Meyer D E, Hampson S, Ormsbee L, Bhattacharyya D
Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506.
Environ Prog Sustain Energy. 2009 Jan 30;28(4):507-518. doi: 10.1002/ep.10334.
Iron nanoaggregates have been prepared using the sodium borohydride reduction method and post-coated with Pd using aqueous phase electro-deposition. The Fe/Pd nanoaggregates were used to examine dechlorination of trichloroethylene (TCE) with regard to matrix effects using materials representative of a potential zero-valent metal remediation site surrounding the Paducah gaseous diffusion plant in Paducah, KY. A surface-area-normalized first-order rate constant of 1.4 x 10(-1) L m(-2) h(-1) was obtained for the case of ideal dechlorination of 19.6 mg L(-1) TCE at room temperature and pH 6.2 using 0.5 g L(-1) Fe/Pd (0.42 wt % Pd) loading. This value decreases by an order of magnitude to 1.9 x 10(-2) L m(-2) h(-1) when the reaction is carried out in a realistic background matrix when the pH is high (8.8). For all variables tested, Pd content has the most impact on reaction rates. Circulating batch-column experiments are used to study dechlorination under flow conditions and demonstrate the ability of nonstabilized Fe/Pd nanoaggregates to remove significant amounts of TCE (80-90%) over a broad range of groundwater velocities (12.9-83 ft per day) using moderate metal loadings (0.23-0.5 g L(-1)).
通过硼氢化钠还原法制备了铁纳米聚集体，并采用水相电沉积法在其表面包覆钯。使用肯塔基州帕迪尤卡气态扩散厂周围潜在的零价金属修复场地的代表性材料，用铁/钯纳米聚集体研究了三氯乙烯（TCE）脱氯的基质效应。在室温及pH值为6.2的条件下，使用0.5 g/L铁/钯（0.42 wt%钯）负载量对19.6 mg/L TCE进行理想脱氯时，获得的表面积归一化一级速率常数为1.4×10⁻¹ L m⁻² h⁻¹。当在pH值较高（8.8）的实际背景基质中进行反应时，该值下降一个数量级，降至1.9×10⁻² L m⁻² h⁻¹。对于所有测试变量，钯含量对反应速率的影响最大。采用循环间歇柱实验研究流动条件下的脱氯情况，并证明了非稳定化铁/钯纳米聚集体在中等金属负载量（0.23 - 0.5 g/L）下，能够在广泛的地下水速度范围（每天12.9 - 83英尺）内去除大量的TCE（80 - 90%）。
