Adsorption of Heavy Metal Ions onto Green Microalga Chlamydomonas reinhardtii

Microalga Chlamydomonas reinhardtii was used for adsorption of Pb(II), Fe(III) and Ni(II) ions. FT-IR analysis and pH titration of the algal biomass revealed the presence of amino, carboxyl and sulfonate groups, which were responsible for adsorption of the metal ions. The optimum pH for adsorption of Pb(II), Fe(III) and Ni(II) ions were found to be 5.0, 4.0 and 7.0, respectively. The adsorption equilibrium was established in about 200 min for Pb(II) and Fe(III) ions and 120 min for Ni(II) ion. The maximum adsorption capacities of the microalga for Pb(II), Fe(III) and Ni(II) ions were 1.47, 1.13 and 0.870 mmol/g-biomass, respectively. The order in metal affinity for the algal biomass was Fe(III)> Pb(II)> Ni(II). The adsorption equilibrium was well described by the Langmuir adsorption isotherm. C. reinhardtii could be considered as one of the suitable biosorbents for the removal of metal ions in waste water treatment because of the relatively high adsorption capacities. The biosorbents could be reused five times in consecutive adsorption/desorption cycles for Fe(III) ion with 25% loss in the adsorption capacity..