溶解有机质作用下氧化铜纳米颗粒的溶解释放

Copper oxide nanoparticles (CuO NPs), as one of the five most commonly used metal based nanoparticles on the world market at present, have been widely added in the products such as catalysts, sensors, heat transfer fluid, semiconductor, photovoltaic cells, and pesticides. Due to a large number of production and usage, it is more likely that CuO NPs will find their way into the environment such as through sewage discharge or contaminated sludge fertilization. It is also worth noting that CuO NPs can release copper ions in aqueous solution at room temperature and atmospheric pressure, which is often described as ‘dissolution’. This will inevitably result in potential threats of CuO NPs to organisms living in the environment and even human health. In order to accurately assess the behavior and risks of CuO NPs in the environment, the point is supposed to comprehensively understand the dissolution of CuO NPs, as affected by dissolved organic matters (DOM). Thereupon, this study aims at systematically investigating the impacts of DOM on the dispersion and suspension of CuO NPs, the surface change of CuO NPs due to the reduction of DOM, the complexation reaction between DOM and copper ions released from CuO NPs, and the stable isotope fractionation of copper during the above processes. Special emphasis will be on elaborating the mechanism of copper ion release of CuO NPs under the influence of multiple processes as described above. From a technical point of view, the core driving force of the dissolution of CuO NPs can be determined by identifying the surface of CuO NPs that exposed to the solution. The total amount of complexed copper with DOM can be calculated according to the estimated stability constants and the total amount of DOM. This will avoid the difficulty in determining the complexed copper in solid phase and in liquid phase. Moreover, the introduction of the stable isotope fractionation method for copper will be beneficial to investigate the environmental behavior of CuO NPs. With the experimental design and analysis presented above, this research will undoubtedly provide the scientific basis for the environmental risk assessment and for the application or effects control of CuO NPs in the near future.

氧化铜纳米颗粒（CuO NPs）作为五种最常用的金属基纳米颗粒之一，被广泛应用于催化剂、传感器、传热流体、半导体、光伏电池、农药等产品中。其大量生产和使用不可避免地使CuO NPs进入到环境当中，并向水溶液中释放铜离子，对生态系统和人类健康产生潜在威胁。为准确评估CuO NPs的环境行为和风险，系统理解溶解有机质（DOM）作用下CuO NPs的溶解释放是关键。本研究拟系统研究DOM对CuO NPs的分散悬浮、表面还原，DOM与释放的铜离子之间的络合，铜元素在以上过程中的同位素分馏等过程，理解在以上多过程影响下铜离子释放的机制。从技术手段上，通过对暴露CuO NPs表面的识别，判断其溶解释放的核心推动力；据络合常数和DOM总量计算络合铜总量，避免固相、液相络合铜的测定；引入稳定同位素分馏手段，探讨铜分馏特征在其行为识别上的应用。以上研究将为CuO NPs的环境风险评估和应用控制提供科学依据。

氧化铜纳米颗粒（CuO NPs）以其独特的物化性质，被广泛应用于催化、介电等领域。大量的生产、使用及处理，使其不可避免地排放到环境当中，从而对生态系统和人类健康造成威胁。系统研究环境中存在的大量溶解性有机质（DOM）作用下CuO NPs的溶解释放是准确评估其环境行为和风险的前提条件。DOM的去质子化及络合作用均能促使CuO NPs进一步溶解，但DOM的吸附反而有可能减少颗粒表面暴露在环境介质中的表面积从而抑制溶解，理解各个动力学过程间的相互联系成为找到CuO NPs溶解驱动力的关键环节。.经过三年的持续研究，基本上实现了预期的科研目标，并在此基础上，针对研究中发现的新问题，将研究内容进行了有效的扩展。本项目完成的主要研究内容包括：不同性质、结构的腐殖酸（HA）、单宁酸（TA）作用下，不同浓度、粒径的CuO NPs的溶解动力学、聚集过程的测定；不同pH值下不同浓度的CuO NPs的溶解动力学、聚集过程的测定；区分CuO NPs在上述不同环境影响因子作用下溶解部分的自由离子态及络合态占比；TA在不同粒径的CuO NPs表面的吸附动力学测定。基于以上研究内容，取得的主要研究结果包括：.1、探明了pH值的变化和络合作用是DOM作用下CuO NPs的两大溶解驱动力，并量化了以上两个影响因素对释放铜的游离态和络合态的相对贡献；.2、发现一般意义上的分散或聚集状态并不能准确描述DOM吸附作用与CuO NPs溶解释放的关系，DOM吸附后颗粒表面Cu的暴露程度对CuO NPs溶解释放起到控制性作用，DOM的厚吸附会减少颗粒的溶解释放量；.3、大分子DOM在高浓度时发生的自聚集现象会减弱其在颗粒表面的吸附，静电辅助氢键是导致分子间自聚集现象发生的主要因素之一，这时颗粒铜溶解释放的增加主要源于络合作用。.4、DOM均能在不同粒径的CuO NPs表面产生吸附，阻滞溶解，虽然颗粒的分散性表现会有所差异。.在本项目的支持下，研究团队发表SCI期刊论文6篇，中文核心期刊论文4篇，1篇在修。以上研究结果为CuO NPs的环境风险评估建立了数据储备，并为进一步探究DOM与金属基纳米颗粒的相互作用提供了理论基础。