Rice straw modified by click reaction for selective extraction of noble metal ions

Rice straw was modified by azide-alkyne click reaction in order to realize selective extraction of noble metal ions. The ability of the modified straw to adsorb Pd2+ and Pt4+ was assessed using a batch adsorption technique. It was found that the sorption equilibrium could be reached within 1 h and the adsorption capacity increased with temperature for both Pd2+ and Pt4+. The maximum sorption capacities for Pd2+ and Pt4+ were respectively attained in 1.0 and 0.1 mol/L HCl. The modified straw showed excellent selectivity for noble metal ions in comparison to the pristine straw. In addition, the modified straw was examined as a column packing material for extraction of noble metal ions. It was indicated that 1.0 mL/min was the best flow rate for Pd2+ and Pt4+. The modified straw could be repeatedly used for 10 times without any significant loss in the initial binding affinity. (C) 2014 Elsevier Ltd. All rights reserved.