BIOSORPTION OF METAL-IONS FROM AQUEOUS-SOLUTIONS

Copper biosorption from aqueous solutions by calcium alginate is repor ted in this paper. The experimental section includes potentiometric ti trations of biosorbents, batch equilibrium and kinetic studies of copp er biosorption, as well as fixed-bed biosorption experiments. The pote ntiometric titration results show that the surface charge increases wi th decreasing pH. The biosorption of copper strongly depends on soluti on pH; the metal ion binding increases from 0 to 90 percent in pH rang ing from 1.5 to 5.0. In addition, a decrease in ionic strength results in an increase of copper ion removal. Kinetic studies indicate that m ass transfer plays an important role in the biosorption rate. Furtherm ore, a fixed-bed biosorption experiment shows that calcium alginate ha s a significant capacity for copper ion removal. The two-pK Basic Ster n model Successfully represents the surface charge and equilibrium bio sorption experimental data. The calculation results demonstrate that t he copper removal may result from the binding of free copper and its h ydroxide with surface functional groups of the biosorbents.