH of the solution to 10, heating and stirring the reaction at 60°C for 5h, and after the reaction is completed, filtering, washing and drying 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 and react at room temperature for 6 h. After the reaction is completed, filter, wash and dry to obtain a composite bio-based wastewater treatment agent.

[0062] Compared with Example 1, Comparative Example 1 did not carry out titanium dioxide loading treatment on the biochar.

[0063] Comparative Example 2

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

[0065] S1. 4 g of tetrabutyl titanate and 60 g of ethanol were mixed evenly, and then 10 g of straw powder was added thereto, stirred and dispersed evenly, and then 8 g of deionized water was added, stirred and reacted for 3 h, centrifuged, and the centrifuged product was dried and calcined in a nitrogen atmosphere at a calcination temperature of 450 ° C and a calcination time of 3 h to obtain a titanium dioxide / biochar composite carrier;

[0066] S2, dispersing 10 g of titanium dioxide / biochar composite carrier in 100 g of 60 wt% ethanol aqueous solution, then adding 1 g of γ-aminopropyltriethoxysilane thereto, stirring for 3 h, then filtering, washing, and drying to obtain an amino-modified composite carrier;

[0067] S3. Disperse 10 g of the amino-modified composite carrier 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 a composite bio-based wastewater treatment agent.

[0068] Compared with Example 1, in Comparative Example 2, the amino-modified composite carrier is not grafted with polyethyleneimine.

[0069] Comparative Example 3

[0070] A method for preparing a composite bio-based wastewater treatment agent comprises the following steps:

[0071] S1. 4 g of tetrabutyl titanate and 60 g of ethanol were mixed evenly, and then 10 g of straw powder was added thereto, stirred and dispersed evenly, and then 8 g of deionized water was added, stirred and reacted for 3 h, centrifuged, and the centrifuged product was dried and calcined in a nitrogen atmosphere at a calcination temperature of 450 ° C and a calcination time of 3 h to obtain a titanium dioxide / biochar composite carrier;

[0072] S2, dispersing 10 g of titanium dioxide / biochar composite carrier in 100 g of 60 wt% ethanol aqueous solution, then adding 1 g of γ-aminopropyltriethoxysilane thereto, stirring for 3 h, then filtering, washing, and drying to obtain an amino-modified composite carrier;

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

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

[0075] The wastewater treatment agents prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to a wastewater treatment test, and the specific steps were as follows:

[0076] The wastewater solution was prepared in the laboratory to simulate chemical wastewater. 1L of wastewater solution was prepared. Pb 2+ , Cu 2 + 、Zn 2+The concentration of each of the wastewater treatment agents is 200 mg / L, the concentration of phenol is 100 mg / L, 1 g of the wastewater treatment agent prepared in Examples 1-3 and Comparative Examples 1-3 is added respectively, and the adsorption treatment is carried out at 25°C for 2 hours, and then the filtrate is obtained by filtration. The concentrations of heavy metal ions and phenol in the filtrate are detected, and the removal rate is calculated. The removal rate = (initial concentration of pollutants - concentration of pollutants after adsorption) / initial concentration of pollutants × 100%. Three parallel tests are set for each group, and the results are averaged. The test results are shown in Figure 1 As shown, from Figure 1 It can be seen that, compared with Comparative Examples 1-3, the wastewater treatment agent prepared in the embodiment of the present invention has a good removal effect on 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, some modifications and improvements can be made to the present invention. Therefore, any modification or improvement made without departing from the spirit of the present invention belongs to the scope of protection claimed in 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 evenly, straw powder is added thereto, and the mixture is stirred and dispersed evenly. Deionized water is then added, and the mixture is stirred and reacted for 2-4 hours. The mixture is centrifuged and dried, and the centrifuged product is calcined in a nitrogen atmosphere to obtain a titanium dioxide / biochar composite carrier. S2, dispersing the titanium dioxide / biochar composite carrier 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 carrier; 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 the 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 2-3h.

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 carrier 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 of the heating and stirring reaction is 60-80° C., and the time of 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 carrier, 2,2'-bipyridine-3,3'-dicarboxylic acid, EDC and NHS is 10-15:3-5:0.5-1:0.5-1.

8. A method for treating wastewater, 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 amount of 0.5 to 1 g per liter of wastewater.

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