A method for recycling and refining hazardous waste chloroacetic acid

Abstract

The present invention relates to the technical field of industrial waste liquid recycling and utilization, and discloses a method for recovering and refining hazardous waste chloroacetic acid, which comprises the following steps: (1) quantitatively analyzing the components and contents of the hazardous waste chloroacetic acid solution by using a plasma emission spectrometer, an ion chromatograph, a gas chromatography-mass spectrometry instrument and a gas chromatograph; (2) quantitatively analyzing the insoluble impurities in the hazardous waste chloroacetic acid solution; (3) adsorbing metal ions in the chloroacetic acid solution by using an ion exchange resin; (4) rectifying the adsorbed chloroacetic acid solution by using a rectifying device to separate chloroacetic acid and water. The process of the present invention has low cost and few steps, and the prepared chloroacetic acid has high purity and few impurities.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial waste liquid recycling, and particularly relates to a method for recycling and refining hazardous waste chloroacetic acid. Background Art

[0002] As an intermediate for dyes, pharmaceuticals, pesticides, synthetic resins and other organic synthesis materials, chloroacetic acid is an important chemical raw material. Each year, about 650,000 tons of chloroacetic acid are consumed in China. However, due to the low purity of domestic chloroacetic acid and the serious dependence on imported high-purity chloroacetic acid, China's chloroacetic acid still faces a serious structural shortage. The large-scale industrial production of chloroacetic acid in China mainly adopts the acetic acid catalytic chlorination process. The acetic acid catalytic chlorination process is simple, has small investment and flexible operation. However, the acetic acid catalytic chlorination process consumes a large amount of raw materials, generates serious three wastes pollution, has low yield and purity of chloroacetic acid and a long production cycle, which severely restricts the development of the chloroacetic acid industry.

[0003] The acetic acid catalytic chlorination process includes two types: batch chlorination method and continuous chlorination method. The batch chlorination method is mostly used in the industrial production of chloroacetic acid. During the production process of chloroacetic acid, hazardous waste chloroacetic acid will be generated, which belongs to industrial hazardous waste. The generated hazardous waste chloroacetic acid is mostly a chloroacetic acid mother liquor composed of components such as acetic acid, monochloroacetic acid, and dichloroacetic acid. Moreover, most of the hazardous waste chloroacetic acid generated by enterprises is stored in barrels outdoors and cannot be recycled, which has a great impact on the enterprise environment and subsequent production.

[0004] For the low-purity chloroacetic acid produced by the acetic acid catalytic chlorination method, the industrial method mainly uses crystallization method and hydrogenation method to process it to achieve the purpose of improving the yield and purity. The crystallization method has a simple process and low investment cost, but the product yield and product purity after being processed by the crystallization method are still low and difficult to meet the specified standards, and this defect will affect the development of downstream products of chloroacetic acid; the hydrogenation method is mainly used to reduce impurities such as dichloroacetic acid and trichloroacetic acid, so it can only be applied to the recovery and purification of specific chloroacetic acid products.

[0005] At present, there are still many problems in the production process of chloroacetic acid recovery and purification. For example, the impurity content in chloroacetic acid products of different production batches is different, which not only increases the processing difficulty of chloroacetic acid products, raises the production cost and causes waste of resources, but also leads to the destruction of the ecological environment, making the market competitiveness of chloroacetic acid products gradually decline. With the development of the chloroacetic acid industry and the increasing demand at home and abroad, how to treat hazardous waste chloroacetic acid and effectively utilize its residual value has become one of the key factors for survival in the chloroacetic acid industry. Summary of the Invention

[0006] The purpose of the present invention is to solve the above problems, and provide a method for recycling and refining hazardous waste chloroacetic acid, which has a low process cost, few steps, high purity and few impurities of the obtained chloroacetic acid.

