Adsorption of Cadmium (II) onto thiolated graphene oxide and kinetic investigations

Cadmium is a very toxic metal that have adverse effects on human health and aquatic environments even at low concentrations. It can cause some diseases in human lungs and kidney. Therefore, efforts should be made to eliminate this metal from aquatic ecosystems. This study was carried out in order to remove cadmium ions from aqueous solutions by thiolated graphene oxide in batch system. In this study, effect of experimental parameters such as pH, adsorbent dosage and initial cadmium concentration were investigated. To characterize the adsorbent properties, SEM and FT-IR analyses were utilized. The results showed that, with increasing initial concentration of cadmium, the amount of adsorption decreased and increasing the dose of adsorbent and pH increased the percentage of cadmium removal. Comparison of isotherm and kinetic adsorption models showed that Langmuir and Pseudo-second order models, with R2 values of 0.97 and 0.99 respectively, had a better fitness and describe the adsorption data better than other models. Thus, as a general conclusion it can be said that the synthesized adsorbent had high capability to remove cadmium from aqueous solutions.