Abstract:

The influence of co\|existing heavy metals on the adsorption of cadmium and copper onto solid phases was investigated by simulating aquatic multiphase system comprising three types of solid phases, including biofilms, suspended particulate materials and sediments, in the absence and presence of co\|existing heavy metals. The results indicate that co\|existing metals (copper and lead) reduced the adsorption of cadmium to all solid phases remarkably. Under  the conditions of the adsorption of cadmium onto suspended particulate materials, the reduction effects increased as the initial concentration of copper and le
ad increased. Under the conditions of the adsorption of cadmium to biofilm and sediments, increasing lead initial concentration enhanced the reduction effects on cadmium adsorption, but increasing copper initial concentration had little influence on the reduction effects. The co-existing lead reduced the adsorption of c
opper to solid materials and these reduction effects increased with the increase of lead concentration for all the solid materials, while the co-existing cadmium had only a little effect on copper adsorption. Overall, the mpetitive adsorption between heavy metals was insignificant at low concentrations, and enhanced with the increasing of the concentration of co-existing heavy metals. The concentration of co-existing metals influenced the reduction of the adsorption of copper and cadmium to suspended particulate materials. The greater the concentrations of co-existing heavy metals were, the stronger the reduction of the adsorption of
 cadmium and copper to suspended particulate materials was.

Key words:  biofilms, suspended particulate materials, sediments, competitive adsorption, heavy metals