IMMOBILIZED DITHIOCARBAMATE GROUPS ON SILICA - CHEMISORPTION OF SOME CATIONS FROM ETHANOLIC SOLUTION

Immobilized dithiocarbamate was prepared by reacting a 3-propylethylenediamine group, covalently bonded to silica gel, with carbon disulfide in toluene. This modified surface has 6.7 x 10(-4) mol g(-1) of ligand sites available to extract cobalt, nickel, copper and zinc from ethanol solution. The adsorption isotherms are very similar in shape for all cations and conform to the Langmuir model. However, the degree of adsorption indicated a metal: a ligand ratio of 1:3 for cobalt, 1:2 for nickel and 1:1 for copper and zinc complexes. These cations are sulfur-bonded to the anchored ligand. The isotherm of the cobalt chemisorption data agrees with oxidation of cobalt to the trivalent state. The geometries of these complexes are similar to those obtained in solution. The results suggest a very similar behavior of the dithiocarbamate chemically bonded on silica gel with that of these ligands in the unbonded state.