Synthesis of superabsorbent hydrogels for water desalination in emergencies

Abstract

The Emergency Events Database showed an increase in the frequency and intensity of global natural disasters. Supplying adequate and safe drinking water is one of the priorities in the aftermath of disasters. Due to the shortage of power and energy in the regions impacted by disasters, water purification methods that are portable and feasible to be used under limited conditions, would be valuable and efficient. Forward osmosis (FO) is an emerging membrane technology that can desalinate with negligible energy requirement. Hence, FO is a reliable way of meeting the water demands for small communities such as in refugee camps when only saline water sources are available.

This research project focuses on the synthesis of hydrogels which are suitable for brackish water desalination by adopting a new formulation. The performance of the hydrogels was evaluated in terms of the swelling ratio, reusability as well as the desalination capability. For brackish water desalination, our approach employs the use of superabsorbent hydrogels to draw pure water across the FO membrane. The absorbed water can be subsequently recovered via external stimulus. The new formulation that involves the formation of semi-penetrating networks of PNIPAM and PSA allows a swelling ratio to reach around 20 g/g. The new formulation sees a significant improvement in thermo-responsive behavior. Furthermore, these hydrogels can be reused after heat treatment that releases the absorbed water.