Unlocking Hydrogel-Based Desalination with Ammonia Gas Dewatering

Water scarcity is a growing global challenge. Developing energy-efficient and sustainable desalination methods is crucial to addressing the global water crisis. In recent years, hydrogel-based desalination has emerged as a promising approach due to the excellent water absorption capacity and stimuli-responsive properties of hydrogels. However, conventional dewatering methods for recovering water from hydrogels often suffer from low efficiency and poor stability. To address these challenges, a novel approach using ammonia gas to dewater poly(acrylic acid-co-acrylamide) hydrogels was investigated, achieving significantly higher dewatering rates (up to 110 g_H2O/g_hydrogel/h), among the highest reported, with water production rates ranging from 600 to 1140 L_H2O/kg_hydrogel/day and an average salt rejection of around 60% for both synthetic and real seawater water. The process also demonstrated excellent stability, maintaining a consistent performance over 100 cycles. This technology shows great potential for desalinating brackish water for agricultural irrigation or integration with reverse osmosis systems for seawater desalination, significantly reducing energy consumption and capital costs. This innovative dewatering method could enable practical applications of hydrogel-based desalination.