Enhanced desorption of hexachlorobenzene from kaolin by single and mixed surfactants.

This study investigated the enhanced desorption of hexachlorobenzene (HCB) from spiked kaolin by single and mixed surfactants. The sorption of surfactants on kaolin followed myristyl pyridinium bromide (MPB) > Tween 80 > sodium dodecyl benzene sulfonic (SDBS). The desorption of HCB by single surfactant increased linearly with the increase of the aqueous micelle concentrations. The potential to enhance HCB desorption was Tween 80 > SDBS > MPB. When the dual mixed surfactants of SDBS-Tween 80 (MPB-Tween 80) were present, the desorption of HCB was larger than that by single SDBS (MPB) and less than that by single Tween 80. The total adsorbed surfactants were kept almost constant in SDBS-Tween 80 but decreased with the increased fraction of Tween 80 above 0.5 in MPB-Tween 80. The presence of little MPB in Tween 80 highly reduced the sorption loss of Tween 80 but slightly decreased the desorption of HCB. Whereas in SDBS-MPB, the presence of little MPB in SDBS remarkably decreased the desorption of HCB and enhanced the loss of SDBS, while the addition of little SDBS in MPB significantly enhanced the desorption and reduced the loss of MPB.