Treatment method of chemical wastewater

Abstract

The invention discloses a chemical wastewater treatment method, which comprises: S1, filtering chemical wastewater to remove impurities, and adjusting the pH value to obtain pretreated wastewater; s2, polyacrylamide, zeolite powder, polyaluminum chloride and activated carbon are added into the pretreated wastewater, primary stirring treatment is performed, and primary treated wastewater is obtained after treatment is completed; and S3, adding a wastewater treatment agent into the wastewater subjected to primary treatment in the step S2, carrying out secondary stirring treatment under ultraviolet light, and filtering after the treatment is completed, so as to obtain the treated wastewater. According to the method, heavy metal ions and organic pollutants in the chemical wastewater can be efficiently removed, COD (Chemical Oxygen Demand) in the chemical wastewater and the content of the heavy metal ions are reduced, and the method has a good application prospect.

Description

Technical Field

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

[0002] With the development of the economy and the advancement of the urbanization process, the discharge of industrial wastewater has increased significantly in more than a decade, and the urban population has also increased sharply, resulting in great changes in the quantity and quality of the wastewater entering the urban sewage treatment plant.

[0003] Basic characteristics of chemical industrial wastewater: (1) The composition of the wastewater is complex. Especially, there are many by-products in the mixed wastewater. Due to the commonly used solvents and organic compounds with more ring structures in the molecular structure in the chemical reaction process, compared with domestic sewage, it is more difficult to treat. (2) The concentration of pollutants in the wastewater is high, which is caused by the incomplete reaction of raw materials and the large amount of solvent media that must be used due to reaction conditions and finally enter the wastewater system. These highly concentrated pollutants have poor biodegradability and often lead to a significant reduction in the treatment efficiency of conventional wastewater treatment processes and a high chromaticity of the effluent. (3) The wastewater is more likely to contain toxic and harmful substances. In the production processes of the petroleum, fine chemical, and synthetic chemical industries, toxic and harmful substances are often used as catalysts, etc. Therefore, the wastewater generated is inevitably contaminated with such substances, which are toxic and harmful to microorganisms, animals, and plants. Such as halogenated organic and inorganic compounds, nitro-containing organic compounds, alkali metal phosphate inorganic substances with antibacterial and sterilizing effects, as well as dispersants and surfactants composed of various complex structures.

[0004] Since the chemical industrial wastewater contains a high content of ammonia nitrogen and high COD (chemical oxygen demand), and also contains a large amount of heavy metal ions, ordinary domestic sewage treatment means cannot achieve good treatment effects. At present, the treatment methods for chemical industrial wastewater include chemical precipitation method, flocculation-flotation method, flotation method, ion exchange method, membrane filtration method, and adsorption method. The chemical precipitation method refers to using a precipitant to cause the heavy metal ions to coagulate and precipitate, and then removing them by filtration; the flocculation-flotation method and the flotation method mainly use flotation agents / flocculants, etc. to cause the heavy metal ions to aggregate and be floated and then removed by filtration; the ion exchange method, the membrane filtration method, and the adsorption method mainly use some materials that can adsorb heavy metal ions to adsorb the heavy metal ions in the sewage.

[0005] Chinese Patent Application CN114436453A specifically discloses a chemical wastewater treatment method and its application. The chemical wastewater treatment method rationally blends raw materials such as zeolite, fly ash, diatomite, brewer's grains, potato extract, dimethylformamide, sodium polyacrylate, cellulase, attapulgite, polyvinylpyrrolidone, polyaluminum sulfate, fish bone meal, chitosan, baking soda, and Anabaena powder. At the same time, through processes such as flocculation, aeration, ozone injection, static settlement, sedimentation treatment, ultraviolet disinfection, and disinfectant disinfection, it can effectively improve the treatment effect of the chemical wastewater treatment method on chemical wastewater, and solve the problem that the existing chemical wastewater treatment methods cannot have good treatment effects on both COD and ammonia nitrogen at the same time. However, this invention does not solve the problem of removing heavy metal ions in chemical wastewater. Chinese Patent Application CN113277680A discloses a method for treating heavy metal ions in chemical wastewater using silica. The method includes the following steps: preparing nano-silica; adding the nano-silica to a sodium hydroxide solution, stirring at 70 - 85°C, filtering, washing the precipitate to neutral, filtering, collecting the precipitate, and drying to obtain Substance A; dispersing Substance A and glycidyl methacrylate in N,N-dimethylformamide, adding a sulfuric acid solution to the dispersion system, stirring and reacting under a nitrogen atmosphere and at 90 - 100°C, centrifuging to collect the precipitate, washing, and drying to obtain Substance B; removing solid particles in the chemical wastewater, adjusting the pH of the filtrate, adding pollutant-degrading bacteria to treat the wastewater, then adjusting the pH, and adding Substance B to treat the wastewater. The method of the present invention can still treat heavy metal ions in wastewater in the presence of organic pollutants with high efficiency. However, this invention does not solve the problem of removing organic pollutants in chemical wastewater.

