SORPTION INTERACTIONS BETWEEN TRACE-METALS (CD AND NI) AND PHENOLIC SUBSTANCES ON SUSPENDED CLAY-MINERALS

The phenomena of pollutant fixation on suspended clay minerals (chlorite, illite and kaolinite) were studied in an estuarine system. Isotherms and the dependence of adsorption on time for Cd, Ni and phenolic compounds (eugenol and vanillic acid) were studied. Clay minerals (as suspended matter) were exposed to trace metals and phenolic compound solutions. It was found that chlorite was a better adsorbent with 71% of Cd and 79% of Ni adsorbed at concentrations of suspended particulate matter of 400 mg l-1. At pH 8, the quantity of adsorbed phenolic compounds was lower than that of trace metals (up to 23% as compared to up to 79%). After examinations of adsorption capacities, investigation of the interactive effects of these pollutants on the sorption phenomena was studied. Cadmium would compete with nickel for the same adsorption sites. Vanillic acid was less sorbed than eugenol, but phenolic compounds generally enhanced the sorption of metallic cations on studied clay minerals. The presence of metallic cations increased the sorption of phenolic compounds. Investigated phenolic compounds represent the structure of humic substances in the environment, which are considered a predominant form of soluble (or colloidal) organic matter in natural waters.