Method for recovering and treating wastewater produced by production of cefixime side chain active thioester

Abstract

The present invention belongs to the technical field of wastewater treatment, and in particular to a method for recycling and treating wastewater produced by active thioester of cefixime side chain. The method comprises the following steps: adjusting the pH of wastewater 1, adding a decolorizing agent and a flocculant to stir, filtering, distilling and recovering acetonitrile by decompression of the filtrate, and concentrating the remaining wastewater to the original 20-30% by negative pressure, centrifuging, and collecting sodium chloride solid; the liquid obtained after centrifugation is concentrated by negative pressure again, and the remaining liquid is collected; water is added to the remaining liquid for extraction, the organic phase is collected, wastewater 2 is added to the organic phase for temperature rise and dissolution, activated carbon is added for filtration, hydrogen peroxide is added dropwise to the filtrate for crystallization, and the reaction is kept warm, and after centrifugation, the solid is collected, methanol is added to the solid for washing, and after centrifugation again, the solid is collected, and 2,2'-dithiodibenzothiazole is dried; the present invention recovers 2,2'-dithiodibenzothiazole from the synthetic residual liquid, reduces the discharge of solid waste in the solvent recovery process, realizes energy conservation and emission reduction, and reduces production costs.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a method for recovering and treating wastewater produced by the production of cefixime side chain active thioester. Background Art

[0002] At present, the production process of active thioester of cefixime side chain comprises the following steps: step 1: dissolving thiourea and sodium acetate trihydrate in water, then adding cefixime ring-opening side chain acid, heating to react, cooling after the reaction, dropping concentrated hydrochloric acid to adjust pH, filtering, washing with water, and draining to obtain white crystals, dissolving the white crystals, triphenylphosphine and 2,2'-dithiodibenzothiazole in acetonitrile, dropping triethylamine, dropping after the dropping, cooling, dropping triphenylphosphine, dropping after the dropping, reacting for 2h, and draining to obtain a crude product after the reaction ends. Wastewater 1 obtained in this step mainly contains acetic acid, hydrochloric acid, sodium chloride, acetonitrile, triethylamine hydrochloride, triphenylphosphine and 2-mercaptobenzothiazole; step 2: putting the crude product into pre-cooled methanol, keeping warm and stirring, filtering, washing with methanol, and draining to obtain active thioester of cefixime side chain (methyl ester). Wastewater 2 obtained in this step mainly contains methanol.

[0003] With regard to the wastewater generated by the existing production process of active thioesters of the side chain of cefixime, the high-salt wastewater produced in step one is traditionally treated mainly by evaporation and crystallization. The remaining residual liquid is simply treated as solvent recovery, and the remaining waste residue is treated as hazardous waste.

[0004] How to recycle solids in wastewater and reduce production costs is an urgent problem to be solved. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for recovering and treating wastewater produced by the production of cefixime side chain active thioesters. The present invention not only reduces the salt content in the wastewater and reduces the pressure of wastewater treatment, but also recovers 2,2'-dithiodibenzothiazole from the synthetic residual liquid.

[0006] The method for recycling wastewater produced by the production of cefixime side chain active thioesters of the present invention comprises recycling the following two types of wastewater:

[0007] Wastewater 1 mainly contains acetic acid, hydrochloric acid, sodium chloride, triethylamine hydrochloride, acetonitrile, triphenylphosphine and 2-mercaptobenzothiazole;

[0008] Wastewater 2 mainly contains methanol;

[0009] The method for recovering and treating wastewater produced by the production of cefixime side chain active thioester comprises the following steps:

[0010] (1) Using alkali solution to adjust the pH of wastewater 1, adding decolorizing agent and flocculant to stir, filtering, and distilling the filtrate under reduced pressure to recover acetonitrile. The remaining wastewater is put into a multiple-effect evaporator and concentrated under negative pressure to 20-30% of the original value, and centrifuged to collect sodium chloride solid;

[0011] (2) the liquid obtained after centrifugation in step (1) is again put into a multiple-effect evaporator for negative pressure concentration, and when no more liquid is evaporated, the remaining liquid is collected;

[0012] (3) Add water to the remaining liquid for extraction, collect the organic phase, add wastewater 2 to the organic phase and heat it to dissolve, add activated carbon for filtration, add hydrogen peroxide to the filtrate for crystallization, keep warm for reaction, centrifuge, collect the solid, add methanol to the solid for washing, centrifuge again, collect the solid, dry to obtain 2,2'-dithiodibenzothiazole, and recover methanol by vacuum distillation of the liquid after centrifugation; the reaction route of 2-mercaptobenzothiazole and hydrogen peroxide is as follows Figure 1 shown.

