Biosorption, a green approach for heavy metal removal from water

Water contamination with heavy metals due to industrial activities generates serious environmental problems because of their high toxicity and non-biodegradability. Various waste materials for biosorptive removal of heavy metal ions from aqueous solutions: olive leaves, almond shell residues, hazelnut shell, coconut husk, coffee ground, tea leaves, groundnut husk were selected because of a low cost and a higher biosorption capacity. The effective removal of Pb2+ from aqueous solutions using low-cost biosorbents: carrot residue and green tea waste was studied. These waste materials were selected because of a low cost and the availability of functional groups such as carbonyl, hydroxyl, carboxylic etc. due to high cellulose, hemicellulose or lignin content, which favours biosorption of heavy metal ions. The equilibrium data were described by typical Freundlich, Langmuir and Temkin adsorption models for each heavy metal - adsorbent system. The adsorption
equilibrium exhibited better fit to Langmuir model within the concentration range studied for carrot residue and the adsorption of Pb2+ by green tea waste showed a slightly better fit with the Freundlich model compared to Langmuir and Temkin. This study revealed that the biosorption offers a great opportunity for a clean, cheap and high effective process for lead ions removal from polluted water.