Recent progress in ionic liquids as desiccants for energy consumption in cooling applications

Desiccants play a vital position in saving energy and abating emissions in cooling systems. However, choosing the most suitable desiccant to address energy consumption issues is challenging and meaningful. Ionic liquids (ILs) are non-volatile, non-flammable, have a high thermal and chemical stability, and can be regenerative / recyclable. ILs have become popular with researchers as desiccants and this paper reviewed the historical background of ILs as desiccants, before examining the current and possible future applications of ILs. The characteristics of commercial solid and liquid desiccants were summarised, historical milestones were analysed, and dehumidification performance, adsorption mechanisms, vapour pressure, and other measurement models were described. Based upon this research summary, suggestions are made for the future research direction of ILs as desiccants in sustainable recycling. IL desiccants can be functionalised, and synthesised with relative ease by modification of their anions and cations. This means that customisable solutions can be designed with outstanding drying performance. This chemical design aspect can also be harnessed to ensure new IL desiccants are hydrophilic, making them more convenient to recycle and reuse. Aerogels are another promising new approach, and finding a suitable ratio of desiccants to include as an additive to other substances may improve water adsorption and offer a more renewable approach to dehumidification and cooling.