[0013] The alkali solution in step (1) is a sodium hydroxide solution, preferably a 30% sodium hydroxide solution, the decolorizing agent is activated carbon, and the flocculant is a 1-3% polyacrylamide solution.

[0014] In step (1), the mass ratio of the wastewater 1, the decolorizing agent and the flocculant is 1: (0.001-0.005): (0.01-0.05).

[0015] The pH of step (1) is 8.5-9.0.

[0016] The temperature of the reduced pressure distillation to recover acetonitrile in step (1) is 40-50° C. and the vacuum degree is -0.09-0.096 MPa.

[0017] The temperature of the negative pressure concentration in step (1) is 80-90° C., and the vacuum degree is -0.08-0.04 MPa.

[0018] The temperature of the negative pressure concentration in step (2) is 60-70° C., and the vacuum degree is -0.09-0.06 MPa.

[0019] The mass ratio of the remaining liquid, water, wastewater 2, activated carbon, hydrogen peroxide and methanol in step (3) is 1: (0.8-1.2): (0.8-1.2): (0.001-0.003): (0.08-0.2): (0.8-1.2), and the hydrogen peroxide is preferably 25% hydrogen peroxide.

[0020] The temperature of the heating and dissolving in step (3) is 40-45°C, and the temperature of the heat preservation reaction is 40-45°C.

[0021] The temperature of the reduced pressure distillation to recover methanol in step (3) is 40-50° C. and the vacuum degree is -0.096-0.09 MPa.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention uses a multi-effect evaporation method to perform desalination treatment, which significantly reduces the salt content in the wastewater, reduces the COD of the sewage, and alleviates the pressure of wastewater treatment.

[0024] (2) The present invention recovers 2,2'-dibenzothiazole disulfide from the synthetic residual liquid, reduces the emission of solid waste in the solvent recovery process, achieves energy conservation and emission reduction, and reduces production costs. At the same time, the recovered 2,2'-dibenzothiazole disulfide can be used as a production raw material or sold after being refined, which can create benefits for the enterprise.

[0025] (3) The present invention adds wastewater 2 to wastewater 1 to recover 2,2'-dibenzothiazole disulfide, which makes full use of resources, saves costs, and shortens the wastewater recovery process.

[0026] (4) The present invention adds water extraction and methanol washing processes for solids during the recovery reaction of 2,2'-dibenzothiazole disulfide, thereby further increasing the content of 2,2'-dibenzothiazole disulfide. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a reaction route diagram of 2-mercaptobenzothiazole and hydrogen peroxide of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto.

[0029] Unless otherwise specified, all raw materials used in the examples are commercially available.

[0030] Example 1

[0031] (1) Add 4000 kg of wastewater 1 into the reactor, start stirring at 160 r / min, add 30% sodium hydroxide solution to adjust the pH to 8.5, add 10 kg of activated carbon and 100 kg of 2% polyacrylamide solution, stir for 30 min and filter, put the filtrate into the vacuum distillation kettle, start vacuum distillation, the temperature of vacuum distillation is 45±5℃, the vacuum degree is -0.093 MPa, and 1157 kg of acetonitrile is recovered with a purity of 98.5%. The remaining wastewater is pumped into the multi-effect evaporator for negative pressure concentration at 85±5℃ and a vacuum degree of -0.06 MPa. The wastewater is concentrated to 25% of the original, centrifuged at 1500 r / min for 30 min, and 162 kg of white sodium chloride solid is collected. The obtained sodium chloride solid content is 89% and the recovery rate is 81%.

