Copper, nickel and lead adsorption from aqueous solution using chitosan-immobilized on bentonite in a ternary system
Sustain. Environ. Res., 22(6), 345-355 (2012)
Cybelle Morales Futalan, Wan-Chi Tsai, Shiow-Shyung Lin, Kuo-Jung Hsien, Maria Lourdes Dalida and Meng-Wei Wan
Antagonistic, desorption, film diffusion, ionic strength, ternary system
In this study, the competitive removal of copper, nickel and lead from aqueous solution using chitosan immobilized on bentonite (ChB) has been investigated. The presence of Na+ ions was observed to suppress the adsorption capacity in the order of: Ni(II) > Cu(II) > Pb(II). Kinetics study revealed that adsorption of Cu(II), Ni(II) and Pb(II) in a multi-metal system onto ChB follows the pseudo-second order equation. This signifies that the rate-determining step is chemisorption, which means that covalent bonds are formed through sharing of electrons between ChB and metal ions. The isotherm study shows that Pb(II) and Cu(II) follow Freundlich isotherm while Ni(II) is best described with the Langmuir model. In addition, the values of the Langmuir constant, qmL , for Cu(II), Ni(II) and Pb(II) are 12.6, 6.1 and 15.0 mg g-1, respectively. The preferential adsorption of Pb(II) over Cu(II) and Ni(II) onto ChB is due to properties such as electronegativity, hydrolysis constant and softness value. In the regeneration study, HCl provided the highest desorption capacity but with most material damage to ChB. After three cycles of adsorption-desorption, % desorption using HCl was 79, 70 and 81% for Cu(II), Ni(II) and Pb(II), respectively.