[0007] The technical solution adopted by the present invention is:

[0008] A method for recovering and refining hazardous waste chloroacetic acid, characterized in that it comprises the following steps:

[0009] (1) Quantitative analysis of the components and content of hazardous waste chloroacetic acid solution using plasma emission spectrometer, ion chromatograph, gas chromatography-mass spectrometer and gas chromatograph;

[0010] (2) Quantitative analysis of insoluble impurities in hazardous waste chloroacetic acid solution;

[0011] (3) using ion exchange resin to adsorb metal ions in chloroacetic acid solution;

[0012] (4) Using a distillation device to distill the adsorbed chloroacetic acid solution to separate chloroacetic acid and water.

[0013] Furthermore, the hazardous waste chloroacetic acid solution is a 10-30% aqueous solution prepared by adding water to a hazardous waste chloroacetic acid sample.

[0014] Furthermore, the bottom temperature of the distillation device is 120-150° C., and the reflux ratio R=1.

[0015] Furthermore, the plasma emission spectrometer is used to analyze the metal elements in the hazardous waste chloroacetic acid solution; the ion chromatograph is used to analyze the non-metallic elements in the hazardous waste chloroacetic acid solution; the gas chromatography-mass spectrometry is used to perform qualitative analysis of the organic matter in the hazardous waste chloroacetic acid solution; and the gas chromatograph is used to perform quantitative analysis of the organic matter in the hazardous waste chloroacetic acid solution.

[0016] Furthermore, in step (2), after the hazardous waste chloroacetic acid solution is centrifuged, the supernatant is taken out, deionized water is added to the centrifuge tube, and the residue is repeatedly centrifuged and washed until the solution is clear, and the cleaned insoluble impurities are placed in an oven for drying and weighing.

[0017] Furthermore, in step (3), the ion exchange resin is pretreated, and the processing steps are:

[0018] (31) Take a certain amount of ion exchange resin and place it in 4-6 volumes of deionized water for washing until the solution is clear;

[0019] (32) Soak the cleaned ion exchange resin in 2-3 times the volume of methanol solution for 2-3 hours.

[0020] (33) After soaking, the ion exchange resin was rinsed with a large amount of methanol until the solution was clear;

[0021] (34) After the ion exchange resin is cleaned, the water is drained by a vacuum pump;

[0022] (35) The processed ion exchange resin is placed in an oven at 100 - 120 °C and dried for 6 - 8 hours for standby.

[0023] Further, the adsorption method in the step (3) is one of static adsorption of anion resin, static adsorption of cation resin, series static adsorption of anion and cation resins, and series dynamic adsorption of anion and cation resins.

[0024] Further, the adsorption method in the step (3) is series static adsorption of anion or cation resins. The process is as follows: Take 50 g of the centrifuged hazardous waste chloroacetic acid solution and add it to a 200 - 300 mL conical flask, add the pretreated ion exchange resin, place the conical flask on a mechanical shaker, and set the rotation speed to 150 - 250 r / min for adsorption for 2 - 2.5 hours.

[0025] Further, the adsorption method in the step (3) is series static adsorption of anion and cation resins. The process is as follows: Take 50 g of the centrifuged hazardous waste chloroacetic acid solution and add it to a 200 - 300 mL conical flask, add 8 - 10 g of the pretreated anion resin, place the conical flask on a mechanical shaker, and set the rotation speed to 150 - 250 r / min for adsorption for 2 - 2.5 hours. After the adsorption is completed, use a vacuum filtration device to separate the hazardous waste chloroacetic acid solution and the anion resin. Add 4 - 5 g of the pretreated cation resin to the separated hazardous waste chloroacetic acid solution, and continue to place it on the mechanical shaker for adsorption for 2 - 2.5 hours.

[0026] Further, the adsorption method in the step (3) is series dynamic adsorption of anion and cation resins, which is completed by using a dynamic adsorption device. The dynamic adsorption device includes four columns A, B, C, and D arranged side by side. The upper end of column A is the inlet, the lower end of column A is connected to the lower end of column B through a connecting pipe, the upper end of column B is connected to the upper end of column C through a connecting pipe, the lower end of column C is connected to the lower end of column D through a connecting pipe, and the upper end of column D is the outlet.