[0032] (2) The liquid obtained after centrifugation in step (1) was again put into a multiple-effect evaporator for negative pressure concentration at a temperature of 65±5°C and a pressure of -0.088 MPa. When no more liquid was evaporated, 843 kg of remaining liquid was collected.

[0033]

[0034] (3) Add 843 kg of water to the remaining liquid and stir for 30 min. Let stand for 15 min, separate the liquids, collect the organic phase, add 843 kg of waste water 2 to the organic phase, raise the temperature to 45 ° C, stir and dissolve at 160 r / min, add 0.843 kg of activated carbon and stir for 30 min, filter, add 84.3 kg of 25% hydrogen peroxide to the filtrate for crystallization, keep the temperature at 42.5±2.5 ° C for 1 h, centrifuge at 1500 r / min for 30 min, collect the solid, add 843 kg of methanol to the solid and wash it for 30 min. Centrifuge at 1500 r / min for 30 min, collect the solid, and dry the solid to obtain 132 kg of light yellow 2,2'-dithiodibenzothiazole. The content of 2,2'-dithiodibenzothiazole is 98.2%, the recovery rate is 81.6%, and the melting point is 178.4~178.9 ° C. The liquid after centrifugation was collected and put into a vacuum distillation kettle, and the vacuum distillation was started. The temperature of the vacuum distillation was 45±5°C, the vacuum degree was -0.093MPa, and 1246kg of methanol was recovered with a purity of 98.5% and a recovery rate of 73.9%.

[0035] Example 2

[0036] (1) Add 4000 kg of wastewater 1 into the reactor, start stirring at 160 r / min, add 30% sodium hydroxide solution to adjust the pH to 9.0, add 20 kg of activated carbon and 200 kg of 1% polyacrylamide solution, stir for 30 min and filter, put the filtrate into the vacuum distillation kettle, start vacuum distillation, the temperature of vacuum distillation is 45±5℃, the vacuum degree is -0.096 MPa, and 1175 kg of acetonitrile is recovered with a purity of 98.8%. The remaining wastewater is pumped into the multi-effect evaporator for negative pressure concentration at 85±5℃ and vacuum degree of -0.08 MPa. The wastewater is concentrated to 30% of the original, centrifuged at 1500 r / min for 30 min, and 158 kg of white sodium chloride solid is collected. The obtained sodium chloride solid content is 88% and the recovery rate is 79%.

[0037] (2) The liquid obtained after centrifugation in step (1) was again put into the multiple-effect evaporator for negative pressure concentration at a temperature of 65±5°C and a pressure of -0.09 MPa. When no more liquid was evaporated, 825 kg of the remaining liquid was collected.

[0038]

[0039] (3) Add 990 kg of water to the remaining liquid and stir for 30 min. Let stand for 15 min, separate the liquids, collect the organic phase, add 990 kg of waste water 2 to the organic phase, heat to 40 ° C, stir and dissolve at 160 r / min, add 2.480 kg of activated carbon and stir for 30 min, filter, add 165 kg of 25% hydrogen peroxide to the filtrate for crystallization, keep the reaction at 42.5±2.5 ° C for 1 h, centrifuge at 1500 r / min for 30 min, collect the solid, add 990 kg of methanol to the solid and wash it for 30 min. Centrifuge at 1500 r / min for 30 min, collect the solid, and dry the solid to obtain 130 kg of light yellow 2,2'-dithiodibenzothiazole. The content of 2,2'-dithiodibenzothiazole is 98.2%, the recovery rate is 80.2%, and the melting point is 178.0~179.1 ° C. The liquid after centrifugation was collected and put into a vacuum distillation kettle. The vacuum distillation was started. The temperature of the vacuum distillation was 45±5°C, the vacuum degree was -0.096MPa, and 1450kg of methanol was recovered with a purity of 98.5% and a recovery rate of 73.2%.

