Liu Juncheng, He Feng, Durham Ed, Zhao Dongye, Roberts Christopher B
Department of Chemical Engineering and Department of Civil Engineering, Auburn University, Auburn, AL 36849, USA.
Langmuir. 2008 Jan 1;24(1):328-36. doi: 10.1021/la702731h. Epub 2007 Nov 29.
In this paper, we present a straightforward and environmentally friendly aqueous-phase synthesis of small Pd nanoparticles (approximately 2.4 nm under the best stabilization) by employing a "green", inexpensive, and biodegradable/biocompatible polysugar, sodium carboxymethylcellulose (CMC), as a capping agent. The Pd nanoparticles exhibited rather high catalytic activity (observed pseudo-first-order reaction kinetic rate constant, k(obs), is up to 828 L g(-1) min(-1)) for the hydrodechlorination of environmentally deleterious trichloroethene (TCE) in water. Fourier transform IR (FT-IR) spectra indicate that CMC molecules interact with the Pd nanoparticles via both carboxyl (-COO-) and hydroxyl (-OH) groups, thereby functioning to passivate the surface and suppress the growth of the Pd nanoparticles. Hydrodechlorination of TCE using differently sized CMC-capped Pd nanoparticles as catalyst was systematically investigated in this work. Both the catalytic activity (k(obs)) and the surface catalytic activity (turnover frequency, TOF) of these CMC-capped Pd nanoparticles for TCE degradation are highly size-dependent. This point was further verified by a comparison of the catalytic activities and surface catalytic activities of CMC-capped Pd nanoparticles with those of beta-D-glucose-capped Pd and neat Pd nanoparticles for TCE degradation.
在本文中，我们展示了一种直接且环境友好的水相合成小尺寸钯纳米颗粒（在最佳稳定条件下约为2.4纳米）的方法，该方法采用了一种“绿色”、廉价且可生物降解/生物相容的多糖——羧甲基纤维素钠（CMC）作为封端剂。钯纳米颗粒对水中环境有害的三氯乙烯（TCE）的加氢脱氯表现出相当高的催化活性（观察到的准一级反应动力学速率常数k(obs)高达828 L g⁻¹ min⁻¹）。傅里叶变换红外（FT-IR）光谱表明，CMC分子通过羧基（-COO⁻）和羟基（-OH）基团与钯纳米颗粒相互作用，从而起到钝化表面并抑制钯纳米颗粒生长的作用。在这项工作中，系统地研究了使用不同尺寸的CMC封端钯纳米颗粒作为催化剂对TCE进行加氢脱氯的情况。这些CMC封端钯纳米颗粒对TCE降解的催化活性（k(obs)）和表面催化活性（周转频率，TOF）都高度依赖于颗粒尺寸。通过比较CMC封端钯纳米颗粒与β-D-葡萄糖封端钯纳米颗粒以及纯钯纳米颗粒对TCE降解的催化活性和表面催化活性，进一步验证了这一点。
