High-concentration organic toxic wastewater efficient treatment process and application

Abstract

The application belongs to the technical field of wastewater treatment, and specifically provides a high-concentration organic toxic wastewater efficient treatment process and application, which comprises the following steps: step one: high-concentration organic toxic wastewater is discharged into a wastewater collection tank, and mechanical stirring in the tank is started to perform homogenization treatment and fully mix uniformly; the high-concentration organic toxic wastewater is electroplating wastewater; step two: the homogenization-treated wastewater is pumped into a reduction reaction tank, and after treatment, is pumped into a neutralization and sedimentation treatment tank; then, after sedimentation flocculation, the clear liquid is subjected to adsorption treatment, and finally, after solid-liquid separation, is discharged or sent into a reuse system after detection. The treatment process can enhance the removal effect of perfluorooctane sulfonic acid in electroplating wastewater.

Description

Technical Field

[0001] This application belongs to the field of wastewater treatment technology, and in particular relates to a high-efficiency treatment process and application for high-concentration organic toxic wastewater. Background Technology

[0002] Electroplating wastewater is a typical type of toxic industrial wastewater. In the electroplating process, to suppress the diffusion of highly oxidizing chromic acid mist, polyfluoroalkyl surfactants are often added to reduce the surface tension of the plating bath. However, these surfactants have high chemical stability and poor biodegradability, resulting in excessive organic fluorine pollutants remaining in the treated effluent. Among them, perfluorooctane sulfonate (PFOS), as a typical representative of perfluorinated and polyfluoroalkyl substances, has become a globally persistent organic pollutant due to its widespread application, extremely high chemical and thermal stability, and significant bioaccumulation. Water bodies are a crucial medium for PFOS migration and accumulation, posing a serious threat to drinking water safety and human health. Therefore, developing economical and efficient PFOS removal technologies for water is of great practical significance.

[0003] Among existing treatment technologies, adsorption has attracted much attention due to its advantages such as simple operation, relatively controllable cost, and low likelihood of generating toxic byproducts. However, the adsorption of PFOS by traditional adsorbents (such as activated carbon and ion exchange resins) mainly relies on hydrophobic interactions or simple electrostatic attraction, and generally suffers from problems such as low adsorption capacity, poor selectivity in complex water bodies, and slow mass transfer kinetics, which seriously limit its practical application.

[0004] Therefore, there is an urgent need to study an advanced treatment process for organic toxic wastewater that can efficiently adsorb PFOS and reduce the concentration of such pollutants in wastewater. Summary of the Invention

[0005] To address the above problems, this application provides a highly efficient treatment process and application for high-concentration organic toxic wastewater, comprising the following steps: A highly efficient treatment process for high-concentration organic toxic wastewater includes the following steps: 1) Discharge the high-concentration organic toxic wastewater into the wastewater collection tank, and turn on the mechanical agitator in the tank to homogenize and mix it thoroughly; the high-concentration organic toxic wastewater is electroplating wastewater; the initial concentration of perfluorooctane sulfonic acid in the high-concentration organic toxic wastewater is not less than 1200 μg / L. 2) Pump the homogenized wastewater from step 1) into the reduction reaction tank, start the stirring device and maintain the speed at 60-80 r / min, then add sulfuric acid to adjust the pH of the wastewater to 2.5-3.0, then add NaHSO3, control the ORP at 230-275mV, add NaHSO3 appropriately when the ORP is higher than 275mV, and stop adding when it is lower than 230mV. When the hexavalent chromium ion in the wastewater is detected to be <0.5mg / L, pump the wastewater into the neutralization precipitation treatment tank. 3) Add calcium hydroxide to the neutralization and sedimentation treatment tank in step 2) to adjust the pH to 8.0-9.0, then add the sedimentation flocculant, keep the mixture stirred rapidly for 10-15 minutes to allow the sedimentation reaction to proceed fully, then let it stand for 1.5-2 hours to settle, and discharge the clear liquid into the intermediate water tank, and discharge the bottom sedimented sludge into the sludge thickening tank. 4) Pump the clear liquid from the intermediate water tank in step 3) into the pH adjustment tank, adjust the pH to 5.5-6.5 with hydrochloric acid, let it stand for treatment, then transfer the clear liquid to the adsorption treatment tank, add adsorbent and stir for treatment, then separate the solid and liquid, pump the liquid part into the clear water tank, and discharge or send it into the reuse system after testing and meeting the standards. The adsorbent is prepared using the following steps: S01. Take grapefruit peel, wash, dry, crush and sieve to obtain grapefruit peel powder; S02. Zinc salt, carrageenan derivative, benzoic acid, iron salt, and zirconium salt are mixed and dispersed in a solvent to obtain a hybrid precursor liquid; S03. The grapefruit peel powder obtained in step S01 is added to the hybrid precursor liquid obtained in step S02 for impregnation treatment, then filtered and dried, and then subjected to programmed temperature rise heat treatment under inert atmosphere protection. After cooling, it is crushed and sieved to obtain the adsorbent.