[0040] Example 3

[0041] (1) Add 4000 kg of wastewater 1 into the reactor, start stirring at 160 r / min, add 30% sodium hydroxide solution to adjust the pH to 8.7, add 4 kg of activated carbon and 40 kg of 3% polyacrylamide solution, stir for 30 min and filter, put the filtrate into the vacuum distillation kettle, start vacuum distillation, the temperature of vacuum distillation is 45±5℃, the vacuum degree is -0.09 MPa, and 1134 kg of acetonitrile is recovered with a purity of 98.9%. The remaining wastewater is pumped into the multi-effect evaporator for negative pressure concentration at 85±5℃ and vacuum degree of -0.04 MPa. The wastewater is concentrated to 20% of the original amount, centrifuged at 1500 r / min for 30 min, and 153 kg of white sodium chloride solid is collected. The obtained sodium chloride solid content is 90%, and the recovery rate is 76.5%.

[0042] (2) The liquid obtained after centrifugation in step (1) was again put into the multiple-effect evaporator for negative pressure concentration at a temperature of 65±5°C and a pressure of -0.06MPa. When no more liquid was evaporated, 866kg of the remaining liquid was collected.

[0043]

[0044] (3) Add 693 kg of water to the remaining liquid and stir for 30 min. Let stand for 15 min, separate the liquids, collect the organic phase, add 693 kg of waste water 2 to the organic phase, heat to 43 ° C, stir and dissolve at 160 r / min, add 1.732 kg of activated carbon and stir for 30 min, filter, add 70 kg of 25% hydrogen peroxide to the filtrate for crystallization, keep the reaction at 42.5±2.5 ° C for 1 h, centrifuge at 1500 r / min for 30 min, collect the solid, add 693 kg of methanol to the solid and wash it for 30 min. Centrifuge at 1500 r / min for 30 min, collect the solid, and dry the solid to obtain 128 kg of light yellow 2,2'-dithiodibenzothiazole. The content of 2,2'-dithiodibenzothiazole is 98.5%, the recovery rate is 79.0%, and the melting point is 178.4~179.0 ° C. The liquid after centrifugation was collected and put into a vacuum distillation kettle. The vacuum distillation was started at a temperature of 45±5°C and a vacuum degree of -0.09MPa. 1080kg of methanol was recovered with a purity of 98.5% and a recovery rate of 77.9%.

[0045] Comparative Example 1

[0046] (1) Add 4000 kg of wastewater 1 into the reactor, start stirring at 160 r / min, add 30% sodium hydroxide solution to adjust the pH to 8.5, stir for 30 min and filter, put the filtrate into the vacuum distillation kettle, start vacuum distillation, the temperature of vacuum distillation is 45±5℃, the vacuum degree is -0.093MPa, and 1238 kg of acetonitrile is recovered with a purity of 98.8%. The remaining wastewater is pumped into a multi-effect evaporator for negative pressure concentration at 85±5℃ and a vacuum degree of -0.06MPa. The wastewater is concentrated to 25% of the original, centrifuged at 1500 r / min for 30 min, and 143 kg of light yellow sodium chloride solid is collected. The obtained sodium chloride solid content is 87% and the recovery rate is 71.5%.

[0047] (2) The liquid obtained after centrifugation in step (1) was again put into a multiple-effect evaporator for negative pressure concentration at a temperature of 65±5°C and a pressure of -0.088 MPa. When no more liquid was evaporated, 924 kg of remaining liquid was collected.

[0048]

[0049] (3) Add 924 kg of water to the remaining liquid and stir for 30 min. Let stand for 15 min, separate the liquids, collect the organic phase, add 924 kg of waste water 2 to the organic phase, heat to 45 ° C, stir and dissolve at 160 r / min, add 0.924 kg of activated carbon and stir for 30 min, filter, add 92.4 kg of 25% hydrogen peroxide to the filtrate for crystallization, keep the temperature at 42.5±2.5 ° C for 1 h, centrifuge at 1500 r / min for 30 min, collect the solid, add 924 kg of methanol to the solid and wash it for 30 min. Centrifuge at 1500 r / min for 30 min, collect the solid, and dry the solid to obtain 128 kg of light yellow 2,2'-dithiodibenzothiazole. The content of 2,2'-dithiodibenzothiazole is 98.0%, the recovery rate is 79%, and the melting point is 178.2~178.7 ° C. The liquid after centrifugation was collected and put into a vacuum distillation kettle, and the vacuum distillation was started. The temperature of the vacuum distillation was 45±5°C, the vacuum degree was -0.093MPa, and 1342kg of methanol was recovered with a purity of 98.5% and a recovery rate of 79.6%.