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

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a treatment method for 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 purpose, the present invention provides the following technical solutions:

[0009] A treatment method for chemical wastewater, comprising the following steps:

[0010] S1. Filter and remove impurities from the chemical wastewater, and then adjust the pH to obtain pretreated wastewater;

[0011] S2. Add polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon to the pretreated wastewater, and conduct a primary stirring treatment. After the treatment is completed, obtain the primary treated wastewater.

[0012] S3. Add a wastewater treatment agent to the primary treated wastewater in step S2, and conduct a secondary stirring treatment under ultraviolet light. After the treatment is completed, filter to obtain the treated wastewater.

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

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

[0015] In the present invention, the zeolite powder has good adsorption capacity and has many cavities and pores; the zeolite powder can effectively adsorb the suspended substances in the water that have not been flocculated and precipitated; moreover, the zeolite powder can also be adsorbed on the flocs to improve the precipitation speed of the flocs; the zeolite powder and polyaluminum chloride cooperate with each other to effectively improve the flocculation and precipitation of organic pollutants in the sewage; the polyacrylamide and activated carbon are used in combination, which can cause the suspended particles in the wastewater to agglomerate and clarify, improving the treatment effect of the wastewater.

[0016] Preferably, in step S2, the time of the primary stirring treatment is 50 - 80 min.

[0017] Preferably, the preparation method of the wastewater treatment agent in step S3 includes the following steps:

[0018] (a) Add diatomite to an aqueous nitric acid solution, conduct an impregnation treatment, then filter, wash, and dry to obtain acidified diatomite; subsequently, add the acidified diatomite to a sodium hydroxide solution, conduct a stirring and heating treatment, and after the treatment is completed, filter, wash, dry, and calcine to obtain pretreated diatomite.

[0019] (b) Add the pretreated diatomite in step S1 and Tween 20 to an aqueous ethanol solution, then add tetrabutyl titanate and ammonia water, conduct ultrasonic dispersion, and then carry out a hydrothermal reaction. After the reaction ends, let it stand, filter, wash, and dry to obtain composite diatomite.

[0020] (c) Add the composite diatomite in step (b) to an aqueous ethanol solution, then add vinyltriethoxysilane, and conduct a stirring reaction. After the reaction is completed, filter, wash, and dry to obtain vinylated composite diatomite.

[0021] (d) Add the vinylated composite diatomaceous earth in step (c) to N,N-dimethylformamide, then add 5-amino-2-mercaptobenzimidazole and benzophenone, and carry out a constant-temperature reaction under ultraviolet light. After the reaction is completed, filter, wash, and dry to obtain a solid product; add 4-carboxybenzo-15-crown-5 to N,N-dimethylformamide, then add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. After stirring for 30 min, add the solid product and N-hydroxysuccinimide, and carry out a heating reaction. After the reaction is completed, filter, wash, and dry 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 a large specific surface area, many micropores and surface active groups, and a negatively charged surface, and is widely used for adsorbing heavy metals and pigments in water bodies. However, due to the impurities contained in natural diatomaceous earth and the defects in its physical and chemical structure, the exertion of its adsorption capacity is restricted. Therefore, in the present invention, by modifying it, on the one hand, the pore structure can be modified to fully improve the adsorption capacity, and on the other hand, functional functional groups are introduced to improve its ability to complex organic pollutants, significantly improving the comprehensive adsorption capacity of diatomaceous earth.

