Removal of lead (Pb2+) from synthetic wastewater using calcium pectate

Abstract

The present work deals with the use of calcium pectate as a biosorbent for Pb(II) ions removal from aqueous solutions. Surface morphology of the adsorbent was analysed by scanning electron microscopy (SEM). The surface chemical nature of the biosorbent was studied by Fourier transform infrared spectroscopy (FTIR). The FTIR results revealed that amide, ether, alcohol and carbonyl functional groups are responsible for Pb(II) biosorption onto calcium pectate. Batch experiments were carried out to investigate the effects of pH, time, and initial metal ion concentration on the adsorption of Pb(II) ions by the biosorbent in synthetic wastewater. The optimum contact time and pH for the removal of Pb(II) ions were 480 min and pH 5.0, respectively. It was found that the maximum loading capacity of the biosorbent was 4.45 mg·g−1 for Pb(II) ions. Results indicated that the mechanism of Pb(II) ions adsorption onto calcium pectate is ion exchange between Ca(II) and Pb(II) ions in the solution. The equilibrium data were analysed according to the linear forms of the Langmuir and Freundlich isotherms. Freundlich model gives a better fit than the Langmuir model. The results suggest that calcium pectate can be used as an effective, low cost, and eco-friendly green adsorbent for the removal of Pb(II) ions from aqueous solutions.