Voltammetric study of the role of organic acids on the sorption of Cd and Cu ions by alumina particles

The adsorption of Cd and Cu ions was studied on bare gamma-Al2O3 particles and on gamma-Al2O3 particles pre-equilibrated with humic acid (HA), t-carra geenan or polyacrylic acid (PAA) in 0.55M NaCl solution, similar to natural seawater. The adsorption of the mentioned organic substances on alumina pa rticles was studied simultaneously. It was found that the interaction of co pper ions with alumina particles was enhanced in the presence of HA, and wa s not significantly changed in the presence of PAA or t-carrageenan when co mpared to the interaction with the bare alumina surface. For cadmium ions, which interact to a very small extent with the HA in the solution as well a s with mineral particles, the interaction observed on the gamma-Al2O3 parti cles pre-equilibrated with HA was also negligible. There was no indication of the change in adsorption of organic matter on the alumina particles in t he presence of metal ions. (C) 1999 Elsevier Science B.V. All rights reserv ed.