Dehydration of Ethylene Glycol Using Sodium-Mediated Hydrophilic Carbon Molecular Sieve Membranes

Organic solvents play a crucial role in the pharmaceutical and chemical industries, making dehydration processes essential for an environmentally friendly process design and compliance with environmental regulations. Ethylene glycol, as a valuable raw material, is gaining attention for regeneration through dehydration processes from the perspective of resource recycling. In this study, sodium was introduced through functional group substitution of precursor PIM-1, enhancing the hydrophilicity of the carbon molecular sieve (CMS) membrane for applications in ethylene glycol (EG)/water dehydration processes. Na-PIM, synthesized through nitrile group substitution of PIM-1 via hydrolysis, was confirmed by spectroscopic analysis. The pyrolyzed Na-PIM CMS revealed improved hydrophilic characteristics compared to PIM-1 CMS, demonstrating over 70% higher water permeability in dehydration experiments without a loss in the separation factor. This research successfully developed a hydrophilic CMS through precursor functional group substitution, proposing a method to enhance the applicability of carbon membranes, which are challenging in dehydration processes due to hydrophobicity.