Research On The Recovery Of N, N-Dimethylformamide In Wastewater With Pulse Extraction Column

N, N-Dimethylformamide (DMF) is recognized as a sort of alkahest, which has quite strong extraction ability. DMF is widely used in many industry fields such as medicine, leather, fibre, petroleum, latex, dyestuff and oil paint etc. And also it is a sort of important raw material in organic chemical engineering with significant prospect. However, there comes much wastewater containing DMF in the process. So recoverying DMF from wastewater makes a great sense both in reducing cost and in protecting environment.Rectifying is mainly recycling DMF method in industry at present. Because DMF has high boiling point and water has high latent heat of vaporization, when the consistence of DMF in wastewater gets low, too much water needs to be removed by rectifying. The energy cost is too much even though in use of vacuum rectification. So that makes researchers to find a new recycling method eagerly, especially under the conditions of increasing throughput. It is important that the method should cost less energy with high recycling ratio of DMF. The way has been promulgated that amide in the solution was recycled by pulse extraction column. And it has been approved in laboratory, but in the condition of large tower in industry it is hard to produce symmetrical pulse for industry use, which restricts the use of pulse extraction in industry. This paper is aim to do basic research and technique support by medium scale experiment.The research content of this paper is listed as follows, confirming the best conditions by bench scale experiment, designing and manufacturing medium scale experiment with stainless steel which is used to countercurrent extract and rectify DMF in wastewater.The best extraction parameters are confirmed. The extraction temperature is 30℃, the extraction time is 20min, the extraction ratio is 4:1, and the extraction solution is alkalescency. Pulse extraction column is used under the conditions that the frequency of pulse is 80/min, the swing of pulse is 25 mm, and the extraction ratio is 2:1. As a result, the consistence of DMF in wastewater drop to 0.23%, and the reclaimed DMF contains water 0.7%.The results show that the technique is feasible for recoverying DMF in wastewater with pulse extraction column. And the equipment has many excellences such as simple configuration, wide use range, well extraction, less energy cost, and long use time. So it has superexcellent applied value.