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

[0024] In the present invention, the diatomaceous earth is first acidified. The acid treatment can effectively remove soluble impurities such as organic matter on the surface and in the pores of the diatomaceous earth, improve the surface and pore structure of the diatomaceous earth, increase the specific surface area, and increase the effective adsorption sites, which is beneficial to the occurrence of adsorption; then, it is alkali-washed. The reduction effect of the strong base on the silicon hydroxyl groups on the surface of the diatomaceous earth not only improves the purity of the diatomaceous earth, but also increases the specific surface area and pore volume, improves the structure of the diatomaceous earth, and improves the adsorption capacity. Then, through high-temperature calcination, the pores of the diatomaceous earth are fully expanded, and the stability of the pore structure of the diatomaceous earth is increased.

[0025] Preferably, in step (b), the mass concentration of the ammonia water 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 h.

[0026] In the present invention, titanium dioxide is in-situ generated on diatomite 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, directly oxidize organic molecules into carbocation radicals or oxidize surface water molecules into hydroxyl radicals, thereby improving the removal of COD and heavy metal ions in wastewater by the wastewater treatment agent.

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

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

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

[0030] In the present invention, the vinylated composite diatomite and 5-amino-2-mercaptobenzimidazole undergo a thiol-ene reaction, enabling the composite diatomite and 5-amino-2-mercaptobenzimidazole to be combined 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 undergo a coordination interaction with the empty orbital of the metal ion to form a coordination bond with the metal ion, thereby improving the adsorption of heavy metal ions by the wastewater treatment agent. Subsequently, 4-carboxybenzo-15-crown-5 reacts with the diatomite to introduce a crown ether on the diatomite. 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 heavy metal ions by the wastewater treatment agent. At the same time, the benzene ring in the crown ether can interact with aromatic organic compounds in the sewage through π-π stacking, and the alkyl chain segment in the crown ether can have a hydrophobic interaction with hydrophobic organic molecules, thereby significantly increasing the adsorption amount of organic pollutants in the wastewater by the wastewater treatment agent and improving the efficiency of the wastewater treatment agent for organic pollutants.

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

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

[0033] (1) For the chemical wastewater treatment method provided by the present invention, the chemical wastewater is first purified, and then the pH is adjusted to weakly alkaline, which is beneficial to the subsequent flocculation precipitation and adsorption catalysis processes. Then, polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon are added to the pretreated wastewater. Zeolite powder and activated carbon have good abilities to adsorb heavy metals and organic pollutants, and can effectively adsorb heavy metal ions in the water body. Polyaluminum chloride has a sedimentation effect, and polyacrylamide is used as a flocculant to remove suspended solids and colloids in the water. Then, a wastewater treatment agent is added, which can further remove heavy metal ions in the wastewater, and at the same time, can also degrade the COD in the wastewater and reduce the total amount of organic pollutants in the wastewater.

[0034] (2) For the chemical wastewater treatment method provided by the present invention, the added wastewater treatment agent acidifies, alkali-washes, and calcines diatomite, which improves the purity of diatomite, increases the specific surface area and pore volume, improves the structure of diatomite, and enhances the adsorption capacity. The pore channels of diatomite are fully expanded, and the stability of the pore channel structure of diatomite is increased. Then, titanium dioxide is in-situ generated on diatomite by the hydrothermal method. Titanium dioxide has strong catalytic performance and a strong tendency to receive electrons. Under the irradiation of ultraviolet light, it can participate in redox reactions, directly oxidize organic molecules to positive carbon radicals or oxidize surface water molecules to hydroxyl radicals. The generated hydroxyl radicals attack organic molecule molecules, oxidize and decompose them, and finally convert organic pollutants into CO 2 , H 2O and inorganic salts achieve mineralization, thereby improving the removal of COD in wastewater by the wastewater treatment agent. At the same time, adding Tween-20 during the preparation process can effectively improve the dispersibility of the wastewater treatment agent. Then, 5-amino-2-mercaptobenzimidazole and 4-carboxybenzo-15-crown-5 are grafted onto diatomite in the form of covalent bonds through a chemical reaction, thereby introducing benzimidazole groups and crown ether groups. The benzimidazole group contains nitrogen atoms, and the lone pair electrons on the nitrogen atoms can undergo coordination with the empty orbitals of metal ions to form coordination bonds with metal ions, thereby improving the adsorption of heavy metal ions by the wastewater treatment agent. At the same time, the lone pair electrons on the oxygen atoms in the crown ether form coordination bonds with metal ions, and the two act synergistically to significantly improve the adsorption of heavy metal ions by the wastewater treatment agent. At the same time, the benzene ring in the crown ether can interact with aromatic organic compounds in sewage through π-π stacking, and the alkyl chain segments in the crown ether can have hydrophobic interactions with hydrophobic organic molecules, thereby significantly increasing the adsorption amount of organic pollutants in wastewater by the wastewater treatment agent and improving the efficiency of the wastewater treatment agent for organic pollutants.

