Effects of addition of engineered ZnO nanoparticles on the stability of colloidal suspensions containing TiO2 interacting with sandy soil

Abstract The stability of colloidal suspensions of engineered nanoparticles in the environment is of great interest for the risk assessment and treatment of hazardous materials. The relevance of this study is due to the evidence that engineered nanoparticles have been produced and used in commercial products in large scale, especially ZnO and TiO2, which are transported through the environmental components interacting with soil and water, representing the high potential impact on the ecosystems. In this research, we newly investigated the influence of nanoparticles of zinc oxide (NPZnO) on the behavior of nanoparticles of titania (NPTiO2). The impact of parameters such as pH, zeta potential, ionic strength, electric conductivity, suspended nanoparticles size of the colloidal suspensions containing hazardous nanoparticles on its stability, were studied using experimental and theoretical approaches. Leaching experiments were carried out within a sandy soil column model. It was found that the NPTiO2 in suspensions enhance the stability of the nanoparticles colloidal suspensions, keeping higher nanoparticles concentrations, while NPZnO promotes rapid aggregation, improving the soil particle collector efficiency with a lower concentration in equilibrium in the colloidal suspension, which can be used for promoting environmental impact attenuation and mitigation.

摘要：工程纳米颗粒在环境中的胶体悬浮液稳定性，对于危险物质的风险评估与修复治理具有重要研究意义。本研究的研究意义在于，已有研究证实工程纳米颗粒已被大规模生产并应用于商业产品中，尤其是氧化锌（ZnO）与二氧化钛（TiO₂）；这类纳米颗粒可通过与土壤、水体相互作用的环境介质进行迁移，对生态系统具备较高的潜在影响。本研究首次探究了氧化锌纳米颗粒（NPZnO）对二氧化钛纳米颗粒（NPTiO₂）迁移与聚集行为的影响。本研究采用实验与理论相结合的方法，系统探究了pH值、zeta电位（Zeta Potential）、离子强度、电导率以及悬浮胶体体系中有害纳米颗粒的粒径等参数，对胶体悬浮液稳定性的影响。本研究通过砂质土壤柱模型开展了淋溶实验。研究结果表明，悬浮液中的二氧化钛纳米颗粒（NPTiO₂）可提升纳米颗粒胶体悬浮液的稳定性，维持更高的纳米颗粒浓度；而氧化锌纳米颗粒（NPZnO）则会促进纳米颗粒快速团聚，提升土壤颗粒的捕获效率，使胶体悬浮液平衡态中的纳米颗粒浓度更低，该结果可用于推动环境影响的衰减与缓解工作。