Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology , Daejeon, 305-701, Korea.
Environ Sci Technol. 2014 Jul 1;48(13):7503-10. doi: 10.1021/es501003m. Epub 2014 Jun 12.
Ion-exchange has been frequently used for the treatment of perchlorate (ClO4(-)), but disposal or regeneration of the spent resins has been the major hurdle for field application. Here we demonstrate a synergistic integration of ion-exchange and catalytic decomposition by using Pd-supported ion-exchange resin as an adsorption/catalysis bifunctional material. The ion-exchange capability of the resin did not change after generation of the Pd clusters via mild ethanol reduction, and thus showed very high ion-exchange selectivity and capacity toward ClO4(-). After the resin was saturated with ClO4(-) in an adsorption mode, it was possible to fully decompose the adsorbed ClO4(-) into nontoxic Cl(-) by the catalytic function of the Pd catalysts under H2 atmosphere. It was demonstrated that prewetting the ion-exchange resin with ethanol significantly accelerate the decomposition of ClO4(-) due to the weaker association of ClO4(-) with the ion-exchange sites of the resin, which allows more facile access of ClO4(-) to the catalytically active Pd-resin interface. In the presence of ethanol, >90% of the adsorbed ClO4(-) could be decomposed within 24 h at 10 bar H2 and 373 K. The ClO4(-) adsorption-catalytic decomposition cycle could be repeated up to five times without loss of ClO4(-) adsorption capacity and selectivity.
离子交换已被广泛用于处理高氯酸盐（ClO4(-)），但废树脂的处理或再生一直是现场应用的主要障碍。在这里，我们展示了一种通过使用负载钯的离子交换树脂作为吸附/催化双功能材料来协同整合离子交换和催化分解的方法。通过温和的乙醇还原生成钯簇后，树脂的离子交换能力没有改变，因此对 ClO4(-)表现出非常高的离子交换选择性和容量。在吸附模式下，树脂被 ClO4(-)饱和后，在 H2 气氛下，Pd 催化剂的催化作用可以将吸附的 ClO4(-)完全分解为无毒的 Cl(-)。研究表明，由于 ClO4(-)与树脂的离子交换位点的结合较弱，用乙醇预先润湿离子交换树脂可以显著加速 ClO4(-)的分解，从而使更多的 ClO4(-)更容易进入催化活性的 Pd-树脂界面。在乙醇存在的情况下，在 10 巴 H2 和 373 K 下，超过 90%的吸附 ClO4(-)可以在 24 小时内分解。ClO4(-)吸附-催化分解循环可以重复五次以上，而不会损失 ClO4(-)的吸附容量和选择性。
