Modeling, Thermodynamic Study and Sorption Mechanism of Cadmium Ions onto Isopropyl Alcohol Mediated Tin Dioxide Nanoparticles

The microporous tin dioxide nanoparticles (SnO2 NPs) were synthesized by sol–gel method using isopropyl alcohol exhibit high surface area (128 m2/g). The crystal phase and geometry of SnO2 NPs was studied by X-ray diffractometer and the calculated crystallite size is 15.78 nm. The percentage composition and purity was confirmed by energy dispersive X-ray analysis. The morphology was examined through scanning electron microscopy which confirm the presence of the grains, cluster and agglomerated particles in the sample. The space groups were assigned to different vibrational modes of the SnO2 NPs on the basis of Raman spectroscopy. The surface functional moieties were identified by Fourier transform infrared spectroscopy. The batch method was used for the sorption of cadmium (Cd2+) ions from aqueous solution at pH 5. The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) models were applied to the adsorption data to determine the nature adsorption process, binding energy and maximum sorption capacity of the adsorbent. A set of equations were used to study the thermodynamic feasibility and endothermic nature of the adsorption process while the ions exchange mechanism was found to be 1:1.