Platinum uptake from chloride solutions using biosorbents

Present work investigates platinum uptake from synthetically prepared, dilute platinum-bearing solutions using biomass residues, i.e. pistachio nut shell and rice husk, which are abundant in Turkey, and provides a comparison between these two biosorbents. Effects of the different uptake parameters, sorbent dosage, contact time, temperature and pH of solution on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell was activated, platinum uptake (%) was poor compared to the rice husk. However, after the pistachio nut shell was activated at 1000 °C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (original and activated) and rice husk were shown to be better than commercially available activated carbon in terms of adsorption capacity. These two sorbents have also been characterized by FTIR and SEM. Adsorption equilibrium data best complied with the Langmuir isotherm model. Maximum adsorption capacities, Q _max, at 25 °C were found to be 38.31 and 42.02 mg.g^-1 for the activated pistachio nut shell and rice husk, respectively. Thermodynamic calculations using the measured ΔH°, ΔS° and ΔG° values indicate that the uptake process was spontaneous and endothermic. The experimental data were shown to be fit the pseudo-second-order kinetic model.