Adsorption of Indium(III) from aqueous solutions using SQD-85 resin

Abstract

The feasibility of using SQD-85 resin as an adsorbent for indium(III) has been investigated. Various conditions such as solution <i style="mso-bidi-font-style: normal">p</i>H, temperature and contact time on the adsorption of indium(III) has also been examined. The results show that the optimal adsorption condition of SQD-85 resin for indium(III) is achieved at the <i>p</i>H value of 5.5 in acetic acid-sodium acetate (HAc-NaAc) buffer solution. The maximum uptake capacity of indium(III) is 297.2 mg/g at 298K at an initial <i>p</i>H value of 5.5. The isotherms data fits well with Langmuir model better than Freundlich model. Kinetics on the adsorption of indium(III) has been studied. The apparent activation energy <i>Ea</i> and adsorption rate constant <i>k</i>₂₉₈ values are 12.11 kJ/mol and 5.07×10^-3 min^-1, respectively. The thermodynamic parameters with the <i>ΔS </i>value of 106.61 J/(K·mol) and <i>ΔH</i> value of 13.55 kJ/mol indicate that the adsorption process is endothermic in nature. While the decrease of Gibbs free energy (<i>ΔG</i>) with the temperature increasing indicates that the process occurred spontaneously. Finally, indium(III) can be eluted using 0.1 mol/L HCl solution and the elution percentage was relatively high (97%). Resins before and after indium(III) and adsorbed and characterized by IR spectroscopy and thermo-gravimetric analysis.