Liou Ya Hsuan, Lo Shang Lien, Lin Chin Jung
Research Center for Environmental Pollution Prevention and Control Technology, Graduate Institute of Environmental Engineering, National Taiwan University, Taipei 106, Taiwan.
Water Res. 2007 Apr;41(8):1705-12. doi: 10.1016/j.watres.2007.01.014. Epub 2007 Mar 6.
Surface area-normalized rate constants (k(SA)) of reaction between metallic nanoparticles and reducible contaminants, such as chlorinated hydrocarbons, heavy metals, and nitrate, have been reported to be dramatically increased as compared to that of commercial metallic powder. However, k(SA) for individual pollutants in previously published data vary by as much as 1-2 orders of magnitude and much of this variability is due to the effect of various sizes. The size dependence of the reactivity of nanoparticles is not yet fully understood; however, yielding nanoparticles with uniform size and without agglomeration during the period of reaction would demonstrate the effect of varying particle size. In this study, resin-supported zerovalent copper with average particle size of 7, 10, 18, 26, and 29, respectively, were successfully synthesized and evidenced no agglomeration during the reaction period of 10h. The k(SA) of copper nanoparticles (k(n,SA)) was 110-120 times higher than that of powdered copper particles (k(p,SA)) when the copper particle size was about 10nm. However, for diameters of 18-29 nm, the ratio of k(n,SA)/k(p,SA) was around 10-20, indicating that the reactivity of small copper nanoparticles (approximately 10nm) varies discontinuously. Thus, most variability in previous k(SA) is attributed to the presence of small nanoparticles.
据报道，与商业金属粉末相比，金属纳米颗粒与可还原污染物（如氯代烃、重金属和硝酸盐）之间反应的比表面积归一化速率常数（k(SA)）显著增加。然而，先前发表数据中针对个别污染物的k(SA)相差多达1 - 2个数量级，且这种变异性大多归因于各种尺寸的影响。纳米颗粒反应性的尺寸依赖性尚未完全理解；然而，在反应期间生成尺寸均匀且无团聚的纳米颗粒将证明粒径变化的影响。在本研究中，成功合成了平均粒径分别为7、10、18、26和29的树脂负载零价铜，并且在10小时的反应期间未出现团聚现象。当铜粒径约为10nm时，铜纳米颗粒的k(SA)（k(n,SA)）比粉末状铜颗粒的k(SA)（k(p,SA)）高110 - 120倍。然而，对于直径为18 - 29nm的情况，k(n,SA)/k(p,SA)的比值约为10 - 20，这表明小铜纳米颗粒（约10nm）的反应性变化不连续。因此，先前k(SA)中的大多数变异性归因于小纳米颗粒的存在。
