Kinetics of single and multiple metal ion sorption processes on humic substances

Heavy metal ion pollution of groundwater must be avoided in land- based waste disposal systems and the role of humic substances in binding organic and inorganic pollutants is well known. The kinetics of single metal and multiple ion competitive sorption on humic acids from 3 sources, using a batch-type reactor and sequential sampling procedures were compared. The overall sorption kinetics of metal ions with humic acids were found to be non-linear and the Langmuir- Hinshelwood model used to describe some of the sorption kinetics for single and multiple ions. The presence of chromium(III) greatly decreased the adsorption of all other metals. For all metal ions less total sorption of each occurred with multiple competing ions, than with single metal ions. The sorption preference between metal ions and humic acids were generally predicted by Pearson's Hard Soft Acid Base principles and Klopmann's generalized perturbation theory of chemical reactivity. There are 49 references.