[0027] The adsorption process is as follows: The hazardous waste chloroacetic acid solution is controlled by a flow pump for the flow rate, enters the dynamic adsorption device from the inlet of column A, enters column B from the bottom through the connecting pipe between column A and column B. The packing in column B is anion resin. After penetrating through the anion resin bed, it enters column C, enters column D from the bottom through the connecting pipe between column C and column D. The packing in column D is cation resin. The hazardous waste chloroacetic acid solution penetrates through the cation resin bed and is output and recovered from the outlet of column D.

[0028] The beneficial effects of the present invention are:

[0029] (1) The chloroacetic acid prepared by the present invention has few impurities and high purity. After separation, the chloroacetic acid can be sold as a product or esterified to form methyl chloroacetate, making the treatment of hazardous waste chloroacetic acid more flexible;

[0030] (2) The process of the present invention has the advantages of simple process, high resource utilization rate, and low energy consumption, and has good application prospects and academic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attached Figure 1 is a schematic diagram of the dynamic adsorption device of the ion exchange resin of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] The following describes in detail the specific implementation manners of a method for recycling and refining hazardous waste chloroacetic acid of the present invention in conjunction with the drawings.

[0033] The examples illustrate the recovery and refining processes of chloroacetic acid through experiments.

[0034] First, a plasma emission spectrometer (ICP) is used to analyze the metal elements in the hazardous waste chloroacetic acid sample:

[0035] Take 5 g of the hazardous waste chloroacetic acid sample and dissolve it in 20 g of deionized water to prepare a solution with a sample mass fraction of 20%. The prepared sample solution is analyzed by ICP. First, qualitative analysis of the sample solution is carried out, and it is measured that the prepared sample solution contains Fe ions and K ions within the detection range of ICP. Then, quantitative analysis of the prepared sample solution is carried out, and it is measured that the content of Fe ions in the sample solution is 520 mg / kg, and the content of K ions is 2 mg / kg. From this, it can be calculated that the content of Fe ions in the hazardous waste chloroacetic acid sample is 2600 mg / kg, and the content of K ions is 10 mg / kg.

[0036] An ion chromatograph (Ion Chromatography) is used to analyze the non-metal elements in the hazardous waste chloroacetic acid:

[0037] Take 5 g of the hazardous waste chloroacetic acid sample and dissolve it in 20 g of deionized water to prepare a solution with a sample mass fraction of 20%. The prepared sample solution is analyzed by ion chromatography. First, qualitative analysis of the sample solution is carried out, and it is measured that the prepared sample solution contains F - , Cl - , NO3 - , SO4 2- , PO4 3- plasma. Then, quantitative analysis of the prepared sample solution is carried out, and it is measured that the content of F - is 1 mg / kg, the content of Cl - is 2400 mg / kg, and the content of NO3- The content of 2- is 60 mg / kg, and the content of PO4 3- is 5 mg / kg. From this, the content of non-metallic elements in the hazardous waste chloroacetic acid sample can be calculated as shown in Table 1.

[0038] Table 1

[0039] Content (mg / kg) Mass fraction (%) <![CDATA[F - > 5 0.0005 <![CDATA[Cl - > 12000 1.2 <![CDATA[NO3 - > 50 0.005 <![CDATA[SO4 2- > 300 0.03 <![CDATA[PO4 3- > 25 0.0025

[0040] Qualitative analysis of the organic substances in the hazardous waste chloroacetic acid was carried out using a gas chromatography-mass spectrometry (GC-MS):

[0041] By analyzing the gas chromatography-mass spectrometry diagram, the organic substance components in the hazardous waste chloroacetic acid sample can be qualitatively determined. The qualitative analysis results of the hazardous waste chloroacetic acid are shown in Table 2.

