Developing hydrophobic patterned composite membranes for synchronous water and heat recovery to reduce CO2 capture energy demand

Abstract

Abstract Simultaneous recovery of waste heat and water from stripped gas streams in CO 2 chemical absorption is vital for lowering energy penalties. This study reports a novel class of wettability patterned ceramic membranes fabricated via spray-coating commercial hydrophilic substrates with geometrically tailored “window-lattice” hydrophobic patterns and multi-segment wettability gradients. Topological optimization revealed that increasing the pattern count of hydrophobic domains, extending the hydrophilic-hydrophobic boundary length, and tailoring the hydrophobic pattern geometry were beneficial for enhancing heat recovery performance. The tailored membranes achieved a peak heat recovery flux of 22.1 MJ/(m 2 ·h) and a specific heat recovery potential of 853.2 kJ/kg, outperforming the initial hydrophilic membrane by 15.6% and 14.2%, respectively. Furthermore, developing stepwise two-segment and three-segment surface wettability gradients imparted a continuous driving force for directional condensate pumping, delivering a water flux of 18.8 kg/(m 2 ·h), representing a 42.1% enhancement over the hydrophilic membrane. However, the wettability gradient also introduces additional interfacial thermal resistance and promotes gas-filled pore states, thereby constraining overall heat recovery performance. The design of “window-lattice” ceramic membranes offers new strategies and guidelines for efficient water and heat recovery in membrane condensers, which can be applied to humid gases such as stripped gas, flue gas and biogas, thereby offering sustainable pathways for low energy CO 2 separation, water reclamation, and energy savings.