Application of diatomite as a biosorbent material for the removal of chlortoluron and isoproturon from water

Diatomite, one of the cheapest and abundantly available adsorbents was employed for the removal of two phenylurea herbicides, chlortoluron and isoproturon, from aqueous solutions. Physical characteristics of diatomite were investigated. The adsorption batch experiments were carried out as a function of initial herbicide concentrations, stirring speed, temperature and pH to determine the adsorption capacities of studied diatomaceous earth. The study of the pH effect showed a significant increase of adsorption as it passes from 6 to 9. The representation of the isotherms by the most commonly used models, Langmuir and Freundlich, showed that adsorption of the two selected phenylureas on diatomite obeys these two models. The adsorption mode of chlortoluron and isoproturon on diatomite could be primarily physical and under these conditions would lead to an exothermic retention process.