[0035] (3) The method for treating chemical industrial wastewater provided by the present invention prepares modified diatomite through a specific method, and grafts trans-3-(3-pyridyl) acrylic acid and 4-acrylamidobenzo-18-crown-5 onto diatomite in the form of covalent bonds, avoiding secondary pollution caused by the shedding of organic small molecules during sewage treatment. At the same time, through the method of ultraviolet photocatalytic degradation, the COD and the content of heavy metal ions in the wastewater are significantly reduced, and it has good application prospects. Specific embodiments

[0036] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

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

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

[0039] Example 1

[0040] A method for treating chemical industrial wastewater, comprising the following steps:

[0041] S1. Filter and remove impurities from the chemical industrial wastewater, and then adjust the pH to 7.5 to obtain pretreated wastewater;

[0042] S2. Add polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon to the pretreated wastewater, and stir for 70 min. After the treatment is completed, obtain the primary treated wastewater. Among them, 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 polyaluminum chloride is 0.4 g / L, and the addition amount of the activated carbon is 1.5 g / L;

[0043] S3. Add a wastewater treatment agent to the primary treated wastewater in step S2, and stir and treat it under ultraviolet light with an intensity of 40 mW / cm 2 for 3.5 h. After the treatment is completed, filter to obtain the treated wastewater. Among them, the addition amount of the wastewater treatment agent is 0.9 g / L.

[0044] Among them, the preparation method of the wastewater treatment agent in step S3 includes the following steps:

[0045] (a) Add 100 g of diatomite to 1 L of a nitric acid aqueous solution with a mass concentration of 7%, impregnate it at 65 °C for 1.5 h, then filter, wash, and dry to obtain acidified diatomite. Subsequently, add 100 g of acidified diatomite to a sodium hydroxide solution with a mass concentration of 7%, stir and heat it at 65 °C for 1.5 h. After the treatment is completed, filter, wash, and dry, and calcine it at 330 °C for 1.5 h to obtain pretreated diatomite;

[0046] (b) Add 30 g of the pretreated diatomite 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%), then add 55 g of tetrabutyl titanate and 90 g of ammonia water with a mass concentration of 15%, ultrasonically disperse for 30 min, and then carry out a hydrothermal reaction at 140 °C for 8 h. After the reaction is completed, let it stand, filter, wash, and dry to obtain composite diatomite;

[0047] (c) Add 55 g of the composite diatomite in step (b) to 1 L of an ethanol aqueous solution (the mass fraction of ethanol is 65%), then add 10 g of vinyltriethoxysilane, and stir and react at 65 °C for 2.5 h. After the reaction is completed, filter, wash, and dry to obtain vinylated composite diatomite;

[0048] (d) Add 50 g of vinylated composite diatomaceous earth in step (c) to 800 mL of N,N-dimethylformamide, then add 9 g of 5-amino-2-mercaptobenzimidazole and 0.3 g of benzophenone, and carry out a constant-temperature reaction at 75 °C under ultraviolet light with an intensity of 8 mW / cm 2 for 1.5 h. After the reaction is completed, filter, wash, and dry to obtain a solid product; add 8 g of 4-carboxybenzo-15-crown-5 to 800 mL of N,N-dimethylformamide, then add 25 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, stir for 30 min, then add 50 g of the solid product and 25 g of N-hydroxysuccinimide, and react at 85 °C for 5 h. After the reaction is completed, filter, wash, and dry to obtain the wastewater treatment agent.

