Harmless treatment process of coating wastewater

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a harmless treatment process for coating wastewater. The harmless treatment process comprises the following steps: preparing modified radix puerariae powder; preparing a radix puerariae powder based polyacrylic acid / polyether-ether-ketone flocculating agent; preparing a collagen fiber based ZIF-67 adsorbent; and harmlessly treating the coating wastewater. The polyacrylic acid and the polyether-ether-ketone are connected with the radix puerariae powder, and the radix puerariae powder-based polyacrylic acid / polyether-ether-ketone flocculating agent is prepared, so that the radix puerariae powder-based polyacrylic acid / polyether-ether-ketone flocculating agent has the adsorption performance of the radix puerariae powder and the flocculation performance of the polyacrylic acid at the same time; the introduction of polyether-ether-ketone can effectively improve the stability of a starch chain, so that the starch chain is more stable in a wastewater environment, can be kept stable in coating wastewater with complex components, and is not easy to decompose.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and particularly relates to a harmless treatment process for coating wastewater. Background Art

[0002] Coating wastewater mainly comes from equipment cleaning wastewater and process wastewater in the coating production process. It usually has the characteristics of complex water quality, many suspended solids and high chroma. Coating wastewater contains a variety of toxic and difficult-to-biodegradable polymers and organic compounds, such as benzene, phenol, alcohol, aldehyde, ester, emulsion, etc., and also contains a large amount of nano-scale ultra-fine inorganic materials, such as titanium dioxide, kaolin and various colored pigments. Therefore, it also shows an obvious color in appearance.

[0003] The existing treatment methods for coating wastewater mainly include physicochemical methods, biological treatment methods and the coupling of physical and chemical methods with biochemical methods. Among them, the physicochemical methods include coagulation sedimentation method and adsorption method. By adding chemical agents, colloidal particles and fine suspended solids in water are aggregated to play a separation role. Coagulation and flocculation are collectively called coagulation, which is used for the treatment of coating wastewater, mainly to remove fine suspended solids and colloidal particles in the wastewater, reduce the turbidity and pigment of the wastewater, and use the surface of porous solid adsorbents to adsorb one or more pollutants in the wastewater to achieve the purpose of wastewater purification. However, due to the variety of impurities and complex water quality in coating wastewater, the main components of existing organic flocculants are cationic polyacrylamide, anionic polyacrylamide, etc. They are sensitive to pH and may hydrolyze and fail. Therefore, the flocculation effect on wastewater is limited, and it has certain biological toxicity.

[0004] In summary, it is urgent to develop a harmless treatment process for coating wastewater to solve the above defects of the existing technology. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a harmless treatment process for coating wastewater.

[0006] A harmless treatment process for coating wastewater includes the following steps: Collect the coating wastewater into a collecting tank, remove floating substances and larger impurities in the wastewater through a grille and a filter screen, and adjust the pH value of the coating wastewater to 7.5 - 9 with NaOH. Then add a pueraria powder-based polyacrylic acid / polyether ether ketone flocculant, and monitor the pH value of the wastewater in real time to ensure that the pH value of the wastewater is between 7.5 and 9, and heat it to 35 - 40 °C, and flocculate for 24 - 26 h. After filtration, the primary treated wastewater is obtained; Centrifugally separate and filter the primary treated wastewater to remove solids, then add a collagen fiber-based ZIF-67 adsorbent, and stir at a rotation speed of 60 - 80 r / min for 4 - 6 h. Then filter to remove the solid adsorbent to obtain the secondary treated wastewater; The secondary treated wastewater is subjected to evaporation crystallization through multi-effect evaporation crystallization technology to achieve harmless treatment of the coating wastewater; Among them, the preparation method of the kudzu starch-based polyacrylic acid / polyether ether ketone flocculant is as follows: After mixing modified kudzu starch, NaOH, and polyacrylic acid, deionized water, polyether ether ketone, and an initiator are added, and it is prepared by ultraviolet light irradiation; The preparation method of the collagen fiber-based ZIF-67 adsorbent is as follows: Cobalt nitrate solid and methanol are mixed to obtain a cobalt nitrate solution; 2-methylimidazole and methanol are mixed to obtain a 2-methylimidazole solution, and the collagen fiber is immersed in the cobalt nitrate solution and the 2-methylimidazole solution.

