Isotherm data of Fe3+, Cr3+, and Co2+ adsorbed on surface of silica-propylpiperazinedithiocarbamato

The silylant agent chloropropyltrimetoxysilane immobilized on silica gel reacts with piperazine, followed by another reaction with carbon disulfide in the presence of sodium hydroxide, to produce a new matrix sodium propylpiperazinedithiocarbamato silica. The basic centres of the resulting surface complexes are the Cr3+, Fe3+ and Co2+ cations from aqueous solution. The adsorbed isotherms for cations were adjusted to fit Giles models. The isotherm for Cr3+ could be classified as L2, while those for Fe3+ and Co2+ fitted the subgroup 2 of C class. The isotherm data show that the capacity of the final carbamate surface to chemisorb Fe3+ and Co2+ is Only one third that observed for Cr3+. (C) 1998 Elsevier Science B.V.