Experimental and Theoretical Assessment of Water Sorbent Kinetics

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Atmospheric water capture (AWC) devices require efficient water adsorption kinetics.
• Understanding sorbent layer properties is crucial for scaling up AWC technology.

Purpose of the Study:

• To experimentally investigate the water adsorption kinetics of different sorbent materials in powder layers.
• To model the influence of key parameters on adsorption kinetics and daily water yield.
• To identify optimal sorbent layer configurations for enhanced atmospheric water capture.

Main Methods:

• Experimental testing of three sorbents (Cr-MIL-101, NPS, silica gel) in powder layers (0–7.5 mm).
• Utilized a calibrated environmental chamber with controlled humidity (5–95% RH) and temperature (30 °C).
• Applied a mass and energy transfer model to analyze experimental adsorption curves.

Main Results:

• Open porosity significantly enhances water adsorption kinetics in sorbent layers.
• Optimal open porosity exists for each sorbent material to maximize daily water yield.
• Thinner layers with moderate open porosity outperformed thicker layers with high open porosity.

Conclusions:

• Open porosity is a critical factor for improving water adsorption kinetics in AWC.
• Sorbent layer design, specifically thickness and porosity, directly impacts daily water capture efficiency.
• High water uptake capacity and fast single-particle kinetics do not guarantee high daily water yield.