Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849, USA.
Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849, USA.
Water Res. 2017 Sep 1;120:199-210. doi: 10.1016/j.watres.2017.04.059. Epub 2017 Apr 26.
We prepared a new class of anion-exchange-resin supported Pd catalysts for efficient hydrodechlorination of triclosan in water. The catalysts were prepared through an initial ion-exchange uptake of PdCl and subsequent reduction of Pd(II) to Pd(0) nanoparticles at ambient temperature. Two standard strong-base anion exchange resins (IRA-900 and IRA-958) with different matrices (polystyrene and polyacrylic) were chosen as the supports. SEM and TEM images showed that Pd(0) nanoparticles were evenly attached on the resin surface with a mean size of 3-5 nm. The resin supported Pd catalysts (Pd@IRA-900 and Pd@IRA-958) were able to facilitate rapid and complete hydrodechlorination of triclosan. At a Pd loading of 2.0 wt.%, the observed pseudo first-order rate constant (k) was 1.25 ± 0.06 and 1.6 ± 0.1 L/g/min for Pd@IRA-900 and Pd@IRA-958, respectively. The catalysts were more resistant to Cl poisoning and natural organic matter fouling than other supported-Pd catalysts. The presence of 10 mM NaCl suppressed the k value by 31% and 23% for Pd@IRA-900 and Pd@IRA-958, whereas the presence of humic acid at 30 mg/L as TOC lowered the rates by 28% and 27%, respectively. The better performance of Pd@IRA-958 was attributed to the polymeric matrix properties (i.e., hydrophobicity, pore size, and surface area) as well as Pd particle size. GC/MS analyses indicated that very low concentrations of chlorinated intermediates were detected in the early stage of the hydrodechlorination process, with 2-phenoxyphenol being the main byproduct. The catalysts can be repeatedly used in multiple operations without significant bleeding. The catalysts eliminate the need for calcination in preparing conventional supported catalysts, and the resin supports conveniently facilitate control of Pd loading and material properties.
我们制备了一类新型的阴离子交换树脂负载钯催化剂，用于水中三氯生的高效加氢脱氯反应。该催化剂通过钯(II)在室温下的初始离子交换吸附和随后的还原为钯(0)纳米颗粒来制备。选择了两种标准的强碱阴离子交换树脂（IRA-900 和 IRA-958），它们具有不同的基质（聚苯乙烯和聚丙烯酸）。SEM 和 TEM 图像表明，钯(0)纳米颗粒均匀地附着在树脂表面上，平均粒径为 3-5nm。树脂负载钯催化剂（Pd@IRA-900 和 Pd@IRA-958）能够促进三氯生的快速完全加氢脱氯反应。在钯负载量为 2.0wt.%时，Pd@IRA-900 和 Pd@IRA-958 的观察到的准一级反应速率常数（k）分别为 1.25±0.06 和 1.6±0.1L/g/min。与其他负载钯催化剂相比，该催化剂对氯中毒和天然有机物污染的抵抗力更强。10mM NaCl 的存在使 Pd@IRA-900 和 Pd@IRA-958 的 k 值分别降低了 31%和 23%，而 30mg/L 作为 TOC 的腐殖酸使反应速率分别降低了 28%和 27%。Pd@IRA-958 的性能更好归因于聚合物基质的特性（即疏水性、孔径和表面积）以及钯颗粒尺寸。GC/MS 分析表明，在加氢脱氯过程的早期阶段，仅检测到非常低浓度的氯化中间产物，主要副产物为 2-苯氧基苯酚。催化剂可以在多次操作中重复使用，而不会明显流失。催化剂在制备传统负载型催化剂时不需要进行煅烧，树脂载体方便地控制了钯的负载量和材料性能。
