CERITHIDEA OBTUSA (MUD CREEPER SNAIL) SHELL AS A GREEN BIOSORBENT FOR ADSORPTION OF Cu(II), Ni(II) AND Pb(II) IONS FROM AQUEOUS SOLUTIONS

摘要

The feasibility of Cerithidea obtusa shell to adsorb Cu(II), Ni(II) and Pb(II) ions from aqueous solutions was investigated. The effects of solution pH, contact time and initial metal concentration on adsorption capacity were studied in batch adsorption experiments. The equilibrium data were fitted to the Freundlich and Langmuir isotherm models, meanwhile the kinetics data were described by the pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models. The affinity of the biosorbent for metal ion was in the order of Pb(II) > Cu(II) > Ni(II). The Freundlich constant (n) and separation factor (R-L) values suggest that the metal ions were favourably bound to biosorbent. The characterisation studies were performed using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX) and Fourier Transform Infrared Spectrometer (FTIR). The adsorption of Cu(II), Ni(II) and Pb(II) ions onto C. obtusa shell was through electrostatic attraction and complexation mechanisms. C. obtusa shell exhibited a greater capacity to sequester and retain Cu(II) ion from an electroplating wastewater as compared to coconut shell derived activated carbon.