Application of chitosan-modified pumice for antimony adsorption from aqueous solution

In this study, raw pumice (RPMC) was modified successfully by using chitosan and then used to remove of antimony (Sb(III)) ions from aqueous solutions. The chitosan modified pumice (CTS-mPMC) sorbent was characterized by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), and Fourier Transform-Infrared (FT-IR) spectroscopy analysis techniques. The dependency of the adsorption efficiency on initial pH, contact time, sorbent concentration, Sb(III) ion concentration, and temperature were also studied systemically. The equilibrium data were applied to the Langmuir and Freundlich isotherm models. The maximum adsorption capacity at pH 5 was determined to be 44.8 and 88.9 mg g⁻¹ for RPMC and CTS-mPMC sorbents, respectively. The D–R model results confirmed that the adsorption process was taken place dominantly through metal complex formation or chemical ion exchange. The reusability test indicated that the prepared CTS-mPMC sorbent showed a good adsorption-desorption stability even after 10 cycles. The kinetic results showed that the Sb(III) adsorption mechanism was well described by pseudo-second-order kinetic model. The thermodynamic parameters indicated that the adsorption process had exothermic character in nature and was more feasible with decreasing temperature. Based on all results it can be concluded that the prepared CTS-mPMC can be considered as a promising sorbent for the elimination of Sb(III) ions from wastewaters.