Centre for Nano-Biotechnology, School of Bio-Sciences and Technology, VIT University, Katpadi Road, Vellore 632014, Tamilnadu, India.
J Hazard Mater. 2011 Aug 15;192(1):299-306. doi: 10.1016/j.jhazmat.2011.05.024. Epub 2011 Jun 1.
Indiscriminate and increased use of silver nanoparticles (SNPs) in consumer products leads to the release of it into the environment. The fate and transport of SNPs in environment remains unknown. We have studied the interaction of SNPs with extracellular protein (ECP) produced by two environmental bacterial species and the adsorption behavior in aqueous solutions. The effect of pH and salt concentrations on the adsorption was also investigated. The adsorption process was found to be dependent on surface charge (zeta potential). The capping of SNPs by ECP was confirmed by Fourier transform infrared spectroscopy and X-ray diffraction. The adsorption of ECP on SNPs was analyzed by Langmuir and Freundlich models, suggesting that the equilibrium adsorption data fitted well with Freundlich model. The equilibrium adsorption data were modeled using the pseudo-first-order and pseudo-second-order kinetic equations. The results indicated that pseudo-second-order kinetic equation would better describe the adsorption kinetics. The capping was stable at environmental pH and salt concentration. The destabilization of nanoparticles was observed at alkaline pH. The study suggests that the stabilization of nanoparticles in the environment might lead to the accumulation and transport of nanomaterials in the environment, and ultimately destabilizes the functioning of the ecosystem.
在消费产品中不加区分地大量使用银纳米粒子 (SNPs) 会导致其释放到环境中。SNPs 在环境中的迁移转化行为尚不清楚。我们研究了 SNPs 与两种环境细菌产生的细胞外蛋白 (ECP) 的相互作用及其在水溶液中的吸附行为。还研究了 pH 值和盐浓度对吸附的影响。吸附过程依赖于表面电荷（zeta 电位）。通过傅里叶变换红外光谱和 X 射线衍射证实了 SNPs 被 ECP 封闭。通过 Langmuir 和 Freundlich 模型分析了 ECP 在 SNPs 上的吸附，表明平衡吸附数据与 Freundlich 模型拟合良好。使用拟一级和拟二级动力学方程对平衡吸附数据进行建模。结果表明，拟二级动力学方程能更好地描述吸附动力学。在环境 pH 值和盐浓度下，封闭是稳定的。在碱性 pH 值下观察到纳米颗粒的失稳。该研究表明，纳米颗粒在环境中的稳定化可能导致纳米材料在环境中的积累和迁移，并最终破坏生态系统的功能。
