A method for treating chemical wastewater

Abstract

The present invention discloses a method for treating chemical wastewater, comprising the following steps: S1, filtering and removing impurities from the chemical wastewater, and then adjusting the pH to obtain pretreated wastewater; S2, adding polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon to the pretreated wastewater, performing a primary stirring treatment, and obtaining primary treated wastewater after the treatment; S3, adding a wastewater treatment agent to the primary treated wastewater in step S2, performing a secondary stirring treatment under ultraviolet light, and filtering after the treatment to obtain treated wastewater. This method can efficiently remove heavy metal ions and organic pollutants from chemical wastewater, reduce the COD and heavy metal ion contents in the chemical wastewater, and has good application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical wastewater treatment, and particularly relates to a method for treating chemical wastewater. Background Art

[0002] With the development of the economy and the advancement of urbanization, the discharge of industrial wastewater has increased significantly in the past decade, and the urban population has also increased rapidly, resulting in great changes in the amount and quality of wastewater entering urban sewage treatment plants.

[0003] The basic characteristics of chemical wastewater are: (1) The composition of wastewater is complex, especially the wastewater after mixing has many by-products. Because chemical reaction processes often use solvents and organic compounds with more cyclic molecular structures, it is more difficult to treat than domestic sewage. (2) The concentration of pollutants in wastewater is high, which is caused by incomplete reaction of raw materials and the large amount of solvent media that must be used due to reaction conditions eventually entering the wastewater system. These high-concentration pollutants have poor biodegradability, which often leads to a significant reduction in the treatment efficiency of conventional wastewater treatment processes and high effluent color. (3) The wastewater is more likely to contain toxic and harmful substances. The petroleum, fine chemical, and synthetic chemical industries often use toxic and harmful substances as catalysts in their production processes, so the wastewater they produce will inevitably contain such substances, which are toxic and harmful to microorganisms, animals and plants. Such substances include halogen organic and inorganic compounds, nitro-containing organic compounds, alkali metal phosphate inorganic compounds with antibacterial and sterilization effects, and dispersants and surfactants composed of various complex structures.

[0004] Since chemical wastewater contains high ammonia nitrogen content, high COD (chemical oxygen demand), and a large amount of heavy metal ions, ordinary domestic sewage treatment methods cannot achieve good treatment results. At present, the treatment methods for chemical wastewater include chemical precipitation, flocculation-flotation, flotation, ion exchange, membrane filtration and adsorption. Chemical precipitation refers to the use of precipitants to precipitate heavy metal ions, and then remove them by filtration; flocculation-flotation and flotation mainly use flotation agents / flocculants to aggregate heavy metal ions and float them, and then remove them by filtration; ion exchange, membrane filtration and adsorption mainly use some materials that can adsorb heavy metal ions to adsorb heavy metal ions in sewage.

[0005] Chinese patent application CN114436453A discloses a method for treating chemical wastewater and its application. The method comprises a rational blend of raw materials such as medical stone, fly ash, diatomaceous earth, brewer's grains, potato extract, dimethylformamide, sodium polyacrylate, cellulase, attapulgite, polyvinyl pyridone, polyaluminum sulfate, fish bone meal, chitosan, baking soda, and anabaena powder, and is combined with flocculation, aeration, ozone injection, standing, sedimentation, ultraviolet disinfection, and disinfection with fungicides. This method effectively improves the treatment effect of chemical wastewater treatment methods on chemical wastewater, solving the problem that existing chemical wastewater treatment methods cannot simultaneously achieve good treatment effects on COD and ammonia nitrogen. However, the invention does not address the problem of removing heavy metal ions from chemical wastewater. Chinese patent application CN113277680A discloses a method for treating heavy metal ions in chemical wastewater using silica. The method comprises the following steps: preparing nano-silica; adding the nano-silica to a sodium hydroxide solution, stirring at 70-85°C, filtering, washing the precipitate with water until neutral, filtering, collecting, and drying the precipitate to obtain substance A; dispersing substance A and glycidyl methacrylate in N,N-dimethylformamide, adding sulfuric acid solution to the dispersion, stirring under a nitrogen atmosphere at 90-100°C, collecting the precipitate by centrifugation, washing, and drying to obtain substance B; removing solid particles from the chemical wastewater, adjusting the pH of the filtrate, adding pollutant-degrading bacteria to treat the wastewater, adjusting the pH again, and adding substance B to treat the wastewater. The method of the present invention can treat heavy metal ions in wastewater containing organic pollutants with high efficiency. However, this invention does not address the problem of removing organic pollutants from chemical wastewater.

[0006] Therefore, it is of great significance to develop a method for efficiently removing heavy metal ions and organic pollutants from chemical wastewater in this field. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for treating chemical wastewater, which can efficiently remove heavy metal ions and organic pollutants in chemical wastewater, reduce the content of COD and heavy metal ions in chemical wastewater, and has good application prospects.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for treating chemical wastewater comprises the following steps:

[0010] S1, filtering and removing impurities from the chemical wastewater, and then adjusting the pH to obtain pretreated wastewater;

[0011] S2, adding polyacrylamide, zeolite powder, polyaluminium chloride and activated carbon to the pretreated wastewater, performing a stirring treatment, and obtaining a treated wastewater after the treatment is completed;

[0012] S3. Add a wastewater treatment agent to the once treated wastewater in step S2, stir and treat it for a second time under ultraviolet light, and filter after the treatment to obtain treated wastewater.

