Method for recycling acidic aqueous solution
By extracting and separating macromolecular organic byproducts from acidic aqueous solutions, the problems of increased viscosity and filter cake clumping during the recycling of acidic aqueous solutions were solved, achieving more efficient recycling and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-08
- Publication Date
- 2026-04-10
AI Technical Summary
In existing technologies, when acidic aqueous solutions are recycled during the production of UV-0 ultraviolet absorbers, the accumulation of macromolecular organic byproducts leads to increased viscosity, prolonged filtration time, and even filter cake clumping, affecting product quality and increasing processing costs.
The macromolecular organic byproducts in acidic aqueous solution are separated into the organic phase by an extraction method. The extraction is carried out by an extractant such as C3-C6 alkanes, C3-C7 cycloalkanes, C1-C4 alkyl-substituted phenyl and ester compounds, forming an aqueous phase and an organic phase. After neutralization, the extractant and methanol are recovered and recycled to the next batch of reaction.
It enables the reuse of acidic aqueous solutions in multiple batches or even indefinitely, reducing wastewater treatment costs and methanol loss, while maintaining the filtration efficiency and purity of the product.
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Figure CN121824282A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of post-processing of ultraviolet absorber UV-0, in particular to a method for recovering and treating an acidic aqueous solution. BACKGROUND
[0002] Ultraviolet absorber UV-0, also known as 2,4-dihydroxybenzophenone, benzophenone-1, 2,4-dihydroxybenzophenone, 2,4-dihydroxybenzophenone and BP-1 in Chinese, is mainly used as a light stabilizer in plastics and the like, which can effectively protect organic glass and cloth, prevent data from deteriorating due to light, and is also used as an intermediate for synthesizing other ultraviolet absorbers (such as UV-531).
[0003] The main production steps of the ultraviolet absorber UV-0 at present include: (1) synthesizing UV-0 by reacting resorcinol and trichlorobenzene in a methanol aqueous solution; see the following synthesis path for details:
[0004]
[0005] (2) filtering the reaction system after the reaction of step (1) to obtain wet ultraviolet absorber UV-0 and an acidic aqueous solution containing hydrogen chloride and macromolecular organic by-products; (3) drying the wet ultraviolet absorber UV-0 obtained in step (2) or directly using the wet ultraviolet absorber UV-0 for subsequent synthesis.
[0006] However, if the acidic aqueous solution containing methanol, hydrogen chloride and macromolecular organic by-products formed in step (2) is directly treated as waste water, there are problems such as high treatment cost and loss of methanol in the aqueous solution. The conventional method is to directly recycle and use the acidic aqueous solution to the synthesis process of the next batch of ultraviolet absorber UV-0, i.e. to the step (1) of the next batch, but this method has the following problems: (1) as the number of recycled batches increases, the macromolecular organic by-products in the recycled acid water will accumulate, resulting in increasing viscosity of the recycled acid water and increasing filtration time, and even the filter cake may be difficult to completely filter due to balling; (2) if there is no washing process for the ultraviolet absorber UV-0, the impurities in the wet ultraviolet absorber UV-0 will also increase, affecting the quality of the subsequent product. Therefore, the method of recycling the acid aqueous solution used in the prior art is limited to a few batches, and the acid aqueous solution after being recycled for several batches needs to be discarded for waste water treatment, and fresh water and methanol need to be added again, which also has the problems of high treatment cost and loss of methanol in the aqueous solution.
[0007] In view of this, the present application is proposed. SUMMARY
[0008] The application aims to provide a method for recycling and treating an acidic aqueous solution.
[0009] The application is implemented in the following manner:
[0010] In a first aspect, the application provides a method for recycling and treating an acidic aqueous solution, comprising: filtering an acidic aqueous solution formed by a reaction system for forming an ultraviolet absorber UV-0 to form a water phase and an organic phase; and adding the water phase to another batch of the reaction system for forming the ultraviolet absorber UV-0.
[0011] In an optional embodiment, the extractant used in the extraction is selected from any one or a combination of at least two of C3-C6 alkane compounds, C3-C7 cycloalkane compounds, C1-C4 alkyl-substituted phenyl compounds, and ester compounds.
[0012] Preferably, the extractant is selected from any one or a combination of at least two of n-hexane, cyclohexane, toluene, xylene, and methyl acetate.
