Application of L 3 sponge phase in extraction of polycyclic aromatic hydrocarbons

Application of L 3 sponge phase as an extractant in extraction of polycyclic aromatic hydrocarbons (PAHs) from aqueous solution were studied systematically at 25°C with three nonionic surfactants, Tergitol 15‐S‐5, LE‐203 (C 12 E 3 ), and Brij 30 (C 12 E 4 ). The transition temperatures of the coexisting W + L 3 phases of these surfactants could be regulated with the addition of proper salting‐out electrolytes and short‐chain alcohols. The low viscosities of these L 3 ‐phase extractants, ranging from 10 to 40 mPa s, make it not difficult for separation of these extract‐containing L 3 phases from the coexisting water (W) phases. Compared to the conventional cloud‐point extraction techniques, a relatively larger preconcentration factor with satisfactory recovery efficiency of PAHs are achieved in such L 3 ‐phase extraction procedure. For example, a preconcentration factor as much as ca. 200 was achieved in 0.2 wt % Tergitol 15‐S‐5 solution added with 5.6 wt % NaCl. In general, a higher preconcentration factor is attained with a decrease in surfactant concentration and/or with increasing concentrations of additives employed in this work. © 2007 American Institute of Chemical Engineers AIChE J, 2007