[0013] Preferably, the pH is adjusted to 7-8 in step S1.

[0014] Preferably, in step S2, the amount of polyacrylamide added is 30-40 mg / L, the amount of zeolite powder added is 3-4 g / L, the amount of polyaluminum chloride added is 0.3-0.5 g / L, and the amount of activated carbon added is 1-2 g / L.

[0015] In the present invention, zeolite powder has good adsorption capacity and has many cavities and pores; zeolite powder can effectively adsorb suspended matter in water that has not been flocculated and precipitated; and zeolite powder can also be adsorbed on flocs to increase the precipitation rate of the flocs; zeolite powder and polyaluminum chloride work together to effectively improve the flocculation and precipitation of organic pollutants in sewage; polyacrylamide and activated carbon are used in combination to condense and clarify suspended particles in wastewater, thereby improving the treatment effect of wastewater.

[0016] Preferably, the stirring time in step S2 is 50-80 minutes.

[0017] Preferably, the method for preparing the wastewater treatment agent in step S3 comprises the following steps:

[0018] (a) adding diatomaceous earth to an aqueous nitric acid solution, immersing the diatomaceous earth, filtering, washing, and drying to obtain acidified diatomaceous earth; then adding the acidified diatomaceous earth to a sodium hydroxide solution, stirring and heating the solution, and filtering, washing, drying, and calcining the solution to obtain pretreated diatomaceous earth;

[0019] (b) adding the pretreated diatomaceous earth and Tween 20 in step S1 to an ethanol aqueous solution, followed by adding tetrabutyl titanate and ammonia water, ultrasonically dispersing the mixture and then performing a hydrothermal reaction. After the reaction is completed, the mixture is allowed to stand, filtered, washed, and dried to obtain a composite diatomaceous earth;

[0020] (c) adding the composite diatomaceous earth in step (b) to an ethanol aqueous solution, followed by adding vinyltriethoxysilane, and stirring to react. After the reaction is completed, filtering, washing, and drying to obtain vinylated composite diatomaceous earth;

[0021] (d) adding the vinylated composite diatomaceous earth in step (c) to N,N-dimethylformamide, followed by adding 5-amino-2-mercaptobenzimidazole and benzophenone, and reacting under ultraviolet light at a constant temperature. After the reaction is completed, filtering, washing, and drying to obtain a solid product; adding 4-carboxybenzo-15-crown-5 to N,N-dimethylformamide, followed by adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, stirring for 30 minutes, and then adding the solid product and N-hydroxysuccinimide, heating for reaction, filtering, washing, and drying after the reaction is completed to obtain the wastewater treatment agent.

[0022] In the present invention, diatomaceous earth, as a biogenic siliceous rock, has a certain adsorption capacity due to its unique physical and chemical properties such as large specific surface area, many micropores and surfactant groups, and negative surface charge. It is widely used to adsorb heavy metals and pigments in water bodies. However, since natural diatomaceous earth contains impurities and has defects in its physical and chemical structure, its adsorption capacity is limited. Therefore, the present invention modifies it. On the one hand, it can be modified to improve the pore structure and fully enhance the adsorption capacity. On the other hand, functional functional groups are introduced to enhance its ability to complex organic pollutants, thereby significantly enhancing the comprehensive adsorption capacity of diatomaceous earth.

[0023] Preferably, the mass concentration of the nitric acid aqueous solution in step (a) is 5-8%, the temperature of the impregnation treatment is 60-70°C, and the time is 1-2h; the mass concentration of the sodium hydroxide solution is 5-8%, the temperature of the stirring and heating treatment is 60-70°C, and the time is 1-2h, and the temperature of the roasting is 300-350°C, and the time is 1-2h.

[0024] In the present invention, the diatomite is firstly acidified. The acid treatment can effectively remove soluble impurities such as organic matter on the surface and in the pores of the diatomite, thereby improving the surface and pore structure of the diatomite, increasing the specific surface area, and increasing the number of effective adsorption points, which is conducive to the occurrence of adsorption. Subsequently, alkali washing is performed. The strong alkali reduces the silanol groups on the surface of the diatomite, thereby improving the purity of the diatomite and increasing the specific surface area and pore volume, thereby improving the structure of the diatomite and enhancing the adsorption capacity. The diatomite is then calcined at high temperature to fully expand the pores of the diatomite and increase the stability of the pore structure of the diatomite.

[0025] Preferably, the mass concentration of the ammonia water in step (b) is 10-15%, the mass ratio of the pretreated diatomaceous earth, Tween 20, tetrabutyl titanate, and ammonia water is 30:2-3:50-60:80-90, the temperature of the hydrothermal reaction is 130-150° C., and the time is 6-10 hours.