[0013] In an optional embodiment, the volume ratio of the extractant to the acidic aqueous solution used in the extraction is 0.01-30:1, preferably 0.1-6:1.
[0014] In an optional embodiment, the extraction temperature is 0℃ to 90℃, and the extraction temperature is not lower than the freezing point of the acidic aqueous solution under normal pressure; at the same time, the extraction temperature is not higher than the boiling point and azeotropic point of the extractant used in the extraction and the acidic aqueous solution under normal pressure.
[0015] Preferably, the extraction temperature is 5℃-80℃.
[0016] In an optional embodiment, the extraction time is 0.01 hours-20 hours; preferably 0.2 hours-8 hours.
[0017] In an optional embodiment, the extraction includes batch extraction or continuous extraction.
[0018] In an optional embodiment, the method further comprises: performing a neutralization reaction on the organic phase.
[0019] Preferably, the pH of the organic phase after the neutralization reaction is ≥7.0, preferably 7.0-8.0.
[0020] In an optional embodiment, the organic phase after the neutralization reaction is subjected to distillation to recover the extractant and methanol.
[0021] In an optional embodiment, the neutralization or distillation is performed on the organic phase obtained from each batch of extraction;
[0022] or the organic phase obtained from each batch of extraction is directly recycled to the next batch of extraction, and the organic phase formed after several batches of recycling.
[0023] In an optional embodiment, the acidic aqueous solution comprises the acidic aqueous solution formed by filtering the reaction system for forming the ultraviolet absorber UV-0 in each batch;
[0024] or the untreated acidic aqueous solution formed by filtering the reaction system for forming the ultraviolet absorber UV-0 in one batch is directly recycled to the acidic aqueous solution formed by the reaction system for forming the ultraviolet absorber UV-0 in the next batch.
[0025] The present application has the following beneficial effects: the present application can remove the macromolecular organic by-products in the acidic solution by extracting the acidic aqueous solution formed by filtering the reaction system for forming the ultraviolet absorber UV-0, thereby avoiding the accumulation of macromolecular organic by-products in the recycled solution, and improving the problems of increased viscosity of the recycled solution, increased filtration time, and filter cake balling caused by the macromolecular organic by-products. At the same time, the water phase after extraction, which does not contain macromolecular organic by-products, hydrogen chloride and methanol, can be recycled to the next batch of ultraviolet absorber UV-0 synthesis step, which can realize more batches or even infinite recycling. And it can reduce the treatment cost of waste water and the loss of methanol, further reducing the production cost. BRIEF DESCRIPTION OF DRAWINGS
[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.
[0027] Figure 1 The flowchart of the method for recovering and processing the acidic aqueous solution provided by the embodiments of the present application is shown. DETAILED DESCRIPTION
[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased in the market.
[0029] The embodiments of the present application provide a method for recovering and processing an acidic aqueous solution, as shown inFigure 1 The specific steps include:
[0030] The acid aqueous solution formed by filtering the reaction system of synthesizing the ultraviolet absorber UV-0 is extracted.
[0031] The raw materials, the ratio, the reaction temperature and the reaction time used in synthesizing the ultraviolet absorber UV-0 are all prior art and will not be described in detail in the embodiments of the present application. Meanwhile, the filtering is also a conventional filtering mode, for example, including but not limited to plate and frame filter press and centrifugal filter and the like. The acid aqueous solution formed contains methanol, hydrogen chloride and macromolecular organic by-products and the like.
[0032] Further, the extraction can extract the hydrogen chloride, the methanol and the macromolecular organic by-products into the organic phase, and then the methanol can be recovered by distillation, thereby reducing the loss of the methanol. The water phase formed by the extraction does not contain the above-mentioned substances, and can be recycled and applied to the synthesis process of another batch of ultraviolet absorber UV-0, which can realize more batches or even infinite recycling.
[0033] Specifically, the extractant used in the above-mentioned extraction is selected from any one or a combination of at least two of C3-C6 alkane compounds, C3-C7 cycloalkane compounds, C1-C4 alkyl-substituted phenyl compounds and ester compounds; for example, including but not limited to any one or a combination of at least two of n-hexane, cyclohexane, toluene, xylene and methyl acetate.
[0034] Further, the volume ratio of the extractant to the acid aqueous solution is 0.01-30:1, for example, any value between 0.01:1, 0.1:1, 1:1, 10:1, 20:1 and 30:1, for example, preferably 0.1-6:1.
