Abstract

A comparative study was performed on the sorption capacity of the phenoxy acid herbicide cyhalofop on polymerin (from olive oil mill effluents), ferrihydrite, and a ferrihydrite-polymerin complex, by using a batch equilibrium method. The most efficient sorbent showed to be ferrihydrite followed by the ferrihydrite-polymerin complex and polymerin. Cyhalofop acid bound to ferrihydrite by a combination of ionic and ion-dipole bonding, whereas the same herbicide bound to the ferrihydrite-polymerin complex by ionic bonding and to polymerin by hydrogen bonding. Simulated wastewaters contaminated with cyhalofop acid were completely purified by two sorption cycles on ferrihydrite and five cycles on the ferrihydrite-polymerin complex, whereas the same wastewaters maintained a constant residue even after five sorption cycles on polymerin. For the first time, the possible use of a mineral (ferrihydrite) and an organo-mineral complex (ferrihydrite-polymerin) as a filter for the control of the herbicide contamination in point sources is proposed and briefly discussed.