Adsorption and desorption of dicofol pesticide on apatites

In the present work, adsorption-desorption study of dicofol pesticide (4- c hloro-alpha-(4-chloro-phenyl)-alpha-(trichloromethyl) benzene -methanol) in hexane medium was investigated. Adsorbents used were a nonstoichiometric h ydroxy apatite and a pure fluorapatite. The influence of drying temperature and carbonate ions on the adsorption phenomenon was also carried out. Anal ysis of the solution, carried out by UV spectrophotometry, showed that non- stoichiometric hydroxy apatite adsorbed this molecule more than the fluora patite. Adsorption of dicofol by non-stoichiometric hydroxy apatite suggest s that the mechanism of adsorption was incorporation of hydroxyl groups int o OH- vacancies. However, on fluorapatite a physical adsorption mechanism w as involved. The desorption study reveals that the percentage of dicofol de sorbed in solution was higher by using pure fluorapatite.