Active Thermal Field Integration for Marangoni-Driven Salt Rejection and Water Collection

Abstract

Using solar energy to drive seawater desalination via solar steam generation (SSG) is a sustainable strategy for clean water supply. The weak efficiency and poor durability due to salt deposition severely restrict practical SSG operation. Traditional solar evaporators are difficult to simultaneously guarantee efficient evaporation and long-term salt rejection due to increased salinity. Herein, to tackle this dilemma, a thermal gradient fabric (TGF) evaporator with an auxiliary active thermal field is constructed. Different from traditional works where additional energy resources with improved evaporation rate exacerbate salt accumulation, the auxiliary active thermal field is well integrated with external solar energy to boost ion circulation through moderate Marangoni flow, leading to a continuous salt rejection and superior energy utilization under high-salinity desalination. The accelerated evaporation rate (2.42 kg m⁻² h⁻¹) and superior salt resistance (30 days of desalination in 10 wt.% brine) are simultaneously achieved through optimized thermal field construction. An outstanding water collection rate (5.84 kg m⁻²) is observed during high-salinity outdoor desalination, which proves the practical purification ability. This study provides new insight into the construction of active thermal fields for efficient and sustainable clean water production, is believed.