[0026] In the present invention, titanium dioxide is generated in situ on diatomaceous earth by a hydrothermal method. Titanium dioxide has strong catalytic performance and a strong tendency to accept electrons. Under the irradiation of ultraviolet light, it can participate in redox reactions and directly oxidize organic molecules into positive carbon free radicals or oxidize surface water molecules into hydroxyl free radicals, thereby improving the removal of COD and heavy metal ions in wastewater by the wastewater treatment agent.

[0027] Preferably, the mass fraction of ethanol in the ethanol aqueous solution in step (c) is 60-70%, the mass ratio of the composite diatomaceous earth and vinyltriethoxysilane is 50-60:8-12, the stirring reaction temperature is 60-70°C, and the time is 2-3h.

[0028] In the present invention, the composite diatomaceous earth is reacted with vinyltriethoxysilane to introduce double bonds on the surface of the diatomaceous earth, which is beneficial to the subsequent reaction.

[0029] Preferably, in step (d), the mass ratio of the vinyl composite diatomaceous earth, 5-amino-2-mercaptobenzimidazole, and benzophenone is 50:7-11:0.2-0.4, and the intensity of the ultraviolet light is 5-10 mW / cm 2 The temperature of the isothermal reaction is 70-80°C, and the time is 1-2h; the mass ratio of the solid product, 4-carboxybenzo-15-crown ether-5, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, and N-hydroxysuccinimide is 50:6-9:20-30:20-30, and the temperature of the heating reaction is 80-90°C, and the time is 4-6h.

[0030] In the present invention, vinylated composite diatomite and 5-amino-2-mercaptobenzimidazole are reacted through a mercapto-ene reaction, so that the composite diatomite and 5-amino-2-mercaptobenzimidazole are bonded in the form of a covalent bond, thereby introducing a benzimidazole group. The benzimidazole group contains a nitrogen atom, and the lone pair of electrons on the nitrogen atom can coordinate with the empty orbital of the metal ion to form a coordination bond with the metal ion, thereby improving the adsorption of the wastewater treatment agent to heavy metal ions. Subsequently, 4-carboxylbenzo-15-crown-5 is reacted with the diatomite to introduce the crown ether. The lone pair of electrons on the oxygen atom in the crown ether forms a coordination bond with the metal ion, and the two act synergistically to significantly improve the adsorption of the wastewater treatment agent to heavy metal ions. At the same time, the benzene ring in the crown ether can interact with aromatic organic matter in sewage through π-π stacking, and the alkyl chain segment in the crown ether can generate hydrophobic interaction with hydrophobic organic molecules, thereby significantly improving the adsorption amount of the wastewater treatment agent on organic pollutants in the wastewater and improving the efficiency of the wastewater treatment agent on organic pollutants.

[0031] Preferably, the amount of wastewater treatment agent added in step S3 is 0.7-1 g / L, and the intensity of the ultraviolet light is 30-50 mW / cm 2 The time of the secondary stirring treatment is 60-90 minutes.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The method for treating chemical wastewater provided by the present invention first removes impurities from the chemical wastewater, and then adjusts the pH to a weak alkaline state, which is beneficial to the subsequent flocculation precipitation and adsorption catalysis process. Then, polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon are added to the pretreated wastewater. Zeolite powder and activated carbon have good adsorption capabilities for heavy metals and organic pollutants and can effectively adsorb heavy metal ions in water bodies. Polyaluminum chloride has a sedimentation effect. Polyacrylamide is used as a flocculant to remove suspended matter and colloids in water. Then, a wastewater treatment agent is added to further remove heavy metal ions in the wastewater. At the same time, the COD in the wastewater can be degraded to reduce the total amount of organic pollutants in the wastewater.

[0034] (2) The method for treating chemical wastewater provided by the present invention includes the addition of a wastewater treatment agent to acidify, alkaline wash and roast the diatomaceous earth, thereby improving the purity of the diatomaceous earth, increasing the specific surface area and pore volume, improving the structure of the diatomaceous earth, improving the adsorption capacity, fully expanding the diatomaceous earth pores, and increasing the stability of the diatomaceous earth pore structure; then, a hydrothermal method is used to in-situ generate titanium dioxide on the diatomaceous earth. Titanium dioxide has strong catalytic properties and a strong tendency to accept electrons. Under the irradiation of ultraviolet light, it can participate in redox reactions and directly oxidize organic molecules into positive carbon radicals or oxidize surface water molecules into hydroxyl radicals. The generated hydroxyl radicals attack organic molecules, causing them to oxidize and decompose, and ultimately converting organic pollutants into CO2, H2O and inorganic salts to achieve mineralization, thereby improving the removal of COD in wastewater by the wastewater treatment agent. At the same time, Tween-20 is added during the preparation process, which can effectively The dispersibility of the wastewater treatment agent is improved; then, 5-amino-2-mercaptobenzimidazole and 4-carboxylbenzo-15-crown-5 are grafted onto diatomaceous earth in the form of a covalent bond through a chemical reaction, thereby introducing a benzimidazole group and a crown ether group. The benzimidazole group contains a nitrogen atom, and the lone pair of electrons on the nitrogen atom can coordinate with the empty orbital of the metal ion to form a coordination bond with the metal ion, thereby improving the adsorption of the wastewater treatment agent to heavy metal ions. At the same time, the lone pair of electrons on the oxygen atom in the crown ether forms a coordination bond with the metal ion, and the two act synergistically to significantly improve the adsorption of the wastewater treatment agent to heavy metal ions. At the same time, the benzene ring in the crown ether can interact with aromatic organic matter in the sewage through π-π stacking, and the alkyl chain segment in the crown ether can generate hydrophobic interaction with hydrophobic organic molecules, thereby significantly improving the adsorption amount of the wastewater treatment agent on organic pollutants in the wastewater and improving the efficiency of the wastewater treatment agent on organic pollutants.

