A decolorizing aid for treating phenolic wastewater with activated carbon, its preparation method and application

Abstract

This application relates to the technical field of phenolic wastewater treatment, and specifically discloses a decolorizing aid for treating phenolic wastewater with activated carbon, its preparation method and application. The decolorizing aid is mainly made from the following raw materials in parts by weight: 25 - 35 parts of polyaluminum chloride, 20 - 30 parts of polydimethyldiallylammonium chloride, 9 - 11 parts of modified chitosan, 13 - 17 parts of polyvinylpyrrolidone, 13 - 17 parts of polyacrylamide, and 6 - 4 parts of aminotrimethylenephosphonic acid; the modified chitosan is obtained by treating chitosan with sodium hydroxide, ethyl 4-chloroacetoacetate, and 3-chloro-2-hydroxypropyltrimethylammonium chloride. When applied to the treatment of phenolic wastewater, this decolorizing aid has the advantages of high chroma removal rate and high organic matter removal rate, and can make the purity of ammonium sulfate > 99.5%, meeting the market demand.

Description

Technical Field

[0001] The present application relates to the technical field of phenolic wastewater treatment, and more specifically, it relates to a decolorizing aid for treating phenolic wastewater with activated carbon, its preparation method and application. Background Art

[0002] m-Aminophenol, also known as m-hydroxyaniline, is one of the three isomers of aminophenol and can be used in the production of antioxidants, stabilizers, developers, color films, etc. Since m-aminophenol contains both an amino group and a phenol group, when it is exposed to air or sunlight for a long time, it is prone to oxidation, resulting in a deeper color and even turning black.

[0003] Some researchers use nitrobenzene as a raw material and synthesize m-aminophenol through sulfonation and alkali fusion. There are also some researchers who use m-phenylenediamine as a raw material and obtain m-aminophenol by acid hydrolysis of m-phenylenediamine. In the process of obtaining m-aminophenol by acid hydrolysis of m-phenylenediamine, phenolic wastewater is inevitably generated. The phenolic wastewater not only contains organic substances such as m-aminophenol, m-phenylenediamine, and resorcinol, but also has the characteristics of a deep color, and at the same time contains a large amount of ammonium sulfate. If the phenolic wastewater is directly discharged, it will not only cause environmental pollution but also result in the waste of ammonium sulfate.

[0004] In order to reduce environmental pollution and at the same time realize the recovery of ammonium sulfate. If the phenolic wastewater is directly evaporated and concentrated, cooled, ammonium sulfate is obtained. At this time, since the phenolic wastewater contains colored substances and organic substances. During the crystallization process of ammonium sulfate from a supersaturated state, it inevitably adsorbs colored substances and organic substances, thus affecting the purity of ammonium sulfate. If activated carbon is added to the phenolic wastewater, the colored substances and organic substances are adsorbed by the activated carbon to obtain a treatment liquid, and then the treatment liquid is evaporated and concentrated, cooled, and thus ammonium sulfate is obtained. By adopting this method, although the colored substances and organic substances in the treatment liquid can be reduced, the adsorption capacity of activated carbon is limited, and the removal rate of organic substances and chromaticity of phenolic wastewater cannot be further improved. Summary of the Invention

[0005] In order to improve the removal rate of chromaticity and organic substances of phenolic wastewater, the present application provides a decolorizing aid for treating phenolic wastewater with activated carbon, its preparation method and application.

[0006] In the first aspect, the present application provides a decolorizing aid for treating phenolic wastewater with activated carbon, adopting the following technical solution: A decolorizing aid for treating phenolic wastewater with activated carbon is mainly made of the following raw materials in parts by weight: 25-35 parts of polyaluminum chloride, 20-30 parts of polydimethyldiallylammonium chloride, 9-11 parts of modified chitosan, 13-17 parts of polyvinylpyrrolidone, 13-17 parts of polyacrylamide, 6-4 parts of aminotrimethylene phosphonic acid;

[0007] The modified chitosan is obtained by treating chitosan with sodium hydroxide, ethyl 4-chloroacetoacetate, and 3-chloro-2-hydroxypropyltrimethylammonium chloride.

