Removal of Cu (II), Pb (II) and Cd (II) metal ions with modified clay composite: kinetics, isotherms and thermodynamics studies

Abstract

This study investigates a low-cost and economical raw and heat-treated clay sample as a potential adsorbent for a higher uptake of Cu(II), Pb(II) and Cd(II) ions from aqueous solutions. The characterization of the obtained raw and modified clay materials, X-ray fluorescence spectroscopy, thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy were carried out. Compared with the raw clay sample, the adsorption ability of metal ions with the heat-treated clay adsorbent was significantly improved. The effects of calcination temperature, initial metal concentration, solution temperature and contact time on adsorption capacity were investigated. Adsorption data were tested with Langmuir and Freundlich models, and the Langmuir model showed a relatively better fit. The adsorption capacities for Cu (II), Pb (II) and Cd (II) ions were found to be 156.25 mg/g, 172.40 mg/g and 9.15 mg/g, respectively. The adsorption data for heavy metal ions confirmed the pseudo-second-order kinetic model. Heat-treated clay samples showed remarkable adsorption efficiency for heavy metal removal from aqueous systems; therefore, it can be considered as a competent and potential adsorbent for heavy metal removal. [GRAPHICS]