Water Utilisation and Environmental Engineering Division, Department of Chemical Engineering, University of Pretoria, Pretoria, 0002, South Africa.
Sci Rep. 2021 Aug 17;11(1):16674. doi: 10.1038/s41598-021-96024-0.
The discharge of hexavalent chromium [Cr(VI)] from several anthropogenic activities leads to environmental pollution. In this study, we explore a simple yet cost effective method for the synthesis of palladium (Pd) nanoparticles for the treatment of Cr(VI). The presence of elemental Pd [Pd(0)] was confirmed by scanning electron microscope (SEM), electron dispersive spectroscopy and X-ray diffraction (XRD). We show here that the biologically synthesized nanoparticles (Bio-PdNPs) exhibit improved catalytic reduction of Cr(VI) due to their size being smaller and also being highly dispersed as compared to chemically synthesized nanoparticles (Chem-PdNPs). The Langmuir-Hinshelwood mechanism was successfully used to model the kinetics. Using this model, the Bio-PdNPs were shown to perform better than Chem-PdNPs due to the rate constant (k = 6.37 mmol s m) and Cr(VI) adsorption constant (K = 3.11 × 10 L mmol) of Bio-PdNPs being higher than the rate constant (k = 3.83 mmol s m) and Cr(VI) adsorption constant (K = 1.14 × 10 L mmol) of Chem-PdNPs. In addition, product inhibition by trivalent chromium [Cr(III)] was high in Chem-PdNPs as indicated by the high adsorption constant of Cr(III) in Chem-PdNPs of K = 52.9 L mmol as compared to the one for Bio-PdNPs of K = 2.76 L mmol.
来自几种人为活动的六价铬 [Cr(VI)] 的排放会导致环境污染。在这项研究中，我们探索了一种简单而经济有效的方法来合成钯 (Pd) 纳米粒子，以处理 Cr(VI)。扫描电子显微镜 (SEM)、电子分散光谱和 X 射线衍射 (XRD) 证实了元素钯 [Pd(0)] 的存在。我们在这里表明，与化学合成的纳米粒子 (Chem-PdNPs) 相比，生物合成的纳米粒子 (Bio-PdNPs) 由于其尺寸更小且高度分散，因此表现出更好的 Cr(VI) 催化还原性能。Langmuir-Hinshelwood 机制成功地用于模拟动力学。使用该模型，由于 Bio-PdNPs 的速率常数 (k = 6.37 mmol s m) 和 Cr(VI) 吸附常数 (K = 3.11 × 10 L mmol) 高于 Chem-PdNPs 的速率常数 (k = 3.83 mmol s m) 和 Cr(VI) 吸附常数 (K = 1.14 × 10 L mmol)，因此 Bio-PdNPs 的性能优于 Chem-PdNPs。此外，三价铬 [Cr(III)] 的产物抑制在 Chem-PdNPs 中很高，这表明 Chem-PdNPs 中 Cr(III) 的吸附常数 K = 52.9 L mmol 远高于 Bio-PdNPs 的 K = 2.76 L mmol。
