Adsorption of Hg(II) from aqueous solution by ethylenediamine-modified magnetic crosslinking chitosan microspheres

In this work, we examined the effects of various parameters, such as pH, contact time, initial concentration, and temperature, on the adsorption of Hg(II) by ethylenediamine-modified magnetic crosslinking chitosan microspheres (EMCR). EMCR had the diameter size range of 80-250 mu m, average pore size of 826 nm, BET surface area of 68.6 m(2)/g, and saturated magnetization of 15.4 emu/g. The maximum uptake of Hg(II) was recorded at pH 5. At pH 3, Hg(II) could be selectively separated from Cd(II), Pb(II), Zn(II), Cu(II), Ca(II), and Mg(II). Equilibrium data were fitted well with Langmuir isotherms with the maximum adsorption capacity of 2.69 mmol/g for Hg(II). Both kinetics and thermodynamic parameters of the adsorption process were obtained. The data indicated that adsorption process was exothermic spontaneous reaction and kinetically proceeded according to pseudo-second-order model. The metal ion-loaded EMCR were regenerated with an efficiency of more than 90% using 0.02-0.1 M thiourea. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.