Department of Civil and Environmental Engineering, Texas Tech University, 10th and Akron, Lubbock, TX 79409, USA.
Department of Civil and Environmental Engineering, Texas Tech University, 10th and Akron, Lubbock, TX 79409, USA.
Water Res. 2014 Dec 1;66:149-159. doi: 10.1016/j.watres.2014.08.001. Epub 2014 Aug 23.
The incorporation of catalytic metals on iron nanoparticles to form bimetallic nanoparticles (BNPs) generates a class of highly reactive materials for degrading chlorinated hydrocarbons (e.g., trichloroethylene, TCE) in groundwater. Successful implementation of BNPs to groundwater decontamination relies critically on the stability of surface reactive sites of BNPs in groundwater matrices. This study investigated the effect of common groundwater solutes on TCE reduction with Ni-Fe (with Ni at 2 wt.%) bimetallic nanoparticles (herein denoted as Ni-Fe BNPs). Batch experiments involving pre-exposing the nanoparticles to various groundwater solutions for 24 h followed by reactions with TCE solutions were conducted. The results suggest that the deactivation behavior of Ni-Fe BNPs differs significantly from that of the well-studied Pd-Fe BNPs. Specifically, Ni-Fe BNPs were chemically stable in pure water. Mild reduction in TCE reaction rates were observed for Ni-Fe BNPs pre-exposed to chloride (Cl(-)), bicarbonate (HCO3(-)), sulfite (SO3(2-)) and humic acid solutions. Nitrate (NO3(-)), sulfate (SO4(2-)) and phosphate (HPO4(2-)) may cause moderate to severe deactivation at elevated concentrations (>1 mM). Product analysis and surface chemistry investigations using high-resolution X-ray photoelectron spectroscopy (HR-XPS) reveal that NO3(-) decreased particle reactivity mainly due to progressive formation of passivating oxides, whereas SO4(2-) and phosphate elicited rapid deactivation as a result of specific poisoning of the surface nickel sites. At similar levels, phosphate is the most potent deactivation agent among the solutes examined in this study. While our findings point out the desirable quality of Ni-Fe nanoparticles, particularly their greater electrochemical stability compared to Pd-Fe BNPs, its susceptibility to chemical poisoning at high levels of complexing ligands is also noted. Groundwater chemistry is therefore an important factor to consider when choosing appropriate material(s) for decontaminating the complex environmental media.
将催化金属掺入铁纳米颗粒中形成双金属纳米颗粒（BNPs），生成了一类用于降解地下水 中氯代烃（例如三氯乙烯，TCE）的高反应性材料。BNPs 成功应用于地下水净化，关键依赖于 BNPs 在地下水基质中表面反应性位点的稳定性。本研究考察了常见地下水溶质对 Ni-Fe（Ni 含量为 2wt.%）双金属纳米颗粒（此处表示为 Ni-Fe BNPs）还原 TCE 的影响。进行了一系列批实验，涉及将纳米颗粒预先暴露于各种地下水溶液 24 小时，然后与 TCE 溶液反应。结果表明，Ni-Fe BNPs 的失活动力学与研究充分的 Pd-Fe BNPs 显著不同。具体而言，Ni-Fe BNPs 在纯水中化学稳定性高。Ni-Fe BNPs 预先暴露于氯离子（Cl(-)）、碳酸氢根离子（HCO3(-)）、亚硫酸根离子（SO3(2-)）和腐殖酸溶液中，TCE 反应速率略有降低。硝酸盐（NO3(-)）、硫酸盐（SO4(2-)）和磷酸盐（HPO4(2-)）在高浓度（>1mM）时可能导致中度至严重失活。使用高分辨率 X 射线光电子能谱（HR-XPS）进行的产物分析和表面化学研究表明，NO3(-) 降低颗粒反应性主要是由于逐渐形成钝化氧化物，而 SO4(2-)和磷酸盐由于表面镍位的特异性中毒导致快速失活。在相似水平下，磷酸盐是本研究中考察的溶质中最有效的失活剂。虽然我们的发现指出了 Ni-Fe 纳米颗粒的可取质量，特别是与 Pd-Fe BNPs 相比其具有更大的电化学稳定性，但也注意到其在高浓度络合剂存在下易受化学中毒的影响。因此，地下水化学是选择用于净化复杂环境介质的合适材料时需要考虑的一个重要因素。
