Kang Jia, Wang Ao-di, Zhang Yao-Wen, Dai Fei, Zhu Jing-Jing, Song Chu-Qiong, Song Gang-Fu
School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power Zhengzhou 450046 China
Hubei Institute of Water Resources Survey and Design Co., Ltd Wuhan 430070 China.
RSC Adv. 2025 Aug 22;15(36):29978-29988. doi: 10.1039/d5ra03336e. eCollection 2025 Aug 18.
The extensive application of silver nanoparticles (AgNPs) has resulted in them ending up in wastewater treatment plant (WWTP) facilities at concentrations varying between 0.13 and 20.02 mg L. Soluble microbial products (SMPs) in activated sludge systems can form the first barrier against AgNPs before attached metabolites and microorganisms react with these biotoxicants. Based on this, the present study investigated the adsorption and bonding resistance mechanisms of AgNPs on SMPs in activated sludge systems and analysed the typical influencing factors. Analysis using quasi-second-order kinetics and the Freundlich isotherm model revealed that the adsorption of AgNPs onto SMP is chemisorption-controlled, with multi-layer adsorption being the main mechanism, and the adsorption capacity reached 263.9 mg g at 35 °C. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses indicated that aldehydes, carbonyl groups, and amide groups in SMPs were able to interact with AgNPs through electrostatic forces, hydrogen bonding and chelate-forming, metal-bound organometallic complexes (M-C[double bond, length as m-dash]NOHC[double bond, length as m-dash]NOH-M), resulting in conformational changes in SMP proteins. An increase in pH and ionic strength favoured the resistance of SMPs to AgNPs, and as the valence of the metal cation increased, the enhancement of this resistance became more significant. This study confirmed that SMP functions as an effective natural adsorbent for immobilizing AgNPs in activated sludge systems and provides a mechanistic foundation for developing targeted bioremediation strategies.
银纳米颗粒（AgNPs）的广泛应用导致其最终进入污水处理厂（WWTP）设施，浓度在0.13至20.02 mg/L之间变化。活性污泥系统中的可溶性微生物产物（SMPs）在附着的代谢产物和微生物与这些生物毒性物质发生反应之前，可以形成抵御AgNPs的第一道屏障。基于此，本研究调查了活性污泥系统中AgNPs在SMPs上的吸附和结合抗性机制，并分析了典型影响因素。采用准二级动力学和Freundlich等温线模型分析表明，AgNPs在SMP上的吸附受化学吸附控制，多层吸附为主要机制，在35℃时吸附容量达到263.9 mg/g。傅里叶变换红外光谱和X射线光电子能谱分析表明，SMPs中的醛基、羰基和酰胺基能够通过静电力、氢键和形成螯合物的金属结合有机金属配合物（M-C=NOHC=NOH-M）与AgNPs相互作用，导致SMP蛋白质构象发生变化。pH值和离子强度的增加有利于SMPs对AgNPs的抗性，并且随着金属阳离子价态的增加，这种抗性的增强变得更加显著。本研究证实SMP在活性污泥系统中作为一种有效的天然吸附剂固定AgNPs，并为制定有针对性的生物修复策略提供了机理基础。
