N,N-dimethylacetamide (DMAC) is widely used as chemical raw materials and organic solvents in petroleum, chemical, pharmaceutical, pesticide and other industries. It has strong polarity, chemical stability and biological toxicity.

  1. The wide use of dimethylacetamide causes a large amount of DMAC wastewater pollution

Dimethylacetamide (DMAC) is an important pharmaceutical raw material and is widely used in the production of antibiotic drugs such as cephalosporins and amoxicillin. In addition, the strong solubility of dimethylacetamide makes it widely used in coatings, medicines, plastic films, heat-resistant synthetic fibers, acrylonitrile spinning and other fields. At present, dimethylacetamide is mostly used as a solvent in the production of foreign polyimide films, soluble polyimide, polyimide-polyperfluoroethylene-propylene composite films, polyimide (aluminum) films, soluble polyimide molding powder and other materials. It is also used as an excellent polar solvent in the domestic field of polymer synthetic fiber spinning.

Due to the excellent performance and wide range of uses of dimethylacetamide (DMAC), a large amount of DMAC-containing wastewater is dumped into the environment during the production process every year. The toxic substances in these wastewater can cause huge damage to the water environment.

  1. Solvent extraction process for treating DMAC wastewater

At present, extraction methods, biochemical methods, supercritical water oxidation methods, photocatalytic oxidation, physical and chemical methods, chemical methods, etc. are mostly used to treat DMAC-containing wastewater at home and abroad. The solvent extraction method is undoubtedly a more economical and feasible treatment method. It can not only pretreat DMAC wastewater, but also recover the DMAC solvent in the wastewater and return it to production. 

Liquid-liquid solvent extraction is an operation method that uses the principle of different solubilities of solutes in mutually immiscible solvents to transfer solutes from one solvent to another. Chloroform can be used as the extraction agent to treat DMAC wastewater, and the concentration of DMAC in the final discharged wastewater can be reduced to 180 mg/kg.

The liquid-liquid solvent extraction method has low energy consumption and high recovery rate for low-concentration DMAC.

  1. Centrifugal extraction process to treat DMAC wastewater

The centrifugal extraction process is:

Inject DMAC wastewater and suitable extraction agent into the centrifugal extractor in a certain proportion. With the rotation of the drum, the two phases are quickly mixed and dispersed through the impeller to complete the mixing and mass transfer process. The mixed liquid enters the drum under the action of the vortex plate. Under the action of centrifugal force, the two-phase liquid is quickly separated and discharged from the body through different outlets, completing the two-phase separation process. The loaded organic matter is then added with a stripping agent for stripping, and the DMAC is separated from the extracting agent. The extracting agent can be recovered and recycled.

Tiei Extraction CWL-M series high-efficiency centrifugal extractors solve the problems of high energy consumption, poor corrosion resistance, and difficult maintenance of existing equipment, greatly reducing the cost of DMAC wastewater treatment, and the application results are good.
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