Removal of Hexavalent Chromium from Aqueous Solutions using Some Plants Bark Powder as Adsorbents

Abstract

Heavy metals that have been associated only with chemists have now become a concern of environmentalist also. They impact the ecosystems when released into water bodies or soil by various human activities resulting in the environmental pollution. High concentration of Cr (VI) is harmful to animal and human health. The hexavalent chromium exists in aquatic media as water soluble complex anions and persist. These are concentrated in industrial waste water especially from the tannery industries and release of effluents from industries adversely affects the environment. The removal of heavy metals from aqueous solutions is carried out by different physical, chemical and biological methods. Now a days, use of plants waste products such as: barks, manures or lignocellulosic materials, for the removal of heavy metals from polluted water are becoming of more concern. In the present study, low-cost and easily available material such as plant barks for the removal of chromium VI from its aqueous solution was investigated. Bark powders of plants namely, Pongamia glabra, Tamarindus indicus, Tesphesia populnea, and Mangifera indica obtained from nearby saw mills, were used as adsorbent for the removal of Cr (VI) from aqueous solutions in excess of maximum permissible limits. Adsorption for chromium (VI) was found to be highly dose dependent compared to the other parameters observed with almost 100 % efficiency at pH 2, contact time of 2h at room temperature with 3 g l-1 bark dosage. The adsorption capacities of all the plant barks for chromium (VI) was found to be comparable to other commercial adsorbents currently employed for the removal of heavy metals from aqueous wastes. The results have demonstrated the immense potential of plants bark powder as an alternative adsorbent for removal of Cr(VI) ions from polluted water.