[0008] By adopting the above technical solution, the decolorizing aid of the present application is applied to the treatment of phenol-containing wastewater, so that the chromaticity removal rate of the phenol-containing wastewater > 98%, the m-aminophenol removal rate > 94%, the m-phenylenediamine removal rate > 96%, and the resorcinol removal rate > 91%, effectively increasing the chromaticity removal rate and the organic matter removal rate of the phenol-containing wastewater. Further, the purity of ammonium sulfate > 99.5% is also achieved, meeting the market demand.

[0009] Adding polyaluminum chloride to the raw materials has a good removal effect on colored substances and also has a certain removal effect on organic matter, and can effectively reduce the chromaticity and the organic matter content of the phenol-containing wastewater. Adding poly(dimethyldiallylammonium chloride) to the raw materials can form precipitates with colored substances and reduce the chromaticity of the phenol-containing wastewater. Adding modified chitosan to the raw materials, chitosan is treated with sodium hydroxide, ethyl 4-chloroacetoacetate, and 3-chloro-2-hydroxypropyltrimethylammonium chloride, and cationic groups and polar groups are introduced on the surface of chitosan, greatly increasing the removal effect of chitosan on chromaticity and organic matter. Through the synergistic effect between modified chitosan and poly(dimethyldiallylammonium chloride), combined with polyaluminum chloride, the organic matter content and chromaticity of the phenol-containing wastewater are effectively reduced, and the treatment effect of the phenol-containing wastewater is increased.

[0010] At the same time, polyvinylpyrrolidone, polyacrylamide, and aminotrimethylenephosphonic acid are also added to the raw materials, and combined with polyaluminum chloride, poly(dimethyldiallylammonium chloride), and modified chitosan, not only can the precipitates aggregate quickly, but also the density of the precipitates is increased, the precipitation of the precipitates is accelerated, the treatment efficiency of the phenol-containing wastewater is improved, and the volume of the precipitates is also reduced.

[0011] Optionally, the modified chitosan is prepared by the following method: adding sodium hydroxide to water and mixing, adding isopropanol and mixing, heating to 50 - 60 °C, then adding chitosan, stirring for 3 - 5 h, then adding ethyl 4-chloroacetoacetate and 3-chloro-2-hydroxypropyltrimethylammonium chloride, stirring for 20 - 24 h, adjusting the pH value to 6 - 7, cooling, filtering to remove the filtrate, washing, and drying to constant weight to obtain the modified chitosan.

[0012] Optionally, the weight ratio of chitosan, sodium hydroxide, ethyl 4-chloroacetoacetate, and 3-chloro-2-hydroxypropyltrimethylammonium chloride is 100:(95 - 105):(14 - 16):(14 - 16).

[0013] By adopting the above technical solution, first, chitosan is alkali-treated with sodium hydroxide to increase the active groups on the surface of chitosan, facilitating the grafting of chitosan. Then, ethyl 4-chloroacetoacetate and 3-chloro-2-hydroxypropyltrimethylammonium chloride are added and grafted to introduce cationic groups and polar groups on the surface of chitosan, enhancing the application effect of modified chitosan and improving the removal rates of organic matter and chromaticity in phenol-containing wastewater.

[0014] Optionally, the weight ratio of chitosan, water, and isopropanol is 100:(170 - 230):(370 - 430).

[0015] By adopting the above technical solution, the addition amounts of water and isopropanol are optimized, facilitating the preparation of modified chitosan.

[0016] Optionally, the deacetylation degree of chitosan is ≥85%.

[0017] By adopting the above technical solution, the deacetylation degree of chitosan is the proportion of the number of acetyl-free monomers in chitosan to the total amount of monomers. And the higher the deacetylation degree of chitosan, the better the activity of chitosan. Therefore, optimizing the deacetylation degree of chitosan facilitates the grafting and modification of chitosan.

