The biosorption of cadmium(II) and zinc(II) ions onto dried Fontinalis antipyretica, a widely spread aquatic moss,
was studied under different values of temperature, initial pH and water hardness. The equilibrium was well described by
Langmuir adsorption isotherms. Maximum biosorption capacity of cadmium was independent on temperature and
averaged 28.0mg g 1 moss, whereas for zinc, capacity increased with temperature, from 11.5mg g 1 moss at 5 C to
14.7mg g 1 moss at 30 C. Optimum adsorption pH value was determined as 5.0 for both metal ions. Cadmium uptake
was unaffected by the presence of calcium ions, but zinc sorption was improved when water hardness increased from
101.1 to 116.3mg CaCO3 l 1. Inversely, as hardness increases, the competition with calcium ions strongly reduces the
affinity of the biosorbent for zinc.