[0035] (3) The method for treating chemical wastewater provided by the present invention is to prepare modified diatomaceous earth by a specific method, and to graft trans-3-(3-pyridyl)allylic acid and 4-acrylamidebenzo-18-crown ether onto the diatomaceous earth in the form of covalent bonds, thereby avoiding secondary pollution caused by the shedding of small organic molecules during wastewater treatment. At the same time, through ultraviolet light catalytic degradation, the COD and heavy metal ion contents of the wastewater are significantly reduced, and the method has good application prospects. DETAILED DESCRIPTION

[0036] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] In the present invention, the zeolite powder was purchased from Zhongzheng Perlite Factory in Pingqiao District, Xinyang City, with a particle size of 300-400 μm; the activated carbon was purchased from Chengde Tianyuan Activated Carbon Co., Ltd., with a particle size of 100-200 μm; the polyaluminum chloride was purchased from Gongyi Shuizhiyuan Water Purification Materials Co., Ltd., with an alumina content of 28%; the polyacrylamide was purchased from Wuxi Lanbo Chemicals Co., Ltd., with a molecular weight of 8 million.

[0038] In the present invention, the chemical wastewater used is simulated chemical wastewater with a COD content of 1050 mg / L and Cd 2+ 、Cu 2+ , Pb 2+ Cr 3+ 、Ni 2+ The concentration is 500 mg / L.

[0039] Example 1

[0040] A method for treating chemical wastewater comprises the following steps:

[0041] S1, filtering and removing impurities from the chemical wastewater, and then adjusting the pH to 7.5 to obtain pretreated wastewater;

[0042] S2. Add polyacrylamide, zeolite powder, polyaluminium chloride and activated carbon to the pretreated wastewater, stir and treat for 70 min, and obtain a treated wastewater after the treatment is completed; wherein, the addition amount of polyacrylamide is 35 mg / L, the addition amount of the zeolite powder is 3.5 g / L, the addition amount of the polyaluminium chloride is 0.4 g / L, and the addition amount of the activated carbon is 1.5 g / L;

[0043] S3, add wastewater treatment agent to the primary treated wastewater in step S2, at an intensity of 40mW / cm 2 The mixture was stirred and treated under ultraviolet light for 3.5 hours, and filtered after the treatment was completed to obtain the treated wastewater; wherein, the addition amount of the wastewater treatment agent was 0.9 g / L.

[0044] The method for preparing the wastewater treatment agent in step S3 comprises the following steps:

[0045] (a) adding 100 g of diatomaceous earth to 1 L of a 7% nitric acid aqueous solution, immersing the mixture at 65° C. for 1.5 h, filtering, washing, and drying to obtain acidified diatomaceous earth; then adding 100 g of the acidified diatomaceous earth to a 7% sodium hydroxide solution, stirring and heating the mixture at 65° C. for 1.5 h, filtering, washing, drying, and calcining the mixture at 330° C. for 1.5 h to obtain pretreated diatomaceous earth;

[0046] (b) adding 30 g of the pretreated diatomaceous earth and 2.5 g of Tween 20 in step S1 to 800 mL of an ethanol aqueous solution (the mass fraction of ethanol is 75%), followed by adding 55 g of tetrabutyl titanate and 90 g of 15% ammonia water, ultrasonically dispersing for 30 min, and hydrothermally reacting at 140° C. for 8 h. After the reaction is completed, the mixture is allowed to stand, filtered, washed, and dried to obtain a composite diatomaceous earth;

[0047] (c) adding 55 g of the composite diatomaceous earth obtained in step (b) to 1 L of an aqueous ethanol solution (the mass fraction of ethanol being 65%), followed by adding 10 g of vinyltriethoxysilane, and stirring the mixture at 65° C. for 2.5 h. After the reaction is complete, filtering, washing, and drying the mixture to obtain vinyl composite diatomaceous earth;

[0048] (d) 50 g of vinyl composite diatomite in step (c) was added to 800 mL of N,N-dimethylformamide, followed by 9 g of 5-amino-2-mercaptobenzimidazole and 0.3 g of benzophenone. 2 The mixture was reacted under ultraviolet light at a constant temperature of 75°C for 1.5 hours. After the reaction was completed, it was filtered, washed, and dried to obtain a solid product. 8 g of 4-carboxybenzo-15-crown-5 was added to 800 mL of N,N-dimethylformamide, followed by the addition of 25 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. After stirring for 30 minutes, 50 g of the solid product and 25 g of N-hydroxysuccinimide were added, and the mixture was reacted at 85°C for 5 hours. After the reaction was completed, it was filtered, washed, and dried to obtain the wastewater treatment agent.

