A versatile solar-powered vapor generating membrane for multi-media purification

Water evaporation driven by solar energy is an efficient, renewable, and environmentally friendly method to purify polluted or saline water. However, current solar-powered evaporation systems generally suffer from the poor stability, high materials cost, and complex fabrication processes. In this work, an inexpensive and versatile photothermal membrane (PTM) is prepared with basalt-fibers, which are prepared from natural basalt and synthesized by fiber forming and annealing. Owing to the special chemical composition and physical structure, the basalt-fiber PTM is very robust and corrosion resistant in extreme environments such as a strong acid, organic solvent, and alkali. The water evaporation processes are investigated and the floating-with-insulator mode shows the lowest heat dissipation and highest water evaporation rate. The basalt-fiber fabric is optimized by carbonization and a vaporization rate of 1.50 kg·m⁻²·h⁻¹ and energy utilization efficiency of 82.5% are achieved for evaporation of pure water. The basalt-fiber PTM can be hand washed at least 30 times without efficiency deterioration and the process can be readily scaled up to address commercial needs.