Studies on the evaluation of Sulphonated Pungan Pongamia Pinnata seedpod carbon for the removal of toxic trace metals from aqueous system

Abstract

The increased amount of heavy metals in the aqueous environment poses great threat to human beings and other living things. Adsorption techniques have been followed for treating the heavy metals with the help of commercial activated carbon since long back. The present study is aimed at preparing an activated carbon from Pungan seedpod, an agricultural waste, also available in plenty, using sulphuric acid treatment and comparing its characteristics with a commercial activated carbon to evaluate its suitability in the removal of heavy metals present in aqueous system. The batch experiments were conducted using 100 mL of 10 mg L-1 solutions. The batch experiments showed that the metal removal efficiency of BSPAC was high even under lower quantities. To understand the desorbing nature of adsorbents, desorption experiments were carried out using hydrochloric acid solutions. Experiments with wastewater were also carried out to know the suitability of adsorbents for industrial wastewater. The popular kinetic models namely reversible-first order, pseudo-first order and pseudo-second order were applied to study the kinetic data. The straight lines obtained in the Weber Morris model did not pass through the origin. FTIR studies were carried out to identify the functional groups responsible for metal ion adsorption. FTIR spectral studies showed the presence of active carboxyl, hydroxyl, alkyl, amide and sulphonyl functional groups involved in the adsorption. SEM analysis showed the presence of micro pores and heterogeneity of carbon. The EDAX studies confirmed the participation of metal ions in the adsorption process by the presence of their characteristic peaks. Hence based on the performance of BSPAC in the removal of cadmium (II), lead (II) and nickel (II) metal ions, it was concluded that bicarbonate impregnated sulphonated pungan seedpod carbon would be considered as an efficient alternative adsorbent for the removal of metal ions from water system. newline