[0042] Table 2

[0043] Component CAS Methyl chloroacetate 96-34-4 1,4-Dioxane-2,5-dione 502-97-6 Methyl acetate 79-20-9 Ethyl chloroacetate 105-39-5 Bicyclo[2.2.1]heptane 279-23-2 Acetoxyacetic acid 13831-30-6 Dichloroacetic acid 79-43-6 3,5-Dihydroxytoluene 504-15-4

[0044] Quantitative analysis of the organic substances in the hazardous waste chloroacetic acid was carried out using a gas chromatograph (GC):

[0045] Standard solutions with mass ratios of chloroacetic acid to acetic acid of 0.5:1, 1:1, 2:1, 3:1, and 4:1 were prepared. The five concentration-level standard solutions were injected into the gas chromatograph for analysis under the same chromatographic conditions, and gas chromatograms at different standard concentrations could be obtained. By analyzing the chloroacetic acid and acetic acid chromatograms, with the mass ratio of chloroacetic acid to acetic acid as the y-axis and the peak area ratio of chloroacetic acid to acetic acid as the x-axis, an internal standard curve was plotted, and the linear regression equation was obtained, which is the internal standard formula for chloroacetic acid - acetic acid.

[0046] 10 g of the hazardous waste chloroacetic acid and 7.5 g of acetic acid were taken to prepare a sample solution, which was analyzed using gas chromatography. The peak area ratio of chloroacetic acid to acetic acid in the gas chromatogram was calculated and substituted into the chloroacetic acid internal standard curve to calculate the mass ratio of chloroacetic acid to acetic acid, and thus the content of chloroacetic acid in the hazardous waste chloroacetic acid was calculated to be 81.92%.

[0047] Benzene was selected as the internal standard for methyl chloroacetate to plot the internal standard curve for methyl chloroacetate. Standard solutions with mass ratios of methyl chloroacetate to benzene of 2:1, 3:1, 4:1, 5:1, and 6:1 were prepared. The five concentration-level standard solutions were analyzed under the same chromatographic conditions, and the gas chromatogram results at different standard concentrations could be obtained. By analyzing the methyl chloroacetate and benzene chromatograms, with the mass ratio of methyl chloroacetate to benzene as the y-axis and the peak area ratio of methyl chloroacetate to benzene as the x-axis, an internal standard curve was plotted, and the linear regression equation was obtained, which is the internal standard formula for methyl chloroacetate - benzene.

[0048] After taking 10 g of hazardous waste chloroacetic acid and heating it to 40 °C for dissolution, 0.8 g of benzene was added to prepare a sample solution, which was analyzed by gas chromatography. The peak area ratio of methyl chloroacetate and benzene in the gas chromatogram was calculated and substituted into the internal standard curve of methyl chloroacetate to calculate the mass ratio of methyl chloroacetate and benzene, so that the content of methyl chloroacetate in the hazardous waste chloroacetic acid could be calculated to be 7.86%.

[0049] Dissolve 200 g of hazardous waste chloroacetic acid in 200 g of water, and centrifuge to separate the insoluble impurities. Centrifuge at a speed of 4500 r / min for 8 min, take out the supernatant, add deionized water to the centrifuge tube, and repeatedly centrifuge and wash the residue until the solution is clear. Put the washed insoluble impurities into the oven for drying and weighing. From this, the content of insoluble impurities in the hazardous waste chloroacetic acid was calculated to be 0.93%.

[0050] By methods such as internal standard method, centrifugal separation, drying and weighing to measure constant weight, the contents of each component in the hazardous waste chloroacetic acid were measured as shown in Table 3.

[0051] Table 3

[0052] Component CAS Content (%) Chloroacetic acid 79-11-8 81.92 Methyl chloroacetate 96-34-4 7.86 Methyl acetate 79-20-9 2.31 Ethyl chloroacetate 105-39-5 2.17 Water 7732-18-5 3.86 Other organic matters - <1 Insoluble impurities - 0.93

[0053] From the results of qualitative and quantitative analysis of elements in the hazardous waste chloroacetic acid, it can be seen that the value of R in the hazardous waste chloroacetic acid is relatively large. Therefore, the complex ions formed by Cl and Fe in the solution are mainly [FeCl4] and a small amount of [Fe(H2O)5Cl], among which the ion exchange potential of [FeCl4] is relatively high and it is more likely to undergo ion exchange. Based on the existence and characteristics of [FeCl4] and [Fe(H2O)5Cl] in the hazardous waste chloroacetic acid solution, the optimal scheme for Fe ion removal was determined. Cl / Fe has a relatively large value, so the complex ions formed by Cl - and Fe 3+ in the solution are mainly [FeCl4] - and a small amount of [Fe(H2O)5Cl 2 + , among which the ion exchange potential of [FeCl4] - is relatively high and it is more likely to undergo ion exchange. Based on the existence of [FeCl4] - and [Fe(H2O)5Cl 2 + in the hazardous waste chloroacetic acid solution and their characteristics, the optimal scheme for Fe ion removal was determined.

