Influence of surfactants on the sorption of contaminants in natural waters
Surfactants are a group of chemicals that comprise both polar and nonpolar regions, and are classified according to the nature of the hydrophile as anionic, cationic, non-ionic or amphoteric. Surfactants have a range of domestic and industrial applications and are, therefore, important contaminants in their own right. However, they have the potential to strongly influence the behaviour of co-contaminants such as organic micropollutants and trace metals. We have studied the effects of ionic surfactants on the behaviour of phenanthrene, a polycyclic aromatic hydrocarbon, and two strongly-complexing metals, mercury and palladium. Anionic surfactants like sodium dodecyl sulphate (SDS) generally results in a reduction in the sorption of co-contaminants to sediment particles through competition from the surfactant tail for particle sorption sites. In contrast, cationic surfactants like hexadecyltrimethylammonium bromide (HDTMA) enhance the sorption of co-contaminants by conferring a more hydrophobic surface on the particles for the sorption of organic pollutants and strongly-complexed metals. Results from this kind of study also have important implications for possible remediation measures of contaminated surface waters.
Above: Isotherms defining the adsorption to phenanthrene to Plym estuarine sediment in the absence (filled squares) and presence of SDS
Above: Isotherms defining the adsorption to phenanthrene to Plym estuarine sediment in the absence (filled squares) and presence of HDTMA
Publications
Jones-Hughes, T.L. and Turner, A. (2005). Sorption of ionic surfactants to estuarine sediment and their influence on the sequestration of phenanthrene. Environmental Science and Technology 39, 1688-1697.
Turner, A. and Xu, J. (2008). Influence of ionic surfactants on the flocculation and sorption of palladium and mercury in the aquatic environment. Water Research 42, 318-326.