Application of L3 sponge phase in extraction of polycyclic aromatic hydrocarbons



Application of L3 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 (C12E3), and Brij 30 (C12E4). The transition temperatures of the coexisting W + L3 phases of these surfactants could be regulated with the addition of proper salting-out electrolytes and short-chain alcohols. The low viscosities of these L3-phase extractants, ranging from 10 to 40 mPa s, make it not difficult for separation of these extract-containing L3 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 L3-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