[0035] Further, the extraction temperature is 0-90℃, the extraction temperature is not lower than the freezing point of the acid aqueous solution under normal pressure; at the same time, the extraction temperature is not higher than the boiling point and the azeotropic point of the extractant and the acid aqueous solution under normal pressure; for example, any value between 0-90℃, for example, preferably 5-80℃.
[0036] Further, the extraction time is 0.01-20 hours; preferably 0.2-8 hours. For example, any value between 0.01-20 hours, for example, preferably 0.2-8 hours, of 0.01 hours, 0.1 hours, 0.2 hours, 0.5 hours, 1 hour, 5 hours, 10 hours, 15 hours and 20 hours.
[0037] The above extraction agent, extraction temperature and extraction time are beneficial to improving the extraction effect and separating macromolecular organic byproducts and the like.
[0038] It should be noted that the above extraction can be intermittent extraction or continuous extraction.
[0039] Further, after the ultraviolet absorber UV-0 is formed in each batch of reaction, the reaction system of the batch is filtered to form an acidic aqueous solution, and then the acidic aqueous solution is extracted.
[0040] Alternatively, after the reaction of one batch is completed, the reaction system is filtered, and the acidic aqueous solution formed by the filtering is directly recycled and applied to the synthesis process of the next batch of ultraviolet absorber UV-0, and the recycling is performed for multiple batches before extraction.
[0041] Further, the organic phase obtained by extraction is subjected to neutralization treatment to neutralize a small amount of acid in the organic phase. Specifically, an alkali, for example, including but not limited to sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or ammonia, is added in the neutralization process, so that the organic phase changes from acidic to near neutral or alkaline, for example, the solution PH≥7.0 after neutralization; further preferably, the solution PH=7.0-8.0 after neutralization.
[0042] After neutralization, the extraction agent and methanol are distilled and recovered, which can be directly recycled and applied to the extraction of the next batch, and the heavy phase residual liquid containing macromolecular organic byproduct impurities, water, chlorinated salt and a small amount of alkali.
[0043] Further, the organic phase obtained by extraction can be neutralized and distilled after each extraction; or the organic phase obtained by extraction can be directly recycled and applied to the extraction of the next batch, and the organic phase is neutralized and distilled after a plurality of batches.
[0044] The features and performances of the present application are further described in detail in combination with the following examples.
[0045] Example 1
[0046] The present example provides a method for recovering and treating an acidic aqueous solution, comprising:
[0047] First, the ultraviolet absorber UV-0 is synthesized:
[0048] The methanol, water, trichloromethylbenzene and resorcinol are added in the reaction kettle according to the proportion, and after mixing, the mass fraction of each substance is: methanol 10%, water 40%, resorcinol 20%, trichloromethylbenzene 30%; UV-0 is synthesized under the conditions of 45℃ and slight negative pressure.
[0049] The reaction system for synthesizing the UV absorber UV-0 was filtered to form a 1.0 cubic meter acidic aqueous solution. 0.5 cubic meters of hexane was added as an extractant. Extraction and separation were performed using a single-stage batch extraction tank at a temperature of 30°C, with a total extraction residence time of 1.5 hours. The aqueous phase obtained after extraction and separation was directly reused for the next batch of UV-0 synthesis (the synthesis conditions and process were the same as described above). 22.0 kg of a 1.8% sodium hydroxide aqueous solution was added to the organic phase for neutralization, resulting in a pH of 7.0–8.0. Evaporation was then carried out in a scraped-film evaporator, with the preferred heat medium temperature being 95°C. The light phase obtained by condensing the evaporated gas phase was an extractant containing methanol, which was reused for the next batch of extraction, resulting in a heavy phase residue containing macromolecular organic byproduct impurities, water, sodium chloride, and a small amount of sodium hydroxide.
[0050] Each batch of filtered UV-0 wet product was dried at 120℃ for 5 hours to obtain UV-0 dry product, and its purity was tested by liquid chromatography.
[0051] The above process was repeated for 30 synthesis batches. The viscosity of the mother liquor in subsequent batches gradually increased, and the filter cake did not clump together; compared with the first batch, the cumulative increase in mother liquor viscosity in the last batch did not exceed 10%, and the increase in filtration time did not exceed 5.0%; the purity of UV-0 dry product in each batch was ≥99.4%, and there was no obvious downward trend.
