Progress in enhanced separation of compounds differing in unsaturated bonds by ionic liquids
The separation of structurally similar compounds represents one of the most energy-intensive processes,particularly for compounds that differ in unsaturated bonds.This challenge arises from their extremely similar physicochemical properties.Ionic liquids(ILs)have emerged as promising candidates for the separation of compounds with different unsaturated bonds through molecular recognition,which is mainly attributed to the unique physicochemical properties of ILs,their designable structures,and their ability to facilitate multiple intermolecular interactions.This work aims to provide a comprehensive review of the progress of utilizing ILs for the separation of compounds with disparities in unsaturated bonds.It presents a detailed analysis of some representative systems,including gaseous light hydrocarbons,liquid-state medium-chain hydrocarbons,and solid-state natural active compounds.This review highlights the relationship between the molecular structure and separation efficiency,elucidates the underlying separation mechanisms,and evaluates the effectiveness of the separation process.Furthermore,it briefly discusses the future trend in the design and optimization of ILs for this specific area.