[0054] The skeleton structure of D201 anion resin is styrene - divinylbenzene, which is a strongly basic macroporous resin. Research shows that the D201 resin has a very significant effect on the removal of Fe ions from waste acid solutions. Therefore, D201 resin was selected for the adsorption study of [FeCl4] - in the hazardous waste chloroacetic acid solution.

[0055] ​​The 732(001×7) cationic resin is an ion exchange resin prepared by inserting sulfonic acid groups (-SO3H) into the styrene-divinylbenzene copolymer backbone structure. It has the advantages of high mechanical strength, large exchange capacity, and fast exchange rate. Therefore, 732 resin was selected for the adsorption study of [Fe(H2O)5Cl 2 + in the hazardous waste chloroacetic acid solution.

[0056] Take a certain amount of ion exchange resin, put it into deionized water with a volume 4-6 times that of the resin for cleaning. Place the cleaning solution on a magnetic stirrer and stir to accelerate the cleaning speed. Repeat the cleaning of the ion exchange resin until the solution is clear. Immerse the cleaned resin in a methanol solution with a volume 2-3 times that of the resin for 2-3 hours to remove the residual organic matter during the resin production process. After immersion, rinse the resin with a large amount of methanol until the solution is clear. Then use a vacuum pump to drain the water from the cleaned resin. Place the processed ion exchange resin in an oven at about 100-120 °C and dry it for 6-8 hours. After drying, pack the resin and store it in a dry place for later use.

[0057] Since there are a small amount of insoluble impurities in the hazardous waste chloroacetic acid, which will affect the adsorption process, they are removed by centrifugation. Take the hazardous waste chloroacetic acid solution after centrifugation and analyze the content of Fe ions in the solution. The experimental measurement shows that the content of Fe ions in the solution is 1280 mg / kg.

[0058] The static adsorption method was used for the experiment, and D201 resin was used to adsorb [FeCl4] - in the solution. Take five portions of 50 g of the centrifuged hazardous waste chloroacetic acid solution and add them to 250 mL conical flasks, and add 2 g, 4 g, 6 g, 8 g, and 10 g of pretreated D201 resin respectively. Place the conical flasks on a mechanical oscillator, set the rotation speed to 150-250 r / min and adsorb for 2-2.5 hours. After adsorption, take samples to detect the content of Fe ions in the solution and calculate the adsorption capacity of D201 resin.

[0059] As the amount of D201 resin used increases, the content of Fe ions in the hazardous waste chloroacetic acid solution gradually decreases. When the amount of D201 resin used reaches 8 g, continuing to increase the amount of resin used, the content of Fe ions no longer changes significantly. Therefore, 8 g is selected as the optimal dosage of D201 resin, and at this time, the content of Fe ions in the solution is 560 mg / kg.

[0060] The static adsorption method was used for the experiment, and 732 resin was used to adsorb [Fe(H2O)5Cl 2 + ​​Adsorption was carried out. Five portions of 50 g each of the centrifuged hazardous waste chloroacetic acid solution were added to 250 mL conical flasks, and 2 g, 4 g, 6 g, 8 g, and 10 g of pretreated 732 resin were added respectively. The conical flasks were placed on a mechanical shaker and adsorbed for 120 min at a rotation speed of 200 r / min. After the adsorption was completed, samples were taken to detect the Fe ion content in the solution, and the adsorption capacity of the 732 resin was calculated.

