基于氧化石墨烯太阳能海水淡化的能量转换机理研究

The shortage of fresh water resources has attracted the increasing interest all over the world, and seawater desalination has been considered as an effective way to solve the problem. More and more attentions have been paid on the solar desalination due to non-pollution and low energy consumption. In recent years, solar desalination with higher energy conversion efficiency can be achieved via graphene-based materials through the heat localization effect, which is expected to be the next generation desalination technology. However, the energy conversion mechanism under the coupling effects of highly efficient solar absorption and rapid water transport in the two-dimensional (2D) nano-channels originating from the graphene oxide membranes has not been systematically investigated. Meanwhile, the factors affecting the energy conversion mechanism have not been quantitatively studied. Therefore, this project will focus on the energy conversion mechanism of solar energy in the 2D nano-channels, and the mechanism and the rate-limiting factors will be explored in details and summarized through the experimental results, molecular dynamics simulations and numerical models. Furthermore, a mathematical model will be proposed to quantitatively describe the variables which influence the efficiency. The project is expected to provide a theoretical basis for the realization of high-efficient solar desalination with graphene materials, having important scientific value and practical significance.

淡水资源短缺一直是世界各国关注的焦点，海水淡化是一种解决淡水短缺的有效方法，太阳能海水淡化由于具有无污染、低能耗等优点得到广泛关注。近年来，利用氧化石墨烯薄膜进行太阳能海水淡化可实现较高的能量转换效率，有望成为下一代海水淡化技术。但是，关于氧化石墨烯对太阳能的高效吸收和水分在纳米通道内的快速输运耦合作用下的能量转换机理并没有深入研究，也没有系统地定量研究哪些因素会影响能量转换效率。本项目将围绕太阳能在氧化石墨烯纳米片层间的能量转换机理这个关键问题展开，结合实验、分子动力学模拟以及数值分析，深入探究二维纳米通道内水分输运和能量转换机制，分析和总结影响水分传输和能量转换效率的因素，测定和归纳各因素的影响程度，并提出定量反映影响效果的数学模型。该项目有望为石墨烯材料实现高效太阳能海水淡化提供理论基础，具有重要的科学价值和实用意义。

淡水资源的日益匮乏已成为普遍的全球性问题之一。近年来，相对于传统海水淡化技术需要复杂的基础设施、较高的投资成本以及大量的化石能源消耗，利用太阳能驱动的界面蒸发技术凭借其高效产水速率和超低的投入成本已成为科学家的研究热点。本项目以具有优异吸光和传质特性的氧化石墨烯薄膜作为研究对象，结合实验和分子动力学模拟，探究了氧化石墨烯结构参数对太阳能吸光率和水分输运速率的定量化影响，以及对光热转换过程中能量转换效率的影响规律。实验结果表明，通过对氧化石墨烯的还原，可大大提高其吸光率和疏水性；通过分子动力学模拟得出氧化石墨烯层间的壁面滑移速度随着氧化度的增大而减小，而与羟基的排列没有关系，其中流量与滑移速度成线性关系，水通过氧化石墨烯的渗流速率也远小于经还原后的氧化石墨烯的渗流速率。利用还原氧化石墨烯的超高吸光率、超快的水分输运能力以及超高的阻盐率，开发了基于石墨烯基材料的光热膜蒸馏技术，有效消除了膜蒸馏技术中温度极化和浓度极化效应，大大提高了其产水速率。本项目的开展为利用石墨烯材料实现高效太阳能界面蒸发海水淡化技术提供了理论基础，对于这种新型太阳能海水淡化技术的推广应用具有重要的科学价值和实用意义。