Hydrothermal stability of water sorption ionogels

Adsorption desalination and membrane distillation are the only thermally driven desalination technologies that can be undertaken at temperatures below 70 °C. Adsorption desalination is based on an adsorber whose performance primarily depends on the properties of the water sorbent. Water sorption ionogel represents a novel class of materials offering a large working capacity for desalination. In this study, water-sorptive ionogels were prepared and their hydrothermal stability was assessed. The results show that Syloid 72FP silica-based ionogels are hydrothermally stable. The ionic liquid EMIM Ac can be tightly confined in silica at amounts of up to 50 wt% and still withstand high relative humidity and temperature swings. Water uptake of the synthesized ionogel can be up to 1.64 g_water g_ionogel⁻¹ at 90% RH, which is ∼3 times of that of Syloid 72FP silica and ∼4 times of that of activated carbon. The EMIM Ac/Syloid 72FP ionogel thus exhibits features appropriate for adsorption desalination systems.