[0049] Example 2

[0050] A method for treating chemical industrial wastewater, comprising the following steps:

[0051] S1. Filter and remove impurities from the chemical industrial wastewater, and then adjust the pH to 7.5 to obtain pretreated wastewater;

[0052] S2. Add polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon to the pretreated wastewater, stir and treat for 60 min, and obtain primary 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 polyaluminum chloride is 0.4 g / L, and the addition amount of the activated carbon is 1.5 g / L;

[0053] S3. Add the wastewater treatment agent to the primary treated wastewater in step S2, stir and treat for 3.5 h under ultraviolet light with an intensity of 40 mW / cm 2 After the treatment is completed, filter to obtain the treated wastewater; wherein, the addition amount of the wastewater treatment agent is 0.8 g / L.

[0054] Among them, the preparation method of the wastewater treatment agent in step S3 includes the following steps:

[0055] (a) Add 100 g of diatomaceous earth to 1 L of a 5% nitric acid aqueous solution, impregnate and treat at 60 °C for 2 h, then filter, wash, and dry to obtain acidified diatomaceous earth; then add 100 g of acidified diatomaceous earth to a 5% sodium hydroxide solution, stir and heat at 60 °C for 2 h, filter, wash, and dry after the treatment is completed, and calcine at 300 °C for 2 h to obtain pretreated diatomaceous earth;

[0056] (b) Add 30 g of pretreated diatomaceous earth and 2.5 g of Tween 20 from step S1 into 800 mL of an ethanol aqueous solution (the mass fraction of ethanol is 75%), then add 55 g of tetrabutyl titanate and 85 g of ammonia water with a mass concentration of 10%. After ultrasonic dispersion for 30 min, carry out a hydrothermal reaction at 140 °C for 8 h. After the reaction ends, let it stand, filter, wash, and dry to obtain composite diatomaceous earth;

[0057] (c) Add 55 g of the composite diatomaceous earth from step (b) into 1 L of an ethanol aqueous solution (the mass fraction of ethanol is 65%), then add 10 g of vinyltriethoxysilane, and stir and react at 65 °C for 2.5 h. After the reaction is completed, filter, wash, and dry to obtain vinylated composite diatomaceous earth;

[0058] (d) Add 50 g of the vinylated composite diatomaceous earth from step (c) into 800 mL of N,N-dimethylformamide, then add 9 g of 5-amino-2-mercaptobenzimidazole and 0.3 g of benzophenone, and carry out a constant-temperature reaction at a UV light intensity of 7 mW / cm 2 and a temperature of 75 °C for 1.5 h. After the reaction is completed, filter, wash, and dry to obtain a solid product; add 7 g of 4-carboxybenzo-15-crown-5 into 800 mL of N,N-dimethylformamide, then add 25 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, stir for 30 min, then add 50 g of the solid product and 25 g of N-hydroxysuccinimide, and react at 85 °C for 5 h. After the reaction is completed, filter, wash, and dry to obtain the wastewater treatment agent.

[0059] Example 3

[0060] A method for treating chemical industrial wastewater, comprising the following steps:

[0061] S1. Filter and remove impurities from the chemical industrial wastewater, and then adjust the pH to 7 to obtain pretreated wastewater;

[0062] S2. Add polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon into the pretreated wastewater, and stir and treat for 80 min. After the treatment is completed, obtain primary treated wastewater; wherein, the addition amount of polyacrylamide is 30 mg / L, the addition amount of the zeolite powder is 3 g / L, the addition amount of the polyaluminum chloride is 0.3 g / L, and the addition amount of the activated carbon is 1 g / L;

[0063] S3. Add the wastewater treatment agent into the primary treated wastewater from step S2, and stir and treat under UV light with an intensity of 30 mW / cm 2 for 4 h. After the treatment is completed, filter to obtain the treated wastewater; wherein, the addition amount of the wastewater treatment agent is 0.7 g / L.