[0049] Example 2

[0050] A method for treating chemical wastewater comprises the following steps:

[0051] S1, filtering and removing impurities from the chemical wastewater, and then adjusting the pH to 7.5 to obtain pretreated wastewater;

[0052] S2. Add polyacrylamide, zeolite powder, polyaluminium chloride and activated carbon to the pretreated wastewater, stir and treat for 60 min, and obtain a treated wastewater after the treatment is completed; wherein, the addition amount of polyacrylamide is 35 mg / L, the addition amount of the zeolite powder is 3.5 g / L, the addition amount of the polyaluminium chloride is 0.4 g / L, and the addition amount of the activated carbon is 1.5 g / L;

[0053] S3, add wastewater treatment agent to the primary treated wastewater in step S2, at an intensity of 40mW / cm 2 The mixture was stirred and treated under ultraviolet light for 3.5 hours, and filtered after the treatment was completed to obtain the treated wastewater; wherein, the addition amount of the wastewater treatment agent was 0.8 g / L.

[0054] The method for preparing the wastewater treatment agent in step S3 comprises the following steps:

[0055] (a) adding 100 g of diatomaceous earth to 1 L of a 5% aqueous nitric acid solution, immersing the mixture at 60° C. for 2 h, filtering, washing, and drying to obtain acidified diatomaceous earth; then adding 100 g of the acidified diatomaceous earth to a 5% sodium hydroxide solution, stirring and heating the mixture at 60° C. for 2 h, filtering, washing, drying, and calcining the mixture at 300° C. for 2 h to obtain pretreated diatomaceous earth;

[0056] (b) 30 g of the pretreated diatomaceous earth and 2.5 g of Tween 20 in step S1 were added to 800 mL of ethanol aqueous solution (the mass fraction of ethanol was 75%), followed by the addition of 55 g of tetrabutyl titanate and 85 g of 10% ammonia water. After ultrasonic dispersion for 30 min, the mixture was hydrothermally reacted at 140° C. for 8 h. After the reaction was completed, the mixture was allowed to stand, filtered, washed, and dried to obtain composite diatomaceous earth.

[0057] (c) adding 55 g of the composite diatomaceous earth obtained in step (b) to 1 L of an aqueous ethanol solution (the mass fraction of ethanol being 65%), followed by adding 10 g of vinyltriethoxysilane, and stirring the mixture at 65° C. for 2.5 h. After the reaction is complete, filtering, washing, and drying the mixture to obtain vinyl composite diatomaceous earth;

[0058] (d) 50 g of vinyl composite diatomite in step (c) was added to 800 mL of N,N-dimethylformamide, followed by 9 g of 5-amino-2-mercaptobenzimidazole and 0.3 g of benzophenone. 2 The mixture was reacted under ultraviolet light at a constant temperature of 75°C for 1.5 hours. After the reaction was completed, it was filtered, washed, and dried to obtain a solid product. 7g of 4-carboxybenzo-15-crown-5 was added to 800mL of N,N-dimethylformamide, followed by the addition of 25g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. After stirring for 30 minutes, 50g of the solid product and 25g of N-hydroxysuccinimide were added, and the mixture was reacted at 85°C for 5 hours. After the reaction was completed, it was filtered, washed, and dried to obtain the wastewater treatment agent.

[0059] Example 3

[0060] A method for treating chemical wastewater comprises the following steps:

[0061] S1, filtering and removing impurities from the chemical wastewater, and then adjusting the pH to 7 to obtain pretreated wastewater;

[0062] S2. Add polyacrylamide, zeolite powder, polyaluminium chloride and activated carbon to the pretreated wastewater, stir and treat for 80 min, and obtain a treated wastewater after the treatment is completed; wherein, the amount of polyacrylamide added is 30 mg / L, the amount of the zeolite powder added is 3 g / L, the amount of the polyaluminium chloride added is 0.3 g / L, and the amount of the activated carbon added is 1 g / L;

[0063] S3, add wastewater treatment agent to the primary treated wastewater in step S2, at an intensity of 30mW / cm 2 The mixture was stirred and treated under ultraviolet light for 4 hours, and filtered after the treatment to obtain the treated wastewater; wherein, the addition amount of the wastewater treatment agent was 0.7 g / L.

