Combined Sustainable Water Purification and Remineralization Using an Off-Grid, Nanoparticle-Driven Solar Process

The increasing demand for potable water worldwide necessitates scalable and sustainable approaches to water purification. Here, we demonstrate a solar-driven water purification system that combines nanoparticle-assisted, membrane-free solar distillation with remineralization through a natural sedimentary rock-filled condensation column. The solar distillation is accomplished using carbon black nanoparticles (CBNPs), whose broadband light absorption properties significantly enhance the evaporation rate during distillation. This is paired with a condensation-remineralization column incorporating sedimentary rocks, which effectively replenishes essential minerals such as calcium and magnesium (required for sustainable human consumption) and re-establishes water alkalinity. It achieves a 99% reduction of dissolved ions and restores calcium concentration to levels comparable to the World Health Organization (WHO) standards while also achieving effective microbial decontamination. Combining distillation and remineralization in one simple, low-tech system is a strategy that addresses the urgent demand for sustainably safe drinking water needed in many resource-limited communities and locations.