[0018] In the second aspect, the present application provides a preparation method of a decolorizing aid for treating phenol-containing wastewater with activated carbon as described above, adopting the following technical solution:

[0019] A preparation method of a decolorizing aid for treating phenol-containing wastewater with activated carbon as described above, comprising the following steps: mixing polyaluminum chloride, polydimethyldiallylammonium chloride, modified chitosan, polyvinylpyrrolidone, polyacrylamide, and aminotrimethylenephosphonic acid to obtain the decolorizing aid.

[0020] By adopting the above technical solution, it is convenient to prepare the decolorizing aid.

[0021] In the third aspect, the present application provides an application of a decolorizing aid for treating phenol-containing wastewater with activated carbon as described above, adopting the following technical solution:

[0022] An application of a decolorizing aid for treating phenol-containing wastewater with activated carbon as described above, wherein the decolorizing aid is applied in a method for treating phenol-containing wastewater, and the phenol-containing wastewater is the phenol-containing wastewater produced during the separation of phenol-containing organic matter from the acidic hydrolysis solution of m-phenylenediamine.

[0023] Optionally, the method for treating phenol-containing wastewater includes the following steps:

[0024] T1. Prepare the phenol-containing wastewater, heat it to 70 - 80 °C, and set aside;

[0025] T2. Add solid fillers to the fixed bed, and then introduce phenol-containing wastewater into the fixed bed. Synchronously, introduce air into the fixed bed. The phenol-containing wastewater and air are mixed at the fixed fillers and react, and then are discharged after passing through the solid fillers to obtain a pretreatment liquid.

[0026] T3. While maintaining the temperature of the pretreatment liquid at 70 - 80, add a decolorizing aid to the pretreatment liquid, stir for 50 - 70 min, filter to remove the filter residue, then add activated carbon, stir for 50 - 70 min, filter to remove the filter residue, and obtain a treated liquid.

[0027] S3. Evaporate and concentrate the treated liquid, cool down, filter to remove the filtrate, and dry to constant weight to obtain ammonium sulfate.

[0028] By adopting the above technical solution, first oxidize the organic matter in the phenol-containing wastewater to turn it into a colored substance and obtain a pretreatment liquid. Then add a decolorizing aid to remove the organic matter and color in the pretreatment liquid by using the decolorizing aid. After that, add activated carbon to deeply remove the organic matter and color in the pretreatment liquid by using the activated carbon. In this application, the synergistic effect of the decolorizing aid and activated carbon is utilized to improve the removal rate of organic matter and color in the phenol-containing wastewater. Further, evaporate and concentrate the treated liquid, cool down to obtain ammonium sulfate, and improve the purity of ammonium sulfate.

[0029] Meanwhile, add the decolorizing aid first and then add the activated carbon, that is, add the decolorizing aid and activated carbon separately. At this time, it can effectively reduce the influence of the precipitate generated by the decolorizing aid on the activated carbon and also reduce the accumulation of the precipitate on the surface of the activated carbon. When the activated carbon is used for treatment, after the activated carbon adsorbs the colored substances and organic matter, treated activated carbon is obtained. The treated activated carbon can be further activated at high temperature to remove the colored substances and organic matter adsorbed by the activated carbon, realizing the recycling of the activated carbon.

[0030] Optionally, the weight ratio of the pretreatment liquid, decolorizing aid, and activated carbon is 2000:(1 - 3):(0.3 - 0.7).

[0031] By adopting the above technical solution, the addition amounts of the decolorizing aid and activated carbon are optimized to increase the stability of the treatment of phenol-containing wastewater.

[0032] In one embodiment, the weight ratio of the pretreatment liquid, decolorizing aid, and activated carbon is 2000:2:0.5. It can also be designed as one of 2000:1:0.7, 2000:3:0.3, 2000:1:0.3, 2000:3:0.7 according to needs.

[0033] Optionally, the color of the phenol-containing wastewater is 10000 - 30000 degrees, and the pH value is 6 - 7.

[0034] The phenolic wastewater contains ammonium sulfate, m-aminophenol, m-phenylenediamine, and resorcinol, and ammonium sulfate accounts for 30-40 wt% of the total amount of the phenolic wastewater, the content of m-aminophenol is 100-1000 mg / L, the content of m-phenylenediamine is 100-300 mg / L, and the content of resorcinol is 100-800 mg / L.