[0061] As the dosage of 732 resin increased, the Fe ion content in the hazardous waste chloroacetic acid solution gradually decreased. When the dosage of 732 resin reached 4 g, continuing to increase the resin dosage, the Fe ion content in the solution no longer changed significantly. Therefore, 4 g was selected as the optimal dosage of 732 resin, and at this time, the Fe ion content in the solution was 1040 mg / kg.

[0062] An experiment on the tandem adsorption of anion and cation exchange resins was carried out: 50 g of the centrifuged hazardous waste chloroacetic acid solution was added to a 250 mL conical flask, and 8 g of pretreated D201 resin was added. The conical flask was placed on a mechanical shaker and adsorbed for 120 min at a rotation speed of 200 r / min. After the adsorption was completed, the hazardous waste chloroacetic acid solution and D201 resin were separated by a vacuum filtration device. 4 g of pretreated 732 resin was added to the separated hazardous waste chloroacetic acid solution, and it was continued to be placed on the mechanical shaker for adsorption for 120 min. After the adsorption was completed, samples were taken to detect the Fe ion content in the solution, and the measured result was 420 mg / kg. The removal rate of Fe ions in the solution was 67%.

[0063] A dynamic adsorption experiment was carried out by the tandem adsorption method of D201 resin and 732 resin.

[0064] The diagram of the dynamic adsorption device is as Figure 1 shown. It includes four columns ABCD arranged side by side. The upper end of column A is the inlet. The lower end of column A is connected to the lower end of column B through a connecting pipe. The upper end of column B is connected to the upper end of column C through a connecting pipe. The lower end of column C is connected to the lower end of column D through a connecting pipe. The upper end of column D is the outlet. Valves are provided on each connecting pipe to control the experimental process.

[0065] The hazardous waste chloroacetic acid solution is controlled by a flow pump to enter the adsorption device from the left inlet of column A, enters column B from the bottom through the connecting pipe between A and B. The packing in column B is D201 resin. After penetrating the D201 resin bed, it enters column C, enters column D from the bottom through the connecting pipe between C and D columns. The packing in column D is 732 resin. The hazardous waste chloroacetic acid solution is taken out and recycled from the right outlet of column D after penetrating the 732 resin bed.

[0066] Use D201 resin and 732 resin for [FeCl4] in the solution - and [Fe(H2O)5Cl2 + Adsorption was carried out. The inner diameter of the adsorption column was 32 mm and the height was 280 mm. The resin bed heights in the adsorption column were 30 mm, 60 mm, 90 mm, 120 mm, and 150 mm respectively. The initial Fe ion content in the solution was 1280 mg / kg. 600 mL of the hazardous waste chloroacetic acid solution was passed into the adsorption column at a flow rate of 4 mL / min. The hazardous waste chloroacetic acid solution gradually penetrated the resin bed from the bottom of the adsorption column, and the Fe ion content in the solution passing through the resin bed was measured.

[0067] The bed height of D201 resin was selected as 120 mm and the bed height of 732 resin was 60 mm for a series adsorption experiment. 600 mL of the hazardous waste chloroacetic acid solution was passed into the adsorption column at a flow rate of 4 mL / min, so that the hazardous waste chloroacetic acid solution penetrated the D201 resin bed and the 732 resin bed successively. After the hazardous waste chloroacetic acid solution penetrated the 732 resin bed, the solution after penetration was taken to detect and analyze the Fe ion content in the solution. The detection result was 80 mg / kg.

[0068] The [FeCl4] in the solution was adsorbed by using the series connection method of D201 resin and 732 resin - and [Fe(H2O)5Cl 2 + Adsorption was carried out. The inner diameter of the adsorption column was 32 mm and the height was 280 mm. The D201 resin bed height was 120 mm and the 732 resin bed height was 60 mm. The initial Fe ion content in the solution was 1280 mg / kg. 600 mL of the hazardous waste chloroacetic acid solution was introduced into the adsorption column at flow rates of 2 mL / min, 4 mL / min, 6 mL / min, 8 mL / min, and 10 mL / min respectively. The hazardous waste chloroacetic acid solution penetrated the D201 resin bed and the 732 resin bed successively. After the hazardous waste chloroacetic acid solution penetrated the 732 resin bed, the solution after penetration was taken to detect and analyze the Fe ion content in the solution.