[0007] Furthermore, the preparation method of the kudzu starch-based polyacrylic acid / polyether ether ketone flocculant specifically includes the following steps: Weigh 0.6-1 part by mass of modified kudzu starch, 0.6-1 part by mass of NaOH, and 1.2-2 parts by mass of polyacrylic acid, then add 10-12 parts by mass of deionized water, then add 2-5 parts by mass of polyether ether ketone, stir at a speed of 200-300 r / min for 10-15 min, then add 0.5-1 part by mass of an initiator, irradiate with ultraviolet light for 10-15 min, keep nitrogen passing during irradiation, let it stand and cure for 2-2.5 h after irradiation, then precipitate, wash, and dry to obtain the kudzu starch-based polyacrylic acid / polyether ether ketone flocculant.

[0008] Furthermore, the preparation method of the modified kudzu starch specifically includes the following steps: Weigh 2-3 parts by mass of kudzu starch, add it to 10-12 parts by mass of deionized water, and stir at a speed of 100-150 r / min for 5-10 min. Then weigh 1-2 parts by mass of NaOH solid, add it to ultrapure water during stirring, and raise the temperature to 50-60 °C. Then weigh 1-3 parts by mass of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution, react at 50-60 °C under stirring for 60-80 min, then let it stand for 120-150 min, adjust the pH value to 7-7.5 with glacial acetic acid, precipitate, wash, filter, purify, centrifuge, and vacuum dry to obtain the modified kudzu starch.

[0009] Furthermore, the preparation method of the collagen fiber-based ZIF-67 adsorbent specifically includes the following steps: Mix cobalt nitrate solid and methanol at a material-liquid ratio of (2-3) g: 150 mL and stir until evenly mixed, then perform ultrasonic treatment for 5-10 min to obtain a cobalt nitrate solution; mix 2-methylimidazole and methanol at a material-liquid ratio of (2.5-3.5) g: 150 mL, and perform ultrasonic treatment for 5-10 min to obtain a 2-methylimidazole solution; Put 8-9 parts by mass of collagen fibers into 15-20 parts by mass of cobalt nitrate solution, stir magnetically for 1-1.5 h, then add 15-20 parts by mass of 2-methylimidazole solution, heat up to 40-50 °C, stir magnetically for 24-26 h, take out the soaked collagen fibers, wash and dry to obtain a collagen fiber-based ZIF-67 adsorbent.

[0010] Further, in multi-effect evaporation crystallization, the temperature of the first-effect evaporation crystallization is 100-120 °C, the evaporation time is 3-4 h, the temperature of the second-effect evaporation crystallization is 90-100 °C, the time is 3-4 h, and the temperature of the third-effect evaporation crystallization is 80-90 °C, the time is 2-3 h.

[0011] Further, the ultraviolet light is 1000 W and the wavelength is 365 nm.

[0012] Further, the initiator is 2,2'-azobis(2-methylpropionamidine) dihydrochloride.

[0013] Further, the diameter of the collagen fibers is 5-20 microns.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The present invention connects polyacrylic acid and polyether ether ketone with kudzu powder and prepares a kudzu powder-based polyacrylic acid / polyether ether ketone flocculant. Under the action of free radical groups, polyacrylic acid undergoes a grafting reaction with the components in kudzu powder to form a starch-acrylic acid graft copolymer. At the same time, polyether ether ketone can be combined with the starch-acrylic acid graft copolymer by surface modification or chemical grafting. The three are cross-linked and grafted with each other to form a network structure, so that the kudzu powder-based polyacrylic acid / polyether ether ketone flocculant simultaneously has the adsorption performance of kudzu powder and the flocculation performance of polyacrylic acid. Moreover, the introduction of polyether ether ketone can effectively improve the stability of the starch chain, making it more stable in the wastewater environment, and it can remain stable in the paint wastewater with complex components and a large pH value span and is not easily decomposed.