[0035] By adopting the above technical solution, the chromaticity, pH value, organic matter content, and ammonium sulfate content of the phenolic wastewater are optimized, and when the phenolic wastewater fluctuates within the above range, good organic matter removal rate and chromaticity removal rate are obtained, increasing the stability of the phenolic wastewater treatment.

[0036] In one embodiment, the chromaticity of the phenolic wastewater is 15,200 degrees, the pH value is 6.8, ammonium sulfate in the phenolic wastewater accounts for 33 wt% of the total amount of the phenolic wastewater, the content of m-aminophenol is 610 mg / L, the content of m-phenylenediamine is 190 mg / L, and the content of resorcinol is 420 mg / L.

[0037] Furthermore, in step T2, the filling height of the solid filler is 400-600 mm, the filling volume is 1500-2500 mL, and the average particle size of the solid filler is 1-10 mm. Preferably, the filling height of the solid filler is 500 mm, the filling volume is 2000 mL, and the average particle size of the solid filler is 5 mm.

[0038] Still further, the air flow rate is 100-200 mL / min, and the flow rate of the phenolic wastewater is 50-150 mL / min. Preferably, the air flow rate is 150 mL / min, and the flow rate of the phenolic wastewater is 100 mL / min.

[0039] In summary, the present application has at least the following beneficial effects: for the decolorization aid for decolorizing phenolic wastewater of the present application, polyaluminum chloride is added to the raw materials to increase the treatment effect of the phenolic wastewater. At the same time, polydimethyldiallylammonium chloride and modified chitosan are also added. In the modified chitosan, sodium hydroxide, ethyl 4-chloroacetoacetate, and 3-chloro-2-hydroxypropyltrimethylammonium chloride are used to increase the cationic groups and polar groups on the surface of chitosan. And the synergistic effect between polydimethyldiallylammonium chloride and modified chitosan is utilized to cooperate with the activated carbon adsorption. In the treatment of phenolic wastewater, the chromaticity removal rate of the phenolic wastewater > 98%, the m-aminophenol removal rate > 94%, the m-phenylenediamine removal rate > 96%, and the resorcinol removal rate > 91%, effectively increasing the chromaticity removal rate and the organic matter removal rate. Further, the purity of ammonium sulfate is increased, and the purity of ammonium sulfate > 99.5%, meeting the market demand. Detailed implementation mode

[0040] To make this application easier to understand, the following will further elaborate on this application in combination with embodiments. These embodiments are only illustrative and not limited to the application scope of this application. The raw materials or components used in this application can be obtained through commercial channels or conventional methods without special instructions.

[0041] Preparation Example

[0042] Preparation Example 1

[0043] A modified chitosan is prepared by the following method:

[0044] Add 100 g of sodium hydroxide to 200 g of water and stir for 30 min. Add 400 g of isopropanol and stir for 10 min. Heat up to 55 °C, then add 100 g of chitosan and stir for 4 h. Then add 15 g of ethyl 4-chloroacetoacetate and 15 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride and stir for 22 h. Adjust the pH value to 6.5 with a hydrochloric acid solution with a mass concentration of 20%. Cool down to 25 °C and filter to remove the filtrate. Wash three times with an ethanol solution with a mass concentration of 60%, and 200 g of the ethanol solution is used for each washing. Then dry at 55 °C to constant weight to obtain the modified chitosan.

[0045] Among them, the degree of deacetylation of chitosan is 90%, and it is selected from Qingdao Haipu Biotechnology Co., Ltd.

[0046] Preparation Example 2

[0047] A modified chitosan is prepared by the following method:

[0048] Add 95 g of sodium hydroxide to 170 g of water and stir for 30 min. Add 370 g of isopropanol and stir for 10 min. Heat up to 50 °C, then add 100 g of chitosan and stir for 3 h. Then add 14 g of ethyl 4-chloroacetoacetate and 16 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride and stir for 20 h. Adjust the pH value to 7 with a hydrochloric acid solution with a mass concentration of 15%. Cool down to 25 °C and filter to remove the filtrate. Wash three times with an ethanol solution with a mass concentration of 60%, and 200 g of the ethanol solution is used for each washing. Then dry at 50 °C to constant weight to obtain the modified chitosan.

