Super Moisture-Sorbent Zwitterionic Polyelectrolyte Hydrogel for Ultra-Efficient Atmospheric Water Harvesting

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Sorption-based atmospheric water harvesting (SAWH) is crucial for addressing global freshwater scarcity.
• Current hygroscopic materials face challenges with high thermal and mass transfer resistance, limiting efficiency.
• Improving capacity and kinetics of SAWH materials is essential for practical applications.

Purpose of the Study:

• To develop a novel hierarchical porous architecture for enhanced atmospheric water harvesting.
• To overcome the limitations of existing hygroscopic materials in terms of heat and mass transfer.
• To demonstrate the practical applicability of the developed material in a real-world scenario.

Main Methods:

• Fabrication of a zwitterionic polyelectrolyte hydrogel with enhanced adhesion.
• Loading the hydrogel onto anodized aluminum foam (AAF) to create LC-PIL-SO3Li-CNT@AAF.
• Characterization of moisture absorption capacity, desorption performance, and heat/mass transfer efficiency.

Main Results:

• The LC-PIL-SO3Li-CNT@AAF composite achieved a moisture absorption capacity of 16.33 g·g_hydrogel^-1 at 90% RH, a 322.02% increase.
• Excellent low-temperature desorption performance was observed, with 83.34% efficiency after 2 h at 40°C.
• The 3D hierarchical structure significantly improved heat and mass transfer, leading to enhanced absorption-desorption kinetics.

Conclusions:

• The developed hydrogel composite system demonstrates ultrahigh moisture absorption capacity and efficient low-temperature desorption.
• A 10-day field trial for plant irrigation validated the practical potential of this SAWH technology.
• This research provides key insights for alleviating water shortages and optimizing agricultural water use.