Super Moisture-Sorbent Sponge for Sustainable Atmospheric Water Harvesting and Power Generation

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Sorption-based atmospheric water harvesting (SAWH) offers a solution to global water scarcity, particularly in arid regions.
• Existing salt-based sorbents for SAWH face challenges with complex preparation to prevent salt leakage and often neglect the heat generated during water harvesting.
• Efficient and stable sorbent materials are crucial for practical SAWH applications.

Purpose of the Study:

• To develop a stable, salt-based super moisture-sorbent sponge for efficient atmospheric water harvesting.
• To address salt leakage issues common in traditional salt-based sorbents.
• To create a dual-function system that utilizes the heat generated during water harvesting for simultaneous water and electricity production.

Main Methods:

• Synthesized a novel composite material by chelating lithium chloride (LiCl) with dopamine (DA) and polymerizing DA on a porous melamine sponge (PMS) framework, incorporating carbon nanotubes (CNTs).
• Investigated the water uptake capacity of the LiCl/PMS/CNTs composite under varying relative humidity (RH) conditions.
• Integrated the developed sorbent material with a thermoelectric module to create a system for simultaneous water and electricity generation.

Main Results:

• The LiCl/PMS/CNTs composite demonstrated high water uptake (1.26 g g⁻¹ at 15% RH and 1.81 g g⁻¹ at 30% RH) with no observed salt leakage.
• Achieved a remarkable daily water production rate of 3.47 kg kg⁻¹ day⁻¹ in an arid environment (30% RH).
• The integrated system produced electricity with a maximum output power density of 35.4 mW m⁻² during water absorption and 454.4 mW m⁻² during desorption.

Conclusions:

• The developed LiCl/PMS/CNTs sponge is a stable and highly efficient sorbent for atmospheric water harvesting, overcoming salt leakage issues.
• The integrated system effectively utilizes the heat from water harvesting, enabling simultaneous freshwater and electricity generation.
• This technology holds significant potential for sustainable water and energy solutions in water-stressed regions.