Preparation and Evaluation of Novel Thiourea/Chitosan Composite Beads for Copper(II) Removal in Aqueous Solutions

Thiourea modified chitosan beads (CCST) were prepared through media (citric acid, sodium hypophosphite, glutaraldegyde, and SiO2) to remove copper (Cu) ion from aqueous solutions in this study. CCST beads were characterized by using field emission scanning electron microscopy (FESEM), accelerated surface area and porosimetry (ASAP), and Fourier transform infrared spectroscopy (FTIR). The SiO2 evidently developed surface characteristics of CCST beads, as compared to the thiourea/chitosan beads without SiO2 (CCT). Sorption isotherm of CCST beads was well described by the Langmuir equation, with a maximum sorption at 135.1 milligram of Cu per gram of CCST beads. Sorption kinetics data were well fitted by the pseudo-second-order equation with high regression coefficients. The Cu ion sorption onto CCST beads was highly pH-dependent with the maximum uptake at pH 3. The FTIR and X-ray photoelectron spectroscopy studies indicated that the higher sorption of metal was attributed to the hydroxyl, amino, and carboxyl groups on CCST beads. Desorption studies were also carried out by the repeated sorption/desorption experiments for the application of CCST beads to more complex water containing other metals, which showed that there is high efficiency and reusability for CCST beads.