[0050] Comparative Example 2

[0051] (1) Add 4000 kg of wastewater 1 into the reactor, start stirring at 160 r / min, add 30% sodium hydroxide solution to adjust the pH to 8.5, add 10 kg of activated carbon and 100 kg of 2% polyacrylamide solution, stir for 30 min and filter, put the filtrate into the vacuum distillation kettle, start vacuum distillation, the temperature of vacuum distillation is 45±5℃, the vacuum degree is -0.093 MPa, and 1189 kg of acetonitrile is recovered with a purity of 98.5%. The remaining wastewater is pumped into the multi-effect evaporator for negative pressure concentration at 85±5℃ and vacuum degree of -0.06 MPa. The wastewater is concentrated to 25% of the original, centrifuged at 1500 r / min for 30 min, and 156 kg of white sodium chloride solid is collected. The obtained sodium chloride solid content is 88%, and the recovery rate is 78%.

[0052] (2) The liquid obtained after centrifugation in step (1) was again put into a multiple-effect evaporator for negative pressure concentration at a temperature of 65±5°C and a pressure of -0.088 MPa. When no more liquid was evaporated, 859 kg of remaining liquid was collected.

[0053]

[0054] (3) Add 859 kg of wastewater 2 to the remaining liquid, heat it to 45°C, stir and dissolve it at a speed of 160 r / min, stir for 30 min, filter, slowly drop 85.9 kg of 25% hydrogen peroxide into the filtrate for crystallization, keep the reaction at 42.5±2.5°C for 1 h, centrifuge it at a speed of 1500 r / min for 30 min, collect the solid, dry the solid to obtain 128 kg of brown-yellow 2,2'-dithiodibenzothiazole, with a 2,2'-dithiodibenzothiazole content of 72.8%, a recovery rate of 79.0%, and a melting point of 150.1~151.2°C. Collect the liquid after centrifugation, put it into a vacuum distillation kettle, and start the vacuum distillation. The temperature of the vacuum distillation is 45±5°C, the vacuum degree is -0.093 MPa, and 1274 kg of methanol is recovered with a purity of 98.0% and a recovery rate of 75.6%.

[0055] Comparative Example 3

[0056] (1) Add 4000 kg of wastewater 1 into the reactor, start stirring at 160 r / min, add 30% sodium hydroxide solution to adjust the pH to 8.6, add 10 kg of activated carbon and 100 kg of 2% polyacrylamide solution, stir for 30 min and filter, put the filtrate into the vacuum distillation kettle, start vacuum distillation, the temperature of vacuum distillation is 45±5℃, the vacuum degree is -0.093 MPa, and 1147 kg of acetonitrile is recovered with a purity of 98.2%. The remaining wastewater is pumped into the multi-effect evaporator for negative pressure concentration at 85±5℃ and vacuum degree of -0.06 MPa. The wastewater is concentrated to 25% of the original, centrifuged at 1500 r / min for 30 min, and 148 kg of white sodium chloride solid is collected. The obtained sodium chloride solid content is 71% and the recovery rate is 74%.

[0057] (2) The liquid obtained after centrifugation in step (1) was again put into the multiple-effect evaporator for negative pressure concentration at a temperature of 65±5°C and a pressure of -0.088 MPa. When no more liquid was evaporated, 856 kg of remaining liquid was collected.