[0015] 2. The present invention uses collagen fibers as a substrate to load a combination of cobalt nitrate and 2-methylimidazole to prepare ZIF-67. ZIF-67 has a high specific surface area and a uniform pore size distribution, which can provide a large number of adsorption sites. When loaded on collagen fibers, the collagen fibers can make these adsorption sites better contact with heavy metal ions in the wastewater. Moreover, ZIF-67 has high catalytic activity. After being loaded on collagen fibers, the active sites of ZIF-67 can be more effectively exposed, thereby improving the adsorption performance for heavy metal ions. In addition, the high strength and toughness of collagen fibers can enhance the mechanical properties of the composite material, making it more stable in a complex wastewater treatment environment. Moreover, both collagen fibers and kudzu powder are natural components, with less biological toxicity and environmental pollution effects.

[0016] 3. The present invention modifies kudzu root powder with 3-chloro-2-hydroxypropyltrimethylammonium chloride. 3-chloro-2-hydroxypropyltrimethylammonium chloride is a cationic etherifying agent that can react with kudzu root powder, enabling the modified kudzu root powder to have charge neutralization, adsorption bridging, and net trapping effects. The bridging effect makes the molecular chain of the modified kudzu root powder more extensible, capable of adsorbing multiple particles, thereby providing a functionalized substrate in subsequent steps, enabling the modified kudzu root powder to better graft-polymerize with polyacrylic acid and polyether ether ketone through ultraviolet initiation to form a flocculant, significantly enhancing the removal rate of complex wastewater components. Moreover, the groups introduced by 3-chloro-2-hydroxypropyltrimethylammonium chloride are more resistant to acids and bases than the groups inherent in kudzu root powder, thus stably removing tiny suspended solids and dissolved pollutants in the wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings incorporated in the present invention and constituting a part of the specification illustrate embodiments of the present invention and, together with the specification, are further used to explain the principles of the present invention and enable those skilled in the art to implement and use the present invention.

[0018] Figure 1 It is a process flow diagram for the harmless treatment of paint wastewater adopted in the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following describes in detail a process for the harmless treatment of paint wastewater provided by the present invention in combination with the drawings and specific embodiments. At the same time, it should be noted here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments. For some well-known technologies, those skilled in the art can also adopt other alternative methods for implementation; moreover, the drawing part is only for more specifically describing the embodiments and is not intended to specifically limit the present invention.

[0020] Example 1: A process for the harmless treatment of paint wastewater, as Figure 1 shown, includes the following steps: S1: Preparation of modified kudzu root powder Weigh 2 parts by mass of kudzu root powder, add it to 10 parts by mass of deionized water, and stir at a speed of 100 r / min for 5 min. Then weigh 1 part by mass of NaOH solid, add it to ultrapure water during stirring, and heat up to 50 °C. Then weigh 1 part by mass of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution, and react at 50 °C under stirring for 60 min. Then let it stand for 120 min, adjust the pH value to 7 with glacial acetic acid, precipitate, wash, filter, purify, centrifuge, and vacuum dry to obtain modified kudzu root powder; S2: Preparation of kudzu root powder-based polyacrylic acid / polyether ether ketone flocculant Weigh 0.6 parts by mass of modified kudzu powder, 0.6 parts by mass of NaOH and 1.2 parts by mass of polyacrylic acid, then add 10 parts by mass of deionized water, and then add 2 parts by mass of polyether ether ketone. Stir at a speed of 200 r / min for 10 min, then add 0.5 parts by mass of initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride. Use ultraviolet light with a power of 1000 W and a wavelength of 365 nm to irradiate for 10 min. Keep nitrogen flowing during irradiation. After irradiation, let it stand and cure for 2 h, then precipitate, wash and dry to obtain the kudzu powder-based polyacrylic acid / polyether ether ketone flocculant; S3: Prepare collagen fiber-based ZIF-67 adsorbent Stir cobalt nitrate solid and methanol at a material-liquid ratio of 2 g: 150 mL until evenly mixed, and ultrasonically treat for 5 min to obtain cobalt nitrate solution; then mix 2-methylimidazole and methanol at a material-liquid ratio of 2.5 g: 150 mL, and ultrasonically treat for 5 min to obtain 2-methylimidazole solution; Put 8 parts by mass of collagen fibers into 15 parts by mass of cobalt nitrate solution. The diameter of the collagen fibers is 5 microns. Stir magnetically for 1 h, then add 15 parts by mass of 2-methylimidazole solution, heat up to 40 °C, and stir magnetically for 24 h. Take out the soaked collagen fibers, wash and dry to obtain the collagen fiber-based ZIF-67 adsorbent; S4: Harmless treatment of coating wastewater Collect the coating wastewater into a collecting pool, remove the floating substances and larger impurities in the wastewater through a grille and a filter screen, and adjust the pH value of the coating wastewater to 7.5 with NaOH. Then add 10% of the kudzu powder-based polyacrylic acid / polyether ether ketone flocculant by the mass of the system, and monitor the pH value of the wastewater in real time to ensure that the pH value of the wastewater is 7.5, and heat up to 35 °C and flocculate for 24 h. After filtration, obtain the primary treated wastewater; Centrifuge and filter the primary treated wastewater to remove solid substances, then add 5% of the collagen fiber-based ZIF-67 adsorbent by the mass of the system, and stir at a speed of 60 r / min for 4 h. Then filter to remove the solid adsorbent to obtain the secondary treated wastewater; Carry out evaporation crystallization on the secondary treated wastewater through multi-effect evaporation crystallization technology to complete the harmless treatment of the coating wastewater. In multi-effect evaporation crystallization, the temperature of the first-effect evaporation crystallization is 120 °C, the evaporation time is 4 h, the temperature of the second-effect evaporation crystallization is 100 °C, the time is 4 h, and the temperature of the third-effect evaporation crystallization is 90 °C, the time is 3 h.