[0069] When the flow rates were 2 mL / min and 4 mL / min, the Fe ion content in the solution after adsorption was basically the same. When the flow rate exceeded 4 mL / min, with the increase of the flow rate, the Fe ion content in the solution after adsorption gradually increased. This was because when the flow rate was too fast, some Fe ions in the solution failed to undergo ion exchange with the resin. The faster the flow rate, the more Fe ions that did not undergo ion exchange, resulting in an increase in the remaining Fe ion content in the solution. Therefore, the preferred flow rate was 4 mL / min.

[0070] ​​The color of the hazardous waste chloroacetic acid solution without ion exchange is yellowish-brown, and the Fe ion content in the solution is 1280 mg / kg at this time; the color of the hazardous waste chloroacetic acid solution adsorbed by D201 resin is light yellow, and the Fe ion content in the solution is 320 mg / kg at this time, indicating that the Fe ion content in the hazardous waste chloroacetic acid solution after adsorption by D201 resin has decreased significantly; the hazardous waste chloroacetic acid solution adsorbed by D201 resin and 732 resin together is basically colorless, and the Fe ions in the hazardous waste chloroacetic acid solution have been basically adsorbed completely at this time, and the Fe ion content in the solution is only 80 mg / kg, indicating that the method of series adsorption of D201 resin and 732 resin has a good removal effect on Fe ions in the hazardous waste chloroacetic acid solution.

[0071] In summary, the inner diameter of the adsorption column is 32 mm, and the better adsorption conditions for dynamic adsorption are: the bed height of D201 resin is 120 mm, the bed height of 732 resin is 60 mm, and the flow rate of the hazardous waste chloroacetic acid solution is 4 mL / min. Under these conditions, the Fe ion content in the solution after adsorption is 80 mg / kg, and the removal rate of Fe ions is 94%.

[0072] Separate chloroacetic acid from other components by distillation:

[0073] The temperature of the bottom of the distillation column is 120 - 150 °C, the reflux ratio R = 1, the chloroacetic acid content in the bottom product is 93.14%, and after drying for 8 hours, the chloroacetic acid content can reach 98.13%. The remaining components are mainly 1,4-dioxane-2,5-dione.

[0074] In this experiment, since Fe ions are the main impurities, only the removal of Fe ions is carried out. However, if there are other ions such as Mn, Zn, Cu, etc. in the hazardous waste chloroacetic acid solution, the same method can also be used to remove them through ion exchange resin.

[0075] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for recycling and refining hazardous waste chloroacetic acid, characterized in that: It includes the following steps: (1) Use a plasma emission spectrometer, an ion chromatograph, a gas chromatography-mass spectrometry (GC-MS) instrument, and a gas chromatograph to quantitatively analyze the components and contents of the hazardous waste chloroacetic acid solution. Among them, the hazardous waste chloroacetic acid solution is an aqueous solution with a mass fraction of 10-30% prepared by adding water to a hazardous waste chloroacetic acid sample. The plasma emission spectrometer is used to analyze the metal elements in the hazardous waste chloroacetic acid solution, and the metal elements include Fe and K. The ion chromatograph is used to analyze the non-metal elements in the hazardous waste chloroacetic acid solution, and the ions corresponding to the non-metal elements include F - , Cl - , NO3 - , SO4 2- , PO4 3- . The GC-MS instrument is used to qualitatively analyze the organic compounds in the hazardous waste chloroacetic acid solution, and the organic compounds include methyl chloroacetate, 1,4-dioxane-2,5-dione, methyl acetate, ethyl chloroacetate, bicyclo[2.2.1]heptane, acetoxyacetic acid, dichloroacetic acid, 3,5-dihydroxytoluene. The gas chromatograph is used to quantitatively analyze the organic compounds in the hazardous waste chloroacetic acid solution; (2) Conduct quantitative analysis on the insoluble impurities in the hazardous waste chloroacetic acid solution, including: after centrifuging the hazardous waste chloroacetic acid solution, take the supernatant, add deionized water to the centrifuge tube, repeatedly centrifuge and wash the residue until the solution is clear, put the washed insoluble impurities into the oven to dry and weigh them; (3) Using ion exchange resin to adsorb metal ions in the chloroacetic acid solution, including: adopting the static adsorption method, using D201 resin to adsorb - [FeCl4] in the solution, and using 732 resin to adsorb + [Fe(H2O)5Cl2] in the solution; (4) Rectify the adsorbed chloroacetic acid solution with a rectification device to separate chloroacetic acid and water. Among them, the bottom temperature of the rectification device is 120 - 150 °C, and the reflux ratio R = 1.