[0006] Furthermore, in step 4), the adsorbent is added to the clear liquid at a concentration of 250-300 mg / L.

[0007] Furthermore, in step S02, the method for preparing the carrageenan derivative includes: Take κ-carrageenan, disperse it in water, then add potassium salt and gluconolactone, stir, then add acid to adjust the pH, heat to 50-60℃ for 4-6 hours, then readjust the pH to neutral, and obtain the product by dialysis and drying. The potassium salt is potassium chloride.

[0008] Furthermore, in step S02, the proportions of each raw material by weight are as follows: 1.5-2 parts zinc salt, 0.5-1 part carrageenan derivative, 0.8-1 part benzoic acid, 0.5-0.6 parts iron salt, 0.3-0.5 parts zirconium salt, and 80-100 parts solvent.

[0009] The zinc salt is zinc chloride; The iron salt is ferrous acetate; The zirconium salt is zirconium oxychloride; The solvent is water.

[0010] Furthermore, in step S03, the liquid-to-material ratio for the impregnation treatment is (3-4):1, and the impregnation time is 8-16 hours.

[0011] Furthermore, in step S03, the inert atmosphere is a mixture of nitrogen and argon; the temperature rise rate of the programmed temperature rise heat treatment is 8.5-9.0℃ / min, the heat treatment temperature is 520-550℃, and the holding time is 1-2h.

[0012] This application also provides an application of the above-described treatment process in the treatment of electroplating wastewater.

[0013] Compared with the prior art, this application has the following beneficial effects: 1. The carrageenan derivative used in this application is obtained by acid hydrolysis of κ-carrageenan in a mixed solution. In the mixed solution, gluconolactone decomposes in aqueous solution to obtain gluconic acid, which can construct a protective layer on the surface of the κ-carrageenan molecule through hydrogen bonding. This provides a certain shielding effect on the active sites of the inner carrageenan, preventing the carrageenan from degrading too quickly. The introduced potassium salt ionization K... + It can stabilize the κ-carrageenan double helix structure, preventing excessive decoupling of carrageenan and affecting the subsequent chelation of metal ions.

[0014] 2. In the hybrid precursor solution, benzoic acid and carrageenan derivatives can synergistically chelate metal ions, and the double helix structure of carrageenan derivatives promotes the directional aggregation of metal ions, thus obtaining a metal-organic chelated hybrid precursor. This hybrid precursor penetrates and adsorbs onto the inner wall of the grapefruit peel pores during impregnation, and after drying, it is deposited in situ, completing the uniform loading of the active components. During subsequent heat treatment, the organic phase of the hybrid precursor pyrolyzes, and the isolated metal ions are transformed in situ into intercalated nanoparticles on the carbon matrix, wherein Zr... 4+ The oxygen vacancy defects generated by heterovalent doping, in conjunction with the coordination complexation of sulfonic acid groups by metal sites, enable efficient capture of PFOS. Attached Figure Description

[0015] Figure 1 This is the XRD diffraction pattern of the adsorbent in Example 1 of this application.