[0021] Example 2: A harmless treatment process for coating wastewater, as Figure 1 shown, includes the following steps: S1: Prepare modified kudzu powder Weigh 3 parts by mass of kudzu root powder, add it to 12 parts by mass of deionized water, and stir at a speed of 100 r / min for 5 min. Then weigh 2 parts by mass of solid NaOH, add it to the ultrapure water during stirring, and heat up to 50 °C. Then weigh 3 parts by mass of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution, and react at 50 °C under stirring for 60 min. Then let it stand for 120 min, adjust the pH value to 7 with glacial acetic acid, precipitate, wash, filter, purify, centrifuge, and vacuum dry to obtain modified kudzu root powder; S2: Preparation of kudzu root powder-based polyacrylic acid / polyether ether ketone flocculant Weigh 1 part by mass of modified kudzu root powder, 1 part by mass of NaOH, and 2 parts by mass of polyacrylic acid. Then add 12 parts by mass of deionized water, and then add 5 parts by mass of polyether ether ketone. Stir at a speed of 200 r / min for 10 min. Then add 1 part by mass of initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride, use ultraviolet light with a power of 1000 W and a wavelength of 365 nm for irradiation for 10 min. Keep nitrogen gas passing during irradiation. After irradiation, let it stand and ripen for 2 h, then precipitate, wash, and dry to obtain kudzu root powder-based polyacrylic acid / polyether ether ketone flocculant; S3: Preparation of collagen fiber-based ZIF-67 adsorbent Stir cobalt nitrate solid and methanol at a material ratio of 3 g:150 mL until evenly mixed, and perform ultrasonic treatment for 5 min to obtain cobalt nitrate solution; then mix 2-methylimidazole and methanol at a material ratio of 3.5 g:150 mL, and perform ultrasonic treatment for 5 min to obtain 2-methylimidazole solution; Put 9 parts by mass of collagen fibers into 20 parts by mass of cobalt nitrate solution. The diameter of the collagen fibers is 5 microns. Stir magnetically for 1 h, then add 20 parts by mass of 2-methylimidazole solution, heat up to 40 °C, and stir magnetically for 24 h. Take out the soaked collagen fibers, wash, and dry to obtain collagen fiber-based ZIF-67 adsorbent; S4: Harmless treatment of coating wastewater Collect the coating wastewater in a sump, remove the floating substances and larger impurities in the wastewater through a grille and a filter screen, and adjust the pH value of the coating wastewater to 7.5 with NaOH. Then add 10% of the kudzu root powder-based polyacrylic acid / polyether ether ketone flocculant by the mass of the system, and monitor the pH value of the wastewater in real time to ensure that the pH value of the wastewater is 7.5, and heat up to 35 °C for flocculation for 24 h. After filtration, obtain the primary treated wastewater; Centrifuge and filter the primary treated wastewater to remove solid substances, then add 5% of the collagen fiber-based ZIF-67 adsorbent by the mass of the system, and stir at a speed of 60 r / min for 4 h. Then filter to remove the solid adsorbent to obtain the secondary treated wastewater; The secondary treated wastewater is subjected to evaporation crystallization through the multi-effect evaporation crystallization technology to achieve the harmless treatment of the coating wastewater. In the multi-effect evaporation crystallization, the temperature of the first-effect evaporation crystallization is 120 °C, the evaporation time is 4 h, the temperature of the second-effect evaporation crystallization is 100 °C, the time is 4 h, and the temperature of the third-effect evaporation crystallization is 90 °C, the time is 3 h.

