Novel dual-network-structured hydrogel microspheres for efficient atmospheric water collection

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Atmospheric water harvesting (AWH) is crucial for addressing global fresh water shortages.
• Hygroscopic salt-hydrogel composites show potential but face challenges like complex preparation and low efficiency.
• Existing methods often suffer from salting-out issues, limiting practical application.

Purpose of the Study:

• To develop a novel, efficient, and easily producible material for atmospheric water harvesting.
• To overcome the limitations of traditional salt-hydrogel composites, including salting-out and low water collection efficiency.
• To investigate the performance of a dual-network hydrogel microsphere system for water capture and release.

Main Methods:

• A novel drip-free polymerization method was used to synthesize calcium alginate (CA) and PDMAPS double-network hydrogel microspheres.
• Carbon nanotubes (CNTs) and lithium chloride (LiCl) were incorporated to create a CA/PDMAPS/CNT/LiCl composite adsorbent.
• The material's water absorption capacity, desorption kinetics, and structural properties were evaluated under various conditions.

Main Results:

• The synthesized dual-network hydrogel microspheres demonstrated a high water collection capacity of 3.586 g g⁻¹ at 22 °C and 90% relative humidity.
• The material exhibited a 434% enhancement in water collection efficiency compared to single-network hydrogels.
• The zwitterionic structure effectively bound LiCl, preventing salting-out and forming a beneficial binary salt system.
• Over 80% of adsorbed water was desorbed within 3-4 hours under natural light.

Conclusions:

• The developed dual-network hydrogel microspheres offer a simple, scalable, and highly efficient solution for atmospheric water harvesting.
• The material effectively addresses the salting-out problem and enhances water collection capacity through its unique structure and composition.
• This innovative hydrogel system presents a promising advancement in AWH technology for sustainable water resource management.