2. The method for recycling and refining hazardous waste chloroacetic acid according to claim 1, wherein: In step (3), first pre-treat the ion exchange resin, and the treatment steps are as follows: (31) Take a certain amount of ion exchange resin, put it into deionized water with a volume 4 - 6 times that of the resin and wash until the solution is clear; (32) Immerse the washed ion exchange resin in a methanol solution with a volume 2 - 3 times that of the resin for 2 - 3 hours; (33) After immersion, rinse the ion exchange resin with a large amount of methanol until the solution is clear; (34) Use a vacuum pump to drain the water from the washed ion exchange resin; (35) Place the treated ion exchange resin in an oven at 100 - 120 °C and dry it for 6 - 8 hours for standby.

3. A method for recovering and refining hazardous waste chloroacetic acid according to claim 1 or 2, characterized in that: The adsorption method in step (3) is one of static adsorption of anion resin, static adsorption of cation resin, series static adsorption of anion and cation resins, and series dynamic adsorption of anion and cation resins.

4. A method for recovering and refining hazardous waste chloroacetic acid according to claim 3, characterized in that: The adsorption method in step (3) is series static adsorption of anion or cation resin. The process is as follows: Take the hazardous waste chloroacetic acid solution separated by centrifugation, add 50 g of it to a 200 - 300 mL conical flask, add the pre-treated ion exchange resin, place the conical flask on a mechanical shaker, and set the rotation speed to 150 - 250 r / min for adsorption for 2 - 2.5 hours.

5. A method for recovering and refining hazardous waste chloroacetic acid according to claim 3, characterized in that: The adsorption method in step (3) is series static adsorption of anion and cation resins. The process is as follows: Take 50 g of the hazardous waste chloroacetic acid solution separated by centrifugation and add it to a 200 - 300 mL conical flask, add 8 - 10 g of the pre-treated anion resin, place the conical flask on a mechanical shaker, set the rotation speed to 150 - 250 r / min for adsorption for 2 - 2.5 hours. After the adsorption is completed, use a vacuum filtration device to separate the hazardous waste chloroacetic acid solution and the anion resin, add 4 - 5 g of the pre-treated cation resin to the separated hazardous waste chloroacetic acid solution, and continue to place it on the mechanical shaker for adsorption for 2 - 2.5 hours.

6. A method for recycling and refining hazardous waste chloroacetic acid according to claim 3, characterized in that: The adsorption method in the step (3) is a tandem dynamic adsorption of anion and cation resins, which is completed by using a dynamic adsorption device. The dynamic adsorption device includes four columns A, B, C, and D arranged side by side. The upper end of column A is the inlet, and the lower end of column A is connected to the lower end of column B through a connecting pipe. The upper end of column B is connected to the upper end of column C through a connecting pipe. The lower end of column C is connected to the lower end of column D through a connecting pipe. The upper end of column D is the outlet. The adsorption process is as follows: The hazardous waste chloroacetic acid solution is controlled by a flow pump to enter the dynamic adsorption device from the inlet of column A, enters column B from the bottom through the connecting pipe between column A and column B. The packing in column B is anion resin. After penetrating through the anion resin bed, it enters column C, and then enters column D from the bottom through the connecting pipe between column C and column D. The packing in column D is cation resin. After the hazardous waste chloroacetic acid solution penetrates through the cation resin bed, it is output from the outlet of column D and recovered.

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