[0052] Example 2
[0053] This embodiment provides a method for recovering and treating acidic aqueous solutions, including:
[0054] In this embodiment, the initial addition amounts of each substance and the subsequent addition amounts of trichlorotoluene and resorcinol during the synthesis reaction of the ultraviolet absorber UV-0 are the same as in Example 1, and the reaction conditions are also the same as in Example 1.
[0055] The reaction system for synthesizing UV absorber UV-0 was filtered to form a 1.0 cubic meter acidic aqueous solution. This acidic aqueous solution was directly used in the synthesis reaction of the next batch of UV absorber UV-0 (the synthesis conditions and process were the same as the above synthesis process). After five consecutive synthesis batches, 2.0 cubic meters of methyl acetate extractant was added to the filtered approximately 1.0 cubic meter acidic aqueous solution. Extraction and separation were carried out using a single-stage batch extraction tank at a temperature range of 30°C, with a total extraction residence time of 1.0 hour. The aqueous phase obtained after extraction and separation was directly used in the synthesis process of the next batch of UV absorber UV-0 (the synthesis conditions and process were the same as the above synthesis process). 20.0 kg of 7.7% sodium hydroxide aqueous solution was added to the organic phase for neutralization, resulting in a solution pH of 7.5–8.0. The solution was then evaporated in a scraped film evaporator at a heat transfer medium temperature of 100°C. The light phase obtained by condensing the evaporated gas phase was an extractant containing methanol, which was reused in the next batch of extraction to obtain a heavy phase residue containing macromolecular organic byproduct impurities, water, sodium chloride, and a small amount of sodium hydroxide.
[0056] Each batch of filtered UV-0 wet product was dried at 120℃ for 5 hours to obtain UV-0 dry product, and its purity was tested by liquid chromatography.
[0057] The above process was repeated for 30 synthesis batches. The viscosity of the mother liquor in subsequent repeated batches gradually increased, and the filter cake did not clump together; compared with the first batch, the cumulative increase in mother liquor viscosity in the last batch did not exceed 10.0%, and the increase in filtration time did not exceed 5.0%; the purity of UV-0 dry product in each batch was ≥99.5%, and there was no obvious downward trend.
[0058] Example 3
[0059] This embodiment provides a method for recovering and treating acidic aqueous solutions, including:
[0060] In this embodiment, the initial addition amounts of each substance and the subsequent addition amounts of trichlorotoluene and resorcinol during the synthesis reaction of the ultraviolet absorber UV-0 are the same as in Example 1, and the reaction conditions are also the same as in Example 1.
[0061] The reaction system of the above-mentioned UV absorber UV-0 was filtered to form a 1.0 cubic meter acidic aqueous solution. 2.0 cubic meters of cyclohexane, the extractant, were added. Extraction was carried out in a single-stage batch extraction tank at a temperature range of 20°C, with a total extraction residence time of 1.0 hour. After extraction and separation, the aqueous phase was directly reused for the next batch of UV absorber UV-0 synthesis. The organic phase was directly reused for the next batch of extraction. After five consecutive extraction batches, 50.0 kg of 4.7% sodium hydroxide aqueous solution was added to the organic phase for neutralization, resulting in a solution pH of 7.0–8.0. The solution was then evaporated in a scraped film evaporator, with the preferred heat medium temperature being 85°C. The light phase obtained by condensing the evaporated gas phase was the extractant containing methanol, which was reused for the next batch of extraction, resulting in a heavy phase residue containing macromolecular organic byproduct impurities, water, sodium chloride, and a small amount of sodium hydroxide.
[0062] Each batch of filtered UV-0 wet product was dried at 120℃ for 5 hours to obtain UV-0 dry product, and its purity was tested by liquid chromatography.
[0063] The above process was repeated for 30 synthesis batches. The viscosity of the mother liquor in subsequent repeated batches gradually increased, and the filter cake did not clump together; compared with the first batch, the cumulative increase in mother liquor viscosity in the last batch did not exceed 10.0%, and the increase in filtration time did not exceed 5.0%; the purity of UV-0 dry product in each batch was ≥99.4%, and there was no obvious downward trend.