[0064] The method for preparing the wastewater treatment agent in step S3 comprises the following steps:

[0065] (a) adding 100 g of diatomaceous earth to 1 L of a 6% nitric acid aqueous solution, immersing the mixture at 65° C. for 1.5 h, filtering, washing, and drying to obtain acidified diatomaceous earth; then adding 100 g of the acidified diatomaceous earth to a 6% sodium hydroxide solution, stirring and heating the mixture at 65° C. for 1.5 h, filtering, washing, drying, and calcining the mixture at 320° C. for 1.5 h to obtain pretreated diatomaceous earth;

[0066] (b) adding 30 g of the pretreated diatomaceous earth and 2 g of Tween 20 in step S1 to 800 mL of an ethanol aqueous solution (the mass fraction of ethanol is 70%), followed by adding 50 g of tetrabutyl titanate and 80 g of 15% ammonia water, ultrasonically dispersing for 30 min, and hydrothermally reacting at 130° C. for 10 h. After the reaction is completed, the mixture is allowed to stand, filtered, washed, and dried to obtain a composite diatomaceous earth;

[0067] (c) adding 50 g of the composite diatomaceous earth obtained in step (b) to 1 L of an ethanol aqueous solution (the mass fraction of ethanol being 60%), followed by adding 8 g of vinyltriethoxysilane, and stirring the mixture at 60° C. for 3 h. After the reaction is complete, filtering, washing, and drying the mixture to obtain vinylated composite diatomaceous earth;

[0068] (d) 50 g of vinyl composite diatomite in step (c) was added to 800 mL of N,N-dimethylformamide, followed by 7 g of 5-amino-2-mercaptobenzimidazole and 0.2 g of benzophenone. 2The mixture was reacted under ultraviolet light at a constant temperature of 70°C for 2 hours. After the reaction was completed, it was filtered, washed, and dried to obtain a solid product. 6 g of 4-carboxybenzo-15-crown-5 was added to 800 mL of N,N-dimethylformamide, followed by the addition of 20 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. After stirring for 30 minutes, 50 g of the solid product and 20 g of N-hydroxysuccinimide were added, and the mixture was reacted at 80°C for 6 hours. After the reaction was completed, it was filtered, washed, and dried to obtain the wastewater treatment agent.

[0069] Example 4

[0070] A method for treating chemical wastewater comprises the following steps:

[0071] S1, filtering and removing impurities from the chemical wastewater, and then adjusting the pH to 8 to obtain pretreated wastewater;

[0072] S2. Add polyacrylamide, zeolite powder, polyaluminium chloride and activated carbon to the pretreated wastewater, stir and treat for 50 min, and obtain a treated wastewater after the treatment is completed; wherein, the amount of polyacrylamide added is 40 mg / L, the amount of the zeolite powder added is 4 g / L, the amount of the polyaluminium chloride added is 0.5 g / L, and the amount of the activated carbon added is 2 g / L;

[0073] S3, add wastewater treatment agent to the primary treated wastewater in step S2, at an intensity of 50mW / cm 2 The mixture was stirred and treated under ultraviolet light for 3 hours, and filtered after the treatment was completed to obtain the treated wastewater; wherein, the addition amount of the wastewater treatment agent was 1g / L.

[0074] The method for preparing the wastewater treatment agent in step S3 comprises the following steps:

[0075] (a) adding 100 g of diatomaceous earth to 1 L of an 8% nitric acid aqueous solution, immersing the mixture at 70° C. for 1 h, filtering, washing, and drying to obtain acidified diatomaceous earth; then adding 100 g of the acidified diatomaceous earth to an 8% sodium hydroxide solution, stirring and heating the mixture at 70° C. for 1 h, filtering, washing, drying, and calcining the mixture at 350° C. for 1 h to obtain pretreated diatomaceous earth;

[0076] (b) adding 30 g of the pretreated diatomaceous earth and 3 g of Tween 20 in step S1 to 800 mL of an ethanol aqueous solution (the mass fraction of ethanol is 80%), followed by adding 60 g of tetrabutyl titanate and 100 g of 10% ammonia water, ultrasonically dispersing for 30 min, and hydrothermally reacting at 150° C. for 6 h. After the reaction is completed, the mixture is allowed to stand, filtered, washed, and dried to obtain a composite diatomaceous earth;

[0077] (c) adding 60 g of the composite diatomaceous earth obtained in step (b) to 1 L of an aqueous ethanol solution (70% by mass of ethanol), followed by adding 12 g of vinyltriethoxysilane, and stirring the mixture at 70° C. for 2 h. After the reaction is complete, filtering, washing, and drying the mixture to obtain vinyl composite diatomaceous earth;

[0078] (d) 50 g of vinyl composite diatomite in step (c) was added to 800 mL of N,N-dimethylformamide, followed by 11 g of 5-amino-2-mercaptobenzimidazole and 0.4 g of benzophenone. 2 The mixture was reacted under ultraviolet light at a constant temperature of 80°C for 1 hour. After the reaction was completed, it was filtered, washed, and dried to obtain a solid product. 9 g of 4-carboxybenzo-15-crown-5 was added to 800 mL of N,N-dimethylformamide, followed by the addition of 30 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. After stirring for 30 minutes, 50 g of the solid product and 30 g of N-hydroxysuccinimide were added, and the mixture was reacted at 90°C for 4 hours. After the reaction was completed, it was filtered, washed, and dried to obtain the wastewater treatment agent.

