Group of Environmental Physical Chemistry, Department F.-A. Forel for environmental and aquatic sciences, University of Geneva, Uni Carl Vogt, 66, boulevard Carl-Vogt, CH-1211 Geneva 4, Switzerland.
EA CNRS 4592 Géoressources & Environnement, Université Bordeaux Montaigne, 1 allée F. Daguin, F-3607 Pessac, France; CNRS-INRA-Université de Bordeaux UMS 3420, Bordeaux Imaging Center, 146 rue Léo Saignat, CS 61292, F-33076 Bordeaux, France.
Sci Total Environ. 2023 Jan 15;856(Pt 2):159261. doi: 10.1016/j.scitotenv.2022.159261. Epub 2022 Oct 5.
The presence of NPs in drinking water resources raises a global concern on their potential risk for human health, and whether or not drinking water treatment plants are able to effectively remove NPs to prevent their ingestion by humans. In this study, we investigate the efficiency of granular activated carbon (GAC), commonly used in conventional municipal water treatment processes, for the removal of CeO NPs. In ultrapure water, NPs are found to have a good affinity for GAC and results indicate an increase in the adsorption capacity from 0.62 ± 0.10 to 5.05 ± 0.51 mg/g, and removal efficiency from 35 % ± 4 to 54 % ± 5 with increasing NPs concentration. Kinetic studies reveal that intraparticle diffusion is not the only rate controlling step indicating that mass transfer effect is also playing a role. Adsorption mechanisms are mainly controlled by the electrostatic attractions between the positively charged NPs and negatively charged GAC. Although electrostatic conditions in Lake Geneva water are less favorable for NPs adsorption, the adsorption capacity and removal efficiency are higher than in ultrapure water with values raising from 0.41 ± 0.17 to 7.13 ± 1.13 mg/g and 26 % ± 8 to 75 % ± 11, respectively. Furthermore, the external mass transfer process onto GAC surface is more important than for ultrapure water. NPs adsorption mechanism is explained by the presence of divalent cations and natural organic matter (NOM) which promote the formation of CeO NPs-NOM-divalent cation heteroaggregates increasing both adsorption and removal efficiency by cation bridging.
纳米颗粒（NPs）在饮用水资源中的存在引起了全球范围内对其人类健康潜在风险的关注，以及饮用水处理厂是否能够有效去除 NPs 以防止人类摄入。在这项研究中，我们研究了颗粒状活性炭（GAC）——常用于常规城市水处理工艺中的一种物质——对 CeO NPs 的去除效率。在超纯水中，NPs 与 GAC 具有很好的亲和力，结果表明，随着 NPs 浓度的增加，吸附容量从 0.62±0.10 增加到 5.05±0.51mg/g，去除效率从 35%±4 增加到 54%±5。动力学研究表明，颗粒内扩散不是唯一的速率控制步骤，这表明传质效应也在起作用。吸附机制主要受带正电荷的 NPs 和带负电荷的 GAC 之间的静电吸引控制。尽管日内瓦湖水的静电条件不利于 NPs 的吸附，但吸附容量和去除效率均高于超纯水，分别从 0.41±0.17 增加到 7.13±1.13mg/g 和从 26%±8 增加到 75%±11。此外，外部传质过程到 GAC 表面比在超纯水中更为重要。NPs 的吸附机制可以通过二价阳离子和天然有机物（NOM）的存在来解释，它们促进了 CeO NPs-NOM-二价阳离子异质聚集体的形成，通过阳离子桥接增加了吸附和去除效率。