[0016] Figure 2 The graph shows the change of PFOS content in the adsorption treatment tanks of Examples 1-2 and Comparative Examples 1-2 over time. Detailed Implementation

[0017] To make the inventive purpose, technical solution, and beneficial technical effects of this application clearer, the following detailed description of this application is provided in conjunction with embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0018] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0019] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.

[0020] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0021] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0022] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0023] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0024] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0025] In this application, room temperature refers to 0-40°C, including but not limited to 10-40°C, or further to 20-30°C.

[0026] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0027] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0028] Preparation Example Weigh 25g of κ-carrageenan and dissolve it in 800mL of distilled water. Add 0.5g of KCl and 3.56g of gluconolactone, stir to dissolve, and slowly add 12.5mL of concentrated hydrochloric acid (12M). Add water to make a final concentration of 0.15M hydrochloric acid, then heat to 55℃ for 4 hours to degrade. After cooling, adjust the pH to 7.0 with 1M KOH, filter through a 0.45μm filter membrane, dialyze the filtrate in distilled water for 5 days, changing the water 2-3 times a day, and finally freeze-dry to obtain the carrageenan derivative.

[0029] Example 1 1) Discharge the electroplating wastewater (containing PFOS 1289.5μg / L) into the wastewater collection tank, turn on the mechanical agitator in the tank to homogenize and mix it thoroughly. Control the retention time of the wastewater in the collection tank to 8 hours, and turn on the agitator regularly during the retention period to prevent suspended solids from settling. 2) Pump the homogenized wastewater from step 1) into the reduction reaction tank, start the stirring device and maintain the speed at 60 r / min, then add sulfuric acid to adjust the pH of the wastewater to 2.5, then add NaHSO3, control the ORP between 230-275 mV, add NaHSO3 appropriately when the ORP is higher than 275 mV, and stop adding when it is lower than 230 mV. When the hexavalent chromium ion in the effluent is detected to be <0.5 mg / L, pump the wastewater into the neutralization sedimentation treatment tank. 3) Add calcium hydroxide to the neutralization and sedimentation treatment tank in step 2) to adjust the pH to 8.0. Then add PAC and PAM at a dosage of 50 mg / L and 2 mg / L respectively. Keep the mixture stirring rapidly for 10 minutes to allow the sedimentation reaction to proceed fully. After that, let it stand for 1.5 hours to settle. The clear liquid is discharged into the intermediate water tank, and the bottom sedimented sludge is discharged into the sludge thickening tank. 4) Pump the clear liquid from the intermediate water tank in step 3) into the pH adjustment tank, adjust the pH to 5.5 with hydrochloric acid, and let it stand for 15 minutes. Then transfer the clear liquid to the adsorption treatment tank. The PFOS content of the system at this time is 1071.9 μg / L. Then add adsorbent to the clear liquid at a dosage of 250 mg / L and stir. After solid-liquid separation, pump the liquid part into the clear water tank. After testing and meeting the standards, it is discharged or sent to the reuse system.

[0030] In this embodiment, the preparation steps of the adsorbent are as follows: The grapefruit peel was washed and then dried at 110℃ for 4 hours. After that, it was crushed and passed through a 30-mesh sieve to obtain grapefruit peel powder. Then, 10g of grapefruit peel powder was weighed and added to a hybrid precursor liquid with a liquid-to-material ratio of 3:1. The mixture was treated overnight, then filtered and dried. The dried material was transferred to a high-temperature muffle furnace for heat treatment in a 50% N2 / 50% Ar atmosphere. The temperature was raised to 525℃ with a temperature gradient of 8.5℃ / min and held for 2 hours. Then, the heating was stopped and the sample was cooled with the furnace. After cooling, the sample was crushed and passed through a 60-mesh sieve to obtain the adsorbent.

[0031] In this embodiment, the specific steps for preparing the hybrid precursor fluid are as follows: Take 1.5g zinc chloride, 0.5g carrageenan derivative, 0.8g benzoic acid, 0.5g ferrous acetate, and 0.3g zirconium oxychloride, add 80mL deionized water, and adjust the temperature to disperse.

