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MEAM Seminar: “Physics and Engineering of Moisture-Capturing Hydrogels for Freshwater and Heat Harvesting”
March 28 at 10:00 AM - 11:30 AM
Humidity in the air is a vast water and energy resource available in any location. Air in the atmosphere contains six times more freshwater than that of all rivers and lakes. This moisture also carries over a thousand times more power than the global electricity demand. For over two centuries, numerous water sorbent materials have attempted to harness these resources. However, their performance, scalability, and durability have severely limited their potential. In this talk, I will discuss the material-level to application-level development of hydrogel-salt composites that capture record amounts of water from the air with low-cost (<$0.1/kg of material) and high durability.
I first developed physics-based models elucidating the key thermodynamic interactions and transport mechanisms in hydrogel-salt composites. Through comprehensive synthesis and characterization, I demonstrated that these models accurately predict the key sorption performance metrics (uptake, enthalpy, and kinetics) of hydrogel-salt composites from their composition. I then used these insights to 1) synthesize hydrogels with the highest capability ever demonstrated of any material to capture and store water from the air (~2 kg of water/kg of material), even in arid conditions (30% relative humidity), 2) design and demonstrate a device capable of producing >1 L/m2/day of water from humidity, and 3) develop a heat exchanger that converts moisture capture into heat. Beyond performance, I studied the hydrogel degradation mechanisms, probing an unexplored, yet critical parameter. Specifically, by preventing metal ion-mediated hydrogel degradation, I demonstrated >8-month material durability, exceeding previous state-of-the-art works and providing a path towards <$0.01/L water production from the air.
My rational, physics-based development of hydrogel-salt composites represents a significant step towards the utilization of ambient moisture and its energy for a wide range of applications. These results also open exciting scientific opportunities for leveraging the unconventional transport properties of hydrogels to address grand humanity challenges in the water-food-energy nexus.
Carlos Diaz-Marin
Ph.D. Candidate, Department of Mechanical Engineering, Massachusetts Institute of Technology
Carlos D. Díaz-Marín is a PhD candidate in Mechanical Engineering at MIT. His work, under the supervision of Professors Gang Chen and Evelyn N. Wang, combines polymer physics, transport phenomena, and scalable hydrogel synthesis to push the performance limits of water capture from the air to enable large-yield freshwater production from the air and high energy density sorption-based energy storage. He obtained his M.S. in Mechanical Engineering from MIT (2021) and double B.S. degrees in Mechanical Engineering (2017) and Physics (2018) from the University of Costa Rica.
Carlos is an MIT Martin Family Sustainability Fellow, the Caltech Young Trailblazing Researcher in Mechanical and Civil Engineering (2023), and a selectee of the Mechanical Engineering Rising Stars (University of California, Berkeley, 2023) workshop.