Three-dimensional freeze-casting solar evaporator for highly efficient water evaporation and high salinity desalination
Bo Li, Mengxiao Lin, Changwei Cheng, Xiangfeng Li
Abstract
The escalating global freshwater crisis demands sustainable water management strategies, such as solar-driven interfacial steam generation (SISG). Three-dimensional (3D) photothermal evaporators emerge as a promising solution due to significantly higher evaporation rates compared to two-dimensional (2D) counterparts. This study described the design and fabrication of M-shaped 3D evaporators using the freeze-casting technique with graphite nanopowder (GNP) and polyvinylidene fluoride (PVDF). Under 1.0 kW m −2 solar irradiation and 4 m s-1 convective flow , a high evaporation rate of up to 10.5 kg m −2 h −1 in pure water was achieved. The M-shaped 3D evaporators demonstrated excellent performance in solar desalination and wastewater treatment , maintaining stability even in a 20 wt% sodium chloride (NaCl) solution at 1.0 kW m −2 solar irradiation and 2 m s −1 convective flow , with a rate of approximately 3.8 kg m −2 h −1 . These findings highlight the significant potential for leveraging the synergistic interplay between solar energy and convective flow, which can be harnessed through the fabrication of customized 3D evaporators via freeze-casting. This innovative approach offers a scalable and cost-effective solution, contributing to both efficient water evaporation and environmentally sustainable high salinity desalination for future water treatment .