Sorption of Alkyl Benzyl Dimethyl Ammonium Compounds by Activated Sludge

The adsorption isotherms on activated sludge from wastewater treatment plants and the surface properties in aqueous solution of alkyl benzyl dimethyl ammonium compounds have been investigated. Langmuir and Freundlich adsorption isotherms described satisfactorily the equilibrium adsorption of these cationic surfactants on activated sludge. Adsorption on sludge as well as the affinity of these compounds to be adsorbed in the liquid/gas interface increased with increasing the alkyl chain length in the cationic surfactant molecule. Water hardness decreased the critical micelle concentration values of the alkyl benzyl dimethyl ammonium homologues tested and the extent of their sorption to activated sludge.