[0064] Among them, the preparation method of the wastewater treatment agent described in step S3 includes the following steps:

[0065] (a) Add 100 g of diatomite to 1 L of a nitric acid aqueous solution with a mass concentration of 6%, impregnate at 65 °C for 1.5 h, then filter, wash, and dry to obtain acidified diatomite; subsequently, add 100 g of acidified diatomite to a sodium hydroxide solution with a mass concentration of 6%, stir and heat at 65 °C for 1.5 h, after the treatment is completed, filter, wash, and dry, and calcine at 320 °C for 1.5 h to obtain pretreated diatomite;

[0066] (b) Add 30 g of the pretreated diatomite and 2 g of Tween 20 in step S1 to 800 mL of an ethanol aqueous solution (the mass fraction of ethanol is 70%), then add 50 g of tetrabutyl titanate and 80 g of ammonia water with a mass concentration of 15%, after ultrasonic dispersion for 30 min, carry out hydrothermal reaction at 130 °C for 10 h, after the reaction is completed, let it stand, filter, wash, and dry to obtain composite diatomite;

[0067] (c) Add 50 g of the composite diatomite in step (b) to 1 L of an ethanol aqueous solution (the mass fraction of ethanol is 60%), then add 8 g of vinyltriethoxysilane, stir and react at 60 °C for 3 h, after the reaction is completed, filter, wash, and dry to obtain vinylated composite diatomite;

[0068] (d) Add 50 g of the vinylated composite diatomite in step (c) to 800 mL of N,N-dimethylformamide, then add 7 g of 5-amino-2-mercaptobenzimidazole and 0.2 g of benzophenone, under ultraviolet light with an intensity of 5 mW / cm 2 and at a constant temperature of 70 °C, react for 2 h, after the reaction is completed, filter, wash, and dry to obtain a solid product; add 6 g of 4-carboxybenzo-15-crown-5 to 800 mL of N,N-dimethylformamide, then add 20 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, stir for 30 min and then add 50 g of the solid product and 20 g of N-hydroxysuccinimide, react at 80 °C for 6 h, after the reaction is completed, filter, wash, and dry to obtain the wastewater treatment agent.

[0069] Example 4

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

[0071] S1. Filter and remove impurities from the chemical industrial wastewater, and then adjust the pH to 8 to obtain pretreated wastewater;

[0072] S2. Add polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon to the pretreated wastewater, stir for 50 min, and obtain the primary treated wastewater after the treatment. Among them, the addition amount of polyacrylamide is 40 mg / L, the addition amount of the zeolite powder is 4 g / L, the addition amount of the polyaluminum chloride is 0.5 g / L, and the addition amount of the activated carbon is 2 g / L;

[0073] S3. Add a wastewater treatment agent to the primary treated wastewater in step S2, stir and treat it under ultraviolet light with an intensity of 50 mW / cm 2 for 3 h, filter after the treatment is completed, and obtain the treated wastewater. Among them, the addition amount of the wastewater treatment agent is 1 g / L.

[0074] Among them, the preparation method of the wastewater treatment agent in step S3 includes the following steps:

[0075] (a) Add 100 g of diatomite to 1 L of a nitric acid aqueous solution with a mass concentration of 8%, impregnate it at 70 °C for 1 h, then filter, wash, and dry to obtain acidified diatomite. Subsequently, add 100 g of acidified diatomite to a sodium hydroxide solution with a mass concentration of 8%, stir and heat it at 70 °C for 1 h, filter, wash, and dry after the treatment is completed, and calcine it at 350 °C for 1 h to obtain pretreated diatomite;

[0076] (b) Add 30 g of the pretreated diatomite and 3 g of Tween 20 in step S1 to 800 mL of an ethanol aqueous solution (the mass fraction of ethanol is 80%), then add 60 g of tetrabutyl titanate and 100 g of ammonia water with a mass concentration of 10%, ultrasonically disperse for 30 min, and then carry out a hydrothermal reaction at 150 °C for 6 h. After the reaction is completed, let it stand, filter, wash, and dry to obtain composite diatomite;

