A novel suspended suspension bridge-like evaporator with antibacterial properties for achieving stable solar evaporation in concentrated saline water

Abstract

Salt crystallization and microbial corrosion limit the operation of green and energy-efficient solar-driven evaporation. To enhance the solar evaporation efficiency and achieve the stable evaporation while inhibiting salt crystallization in high-concentration saltwater, this study introduces a novel suspended suspension bridge-like evaporator (CF-Ag-PPy) composed of polypyrrole (PPy), silver (Ag) nanoparticles, and the cotton fabric. CF-Ag-PPy, hanging between two water reservoirs, leverages capillary action, gravity, and siphon effect to draw water from both ends immersed in water to form a suspension bridge-like evaporating surface. This design ensures continuous water supply to the evaporating surface while avoiding direct contact with the water, thereby minimizing additional heat losses and resulting in a high evaporation rate of up to 1.55 kg m−2 h−1. Owing to the siphon effect, the difference in water level height between the supply water and the bottom of the evaporating interface controls the droplet falling speed, so that the evaporator achieves continuous operation at a high evaporation rate of over 1.2 kg m−2 h−1 for six days in 20 wt% high-concentration saltwater, with no salt crystallization formation. This demonstrates the excellent salt resistance of the evaporator. Additionally, the Ag+ ions generated by Ag nanoparticles effectively exhibit antibacterial properties, with a bacterial inhibition rate of up to 99.95 % against specific bacteria, effectively preventing microbial corrosion. This study provides an important design concept for achieving long-term, stable, and efficient purification of high-concentration saltwater in natural environments using solar evaporators.