环保用四氯乙烯的提纯工艺研究

Study on Purification Process of Environmental Tetrachloroethylene

水中油含量测定新国标(HJ 637—2018)采用四氯乙烯为萃取剂,但市售普通四氯乙烯不能满足新国标使用要求。为得到满足新国标使用的合格四氯乙烯产品,对四氯乙烯试剂的提纯工艺条件进行了探究,找到了先脱水、再过滤、最后精馏的提纯工艺流程,具体工艺条件为:脱水剂优选变色硅胶,脱水时间以加入变色硅胶直至沉入容器底部为参照,约为5 min;过滤介质优选经600℃以上灼烧的硅酸铝纤维棉;精馏条件优选全回流20 min、回流比0.25、填料层高为1300 mm。经上述纯化工艺处理后,四氯乙烯在3030、2960、2930 cm^-1处吸光度分别小于0.0000、0.0321和0.3147,满足新国标中四氯乙烯的吸光度分别小于0、0.07和0.34的要求。

The new national standard for determination of oil content in water(HJ 637—2018)uses tetrachloroethylene as the extractant,but commercially available ordinary tetrachloroethylene cannot meet the requirements of the new national standard.In order to obtain qualified tetrachloroethylene products that meet the new national standard,this article explored the purification process conditions of the tetrachloroethylene reagent,and found the purification process flow of dehydration,filtration,and final distillation.The specific process conditions were:The dehydrating agent was preferably color-changing silica gel,and the dehydrating time was about 5 min with reference to adding the color-changing silica gel until it sinked into the bottom of the container;the filter medium was preferably aluminum silicate fiber cotton burned above 600℃.The rectification conditions were preferably total reflux for 20 min,the reflux ratio was 0.25,and the filler layer height was 1300 mm.After the above purification process,the absorbance of tetrachloroethylene at 3030,2960 and 2930 cm-1 was less than 0.0000,0.0321 and 0.3147.It met the requirements that the absorbance of tetrachloroethylene in the new national standard was less than 0,0.07 and 0.34,respectively.