[0064] Example 4
[0065] This embodiment provides a method for recovering and treating acidic aqueous solutions, including:
[0066] In this embodiment, the initial addition amounts of each substance and the subsequent addition amounts of trichlorotoluene and resorcinol during the synthesis reaction of the ultraviolet absorber UV-0 are the same as in Example 1, and the reaction conditions are also the same as in Example 1.
[0067] The reaction system for synthesizing the UV absorber UV-0 was filtered to form a 1.0 cubic meter acidic aqueous solution. 0.5 cubic meters of methyl acetate were added for extraction using a two-stage continuous extraction tower. The extraction temperature range was 28°C, and the total extraction residence time was 1.0 hour. The aqueous phase obtained after extraction was directly reused for the next batch of UV-0 synthesis. A 7.7% sodium hydroxide aqueous solution was added to the organic phase for neutralization, with 20.0 kg of alkali added per cubic meter of organic phase. The pH of the neutralized solution was 7.0–8.0. The solution was then evaporated in a scraped film evaporator, with the preferred heat medium temperature being 98°C. The light phase obtained by condensing the evaporated gas phase was the extractant containing methanol, which was reused for the next batch of extraction, resulting in a heavy phase residue containing macromolecular organic byproduct impurities, water, sodium chloride, and a small amount of sodium hydroxide.
[0068] Each batch of filtered UV-0 wet product was dried at 120℃ for 5 hours to obtain UV-0 dry product, and its purity was tested by liquid chromatography.
[0069] The above process was repeated for 30 synthesis batches. The viscosity of the mother liquor in subsequent repeated batches gradually increased, and the filter cake did not clump together; compared with the first batch, the cumulative increase in mother liquor viscosity in the last batch did not exceed 10.0%, and the increase in filtration time did not exceed 5.0%; the purity of UV-0 dry product in each batch was ≥99.6%, and there was no obvious downward trend.
[0070] Examples 5-7
[0071] Examples 5-7 all provide a method for recovering and treating acidic aqueous solutions. The initial addition amounts of each substance and the subsequent addition amounts of trichlorotoluene and resorcinol during the synthesis reaction of the ultraviolet absorber UV-0 are the same as in Example 1, and the reaction conditions are also the same. Furthermore, the treatment method provided in Example 1 is used to treat acidic aqueous solutions, with the only difference being some of the conditions, as follows:
[0072] Example 5
[0073] Toluene was used as the extractant; the volume ratio of the extractant to the acidic aqueous solution was 0.01:1; the extraction temperature was 0°C; and the extraction time was 20 hours. All other conditions were the same as in Example 1.
[0074] Seven synthesis batches were repeated. The viscosity of the filtrate and the filtration time gradually increased in subsequent batches. Compared to the first batch, the viscosity of the filtrate in the sixth batch increased by 14.4 times, and the filtration time increased by 3.3 times. In the seventh batch, the filter cake clumped and could not be completely filtered. The purity of the UV-0 dry product gradually decreased in each batch, from 99.6% in the first batch to 93.2% in the sixth batch.
[0075] Example 6
[0076] The extractant used was n-hexane; the volume ratio of extractant to the acidic aqueous solution was 30:1; the extraction temperature was 92°C; and the extraction time was 0.01 hours. All other conditions were the same as in Example 1.
[0077] Nine synthesis batches were repeated. The viscosity of the mother liquor and the filtration time gradually increased in subsequent batches. Compared to the first batch, the viscosity of the mother liquor in the eighth batch increased by 12.1 times, and the filtration time increased by 2.2 times. In the ninth batch, the filter cake clumped and could not be completely filtered. The purity of the UV-0 dry product gradually decreased in each batch, from 99.6% in the first batch to 93.1% in the eighth batch.
[0078] Example 7
[0079] The extractant used was cyclohexane; the volume ratio of extractant to the acidic aqueous solution was 6:1; the extraction temperature was 80°C; and the extraction time was 15 hours. All other conditions were the same as in Example 1.
[0080] The synthesis was repeated for 38 batches. The viscosity of the mother liquor in subsequent repeated batches gradually increased, with the cumulative increase in viscosity of the mother liquor in the 38th batch reaching 9.1% compared to the first batch; no pelleting occurred in the filter cake; the filtration time increased by no more than 4.5% compared to the first batch; and the purity of the UV-0 dry product in each batch was ≥99.7%.
