Biosorption of cadmium (II) and copper (II) by pretreated biomass of marine alga Gracilaria fisheri.

The cadmium (II) and copper (II) adsorption properties of chemically pretreated biomass of red marine alga Gracilaria fisheri were investigated. Batch equilibrium experiments showed that the maximum adsorption capacity values of the pretreated biomass for cadmium and copper were 0.63 and 0.72 mmol g(-1), respectively. The equilibrium data fitted well to the Langmuir isotherm model. The adsorption capacity increased as pH increased and reached a plateau at pH 4.0. The cadmium and copper uptake rates were rapid with 90% of the biosorption completed within 30 minutes. The presence of light metal ions (Na+, K+, Mg2+ and Ca2+) in solution had an insignificant effect on cadmium and copper sorption capacity. These findings indicate a positive potential for the biosorbent development with effective heavy metal removal capacity in the presence of light metal ions in waste streams by using the biomass of plentifully available red marine algae.