Sorption of Antibiotics, Pharmaceuticals, and Personal Care Products in Water on Didodecyldimethylammonium Bromide-Montmorillonite Organoclay

Abstract

The sorption of various antibiotics, pharmaceuticals, and personal care products in water onto didodecyldimethylammonium bromide (DDAB)-modified montmorillonite organoclay was studied. The extent of their sorption onto the organoclay was largely dependent on the DDAB content; the effect of DDAB modification on the sorption was also influenced by the hydrophobicity and/or net charge of the pharmaceutical. The binding constants of β-lactam antibiotics were determined from their interaction with the DDAB molecules on the organoclay and were correlated with their aqueous–octanol distribution coefficients. Additionally, they were influenced by the net charge of the antibiotic. A wide range of β-lactam antibiotics, including penicillin- and cephalosporin-type antibiotics, were sorbed on the organoclay and rapidly degraded under mild conditions (pH 7, 25°C). The continuous sorption and degradation of penicillin G in a buffer solution and in synthesized hospital wastewater using an organoclay-packed column were demonstrated. The resulting effluent was free of penicillin, and contained only penicillin degradation products, suggesting the usefulness of DDAB-MT organoclay as a barrier material for controlling the diffusion of antibiotics.