[0081] Comparative Example 1
[0082] The initial addition amounts of each substance and the subsequent addition amounts of trichlorotoluene and resorcinol in the synthesis reaction of the UV absorber UV-0 in this comparative example were the same as in Example 1, and the reaction conditions were also the same as in Example 1.
[0083] The reaction system for synthesizing UV absorber UV-0 was filtered to form a 1.0 cubic meter acidic aqueous solution. This acidic aqueous solution was directly recycled for the next batch of UV absorber UV-0 synthesis. Trichlorotoluene and resorcinol were added to the next batch according to the amount added in the first batch.
[0084] Each batch of filtered UV-0 wet product was dried at 120℃ for 5 hours to obtain UV-0 dry product, and its purity was tested by liquid chromatography.
[0085] The above process was repeated for 5 synthesis batches. Compared to the first batch, the viscosity of the filtration mother liquor and the filtration time gradually increased in subsequent repeated batches. In the fourth batch, the viscosity of the filtration mother liquor increased by 20.3 times and the filtration time increased by 5.7 times. In the fifth batch, the filter cake clumped and could not be completely filtered. The purity of the UV-0 dry product gradually decreased in each batch, with the first batch at 99.6% and the fourth batch at 93.1%.
[0086] The UV-0 synthesis feed ratios used in the above comparative examples and embodiments are only for illustrative purposes. In fact, the application of the present invention includes, but is not limited to, these feed ratios. If only the UV-0 synthesis feed ratio is changed and the same or similar reaction liquid filtration mother liquor treatment method is used, it falls within the scope of protection of this patent.
[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for recovering and treating acidic aqueous solutions, characterized in that, include: The acidic aqueous solution formed by filtering the reaction system that forms the ultraviolet absorber UV-0 is then extracted to form an aqueous phase and an organic phase. The aqueous phase is added to another batch of the reaction system that forms the ultraviolet absorber UV-0.
2. The method for recovering and treating acidic aqueous solutions according to claim 1, characterized in that, The extractant used for extraction is selected from any one or a combination of at least two of the following: C3-C6 alkane compounds, C3-C7 cycloalkane compounds, C1-C4 alkyl-substituted phenyl compounds, and ester compounds; Preferably, the extractant is selected from any one or a combination of at least two of n-hexane, cyclohexane, toluene, xylene, and methyl acetate.
3. The method for recovering and treating acidic aqueous solutions according to claim 1 or 2, characterized in that, The volume ratio of the extractant to the acidic aqueous solution used in the extraction is 0.01-30:1, preferably 0.1-6:
1.
4. The method for recovering and treating acidic aqueous solutions according to claim 1, characterized in that, The extraction temperature is between 0°C and 90°C, and the extraction temperature is not lower than the freezing point of the acidic aqueous solution under normal pressure; at the same time, the extraction temperature is not higher than the boiling point and azeotropic point of the extractant and the acidic aqueous solution under normal pressure. Preferably, the extraction temperature is 5℃-80℃.
5. The method for recovering and treating acidic aqueous solutions according to claim 1, characterized in that, The extraction time is 0.01 hours to 20 hours; preferably 0.2 hours to 8 hours.
6. The method for recovering and treating acidic aqueous solutions according to claim 1, characterized in that, Extraction can be either batch extraction or continuous extraction.
7. The method for recovering and treating acidic aqueous solutions according to claim 1, characterized in that, include: The organic phase is subjected to a neutralization reaction; Preferably, the pH of the organic phase after the neutralization reaction is ≥7.0, and more preferably 7.0-8.
0.
8. The method for recovering and treating acidic aqueous solutions according to claim 7, characterized in that, The organic phase after the neutralization reaction is distilled to recover the extractant and methanol.
9. The method for recovering and treating acidic aqueous solutions according to claim 7 or 8, characterized in that, Neutralization or distillation is applied to the organic phase obtained from each batch of extraction; Alternatively, the organic phase obtained from a single batch extraction can be directly recycled to the next batch extraction, and the organic phase formed after several batches of recycling can be recycled.
10. The method for recovering and treating acidic aqueous solutions according to claim 1, characterized in that, The acidic aqueous solution includes the acidic aqueous solution formed by filtering the reaction system that forms the ultraviolet absorber UV-0 in each batch; Alternatively, the untreated acidic aqueous solution formed by filtering the reaction system that forms UV-0 in one batch can be directly recycled to the acidic aqueous solution formed in the reaction system that forms UV-0 in the next batch.