相分离辅助方法对有机硅表面活性剂浊点萃取PAHs的影响

Effect of Assisting Methods for Phase Separation on the Performance of Cloud Point Extraction of PAHs with Silicone Surfactant

相分离性能和萃取率是评价浊点萃取(CPE)性能的两个重要因素。对于采用非离子表面活性剂的CPE,当溶液加热至浊点以上,仅依靠热运动来促使其发生相分离是十分缓慢的,因此通常需要一定的辅助方法来加速其相分离的进程。今利用两种聚醚型有机硅表面活性剂DC-193和DC-190,对蒽、菲、芘和苊四种多环芳烃(PAHs)进行浊点萃取研究,分别使用加热、加盐、离心和搅拌等辅助方法改变相分离过程的速度。通过测定表面活性剂富集相的体积百分率Vs/(Vs+Vw)随时间的变化和最终的萃取率,研究上述四种不同辅助方法对相分离行为和萃取性能的影响。结果表明,相分离速度:加盐<加热<离心<搅拌;Vs/(Vs+Vw):搅拌<离心<加盐<加热;萃取率:加热<加盐≈离心<搅拌。可见,离心与搅拌辅助CPE具有较大的优势,可同时提供更高的相分离性能和萃取率。与离心相比,搅拌的引入所需设备更简单,而且对于容器的体积没有限制,易于实现连续操作,更有望应用于实际的大规模水处理之中。

Phase separation performance and recovery are two important factors for the cloud point extraction （CPE） process. Since the phase separation speed of surfactant micelle solution is slow when the method of simply heating the solution to a temperature above its cloud point is used, an efficient assisting method is required to accelerate the phase separation of the CPE process. In this study, the CPE processes of four different kinds of polyaromatic hydrocarbons （PAHs）, acenaphthene, anthracene, phenanthrene and pyrene, with two kinds of silicone surfactants, DC-193 and DC-190, were studied separately, and four different assisting methods for the phase separation of the CPE process including heating at a higher temperature, adding salts, centrifugation and stirring were introduced, respectively. The phase separation speed, surfactant-rich phase volume percentage （Vs/（Vs＋Vw）） and recovery of PAHs were used to evaluate the CPE performance. The results show that the assisting methods make the phase separation speed increased in following order： adding salts〈 heating 〈 centrifugation 〈 stirring; the increase of Vs/（Vs＋ Vw） in the order of stirring 〈 centrifugation 〈 adding salts〈heating, and the increase of recovery of PAHs in the order of heating〈adding salts≈centrifugation〈 stirring. The CPE process assisted with centrifugation or stirring has a large advantage of having high phase separation performance and recovery at the same time. In addition, comparing with the CPE process assisted with centrifugation, the process assisted with stirring method needs simpler apparatus and has no limitation in container volume used, therefore it is easier to be used in the continuous operation and is more expected to be applied in practical water treatment.