[0049] Among them, the degree of deacetylation of chitosan is 90%, and it is selected from Qingdao Haipu Biotechnology Co., Ltd.

[0050] Preparation Example 3

[0051] A modified chitosan is prepared by the following method:

[0052] Add 105 g of sodium hydroxide to 230 g of water and stir for 30 min. Add 430 g of isopropanol and stir for 10 min. Heat up to 60 °C, then add 100 g of chitosan and stir for 5 h. Then add 16 g of ethyl 4-chloroacetoacetate and 14 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride and stir for 24 h. Adjust the pH value to 6 with a hydrochloric acid solution with a mass concentration of 25%. Cool down to 25 °C and filter to remove the filtrate. Wash three times with an ethanol solution with a mass concentration of 60%, and 200 g of the ethanol solution is used for each washing. Then dry at 60 °C to constant weight to obtain modified chitosan.

[0053] Among them, the degree of deacetylation of chitosan is 90%, and it is selected from Qingdao Haipu Biotechnology Co., Ltd.

[0054] Example

[0055] Table 1 Content of each raw material of the decolorizing aid (unit: g)

[0056]

[0057]

[0058] Example 1

[0059] A decolorizing aid for treating phenolic wastewater with activated carbon, and the raw material ratio is shown in Table 1.

[0060] Among them, the effective ingredient content of polyaluminum chloride is 30%, and it is selected from Henan Shuanglong Water Treatment Materials Co., Ltd.; the effective ingredient content of polydimethyldiallylammonium chloride is 90%, and it is selected from Zhejiang Dachuan New Materials Co., Ltd.; polyvinylpyrrolidone is PVP-K30, and it is selected from Shandong Qiansheng Chemical Co., Ltd.; polyacrylamide is non-ionic polyacrylamide, and it is selected from Guangdong Shouxin Environmental Protection Materials Technology Co., Ltd.; the modified chitosan is obtained by using Preparation Example 1.

[0061] A preparation method of a decolorizing aid for treating phenolic wastewater with activated carbon, comprising the following steps:

[0062] Add polydimethyldiallylammonium chloride, modified chitosan, polyvinylpyrrolidone, polyacrylamide, and aminotrimethylenephosphonic acid to polyaluminum chloride and stir for 10 min to obtain the decolorizing aid.

[0063] Examples 2-3

[0064] A decolorizing aid for treating phenolic wastewater with activated carbon, and the difference from Example 1 is that the raw material ratio of the decolorizing aid is different, and the raw material ratio of the decolorizing aid is shown in Table 1.

[0065] Example 4

[0066] A decolorizing aid for treating phenolic wastewater with activated carbon, the difference between it and Example 1 is that in the raw materials of the decolorizing aid, the source of the modified chitosan is different, and the modified chitosan is obtained by using Preparation Example 2.

[0067] Example 5

[0068] A decolorizing aid for treating phenolic wastewater with activated carbon, the difference between it and Example 1 is that in the raw materials of the decolorizing aid, the source of the modified chitosan is different, and the modified chitosan is obtained by using Preparation Example 3.

[0069] Comparative example

[0070] Comparative Example 1

[0071] A decolorizing aid for treating phenolic wastewater with activated carbon, the difference between it and Example 1 is that in the raw materials of the decolorizing aid, an equal amount of polyaluminum chloride is used to replace polydimethyldiallylammonium chloride and modified chitosan.

[0072] Comparative Example 2

[0073] A decolorizing aid for treating phenolic wastewater with activated carbon, the difference between it and Example 1 is that in the raw materials of the decolorizing aid, an equal amount of polydimethyldiallylammonium chloride is used to replace the modified chitosan.

[0074] Comparative Example 3

[0075] A decolorizing aid for treating phenolic wastewater with activated carbon, the difference between it and Example 1 is that in the raw materials of the decolorizing aid, an equal amount of chitosan is used to replace polydimethyldiallylammonium chloride and modified chitosan.

