Biosorption of toxic metals: Effect of pH, reversibility and comparison with a kaolin as adsorbent material

An Arthrobacter sp. biomass was tested as the biosorbent material for Cu(2+), Cd(2+) and Fe(3+) Biosorption trials were performed for each metal at different equilibrium pH values and levels of biomass concentration. Experimental results pointed out that both pH increase and low biomass concentrations influenced positively metals uptake. The reversibility of the biosorption equilibrium was investigated by analysing the effect of the order of the addition of two different metals to the cellular suspension. Equilibrium modification tests were carried out by dilution and acidification of the cellular suspension containing the metal distributed at the equilibrium between biomass and solution. Experimental data showed that biosorption equilibrium was not reversible in the conditions examined. In this work biomass was compared with a kaolin. In the range of metal concentrations typically treated by biosorption (0-200 ppm), the biomass tested gave better results than those of the kaolin.