Removal of Pesticide (Endosulphan) from Water via Adsorption onto Activated Carbons Developed from Date Pits

Abstract

Activated carbons were prepared by impregnation of crushed clean date pits in concentrated solutions of phosphoric acid or zinc chloride followed by carbonization in absence of air at 600ºC. Steam-activated carbon was prepared by gasifying 600ºCcarbonization product at 950ºC to a burn-off = 50%. KOH-activated carbon was prepared by impregnating date pitscarbonization product obtained at 450ºC in concentrated KOH solution followed by carbonization at 840ºC. Textural properties of these carbons were determined from nitrogen adsorption at −196ºC and the chemistry of the carbon surface was investigated by determination and of the surface carbon-oxygen (C-O) groups using bases of variable strength and dilute HCl. The adsorption of endosulphan at 27ºC on all the carbons prepared was undertaken. Adsorption of this pesticide at 32 and 37ºC was also undertaken for steam-activated and KOH-activated carbons. Phosphoric acid-activated carbons and steamactivated carbons are mainly microporous and have high surface concentration of C-O groups of acidic nature. Steamactivated and KOH-activated carbons exhibited surface areas > 1000 m 2 /g and contain micro and non-micrpores. The adsorption of endosulphan was related to the surface area of non-micropores and was retarded by the high concentration of surface C-O groups. The thermodynamic properties indicated the feasibility of the adsorption process and the possible regeneration of the carbon for further use.