[0079] Comparative Example 1

[0080] A method for treating chemical wastewater comprises the following steps:

[0081] S1, filtering and removing impurities from the chemical wastewater, and then adjusting the pH to 7.5 to obtain pretreated wastewater;

[0082] S2. Add polyacrylamide, zeolite powder, polyaluminium chloride and activated carbon to the pretreated wastewater, stir and treat for 70 min, and obtain a treated wastewater after the treatment is completed; wherein, the addition amount of polyacrylamide is 35 mg / L, the addition amount of the zeolite powder is 3.5 g / L, the addition amount of the polyaluminium chloride is 0.4 g / L, and the addition amount of the activated carbon is 1.5 g / L;

[0083] S3, add wastewater treatment agent to the primary treated wastewater in step S2, at an intensity of 40mW / cm 2 The mixture was stirred and treated under ultraviolet light for 3.5 hours, and filtered after the treatment was completed to obtain the treated wastewater; wherein, the addition amount of the wastewater treatment agent was 0.9 g / L.

[0084] The method for preparing the wastewater treatment agent in step S3 comprises the following steps:

[0085] (a) adding 100 g of diatomaceous earth to 1 L of a 7% nitric acid aqueous solution, immersing the mixture at 65° C. for 1.5 h, filtering, washing, and drying to obtain acidified diatomaceous earth; then adding 100 g of the acidified diatomaceous earth to a 7% sodium hydroxide solution, stirring and heating the mixture at 65° C. for 1.5 h, filtering, washing, drying, and calcining the mixture at 330° C. for 1.5 h to obtain pretreated diatomaceous earth;

[0086] (b) adding 30 g of the pretreated diatomaceous earth and 2.5 g of Tween 20 in step S1 to 800 mL of an ethanol aqueous solution (the mass fraction of ethanol is 75%), followed by adding 55 g of tetrabutyl titanate and 90 g of 15% ammonia water, ultrasonically dispersing for 30 min, and hydrothermally reacting at 140° C. for 8 h. After the reaction is completed, the mixture is allowed to stand, filtered, washed, and dried to obtain a composite diatomaceous earth;

[0087] (c) adding 55 g of the composite diatomaceous earth obtained in step (b) to 1 L of an aqueous ethanol solution (the mass fraction of ethanol being 65%), followed by adding 10 g of vinyltriethoxysilane, and stirring the mixture at 65° C. for 2.5 h. After the reaction is complete, filtering, washing, and drying the mixture to obtain vinyl composite diatomaceous earth;

[0088] (d) 50 g of vinyl composite diatomite in step (c) was added to 800 mL of N,N-dimethylformamide, followed by 9 g of 5-amino-2-mercaptobenzimidazole and 0.3 g of benzophenone. 2 The reaction was carried out under ultraviolet light and a constant temperature of 75° C. for 1.5 hours. After the reaction was completed, the wastewater treatment agent was obtained by filtering, washing, and drying.

[0089] Compared with Example 1, the wastewater treatment agent used in this comparative example does not introduce 4-carboxybenzo-15-crown-5.

[0090] Comparative Example 1

[0091] A method for treating chemical wastewater comprises the following steps:

[0092] S1, filtering and removing impurities from the chemical wastewater, and then adjusting the pH to 7.5 to obtain pretreated wastewater;

[0093] S2. Add polyacrylamide, zeolite powder, polyaluminium chloride and activated carbon to the pretreated wastewater, stir and treat for 70 min, and obtain a treated wastewater after the treatment is completed; wherein, the addition amount of polyacrylamide is 35 mg / L, the addition amount of the zeolite powder is 3.5 g / L, the addition amount of the polyaluminium chloride is 0.4 g / L, and the addition amount of the activated carbon is 1.5 g / L;

[0094] S3, add wastewater treatment agent to the primary treated wastewater in step S2, at an intensity of 40mW / cm 2 The mixture was stirred and treated under ultraviolet light for 3.5 hours, and filtered after the treatment was completed to obtain the treated wastewater; wherein, the addition amount of the wastewater treatment agent was 0.9 g / L.

[0095] The method for preparing the wastewater treatment agent in step S3 comprises the following steps:

[0096] (a) adding 100 g of diatomaceous earth to 1 L of a 7% nitric acid aqueous solution, immersing the mixture at 65° C. for 1.5 h, filtering, washing, and drying to obtain acidified diatomaceous earth; then adding 100 g of the acidified diatomaceous earth to a 7% sodium hydroxide solution, stirring and heating the mixture at 65° C. for 1.5 h, filtering, washing, drying, and calcining the mixture at 330° C. for 1.5 h to obtain pretreated diatomaceous earth;

[0097] (b) 30 g of pretreated diatomaceous earth and 2.5 g of Tween 20 in step S1 were added to 800 mL of ethanol aqueous solution (the mass fraction of ethanol was 75%), followed by the addition of 55 g of tetrabutyl titanate and 90 g of 15% ammonia water. After ultrasonic dispersion for 30 min, the mixture was hydrothermally reacted at 140° C. for 8 h. After the reaction was completed, the mixture was allowed to stand, filtered, washed, and dried to obtain a wastewater treatment agent.

[0098] Compared with Example 1, the wastewater treatment agent used in this comparative example does not introduce 5-amino-2-mercaptobenzimidazole and 4-carboxybenzo-15-crown-5.