[0076] Comparative Example 4

[0077] A decolorizing aid for treating phenolic wastewater with activated carbon, the difference between it and Example 1 is that in the raw materials of the decolorizing aid, an equal amount of chitosan is used to replace the modified chitosan.

[0078] Comparative Example 5

[0079] A decolorizing aid for treating phenolic wastewater with activated carbon, the difference between it and Example 1 is that in the preparation of the modified chitosan, an equal amount of ethyl 4-chloroacetoacetate is used to replace 3-chloro-2-hydroxypropyltrimethylammonium chloride.

[0080] Comparative Example 6

[0081] A decolorizing aid for treating phenolic wastewater with activated carbon, the difference between it and Example 1 is that in the preparation of the modified chitosan, an equal amount of 3-chloro-2-hydroxypropyltrimethylammonium chloride is used to replace ethyl 4-chloroacetoacetate.

[0082] Application Example

[0083] Application Example 1

[0084] A method for treating phenol-containing wastewater, comprising the following steps:

[0085] T1. Prepare phenol-containing wastewater, heat it to 75 °C, and set aside.

[0086] Among them, the chromaticity of the phenol-containing wastewater is 15,200 degrees, the pH value is 6.8, ammonium sulfate in the phenol-containing wastewater accounts for 33 wt% of the total amount of the phenol-containing wastewater, the content of m-aminophenol is 610 mg / L, the content of m-phenylenediamine is 190 mg / L, and the content of resorcinol is 420 mg / L.

[0087] T2. Add solid filler to the fixed bed, and then introduce phenol-containing wastewater into the fixed bed from the water inlet at the bottom of the fixed bed at a rate of 100 mL / min. Synchronously, introduce air into the fixed bed from the air inlet at the bottom of the fixed bed at a rate of 150 mL / min. The phenol-containing wastewater and air in the fixed bed are mixed at the fixed filler and react. Then, it rises to the top of the fixed bed through the solid filler and undergoes gas-liquid separation. The gas is discharged from the exhaust port at the top of the fixed bed, and the liquid is discharged from the liquid discharge port at the top of the fixed bed to obtain a pretreatment liquid.

[0088] Among them, the volume of the solid filler in the fixed bed is 2000 mL, the height is 500 mm, and the solid filler is zeolite with an average particle size of 5 mm, selected from Xinyang Mingyou Industrial Co., Ltd.

[0089] T3. While maintaining the temperature of the pretreatment liquid at 75 °C, add 2 g of decolorizing aid to 2000 g of the pretreatment liquid, stir for 60 min, and filter to remove the filter residue. Then add 0.5 g of activated carbon, stir for 60 min, and filter to remove the filter residue to obtain a treated liquid.

[0090] Among them, the decolorizing aid is prepared according to Example 1. The activated carbon is coconut shell activated carbon with an average particle size of 50 μm, and the iodine value of the activated carbon is 1200 mg / g, selected from Shanghai Xitan Environmental Protection Technology Co., Ltd.

[0091] T4. Evaporate and concentrate the treated liquid to 1 / 10 of the original volume, cool it to 3 °C, and filter to remove the filtrate. Then, dry it to constant weight at a temperature of 90 °C to obtain ammonium sulfate.

[0092] Application Examples 2 - 5

[0093] A method for treating phenol-containing wastewater, which is different from Application Example 1 in that in step T3, the source of the decolorizing aid is different, and the decolorizing aids of Application Examples 2 - 5 are respectively prepared according to Examples 2 - 5.

[0094] Comparative Application Example

[0095] Comparative Application Examples 1-6

[0096] A method for treating phenolic wastewater, which is different from Application Example 1 in that in step T3, the source of the decolorizing aid is different, and the decolorizing aids in Comparative Application Examples 1-6 are sequentially obtained by using Comparative Examples 1-6 for preparation.

[0097] Performance Detection Test

[0098] (1) Respectively take the treatment liquids obtained in step T3 of Application Examples 1-5 and Comparative Application Examples 1-6 as samples, and conduct the following performance detections on the samples. The detection results are shown in Table 2.

