乳化液膜法提取废水中的阿司匹林

Extraction of aspirin from wastewater by emulsion liquid membrane

针对阿司匹林(ASA)结晶母液经处理后产生的废液,采用搅拌和超声结合的方法制备了乳化液膜体系来回收ASA。以环己烷为膜溶剂,Span80做表面活性剂,石蜡做膜稳定剂,氢氧化钠(NaOH)为内水相,研究了表面活性剂浓度、内水相NaOH浓度、内水相类型、外相pH、油内比、乳水比、搅拌速度、膜溶剂类型、盐浓度、ASA初始浓度等试验条件对ASA萃取效果的影响,并进行了破乳研究。结果表明:在最佳实验条件下[环己烷90%(质量分数)、Span80 6%(质量分数)、C(NaOH)=0.1mol/L、油内比1∶1、水乳比1∶4、搅拌速度200r/min、ASA初始浓度500mg/L],不对外相进行p H调节时,15min后ASA的萃取率可高达97.4%。对实验后的乳液进行离心破乳,20min后破乳率可达72.9%,破乳后的油相重复利用5次后,对ASA的提取率仍在76%左右。

The emulsion liquid membrane(ELM)system was prepared by combining agitation with ultrasonic to extract ASA(acetylsalicylic acid)from wastewater produced by ASA crystallization mother liquor.The ELM system is made up of the cyclohexane as diluent,Span80 as the surfactant,liquid wax as the stabilizer,and the sodium hydroxide as the inneraqueous solution.The effect of the experimental conditions that affect the extraction of ASA,such as surfactant concentration,internal phase concentration,type of internal phase,pH of external phase,volume ratio of oil phase to internal phase,treatment ratio(ratio of emulsion phase to external phase),stirring speed,diluent type,salt concentration,and ASA initial concentration was investigated.The experimental results showed that under the optimum operating conditions[diluent(cyclohexane)90%(mass ratio);surfactant(Span80)6%(mass ratio);stabilizer(liquid wax)4%;C(NaOH)=0.1mol/L;V(oil phase)∶V(internal phase)=1∶1;V(emulsion phase)∶V(external phase)=1∶4;stirring speed=200r/min;ASA initial concentration,500mg/L]about 97.4%ASA was removed in less than 15min of contacting time.Meanwhile,the demulsification rate of emulsion was 72.9%after about 20min,and the extraction rate of ASA was still about 76%after demulsification while oil phase was used for 5 times.