Adsorption of diuron and its degradation products from aqueous solution by surfactant-modified pillared clays

Adsorption of the herbicide diuron and its three degradation products: 3-(3,4-dichlorophenyl)-1-methylurea, 1-(3,4-dichlorophenyl) urea and 2,4-dichloroanilin on three organo–inorgano-clay minerals, was investigated. These surfactant-modified pillared clays (SMPC) were prepared by intercalation of polycations of aluminum(III), iron(III) or titanium(IV) into the interlamellar space of a montmorillonite, followed by co-adsorption of cetyl trimethylammonium bromide. The adsorption capacity of these new microporous solids was considerably enhanced especially with Ti- or Fe-SMPC. The adsorption isotherms of diuron and its derivatives at different pH were performed on each SMPC. These isotherms are typically S-type curves and suggested a hydrophobic adsorption mechanism. A comparative study of adsorption of the four compounds on each SMPC adsorbent shows the high adsorption capacity of diuron in comparison with its degradation products. This new generation of adsorbents could thus be considered as powerful competitors to activated carbon for the water treatment of industrial effluents in acidic medium.