Geosmin Sorption on Cyclodextrin Polymers

Abstract

Geosmin is one of the major causative compounds of earthy-musty odor and taste (off-flavor) in drinking water (lakes) and in farmed fish. In this study, the sorption of cyclodextrin polymers (CDPs) towards geosmin in aqueous solution was investigated. Sorption kinetics, the effect of solution pH and contact time on the sorption capability of alpha -, beta - and gamma -cyclodextrin polymers was discussed. Results disclosed that the sorption of geosmin by the CDPs followed the Ho and McKay kinetic mechanism with the liquid film diffusion as the rate-determining step. Both beta -CDP and gamma -CDP exhibit high removal efficiencies of 93.4% and 96%, respectively, within 240 minutes at 25 degrees C and pH 7, whilst alpha -CDP was not effective, removing only 40% geosmin, at an initial concentration of 5 micro g.L-1 and 5 g.L-1of CDP dose. The cyclodextrin polymers can adapt to a wide range of pH from 3.0 to 11.0 for geosmin adsorption with pH 7.0 as optimum. Results indicate that these sorbents demonstrate significant potential in reducing the concentration of geosmin in water that presents taint problems in both drinking water and fish.