[0099] The wastewater treated in Examples 1-4 and Comparative Examples 1-2 was tested respectively, and the test results are shown in Table 1 below:

[0100] Table 1 Pollutant content in treated wastewater

[0101]

[0102] As can be seen from Table 1 above, the chemical wastewater treatment method provided by the present invention can efficiently and quickly remove the COD content in chemical wastewater, and can also remove a variety of heavy metal ions, and has good application prospects.

[0103] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating chemical wastewater, characterized in that: The following steps are involved: S1, filtering and removing impurities from the chemical wastewater, and then adjusting the pH to obtain pretreated wastewater; S2, adding polyacrylamide, zeolite powder, polyaluminium chloride and activated carbon to the pretreated wastewater, performing a stirring treatment, and obtaining a treated wastewater after the treatment is completed; S3, adding a wastewater treatment agent to the primary treated wastewater in step S2, stirring and treating it for a second time under ultraviolet light, and filtering after the treatment is completed to obtain treated wastewater; The method for preparing the wastewater treatment agent in step S3 comprises the following steps: (a) adding diatomaceous earth to an aqueous nitric acid solution, immersing the diatomaceous earth, filtering, washing, and drying to obtain acidified diatomaceous earth; then adding the acidified diatomaceous earth to a sodium hydroxide solution, stirring and heating the solution, and filtering, washing, drying, and calcining the solution to obtain pretreated diatomaceous earth; (b) adding the pretreated diatomaceous earth and Tween 20 in step S1 to an ethanol aqueous solution, followed by adding tetrabutyl titanate and ammonia water, ultrasonically dispersing the mixture and then performing a hydrothermal reaction. After the reaction is completed, the mixture is allowed to stand, filtered, washed, and dried to obtain a composite diatomaceous earth; (c) adding the composite diatomaceous earth prepared in step (b) to an ethanol aqueous solution, followed by adding vinyltriethoxysilane, and stirring to react. After the reaction is complete, filtering, washing, and drying to obtain vinylated composite diatomaceous earth; (d) adding the vinylated composite diatomaceous earth in step (c) to N,N-dimethylformamide, followed by adding 5-amino-2-mercaptobenzimidazole and benzophenone, and reacting at a constant temperature under ultraviolet light. After the reaction is completed, filtering, washing, and drying to obtain a solid product; adding 4-carboxybenzo-15-crown-5 to N,N-dimethylformamide, followed by adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, stirring for 30 minutes, and then adding the solid product and N-hydroxysuccinimide, heating for reaction. After the reaction is completed, filtering, washing, and drying to obtain the wastewater treatment agent.

2. The processing method according to claim 1, characterized in that In step S1, the pH is adjusted to 7-8.

3. The processing method according to claim 1, characterized in that In step S2, the amount of polyacrylamide added is 30-40 mg / L, the amount of zeolite powder added is 3-4 g / L, the amount of polyaluminum chloride added is 0.3-0.5 g / L, and the amount of activated carbon added is 1-2 g / L.

4. The processing method according to claim 1, characterized in that The time for the one-time stirring treatment in step S2 is 50-80 minutes.

5. The processing method according to claim 1, characterized in that The mass concentration of the nitric acid aqueous solution in step (a) is 5-8%, the temperature of the impregnation treatment is 60-70°C, and the time is 1-2 hours; the mass concentration of the sodium hydroxide solution is 5-8%, the temperature of the stirring and heating treatment is 60-70°C, and the time is 1-2 hours; and the temperature of the roasting is 300-350°C, and the time is 1-2 hours.

6. The processing method according to claim 1, characterized in that The mass concentration of the ammonia water in step (b) is 10-15%, the mass ratio of the pretreated diatomaceous earth, Tween 20, tetrabutyl titanate, and ammonia water is 30:2-3:50-60:80-90, the temperature of the hydrothermal reaction is 130-150° C., and the time is 6-10 hours.

7. The processing method according to claim 1, characterized in that In step (c), the mass fraction of ethanol in the ethanol aqueous solution is 60-70%, the mass ratio of the composite diatomaceous earth to vinyltriethoxysilane is 50-60:8-12, the stirring reaction temperature is 60-70° C., and the time is 2-3 hours.

8. The processing method according to claim 1, characterized in that In step (d), the mass ratio of the vinyl composite diatomaceous earth, 5-amino-2-mercaptobenzimidazole, and benzophenone is 50:7-11:0.2-0.4, and the intensity of the ultraviolet light is 5-10 mW / cm 2 The temperature of the isothermal reaction is 70-80°C, and the time is 1-2h; the mass ratio of the solid product, 4-carboxybenzo-15-crown ether-5, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, and N-hydroxysuccinimide is 50:6-9:20-30:20-30, and the temperature of the heating reaction is 80-90°C, and the time is 4-6h.

9. The processing method according to claim 1, characterized in that: The amount of wastewater treatment agent added in step S3 is 0.7-1 g / L, and the intensity of the ultraviolet light is 30-50 mW / cm 2 The time of the secondary stirring treatment is 3-4h.

Images