Synthesis and characterization of a new starch/SnO2 nanocomposite for efficient adsorption of toxic Hg2+ metal ion.

In this study, starch based nanocomposite (starch/SnO 2 ) was synthesized and used as an effective adsorbent for the removal of Hg 2+ from aqueous medium. The as-prepared starch/SnO 2 nanocomposite was characterized by means of the XPS, XRD, BET, FTIR, SEM and TEM analyses. The effects of contact time, pH, initial Hg 2+ concentration and temperature on the adsorption performance of starch/SnO 2 nanocomposite were investigated thoroughly. The experimental results showed that starch/SnO 2 nanocomposite had high ability to remove Hg 2+ ion from aqueous medium. The adsorption of Hg 2+ was maximum at the pH 6 and equilibrium was achieved within 60 min. The pseudo-second-order equation represented the adsorption kinetics with high correlation coefficient (>0.998) and the Freundlich isotherm model fitted the adsorption data better than the Langmuir. The maximum adsorption capacity was found to be 192 mg g −1 at 25 °C which was increased with the temperature, indicated the endothermic adsorption. The feasibility of Hg 2+ adsorption onto starch/SnO 2 nanocomposite was also studied thermodynamically and the results showed that the adsorption was spontaneous and chemical in nature. The adsorption capacity of the regenerated adsorbents could still be maintained at 94% by the fourth adsorption–desorption cycle. [ABSTRACT FROM AUTHOR]