[0032] XRD diffraction tests were performed on the adsorbent of Example 1, and the results are as follows: Figure 1 As shown in the figure, the metal elements adsorbed on grapefruit peel powder in the hybrid precursor fluid are doped and then sintered in situ to transform into oxidized products. The iron element composition can be compared with the standard card in PDF#88-086.

[0033] Example 2 In this embodiment, the preparation steps of the adsorbent are as follows: The grapefruit peel was washed and then dried at 110℃ for 4 hours. After that, it was crushed and passed through a 30-mesh sieve to obtain grapefruit peel powder. Then, 10g of grapefruit peel powder was weighed and added to a hybrid precursor liquid with a liquid-to-material ratio of 4:1. The mixture was treated overnight, then filtered and dried. The dried material was transferred to a high-temperature muffle furnace for heat treatment in a 50% N2 / 50% Ar atmosphere. The temperature was raised to 525℃ with a temperature gradient of 9.0℃ / min and held for 1.5 hours. Then, the heating was stopped and the sample was cooled with the furnace. After cooling, the sample was crushed and passed through a 60-mesh sieve to obtain the adsorbent.

[0034] In this embodiment, the specific steps for preparing the hybrid precursor fluid are as follows: Take 1.8g zinc chloride, 0.8g carrageenan derivative, 1g benzoic acid, 0.5g ferrous acetate, and 0.3g zirconium oxychloride, add 80mL deionized water, and adjust the temperature to disperse.

[0035] In this embodiment, the electroplating wastewater (containing PFOS 130 1.2 μg / L) is treated the same as in Example 1, and the remaining steps are the same.

[0036] Comparative Example 1 The difference between this comparative example and Example 1 is that carrageenan was directly treated with a 0.2M hydrochloric acid solution to obtain carrageenan derivatives.

[0037] The electroplating wastewater in this comparative example (containing PFOS 1400.3 μg / L) was treated in the same way as in Example 1.

[0038] Comparative Example 2 The difference between this comparative example and Example 1 is that the preparation steps of the hybrid precursor fluid are as follows: Take 1.5g zinc chloride, 0.8g benzoic acid, 0.5g ferrous acetate, and 0.3g zirconium oxychloride, add 80mL deionized water, and adjust the temperature to disperse.

[0039] The electroplating wastewater in this comparative example (containing PFOS 1375.2 μg / L) was treated in the same way as in Example 1.

[0040] Performance testing PFOS content detection: The PFOS content in the adsorption treatment tanks of Examples 1-2 and Comparative Examples 1-2 was tested at 40-minute sampling intervals. Referring to standard GB / T44165.8-2025, the change in PFOS content over time in each test group was recorded. The test results are as follows: Figure 2 As shown.

[0041] Take Examples 1-2 and Comparative Examples 1-2 and combine them. Figure 2 It can be seen that when the adsorbent of the embodiment is used to treat electroplating wastewater, the removal effect of PFOS in the wastewater is better. After 200 min, the PFOS content in the wastewater is less than 285.2 μg / L, which is significantly better than the level of comparative examples 1 and 2 at the same time. After 400 min, the adsorption of all test groups is close to stable. After treatment with the embodiment, the PFOS in the wastewater is lower and the adsorption effect is better.