[0099] Among them, according to GB / T11903-89 "Determination of Chromaticity of Water Quality", the chromaticity of the sample is detected.

[0100] Use an LC-10AT high-performance liquid chromatography analyzer to detect the content of m-aminophenol, m-phenylenediamine, and resorcinol in the sample.

[0101] (2) Respectively take the ammonium sulfate obtained in step T4 of Application Examples 1-5 and Comparative Application Examples 1-6 as samples, and conduct the following performance detections on the samples. The detection results are shown in Table 2.

[0102] Among them, according to GB / T535-2020 "Fertilizer Grade Ammonium Sulfate", the purity of the sample is detected.

[0103] Table 2 Detection Results

[0104]

[0105]

[0106] As can be seen from Table 2, when the decolorizing aid of the present application is applied to the treatment of phenolic wastewater, the chromaticity of the treatment liquid is 20-280 degrees, the content of m-aminophenol is 26.5-35.1 mg / L, the content of m-phenylenediamine is 4.8-7.4 mg / L, the content of resorcinol is 32.1-36.8 mg / L, and the chromaticity removal rate of the phenolic wastewater is 98.16-99.87%, the m-aminophenol removal rate is 94.25-95.66%, the m-phenylenediamine removal rate is 96.11-97.47%, and the resorcinol removal rate is 91.24-92.36%, effectively increasing the chromaticity removal rate and the organic matter removal rate. Further, the purity of ammonium sulfate is improved, and the purity of ammonium sulfate is 99.55-99.93%, meeting the market demand.

[0107] Compare Comparative Application Examples 1-4, with Comparative Application Example 1 as the basis. Compared with Comparative Application Example 1, in the raw materials of the decolorization aid in Comparative Application Example 2, polydimethyldiallylammonium chloride is added; compared with Comparative Application Example 1, in the raw materials of the decolorization aid in Comparative Application Example 3, chitosan is added; compared with Comparative Application Example 1, in the raw materials of the decolorization aid in Comparative Application Example 4, polydimethyldiallylammonium chloride and chitosan are added. It can be seen from this that by adding polydimethyldiallylammonium chloride and chitosan simultaneously in the raw materials of the decolorization aid and through their synergistic effect, the chromaticity removal rate and organic matter removal rate of phenol-containing wastewater are significantly increased. Combining with Application Example 1, it can be seen from this that by modifying chitosan, the use effect of the decolorization aid can be further enhanced.

[0108] Compare Application Example 1 with Comparative Application Examples 4-6, with Comparative Application Example 4 as the basis. Compared with Comparative Application Example 4, in Comparative Application Example 5, chitosan is obtained by modification with sodium hydroxide and ethyl 4-chloroacetoacetate; compared with Comparative Application Example 4, in Comparative Application Example 6, chitosan is obtained by modification with sodium hydroxide and 3-chloro-2-hydroxypropyltrimethylammonium chloride; compared with Comparative Application Example 4, in Application Example 1, chitosan is obtained by modification with sodium hydroxide, ethyl 4-chloroacetoacetate, and 3-chloro-2-hydroxypropyltrimethylammonium chloride. It can be seen from this that in the modification treatment of chitosan, ethyl 4-chloroacetoacetate and 3-chloro-2-hydroxypropyltrimethylammonium chloride are simultaneously grafted onto the surface of chitosan, and by using their synergistic effect, the chromaticity removal rate, m-aminophenol removal rate, m-phenylenediamine removal rate, and resorcinol removal rate are further improved, and the purity of ammonium sulfate is increased, and the purity of ammonium sulfate > 99.5%.

[0109] It should be noted that the above-described embodiments are only used to explain the present application and do not constitute any limitation to the present application. The present application has been described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. Modifications can be made to the present application within the scope of the claims of the present application as stipulated, and the present invention can be revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials, and embodiments, it does not mean that the present application is limited to the specific examples disclosed therein. On the contrary, the present application can be extended to all other methods and applications with the same function.