[0022] Example 3: A harmless treatment process for coating wastewater, as Figure 1 shown, includes the following steps: S1: Preparation of modified kudzu powder Weigh 2 parts by mass of kudzu powder, add it to 10 parts by mass of deionized water, and stir at a speed of 150 r / min for 10 min. Then weigh 1 part by mass of NaOH solid, add it to ultrapure water during stirring, and raise the temperature to 60 °C. Then weigh 1 part by mass of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution, and react at 60 °C under stirring for 80 min. Then let it stand for 150 min, adjust the pH value to 7.5 with glacial acetic acid, precipitate, wash, filter, purify, centrifuge, and vacuum dry to obtain modified kudzu powder; S2: Preparation of kudzu powder-based polyacrylic acid / polyether ether ketone flocculant Weigh 0.6 parts by mass of modified kudzu powder, 0.6 parts by mass of NaOH, and 1.2 parts by mass of polyacrylic acid, then add 10 parts by mass of deionized water, and then add 2 parts by mass of polyether ether ketone, stir at a speed of 200 r / min for 10 min, then add 0.5 parts by mass of initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride, use ultraviolet light with a power of 1000 W and a wavelength of 365 nm for irradiation for 15 min, keep nitrogen gas passing during irradiation, let it stand and cure for 2.5 h after irradiation, then precipitate, wash, and dry to obtain kudzu powder-based polyacrylic acid / polyether ether ketone flocculant; S3: Preparation of collagen fiber-based ZIF-67 adsorbent Stir cobalt nitrate solid and methanol with a feed liquid ratio of 2 g:150 mL until evenly mixed, and perform ultrasonic treatment for 10 min to obtain cobalt nitrate solution; then mix 2-methylimidazole and methanol with a feed liquid ratio of 2.5 g:150 mL, and perform ultrasonic treatment for 10 min to obtain 2-methylimidazole solution; Place 8 parts by mass of collagen fibers in 15 parts by mass of cobalt nitrate solution, the diameter of the collagen fibers is 5 microns, stir magnetically for 1.5 h, then add 15 parts by mass of 2-methylimidazole solution, raise the temperature to 50 °C, stir magnetically for 26 h, take out the soaked collagen fibers, wash, and dry to obtain collagen fiber-based ZIF-67 adsorbent; S4: Harmless treatment of coating wastewater Collect the paint wastewater in a collecting tank, remove the floating matters and larger impurities in the wastewater through a grille and a filter screen, and adjust the pH value of the paint wastewater to 9 with NaOH. Subsequently, add 10% of the mass of the system of the kudzu powder-based polyacrylic acid / polyether ether ketone flocculant, and monitor the pH value of the wastewater in real time to ensure that the pH value of the wastewater is 7.5, and then heat it to 40 °C and flocculate for 26 h. After filtration, the primary treated wastewater is obtained. Centrifuge and filter the primary treated wastewater to remove solids, then add 5% of the mass of the system of the collagen fiber-based ZIF-67 adsorbent, and stir at a rotation speed of 80 r / min for 6 h. Subsequently, filter to remove the solid adsorbent to obtain the secondary treated wastewater. Carry out evaporation crystallization on the secondary treated wastewater through a multi-effect evaporation crystallization technology to complete the harmless treatment of the paint wastewater. In the multi-effect evaporation crystallization, the temperature of the first-effect evaporation crystallization is 100 °C, the evaporation time is 3 h, the temperature of the second-effect evaporation crystallization is 90 °C, the time is 3 h, and the temperature of the third-effect evaporation crystallization is 80 °C, the time is 2 h.

