Dual-Effect Salt-Tolerant Slope-Suspended Solar Evaporators: High Evaporation Efficiency and Industrialized Implementation

Abstract

Construction of Janus-wetting interfaces in solar thermal evaporation is one of the most widely applied strategies to overcome salt accumulation to prolong a system’s lifetime. Nevertheless, hydrophobicity and steam escape in traditional Janus floating evaporators are negatively correlated, resulting in the trade-off between salt resistance and the evaporation rate. Herein, a scalable suspended-slope evaporator (SSE) based on the inverse wettability polypyrrole (PPy) fabric is designed to surmount the long-term trade-off for achieving continuous and stable high-rate water desalination. Experiments and numerical simulations indicate that the suspended structure opens the “shackles” brought by the upper hydrophobic PPy fabric to steam escape, and the Marangoni convection induced by the inclined structure further enhances salt resistance performance. With this structure employed, SSEs present good salt tolerance (no obvious salt accumulation in 21 wt % brine for 5 h) and excellent solar evaporation performance (evaporation rate of 2.46 kg m–2 h–1 in 3.5 wt % brine, and the energy efficiency is 85.48%). Additionally, there is no need for special customized high-pressure equipment in the whole synthesis process, which has great significance for the widespread practical application. This work elucidates the intrinsic effects of the device structure on solar evaporators while providing insights for designing high-efficiency and salt-tolerant solar evaporators.