Purification method for recovering dichloromethane from waste solvent

A technology of dichloromethane and a purification method is applied in the field of purification of recovering dichloromethane from pharmaceutical waste solvents or industrial waste liquids, and can solve problems such as environmental impact, difficulty in effective separation, and the like

Active Publication Date: 2019-06-25
XINZHONGTIAN ENVIRONMENTAL PROTECTION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] As a commonly used solvent in the chemical and pharmaceutical fields, dichloromethane has the advantages of strong solubility and low toxicity. However, due to the toxicity of dichloromethane, it will have a very large impact on environmental protection if it is excreted in large quantities as industrial waste liquid.
Aiming at the technical problems encountered in the actual material treatment of dichloromethane waste liquid collected by our company, which are difficult to effectively separate, according to the components in the dichloromethane waste solvent, a recovery process and purification method for waste dichloromethane solvent have been developed.

Method used

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  • Purification method for recovering dichloromethane from waste solvent

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Comparison scheme
Effect test

Embodiment 1

[0021] The recovery, purification of methylene chloride in the pharmaceutical waste liquid of embodiment 1

[0022] Its process steps are as follows:

[0023] 1) Pump the barreled dichloromethane waste solvent (or waste liquid) collected from pharmaceutical companies into the distillation still (the still can be equipped with stirring, vacuuming, nitrogen, lye dripping, steam or electric heating temperature control system as required etc.), use acid or alkali to adjust the pH in the still to 7-10, then heat the still, the temperature in the still is controlled at 39-42°C, the light components are evaporated by heating and passed through the overhead condenser, and the condenser is a secondary condensation , circulating water and 7°C low-temperature water, the dichloromethane at the top distillate condenses and enters the intermediate collection tank (that is, the middle tank of the still), and the residue at the bottom of the still is removed for hazardous waste disposal. The...

Embodiment 2

[0031] The waste dichloromethane solvent collected from a pharmaceutical company consists of (w%): 70.30% dichloromethane, 6.29% methanol, 6.80% ethanol, 5.50% acetone, 4.54% EA, 3.14% toluene, and 1.15% water , the other about 2.28%, PH=4, the color of the waste liquid is yellowish brown.

[0032] The recovery and purification process is:

[0033] 1. Pump the waste liquid into a 5000L still (the still needs to be replaced three times with nitrogen), start stirring at 50 rpm and add liquid caustic soda to adjust the pH to 7-8, open the steam valve and turn on the condensed water in the still to heat up and distill at 45°C , The distillation time is 5h, and the collected fractions flow into the middle tank.

[0034] 2. Pump the dichloromethane in the middle tank into the pipeline mixer (here the pipeline mixer is 1m long and 80mm in diameter and adopts two sections connected in series.), add the sodium hydroxide aqueous solution of PH=9, mix well and send into Oil-water separ...

Embodiment 3

[0039] The waste dichloromethane solvent collected from a pharmaceutical company consists of (w%): 70.30% dichloromethane, 6.29% methanol, 6.80% ethanol, 5.50% acetone, 4.54% EA, 3.14% toluene, and 1.15% water , the other about 2.28%, PH=4, the color of the waste liquid is yellowish brown.

[0040] The recovery and purification process is:

[0041] 1. Pump the waste liquid into a 5000L still (the still needs to be replaced three times with nitrogen), start stirring at 50 rpm and add liquid caustic soda to adjust the pH to 8-10, open the steam valve and turn on the condensed water of the still to raise the temperature at 45°C Distillation, the distillation time is 5h, and the collected fractions flow into the middle tank.

[0042] 2. Pump the dichloromethane in the middle tank and the aqueous sodium hydroxide solution (according to the mass ratio of 1:0.1 to 0.3) into the pipeline mixer (here the pipeline mixer is 1m long and 80mm in diameter). Two sections connected in serie...

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Abstract

The invention discloses a purification method for recovering dichloromethane from a pharmaceutical waste solvent. The method comprises the following steps: 1) adjusting the pH value of the waste dichloromethane solvent to 7-10 by using an acid and / or an alkali, and carrying out heating distillation or / and decolorizing; 2) collecting the obtained fraction dichloromethane, adding an alkali solution,carrying out a reaction, and standing the obtained reaction to carry out layering; 3) removing the obtained upper aqueous phase, taking the obtained lower dichloromethane organic phase, extracting the lower dichloromethane organic phase with ethylene glycol, and rectifying the obtained extract; and 4) collecting a fraction at a temperature of 60-85 DEG C to obtain purified dichloromethane. The method is suitable for the recovery purification of the dichloromethane waste liquid with the complex components in the pharmaceutical industry, and the obtained dichloromethane reaches national standards. The method facilitates environment protection, and reduces the production cost.

Description

technical field [0001] The invention belongs to the field of chemical and pharmaceutical industries, and in particular relates to a purification method for recovering dichloromethane from a pharmaceutical waste solvent or industrial waste liquid. Background technique [0002] As a commonly used solvent in the chemical and pharmaceutical fields, dichloromethane has the advantages of strong solubility and low toxicity. However, due to the toxicity of dichloromethane, it will have a very large impact on environmental protection if it is excreted in large quantities as industrial waste. The recovery and reuse of dichloromethane is not only beneficial to environmental protection, but also saves production costs or generates new economic value. Therefore, the recovery method and mechanical application of dichloromethane are particularly important, especially in the industrial production of pharmaceuticals, the recovery and mechanical application of dichloromethane can greatly redu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C17/38C07C19/03
Inventor 陈国平阳杨林辉荣何睿鸣毛小英左娇汪小飞
Owner XINZHONGTIAN ENVIRONMENTAL PROTECTION
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