[0023] Comparative Example 1: Compared with Example 1, the difference in Comparative Example 1 is that polyacrylic acid is not added in step S2. Specifically: "Weigh 0.6 parts by mass of modified kudzu powder and 0.6 parts by mass of NaOH, add them to 10 parts by mass of deionized water, then add 2 parts by mass of polyether ether ketone, stir at a rotation speed of 200 r / min for 10 min, and then add 0.5 parts by mass of the initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride. Use ultraviolet light with a power of 1000 W and a wavelength of 365 nm for irradiation for 10 min. Keep nitrogen gas passing during the irradiation. After the irradiation is completed, let it stand and cure for 2 h, and then precipitate, wash, and dry to obtain the kudzu powder-based polyether ether ketone flocculant", use the kudzu powder-based polyether ether ketone flocculant to replace the kudzu powder-based polyacrylic acid / polyether ether ketone flocculant, and the remaining steps remain unchanged.

[0024] Comparative Example 2: Compared with Example 1, the difference in Comparative Example 2 is that polyether ether ketone is not added in step S2. Specifically: "Weigh 0.6 parts by mass of modified kudzu powder, 0.6 parts by mass of NaOH and 1.2 parts by mass of polyacrylic acid, then add 10 parts by mass of deionized water, stir at a rotation speed of 200 r / min for 10 min, and then add 0.5 parts by mass of the initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride. Use ultraviolet light with a power of 1000 W and a wavelength of 365 nm for irradiation for 10 min. Keep nitrogen gas passing during the irradiation. After the irradiation is completed, let it stand and cure for 2 h, and then precipitate, wash, and dry to obtain the kudzu powder-based polyacrylic acid flocculant", use the kudzu powder-based polyacrylic acid flocculant to replace the kudzu powder-based polyacrylic acid / polyether ether ketone flocculant, and the remaining steps remain unchanged.

[0025] Comparative Example 3: Compared with Example 1, the difference in Comparative Example 3 is that in step S3, instead of adding collagen fibers, cobalt nitrate solution and 2-methylimidazole solution are directly mixed to prepare ZIF-67. Specifically, "cobalt nitrate solid and methanol are stirred at a material-liquid ratio of 2 g:150 mL until evenly mixed, and then ultrasonically treated for 5 min to obtain cobalt nitrate solution; then 2-methylimidazole and methanol are mixed at a material-liquid ratio of 2.5 g:150 mL, and ultrasonically treated for 5 min to obtain 2-methylimidazole solution; 15 parts by mass of cobalt nitrate solution is magnetically stirred for 1 h, and then 15 parts by mass of 2-methylimidazole solution is added. The temperature is raised to 40 °C and magnetically stirred for 24 h to obtain ZIF-67 adsorbent", using ZIF-67 adsorbent to replace collagen fiber-based ZIF-67 adsorbent, and the remaining steps remain unchanged.

[0026] Comparative Example 4: Compared with Example 1, the difference in Comparative Example 4 is that step S1 is not carried out, and kudzu powder is used to replace the modified kudzu powder in step S2. Specifically, "weigh 0.6 parts by mass of kudzu powder, 0.6 parts by mass of NaOH and 1.2 parts by mass of polyacrylic acid, then add 10 parts by mass of deionized water, then add 2 parts by mass of polyether ether ketone, stir at a speed of 200 r / min for 10 min, then add 0.5 parts by mass of initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride, use ultraviolet light with a power of 1000 W and a wavelength of 365 nm, irradiate for 10 min, keep nitrogen gas passing during irradiation, stand and cure for 2 h after irradiation, then precipitate, wash and dry to obtain kudzu powder-based polyacrylic acid / polyether ether ketone flocculant", and the remaining steps remain unchanged.

