Emerging heat-localized solar distillation systems: Solar interfacial distillation VS photothermal membrane distillation

Heat-localized solar distillation (HLSD) is an emerging environmentally- friendly high-efficiency distillation technology for clean water production. Solar interfacial distillation (SID) and photothermal membrane distillation (PMD) are two featured HLSD processes that have attracted a lot of attentions from researchers recently. Both SID and PMD systems produce water vapor from thin film surfaces where sunlight can be absorbed and converted as localized-heat to minimize heat loss and improve heat conversion efficiency. This article offers an overview of SID and PMD, including their respective classifications and characteristics. Subsequently, the water production capacities and purification efficiencies of the two systems are compared and the influencing factors are analyzed. Moreover, this paper compares the crystallization processes between the two systems and elucidates the methods employed to prevent salt fouling and achieve salt recovery. Finally, this study highlights the current challenges and future prospects of both systems to guide future research.