[0077] (c) Add 60 g of the composite diatomite in step (b) to 1 L of an ethanol aqueous solution (the mass fraction of ethanol is 70%), then add 12 g of vinyltriethoxysilane, stir and react at 70 °C for 2 h, filter, wash, and dry after the reaction is completed to obtain vinylated composite diatomite;

[0078] (d) Add 50 g of the vinylated composite diatomite in step (c) to 800 mL of N,N-dimethylformamide, then add 11 g of 5-amino-2-mercaptobenzimidazole and 0.4 g of benzophenone, and under ultraviolet light with an intensity of 10 mW / cm 2Ultraviolet light was used, and the reaction was carried out at a constant temperature of 80 °C for 1 h. After the reaction was completed, filtration, washing, and drying were performed to obtain a solid product. 9 g of 4-carboxybenzo-15-crown-5 was added to 800 mL of N,N-dimethylformamide, and then 30 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide was added. After stirring for 30 min, 50 g of the solid product and 30 g of N-hydroxysuccinimide were added, and the reaction was carried out at 90 °C for 4 h. After the reaction was completed, filtration, washing, and drying were performed to obtain the wastewater treatment agent.

[0079] Comparative Example 1

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

[0081] S1. Filter and remove impurities from the chemical wastewater, and then adjust the pH to 7.5 to obtain pretreated wastewater.

[0082] S2. Add polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon to the pretreated wastewater, and stir for 70 min. After the treatment is completed, primary treated wastewater is obtained. Among them, 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 polyaluminum chloride is 0.4 g / L, and the addition amount of the activated carbon is 1.5 g / L.

[0083] S3. Add a wastewater treatment agent to the primary treated wastewater in step S2, and stir and treat it under ultraviolet light with an intensity of 40 mW / cm 2 for 3.5 h. After the treatment is completed, filtration is performed to obtain the treated wastewater. Among them, the addition amount of the wastewater treatment agent is 0.9 g / L.

[0084] Among them, the preparation method of the wastewater treatment agent in step S3 includes the following steps:

[0085] (a) Add 100 g of diatomite to 1 L of a 7% nitric acid aqueous solution, impregnate it at 65 °C for 1.5 h, then filter, wash, and dry to obtain acidified diatomite. Subsequently, add 100 g of acidified diatomite to a 7% sodium hydroxide solution, stir and heat it at 65 °C for 1.5 h. After the treatment is completed, filter, wash, and dry, and calcine it at 330 °C for 1.5 h to obtain pretreated diatomite.

[0086] (b) Add 30 g of the pretreated diatomite 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%), then add 55 g of tetrabutyl titanate and 90 g of a 15% ammonia water. After ultrasonic dispersion for 30 min, carry out a hydrothermal reaction at 140 °C for 8 h. After the reaction is completed, let it stand, filter, wash, and dry to obtain composite diatomite.

[0087] (c) Add 55 g of the composite diatomaceous earth in step (b) to 1 L of an ethanol aqueous solution (the mass fraction of ethanol is 65%), then add 10 g of vinyltriethoxysilane, and stir and react at 65 °C for 2.5 h. After the reaction is completed, filter, wash, and dry to obtain vinylated composite diatomaceous earth;

[0088] (d) Add 50 g of the vinylated composite diatomaceous earth in step (c) to 800 mL of N,N-dimethylformamide, then add 9 g of 5-amino-2-mercaptobenzimidazole and 0.3 g of benzophenone, and react at a constant temperature of 75 °C under ultraviolet light with an intensity of 8 mW / cm 2 for 1.5 h. After the reaction is completed, filter, wash, and dry to obtain the wastewater treatment agent.