[0027] Comparative Example 5: The flocculant in Comparative Example 5 is a commercially available flocculant, and the adsorbent is a commercially available adsorbent. The specific harmless treatment steps are as follows: Collect the coating wastewater into a collecting tank, remove the floating substances and larger impurities in the wastewater through a grille and a filter screen, and adjust the pH value of the coating wastewater to 7.5 with NaOH. Then add 10% of the flocculant based on the mass of the system, and monitor the pH value of the wastewater in real time to ensure that the pH value of the wastewater is 7.5, and raise the temperature to 35 °C, and flocculate for 24 h. After filtration, the primary treated wastewater is obtained; Centrifuge and filter the primary treated wastewater to remove solid substances, then add 5% of the adsorbent based on the mass of the system, and stir at a speed of 60 r / min for 4 h. Then filter to remove the solid adsorbent to obtain the secondary treated wastewater; The secondary treated wastewater is evaporated and crystallized by a multi-effect evaporation crystallization technology to complete the harmless treatment of the coating wastewater. In the multi-effect evaporation crystallization, the temperature of the first-effect evaporation crystallization is 120 °C, the evaporation time is 4 h, the temperature of the second-effect evaporation crystallization is 100 °C, the time is 4 h, and the temperature of the third-effect evaporation crystallization is 90 °C, the time is 3 h.

[0028] A total of 8 L of paint wastewater collected from chemical enterprises was evenly divided into 8 groups, with 1 L in each group. The initial turbidity T0 was measured, and the harmless treatment was carried out using the methods of Examples 1 - 3 and Comparative Examples 1, 2, 4, and 5 respectively. Subsequently, the turbidity T of the wastewater after harmless treatment was measured, and the turbidity removal rate RE was calculated, as shown in Table 1.

[0029] The calculation of the turbidity removal rate RE is as follows: RE = (T0 - T) / T0 * 100% Where T0 is the initial turbidity and T is the turbidity after harmless treatment.

[0030] The contents of heavy metal chromium ions in the paint wastewater before and after the harmless treatment of Examples 1 - 3 and Comparative Examples 1 - 5 were measured, as shown in Table 2.

[0031] Table 1

[0032] Table 2

[0033] As can be seen from Table 1, the turbidity removal rates of Examples 1, 2, and 3 are above 95.46%, all higher than those of the comparative examples. It can be seen that the harmless treatment process of the paint wastewater of the present invention effectively flocculates and removes the impurities in the paint wastewater; Comparative Example 5 is a commercially available product. It can be seen that the flocculant in the harmless treatment process of the present invention has a better flocculation effect on the paint wastewater than the commercially available product; the turbidity removal rates of Comparative Examples 1 and 2 are not as good as those of the examples, and the turbidity removal rate of Comparative Example 4 is lower than that of the examples but higher than those of Comparative Examples 1 and 2, indicating that the synergistic effect of kudzu starch, polyacrylic acid, and polyether ether ketone is better than that of single use, and 3-chloro-2-hydroxypropyltrimethylammonium chloride modified kudzu starch will also affect the flocculation effect.

[0034] As can be seen from Table 2, the chromium ion contents after the treatment of Examples 1 - 3 are all lower than 0.067 mg / L, meeting the standard of hexavalent chromium ions after wastewater treatment. Moreover, the treatment effect of Comparative Example 5 is not as good as that of the examples, indicating that the adsorption effect of the adsorbent of the present invention is better than that of the commercially available product, and the chromium ion content of Comparative Example 3 is relatively high, indicating that the addition of collagen fibers has a greater impact on the adsorption effect of the adsorbent on chromium ions.

[0035] The above examples are only illustrative of the principles and effects of the present invention and are not used to limit the present invention. Any person familiar with this technology can modify or change the above examples without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the present invention.

Claims

1. A harmless treatment process for coating wastewater, characterized in that: The steps include: The paint wastewater is collected into a water collection tank, and floating objects and larger impurities in the wastewater are removed through a grid and a filter, and the pH value of the paint wastewater is adjusted to 7.5-9 with NaOH, and then a kudzu powder-based polyacrylic acid / polyetheretherketone flocculant is added, and the pH value of the wastewater is monitored in real time to ensure that the pH value of the wastewater is 7.5-9, and the temperature is raised to 35-40°C, flocculated for 24-26 hours, and filtered to obtain primary treated wastewater; The primary treated wastewater is centrifuged and filtered to remove solid matter, and then a collagen fiber-based ZIF-67 adsorbent is added, and the stirring is maintained at a speed of 60-80 r / min for 4-6 hours, and then the solid adsorbent is removed by filtration to obtain a secondary treated wastewater; The secondary treated wastewater is evaporated and crystallized through multi-effect evaporation and crystallization technology to complete the harmlessness of the paint wastewater; The preparation method of the kudzu root powder-based polyacrylic acid / polyetheretherketone flocculant is as follows: modified kudzu root powder, NaOH and polyacrylic acid are mixed, deionized water, polyetheretherketone and initiator are added, and ultraviolet light is used to irradiate the mixture; The preparation method of the collagen fiber-based ZIF-67 adsorbent is as follows: solid cobalt nitrate and methanol are mixed to obtain a cobalt nitrate solution; 2-methylimidazole and methanol are mixed to obtain a 2-methylimidazole solution; and collagen fibers are immersed in the cobalt nitrate solution and the 2-methylimidazole solution.

