Interaction of Vermiculite with Pb(II), C+d(II), Cu(II) and Ni(II) Ions in Single and Quaternary Mixtures

Abstract

In this study, single and competitive sorption of Pb(II), Cd(II), Cu(II), and Ni(II) ions onto vermiculite were studied. Preliminary examination revealed that vermiculite possesses low bulk density (279kg/m3), a high cation exchange capacity (41.3meq/100g), water holding capacity (62.5%), and air-filled porosity (5.8%). The pH edge experiments indicated that the uptake capacity of vermiculite improved with enhancement in pH and highest value was detected at pH 5. Fourier transform IR spectroscopy along with scanning electron microscopy and energy dispersive X-ray spectroscopy confirmed changes in the sorbent functionality after metal sorption, and the results were in agreement with metal removal studies. It was observed by isotherm experiments that vermiculite was capable of sorbing 0.238, 0.099, 0.199 and 0.115mmol/g of Pb(II), Cd(II), Cu(II) and Ni(II), respectively, according to the Langmuir model. The reaction was rapid and the kinetic experimental data were successfully modelled using the pseudo-first order model. Quaternary biosorption experimental results revealed that severe competition exists between metal ions during the sorption onto vermiculite surface and it was inferred that the total metal uptake was distributed among four elements.