Deputy for Technology Innovation and Commercialization Development, VPST, Tehran 1991745681, Iran.
Department of Applied Geology, Faculty of Earth Sciences, Kharazmi University, Tehran 1571914911, Iran.
Molecules. 2020 Nov 25;25(23):5518. doi: 10.3390/molecules25235518.
Carbon dots (CDs) are a new type of nanomaterials of the carbon family with unique characteristics, such as their small size (e.g., <10 nm), high water solubility, low toxicity, and high metal affinity. Modification of CDs by Nitrogen functional groups (N-CDs) enhances their metal adsorption capacity. This study investigated the influences of pH (4, 6, and 9), ionic strength (1, 50, and 100 mM), and cation valency (Na and Ca) on the competitive adsorption of Pb to quartz and N-CD surfaces, the transport and retention of N-CDs in saturated porous media, and the capacity of N-CDs to mobilize pre-adsorbed Pb in quartz columns. Pb adsorption was higher on N-CDs than on quartz surfaces and decreased with increases in ionic strength (IS) and divalent cations (Ca) concentration. N-CD mobility in quartz columns was highest at pH of 9- and 1-mM monovalent cations (Na) and decreased with decreases in pH and increases in ionic strength and ion valency. N-CDs mobilized pre-adsorbed Pb from quartz due to the higher adsorption affinity of Pb to N-CD than to quartz surfaces. These findings provide valuable insights into the transport, retention, and risk assessment of lead in the presence of carbon-based engineered nanoparticles.
碳点（CDs）是一种新型的纳米碳材料，具有独特的特性，如小尺寸（例如，<10nm）、高水溶性、低毒性和高金属亲和力。通过氮官能团（N-CDs）对 CDs 进行修饰可以增强其对金属的吸附能力。本研究探讨了 pH 值（4、6 和 9）、离子强度（1、50 和 100mM）和阳离子价态（Na 和 Ca）对 Pb 在石英和 N-CD 表面的竞争吸附、N-CD 在饱和多孔介质中的迁移和保留以及 N-CD 对石英柱中预吸附 Pb 的迁移能力的影响。与石英表面相比，Pb 在 N-CDs 上的吸附更高，且随着离子强度（IS）和二价阳离子（Ca）浓度的增加而降低。在 pH 为 9 和 1mM 单价阳离子（Na）时，N-CD 在石英柱中的迁移性最高，且随着 pH 值的降低、离子强度和离子价态的增加而降低。N-CDs 可以从石英中迁移出预吸附的 Pb，因为 Pb 对 N-CD 的吸附亲和力高于对石英表面的吸附亲和力。这些发现为研究在存在碳基工程纳米颗粒的情况下 Pb 的迁移、保留和风险评估提供了有价值的见解。