[0042] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high-efficiency treatment process for high-concentration organic toxic wastewater, characterized in that, Includes the following steps: 1) Discharge the high-concentration organic toxic wastewater into the wastewater collection tank, and turn on the mechanical agitator in the tank to homogenize and mix it thoroughly; the high-concentration organic toxic wastewater is electroplating wastewater; 2) Pump the homogenized wastewater from step 1) into the reduction reaction tank, start the stirring device and maintain the speed at 60-80 r / min, then add sulfuric acid to adjust the pH of the wastewater to 2.5-3.0, then add NaHSO3, control the ORP at 230-275mV, add NaHSO3 appropriately when the ORP is higher than 275mV, and stop adding when it is lower than 230mV. When the hexavalent chromium ion in the wastewater is detected to be <0.5mg / L, pump the wastewater into the neutralization precipitation treatment tank. 3) Add calcium hydroxide to the neutralization and sedimentation treatment tank in step 2) to adjust the pH to 8.0-9.0, then add the sedimentation flocculant, keep the mixture stirred rapidly for 10-15 minutes to allow the sedimentation reaction to proceed fully, then let it stand for 1.5-2 hours to settle, and discharge the clear liquid into the intermediate water tank, and discharge the bottom sedimented sludge into the sludge thickening tank. 4) Pump the clear liquid from the intermediate water tank in step 3) into the pH adjustment tank, adjust the pH to 5.5-6.5 with hydrochloric acid, let it stand for treatment, then transfer the clear liquid to the adsorption treatment tank, add adsorbent and stir for treatment, then separate the solid and liquid, pump the liquid part into the clear water tank, and discharge or send it into the reuse system after testing and meeting the standards. The adsorbent is prepared using the following steps: S01. Take grapefruit peel, wash, dry, crush and sieve to obtain grapefruit peel powder; S02. Zinc salt, carrageenan derivative, benzoic acid, iron salt, and zirconium salt are mixed and dispersed in a solvent to obtain a hybrid precursor liquid; S03. The grapefruit peel powder obtained in step S01 is added to the hybrid precursor liquid obtained in step S02 for impregnation treatment, then filtered and dried, and then subjected to programmed temperature rise heat treatment under inert atmosphere protection. After cooling, it is crushed and sieved to obtain the adsorbent.

2. The high-efficiency treatment process for high-concentration organic toxic wastewater according to claim 1, characterized in that, In step 4), the adsorbent is added to the clear liquid at a concentration of 250-300 mg / L.

3. The high-efficiency treatment process for high-concentration organic toxic wastewater according to claim 1, characterized in that, In step S02, the method for preparing carrageenan derivatives includes: Take κ-carrageenan, disperse it in water, then add potassium salt and gluconolactone, stir, then add acid to adjust the pH, heat to 50-60℃ for 4-6 hours, then readjust the pH to neutral, and obtain the product by dialysis and drying.

4. The high-efficiency treatment process for high-concentration organic toxic wastewater according to claim 3, characterized in that, The potassium salt is potassium chloride.

5. The high-efficiency treatment process for high-concentration organic toxic wastewater according to claim 1, characterized in that, In step S02, the proportions of each raw material by weight are as follows: 1.5-2 parts zinc salt, 0.5-1 part carrageenan derivative, 0.8-1 part benzoic acid, 0.5-0.6 parts iron salt, 0.3-0.5 parts zirconium salt, and 80-100 parts solvent.

6. The high-efficiency treatment process for high-concentration organic toxic wastewater according to claim 5, characterized in that, The zinc salt is zinc chloride; the iron salt is ferrous acetate; the zircon salt is zirconium oxychloride; and the solvent is water.

7. The high-efficiency treatment process for high-concentration organic toxic wastewater according to claim 1, characterized in that, In step S03, the liquid-to-material ratio for the impregnation treatment is (3-4):1, and the impregnation time is 8-16 hours.

8. The high-efficiency treatment process for high-concentration organic toxic wastewater according to claim 1, characterized in that, In step S03, the inert atmosphere is a mixture of nitrogen and argon; the temperature rise rate of the programmed temperature rise heat treatment is 8.5-9.0℃ / min, the heat treatment temperature is 520-550℃, and the holding time is 1-2h.

9. The high-efficiency treatment process for high-concentration organic toxic wastewater according to claim 1, characterized in that, The initial concentration of perfluorooctane sulfonic acid in the high-concentration organic toxic wastewater shall not be less than 1200 μg / L.

10. The application of the high-efficiency treatment process for high-concentration organic toxic wastewater according to any one of claims 1-9 in the treatment of electroplating wastewater.

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