STTR Phase I: Solar-driven, thermally responsive membranes for off-grid water purification

The broader impact of this STTR Phase I project will be the development of a solar-based water purification solution that has the potential to overcome the persistent barriers to safe drinking water access plaguing the more than 81 million Americans living in counties with elevated water quality issues. As the frequency of climate-related natural disasters and the prevalence of contaminated drinking water supplies (e.g., from detection of per-/poly-fluoroalkyl substances (PFAS) ‘forever chemicals’) increases, there is an urgent need for easily implementable water treatment options to maintain access to safe drinking water.

Offering an off-grid, cost effective, energy-free approach, this technology is suited to provide a safe drinking water solution that can be cost-effectively deployed without requiring a water infrastructure overhaul. In contrast to existing water treatment approaches, which rely on energy inputs and infrastructure investment, the proposed technology is both sustainable and reliable, and has the flexibility, modularity, and scalability needed for facile deployment.

Potential commercial impact of this disruptive technology is high, considering the number of communities currently seeking water treatment solutions that would be easily met with the technology, and the subsequent jobs created related to installation and maintenance.

The technical innovation of this project comes from the development of a solar absorber gel (SAG) membrane that passively purifies water using natural sunlight or a waste heat source. This system is designed to selectively capture clean water at low temperatures and release it under natural sunlight at higher temperatures. Compared to other passive solar water purification methods, which rely on the energy-intense evaporation and condensation processes, this technology does not rely on a phase transformation but instead absorbs and releases liquid water due to minor temperature swings and can achieve the critical temperature for water release within a matter of minutes.

This system holds promise for both modular and stationary water purification in a sustainable manner. Phase I project will focus on demonstrating performance capabilities to meet drinking water standards, improving water collection rates, and enhancing the durability of the membranes. The objectives include: 1) investigating the properties and performance of SAG membranes with an open-cell membrane structure that dramatically improves the water purification rate; 2) performing detailed investigation on the SAG rejection rate to harmful mixed impurities and meeting National Sanitation Foundation standards; and 3) assessing the long-term reusability of the SAG membrane, including on accelerated degradation studies.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.