Biosorption of Cr(III) by Microalgae and Macroalgae: Equilibrium of the Process

Equilibrium experiments of chromium(III) biosorption by microalga (Spirulina sp.) and macroalga (Pithophora varia) were investigated in this paper. Influence of the following process parameters was studied: pH, biomass concentration and temperature. The equilibrium of the process was described with Langmuir equation. The model parameters were determined at various process conditions. The best operation conditions for the process were selected: pH 5, T 20^oC, C_s 1g.l^-1 for Pithophora varia and the same for Spirulina sp. Under these conditions, the maximum biosorption capacity 60.6 mg.g^-1 and 34.6 mg.g^-1, and affinity constant 0.182 l.mg^-1 and 0.0553 l.mg^-1 were reached for Pithophora varia and Spirulina sp., respectively. It was found that Pithophora varia was more efficient in biosorption of Cr(III) ions than Spirulina sp. Biosorptive properties of microalgal and macroalgal biomass can be employed either in the production of biological feed supplements for livestock or in wastewater treatment processes.