Adsorption and desorption of dicofol pesticide on apatites

In the present work, adsorption-desorption study of dicofol pesticide (4-chloro-alpha-(4-chloro-phenyl)-alpha-(trichloromethyl) benzene -methanol) in hexane medium was investigated. Adsorbents used were a nonstoichiometric hydroxy apatite and a pure fluorapatite. The influence of drying temperature and carbonate ions on the adsorption phenomenon was also carried out. Analysis of the solution, carried out by UV spectrophotometry, showed that non- stoichiometric hydroxy apatite adsorbed this molecule more than the fluorapatite. Adsorption of dicofol by non-stoichiometric hydroxy apatite suggests that the mechanism of adsorption was incorporation of hydroxyl groups into OH- vacancies. However, on fluorapatite a physical adsorption mechanism was involved. The desorption study reveals that the percentage of dicofol desorbed in solution was higher by using pure fluorapatite.