Claims

1. Application of a decolorizing aid for treating phenolic wastewater with activated carbon, characterized in that: The decolorizing aid is applied to the phenol-containing wastewater treatment method, and the phenol-containing wastewater is the phenol-containing wastewater produced in the process of separating phenol-containing organic substances from the acidic hydrolysis solution of m-phenylenediamine; The phenol-containing wastewater treatment method includes the following steps: T1. Prepare the phenol-containing wastewater, heat it up to 70-80 °C, and set aside; T2. Add solid fillers to the fixed bed, and then introduce the phenol-containing wastewater into the fixed bed. Synchronously, introduce air into the fixed bed. The phenol-containing wastewater and air are mixed at the fixed fillers and react, and then are discharged after passing through the solid fillers to obtain a pretreatment liquid; T3. While maintaining the temperature of the pretreatment liquid at 70-80 °C, add a decolorizing aid to the pretreatment liquid, stir for 50-70 min, filter to remove the filter residue, then add activated carbon, stir for 50-70 min, filter to remove the filter residue, and obtain a treatment liquid; S3. Evaporate and concentrate the treatment liquid, cool down, filter to remove the filtrate, and dry it to constant weight to obtain ammonium sulfate; The chromaticity of the phenol-containing wastewater is 10,000-30,000 degrees, and the pH value is 6-7; the phenol-containing wastewater contains ammonium sulfate, m-aminophenol, m-phenylenediamine, and resorcinol, and ammonium sulfate accounts for 30-40 wt% of the total amount of the phenol-containing wastewater, the content of m-aminophenol is 100-1000 mg / L, the content of m-phenylenediamine is 100-300 mg / L, and the content of resorcinol is 100-800 mg / L; The filling height of the solid filler is 400-600 mm, the filling volume is 1500-2500 mL, and the average particle size of the solid filler is 1-10 mm; the air flow rate is 100-200 mL / min, and the phenol-containing wastewater flow rate is 50-150 mL / min; The weight ratio of the pretreatment liquid, decolorizing aid, and activated carbon is 2000:(1-3):(0.3-0.7); The decolorizing aid is mainly made of the following raw materials in parts by weight: 25-35 parts of polyaluminum chloride, 20-30 parts of polydimethyldiallylammonium chloride, 9-11 parts of modified chitosan, 13-17 parts of polyvinylpyrrolidone, 13-17 parts of polyacrylamide, and 6-4 parts of aminotrimethylenephosphonic acid; the modified chitosan is obtained by treating chitosan with sodium hydroxide, ethyl 4-chloroacetoacetate, and 3-chloro-2-hydroxypropyltrimethylammonium chloride.

2. A decolorizing aid for treating phenol-containing wastewater with activated carbon according to claim 1, characterized in that: The modified chitosan is prepared by the following method: Add sodium hydroxide to water and mix, add isopropanol and mix, heat up to 50-60 °C, then add chitosan, stir for 3-5 h, then add ethyl 4-chloroacetoacetate and 3-chloro-2-hydroxypropyltrimethylammonium chloride, stir for 20-24 h, adjust the pH value to 6-7, cool down, filter to remove the filtrate, wash, and dry to constant weight to obtain modified chitosan.

3. A decolorizing aid for treating phenolic wastewater with activated carbon according to claim 2, characterized in that: The weight ratio of chitosan, sodium hydroxide, ethyl 4-chloroacetoacetate, and 3-chloro-2-hydroxypropyltrimethylammonium chloride is 100:(95-105):(14-16):(14-16).

4. A decolorizing aid for treating phenolic wastewater with activated carbon according to claim 3, characterized in that: The weight ratio of chitosan, water, and isopropanol is 100:(170-230):(370-430).

5. A decolorizing aid for treating phenolic wastewater with activated carbon according to claim 1, characterized in that: The deacetylation degree of the chitosan ≥ 85%.

6. A preparation method of a decolorizing aid for treating phenolic wastewater with activated carbon as described in any one of claims 1-5, characterized in that: It includes the following steps: Mix polyaluminum chloride, polydimethyldiallylammonium chloride, modified chitosan, polyvinylpyrrolidone, polyacrylamide, and aminotrimethylenephosphonic acid to obtain a decolorizing aid.

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