Faced with the dual challenges of energy crisis and water scarcity, desalination using low-grade heat to obtain freshwater has attracted increasing attention. Here, by coupling the temperature gradient with surface wettability in a nanochannel, an efficient desalination method utilizing low-grade heat energy without phase change is proposed. Driven by a temperature gradient, the liquid water in the nanochannel would undergo directional migration depending on surface wettability. Considering the extremely low wetting pressure in the hydrophilic channel, efficient desalination without an external force can be achieved by controlling the channel size. The influence of channel length and temperature difference on water flux is further studied, and the key role of wetting degree between the interface of nanomaterials and water in this thermal osmosis process was revealed. Typically, for a hydrophilic channel with 6.4 nm length and 0.7 nm slit size, a water flux of 1733 kg/(m² s) with salt rejection up to 100% can be achieved at a temperature difference of 75 K. The results presented here provide a new strategy for efficient desalination using low-grade heat energy.

中文翻译：

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石墨烯通道中温度梯度与表面润湿性耦合驱动的海水淡化


面对能源危机和水资源短缺的双重挑战，利用低品位热量获得淡水的海水淡化越来越受到关注。在这里，通过将温度梯度与纳米通道中的表面润湿性耦合，提出了一种利用低品位热能而无相变的高效海水淡化方法。在温度梯度的驱动下，纳米通道中的液态水将根据表面润湿性进行定向迁移。考虑到亲水通道中的极低润湿压力，可以通过控制通道大小来实现无外力的高效海水淡化。进一步研究了通道长度和温差对水通量的影响，揭示了纳米材料与水界面之间的润湿度在该热渗透过程中的关键作用。通常，对于长度为 6.4 nm、狭缝尺寸为 0.7 nm 的亲水通道，在 75 K 的温差下，可以实现 1733 kg/（m² s） 的水通量，脱盐率高达 100%。这里介绍的结果为利用低品位热能进行高效海水淡化提供了一种新策略。