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

[0090] Comparative Example 1

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

[0092] S1. Filter and remove impurities from the chemical industrial wastewater, and then adjust the pH to 7.5 to obtain pretreated wastewater;

[0093] S2. Add polyacrylamide, zeolite powder, polyaluminum chloride, and activated carbon to the pretreated wastewater, and stir and treat for 70 min. After the treatment is completed, obtain the primary treated wastewater; among them, 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 polyaluminum chloride is 0.4 g / L, and the addition amount of the activated carbon is 1.5 g / L;

[0094] S3. Add a wastewater treatment agent to the primary treated wastewater in step S2, and stir and treat for 3.5 h under ultraviolet light with an intensity of 40 mW / cm 2 After the treatment is completed, filter to obtain the treated wastewater; among them, the addition amount of the wastewater treatment agent is 0.9 g / L.

[0095] Among them, the preparation method of the wastewater treatment agent in step S3 includes the following steps:

[0096] (a) Add 100 g of diatomaceous earth to 1 L of a nitric acid aqueous solution with a mass concentration of 7%, impregnate and treat at 65 °C for 1.5 h, then filter, wash, and dry to obtain acidified diatomaceous earth; then add 100 g of acidified diatomaceous earth to a sodium hydroxide solution with a mass concentration of 7%, stir and heat at 65 °C for 1.5 h. After the treatment is completed, filter, wash, and dry, and calcine at 330 °C for 1.5 h to obtain pretreated diatomaceous earth;

[0097] (b) Add 30 g of pretreated diatomite and 2.5 g of Tween 20 in step S1 into 800 mL of an ethanol aqueous solution (the mass fraction of ethanol is 75%), then add 55 g of tetrabutyl titanate and 90 g of ammonia water with a mass concentration of 15%, ultrasonically disperse for 30 min, and then carry out a hydrothermal reaction at 140 °C for 8 h. After the reaction is completed, let it stand, filter, wash, and dry to obtain a wastewater treatment agent.

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

[0099] Respectively detect the treated wastewater in Examples 1-4 and Comparative Examples 1-2, and the test results are shown in Table 1 below:

[0100] Table 1 Contents of various pollutants in the 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 rapidly remove the COD content in chemical wastewater, and at the same time can also remove various heavy metal ions, having good application prospects.

[0103] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present 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 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 once 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.

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 polyaluminium 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 stirring treatment in step S2 is 50-80 minutes.

5. The processing method according to claim 1, characterized in that: The method for preparing the wastewater treatment agent in step S3 comprises the following steps: (a) adding diatomaceous earth to a nitric acid aqueous solution, filtering, washing, and drying after immersion treatment to obtain acidified diatomaceous earth; then adding the acidified diatomaceous earth to a sodium hydroxide solution, stirring and heating, filtering, washing, drying, and calcining after the treatment to obtain pretreated diatomaceous earth; (b) adding the pretreated diatomaceous earth and Tween 20 in step S1 to an ethanol aqueous solution, then adding tetrabutyl titanate and ammonia water, and performing a hydrothermal reaction after ultrasonic dispersion. 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 in step (b) to an ethanol aqueous solution, and then adding vinyltriethoxysilane, stirring to react, and filtering, washing, and drying after the reaction is completed to obtain vinyl composite diatomaceous earth; (d) adding the vinylated composite diatomaceous earth in step (c) to N,N-dimethylformamide, then adding 5-amino-2-mercaptobenzimidazole and benzophenone, reacting at a constant temperature under ultraviolet light, filtering, washing and drying after the reaction is completed to obtain a solid product; adding 4-carboxybenzo-15-crown-5 to N,N-dimethylformamide, then adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, stirring for 30 minutes, 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.

6. The processing method according to claim 4, characterized in that: The mass concentration of the nitric acid aqueous solution in step (a) is 5-8%, the temperature of the immersion 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; the temperature of the roasting is 300-350°C, and the time is 1-2h.

7. The processing method according to claim 4, 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 6-10h.

8. The processing method according to claim 4, 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 and vinyl triethoxysilane is 50-60:8-12, the stirring reaction temperature is 60-70° C., and the time is 2-3 hours.

9. The processing method according to claim 4, characterized in that: The mass ratio of the vinyl composite diatomite, 5-amino-2-mercaptobenzimidazole and benzophenone in step (d) 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.

10. 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 ultraviolet light is 30-50 mW / cm 2 The time of the secondary stirring treatment is 3-4h.

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