[0058]

[0059] (3) Add 856 kg of water to the remaining liquid and stir for 30 min. Let stand for 15 min, separate the liquids, collect the organic phase, add 856 kg of waste water 2 to the organic phase, heat to 45 ° C, stir and dissolve at 160 r / min, add 0.856 kg of activated carbon and stir for 30 min, filter, add 54 kg of 25% hydrogen peroxide to the filtrate for crystallization, keep the reaction at 42.5±2.5 ° C for 1 h, centrifuge at 1500 r / min for 30 min, collect the solid, add 856 kg of methanol to the solid and wash it for 30 min. Centrifuge at 1500 r / min for 30 min, collect the solid, and dry the solid to obtain 63.5 kg of light yellow 2,2'-dithiodibenzothiazole. The content of 2,2'-dithiodibenzothiazole is 97.8%, the recovery rate is 39.2%, and the melting point is 177.8~178.3 ° C. The liquid after centrifugation was collected and put into a vacuum distillation kettle. The vacuum distillation was started at a temperature of 45±5°C and a vacuum degree of -0.093MPa. 1260kg of methanol was recovered with a purity of 98.0% and a recovery rate of 74.7%.

Claims

1. A method for recovering and treating wastewater produced by the production of cefixime side chain active thioesters, characterized in that: Including recycling and treating the following two types of wastewater: Wastewater 1 mainly contains acetic acid, hydrochloric acid, sodium chloride, acetonitrile, triethylamine hydrochloride, triphenylphosphine and 2-mercaptobenzothiazole; Wastewater 2 mainly contains methanol; The method for recovering and treating wastewater produced by the production of cefixime side chain active thioester comprises the following steps: (1) Using alkali solution to adjust the pH of wastewater 1, adding decolorizing agent and flocculant to stir, filtering, and distilling the filtrate under reduced pressure to recover acetonitrile. The remaining wastewater is put into a multiple-effect evaporator and concentrated under negative pressure to 20-30% of the original value, and centrifuged to collect sodium chloride solid; (2) the liquid obtained after centrifugation in step (1) is again put into a multiple-effect evaporator for negative pressure concentration, and when no more liquid is evaporated, the remaining liquid is collected; (3) adding water to the remaining liquid for extraction, collecting the organic phase, adding wastewater 2 to the organic phase and heating it to dissolve, adding activated carbon for filtration, dropping hydrogen peroxide into the filtrate for crystallization, keeping the temperature for reaction, centrifuging, collecting the solid, adding methanol to the solid for washing, centrifuging again, collecting the solid, drying to obtain 2,2'-dithiodibenzothiazole, and recovering methanol by vacuum distillation of the liquid after centrifugation; The pH of step (1) is 8.5-9.0; The temperature of the negative pressure concentration in step (2) is 60-70°C, and the vacuum degree is -0.09-0.06MPa; The mass ratio of the remaining liquid, water, wastewater 2, activated carbon, hydrogen peroxide and methanol in step (3) is 1: (0.8-1.2): (0.8-1.2): (0.001-0.003): (0.08-0.2): (0.8-1.2); The temperature of the heating and dissolving in step (3) is 40-45°C, and the temperature of the heat preservation reaction is 40-45°C.

2. The method for recycling wastewater produced by the production of cefixime side chain active thioester according to claim 1, characterized in that: In step (1), the alkali solution is sodium hydroxide solution, the decolorizing agent is activated carbon, and the flocculant is 1-3% polyacrylamide solution.

3. The method for recycling wastewater produced by the production of cefixime side chain active thioester according to claim 1, characterized in that: In step (1), the mass ratio of the wastewater 1, the decolorizing agent and the flocculant is 1: (0.001-0.005): (0.01-0.05).

4. The method for recycling wastewater produced by the production of cefixime side chain active thioester according to claim 1, characterized in that: The temperature of the reduced pressure distillation to recover acetonitrile in step (1) is 40-50° C. and the vacuum degree is -0.096-0.09 MPa.

5. The method for recycling wastewater produced by the production of cefixime side chain active thioester according to claim 1, characterized in that: The temperature of the negative pressure concentration in step (1) is 80-90° C., and the vacuum degree is -0.08-0.04 MPa.

6. The method for recycling cefixime side chain active thioester production wastewater according to claim 1, characterized in that: The temperature of the reduced pressure distillation to recover methanol in step (3) is 40-50° C., and the vacuum degree is -0.096-0.09 MPa.

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