微生物胞外多聚物对石墨烯纳米材料水环境行为的影响与机制研究

The aquatic environmental behavior of nanomaterials is the key to control pollution and ensure the safety use of water. Increasing production and extensive use of graphenes have raised their exposed possibility to natural waters via discharging from manufacturing plants or wearing out from composite products. As the natural organic matter secreted by microorganisms, extracellular polymeric substances (EPS) may have great impact on the environmental behaviors of graphenes, which is still currently unknown. This project will systematic investigate the effect of EPS on the suspension stability of graphenes in water and to reveal the suspension mechanisms. Meanwhile, the effects of solution chemistry (pH, ion strength and ion types) on the aggregation of EPS-suspended graphenes and the related mechanisms will be deeply investigated. In addition, the removal performances EPS-suspended graphenes by coagulation as affected by different factors (coagulates types and dose, pH, alkalinity) will also be examined. The data obtained from this project will provide important information to predict the geochemical processes and toxicity of graphenes in natural aquatic environments. This project will also provide essential theoretical support on the study and development of environmentally friendly graphene nanomaterials.

纳米材料的水环境行为是控制水体污染与保障水质安全的关键。生产和应用的增加会不可避免地造成石墨烯纳米材料通过排放和损耗进入到水环境中。作为由微生物分泌的天然有机物，胞外多聚物EPS会对石墨烯纳米材料的水环境行为产生影响。然而目前未有此方面的研究报道。本项目拟研究EPS对石墨烯悬浮性能的影响，明确石墨烯对EPS的吸附性能与其自身悬浮性能的相关性，揭示EPS对石墨烯的悬浮作用机制；系统地研究水环境化学因素（pH、离子强度和种类）对该悬浮体系中石墨烯聚集行为的影响，阐明该悬浮液对不同水环境化学因素的响应机制；研究水处理系统中混凝沉淀过程对悬浮石墨烯的去除效果，系统分析混凝沉淀中多因素（絮凝剂的类型和投加量、pH、碱度等）的影响，明确混凝沉淀对悬浮石墨烯的去除机制。本项目试图为深入理解石墨烯纳米材料在自然水环境中的地球化学行为提供理论依据，为环境友好型石墨烯材料的研发提供理论指导。

石墨烯纳米材料（GNMs）是近年来研究的热点材料之一。随着产量和应用的逐年增长，GNMs会不可避免地进入到环境中。GNMs迁移、归宿和毒性等环境行为的研究，对其生态环境风险评估和应用至关重要。本项目研究了在微生物胞外多聚物（EPS）存在情况下GNMs的悬浮稳定性，通过GNMs进入水体后水力学直径、Zeta电位、DLVO拟合，揭示了EPS在GNMs悬浮聚集行为中的作用；以模拟化合物代表EPS中蛋白质、多糖、腐殖质等，分析了EPS的不同组分对GNMs的吸附亲和能力，阐明了其对GNMs与其他有机污染物相互作用的影响机制；拓展研究了氧化石墨烯的光化学反应机制，初探了GNMs转化对微生物的毒性效应。本项目的研究结果为深入理解石墨烯纳米材料在自然水环境中的地球化学行为提供理论依据，为环境友好型石墨烯材料的研发提供了理论指导。