APPLICATION OF MULTICOMPONENT ADSORPTION-ISOTHERMS TO SIMULTANEOUS BIOSORPTION OF IRON(III) AND CHROMIUM(VI) ON CHLORRELA-VULGARIS

Although the biosorption of single metal ions to various microorganism s has been extensively studied and adsorption isotherms have been deve loped for single-metal ion situations, very little attention has been given to the bioremoval and the expression of the adsorption isotherms of multi-metal ions systems. In this study, the competitive biosorpti on of iron(III) and chromium(VI) to Chlorella vulgaris from a binary m etal mixture was studied and compared with the single metal ion situat ion in a batch stirred system. The effects of pH and single and dual m etal ion concentrations on the biosorption rates and equilibrium uptak es were investigated. The optimum biosorption pH for both metal ions w as determined as 2.0. Multi-metal ion biosorption studies were also pe rformed at this pH value. It was observed that the biosorption rates a nd,yields and equilibrium uptakes of iron(III) or chromium(VI) ions we re reduced by the presence of increasing concentrations of the other m etal ion. Adsorption isotherms developed for both single and dual meta l ion systems at the optimum pH were expressed by the non-competitive and competitive Langmuir and Freundlich adsorption models, and model p arameters were determined by computer. It was seen that the adsorption equilibrium data fitted very well to both of the models in the concen tration ranges studied.