Application of modified sepiolite as reusable adsorbent for Pd(II) sorption from acidic solutions
(1. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Biometallurgy, Ministry of Education, Central South University, Changsha 410083, China;
3. State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106, China)
2. Key Laboratory of Biometallurgy, Ministry of Education, Central South University, Changsha 410083, China;
3. State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106, China)
Abstract: The adsorption characteristics and mechanisms of modified sepiolite as an adsorbent to recover Pd(II) from acidic solutions were studied. The Pd(II) adsorption properties were analyzed through isotherm, kinetic and thermodynamic models. In addition, SEM-EDS, TEM and XPS were applied to investigating the Pd(II) adsorption mechanisms onto modified sepiolite. The equilibrium data were well fitted to Langmuir isotherm model with maximum Pd(II) adsorption capacity of 322.58 mg/g at 30 °C. The kinetic data could be satisfactorily simulated by the pseudo- second order model, indicating that the rate-controlling step was chemical adsorption. 99% of Pd(II) could be recovered using 1 g/L modified sepiolite when initial concentration of Pd(II) was 100 mg/L. The results of reusability studies indicated the modified sepiolite had an acceptable stability and reusability. This study indicated that the modified sepiolite might be an efficient and cost-effective material for Pd(II) recovery.
Key words: modified sepiolite; palladium; adsorption; desorption; dynamics