Biosorptive removal of cobalt(II) from aqueous solutions using magnetic cyanoethyl chitosan beads

Biosorption is a cleaner technology for the treatment of heavy metal-containing wastewater. In this study, a cleaner method was proposed for preparing a novel biosorbent, magnetic cyanoethyl chitosan beads, which was characterized by FT-IR, SEM-EDS, XRD, TGA, BET, and vibrating sample magnetometer, and applied for removing Co2+ from aqueous solutions. The influencing factors, such as contact time (0 120 min), pH (5-8), and initial concentration of cobalt ions (10 600 mg L-1), were examined. The first-order, second-order, intraparticle diffusion, and Elovich models were used to simulate the kinetics of the cobalt adsorption process. The experimental data of isotherms were analyzed by the Langmuir, Freundlich, and Temkin models. Among them, the second-order model and Langmuir model were the best fitting. The adsorption capacity was calculated to be 17.92 mg g(-1) according to the Langmuir model. From the analysis of the FT-IR spectra, it can be inferred that -CN and -NH2 were mainly responsible for the adsorption of Co2+ from aqueous solutions. The grafting of cyanoethyl groups on chitosan enhanced the sorption capacity towards Co2+, the magnetic cyanoethyl chitosan bead is economical and effective biosorbent for the treatment heavy metal-containing wastewater.