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以萃取回收甲苯法生产己内酰胺废液中的己内酰胺为目的,选择氯仿作萃取剂,进行了萃取回收己内酰胺的研究。考察了原料液的pH、萃取温度、萃取时间等因素对氯仿萃取己内酰胺过程的影响。结果表明,在酸性条件下该萃取过程分配比随pH的升高而增大,当pH=7时分配比最大;萃取过程为快速过程,20 min即可达到萃取平衡;水相中硫酸铵和1-磺酸基环己烷羧酸对萃取过程有盐析效应,使分配比增大;萃取过程受温度影响不大,焓变值ΔH=2.86 kJ/mol。实验确定了pH=7时己内酰胺在有机相与水相中的分配平衡关系,当有机相和水相体积比为1时,三级错流萃取的萃取率可达到98%以上。同时,进行了工业废水的萃取验证实验,结果表明,氯仿对废水中己内酰胺的萃取效果良好。
For the purpose of extraction and recovery of caprolactam in caprolactam waste liquid by toluene method, chloroform was selected as extractant, and the recovery of caprolactam was studied. The effects of pH, extraction temperature, extraction time and other factors on the extraction of caprolactam from chloroform were investigated. The results showed that the partitioning ratio of the extraction process increased with the increase of pH under acidic conditions. The partition ratio was the highest when pH = 7. The extraction process was rapid and the extraction equilibrium was reached after 20 min. 1-sulfonated cyclohexanecarboxylic acid has a salting-out effect on the extraction process, which increases the partitioning ratio; the extraction process has little effect on temperature, and the enthalpy change ΔH = 2.86 kJ / mol. The equilibrium between caprolactam and the aqueous phase was determined at pH = 7. When the volume ratio of organic phase to aqueous phase was 1, the extraction yield of three-stage cross-flow extraction could reach over 98%. At the same time, the industrial waste water extraction verification experiment was carried out. The results showed that chloroform had a good effect on the extraction of caprolactam from wastewater.