2. A harmless treatment process for coating wastewater according to claim 1, characterized in that: The preparation method of kudzu root powder-based polyacrylic acid / polyetheretherketone flocculant specifically comprises the following steps: Weigh 0.6-1 parts by weight of modified kudzu root powder, 0.6-1 parts by weight of NaOH and 1.2-2 parts by weight of polyacrylic acid, then add 10-12 parts by weight of deionized water, then add 2-5 parts by weight of polyetheretherketone, stir at a speed of 200-300 r / min for 10-15 minutes, then add 0.5-1 parts by weight of initiator, irradiate with ultraviolet light for 10-15 minutes, keep nitrogen flowing during the irradiation period, stand and mature for 2-2.5 hours after the irradiation, then precipitate, wash and dry to obtain a kudzu root powder-based polyacrylic acid / polyetheretherketone flocculant.

3. A harmless treatment process for coating wastewater according to claim 2, characterized in that: The preparation method of modified kudzu root powder specifically comprises the following steps: 2-3 parts by weight of kudzu root powder are weighed, added to 10-12 parts by weight of deionized water, and stirred at a speed of 100-150 r / min for 5-10 minutes, 1-2 parts by weight of NaOH solid are weighed, added to ultrapure water during stirring, and the temperature is raised to 50-60° C., 1-3 parts by weight of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution are weighed, reacted at 50-60° C. under stirring for 60-80 minutes, and then allowed to stand for 120-150 minutes, the pH value is adjusted to 7-7.5 with glacial acetic acid, precipitated, washed, filtered, purified, centrifuged, and vacuum dried to obtain modified kudzu root powder.

4. A harmless treatment process for coating wastewater according to claim 3, characterized in that: The preparation method of the collagen fiber-based ZIF-67 adsorbent specifically comprises the following steps: Cobalt nitrate solid and methanol are stirred at a solid-liquid ratio of (2-3) g:150 mL until they are uniformly mixed, and ultrasonic treatment is performed for 5-10 minutes to obtain a cobalt nitrate solution; 2-methylimidazole and methanol are then mixed at a solid-liquid ratio of (2.5-3.5) g:150 mL, and ultrasonic treatment is performed for 5-10 minutes to obtain a 2-methylimidazole solution; 8-9 parts by weight of collagen fibers are placed in 15-20 parts by weight of cobalt nitrate solution, and magnetically stirred for 1-1.5 hours. Then, 15-20 parts by weight of 2-methylimidazole solution are added, the temperature is raised to 40-50° C., and magnetically stirred for 24-26 hours. The soaked collagen fibers are taken out, washed, and dried to obtain a collagen fiber-based ZIF-67 adsorbent.

5. A harmless treatment process for coating wastewater according to claim 4, characterized in that: In the multi-effect evaporation crystallization, the temperature of the first-effect evaporation crystallization is 100-120℃, the evaporation time is 3-4h, the temperature of the second-effect evaporation crystallization is 90-100℃, the time is 3-4h, and the temperature of the third-effect evaporation crystallization is 80-90℃, the time is 2-3h.

6. A harmless treatment process for coating wastewater according to claim 3, characterized in that: The UV light is 1000W and the wavelength is 365nm.

7. A harmless treatment process for coating wastewater according to claim 5, characterized in that: The initiator is azobisisobutylimidazoline hydrochloride.

8. The harmless treatment process for coating wastewater according to claim 5 is characterized in that: Collagen fibers have a diameter of 5-20 microns.

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