Extraction and Preconcentration Capacity of Bifunctionalized Diamine-Thiol Polysiloxane Immobilized Ligand System Towards Some Divalent Cations

Porous solid bi-organofunctionalized diamine-thiol polysiloxane immobilized ligand system of the general formula P-(CH2)3-X, (where P represents [Si-O]n siloxane network and X represents a mixture of diamine; -NH(CH)2NH2 and thiol; -SH functional groups) has been prepared by hydrolytic polycondensation of TEOS with a mixture of 3-mercaptopropyltrimethoxysilane and 3- (2-aminoethylimino)propyltrimethoxysilane agents. The ligand system was evaluated for extraction and preconcentartion of a series of divalent metal ions from aqueous solutions including: Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+. Both batch and dynamic methods were used to examine maximum sorption capacity. The maximum binding capacity followed the sequence; Cu2+ > Pb2+ > Cd2+ > Ni2+ > Zn2+ > Co2+ at pH 5.5. Measurement of variation of sorption of metal ions with temperature yielded negative values of ΔG° and positive values of ΔS° and ΔH° indicating a spontaneous and endothermic process of binding metal ions to the ligand system