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.