Minimizing Solvent Toxicity in Preparation of Polymeric Membranes for Gas Separation

Toxic solvents such as dimethylformamide (DMF) are widely used for the preparation of polymeric membranes due to the strong dissolving power. Environmentally friendly solvents are available, but the developed membranes suffered from low performance due to the poor solubility of the polymer in the solvent. In this work, polyetherimide membranes were prepared using DMF with the addition of the biodegradable solvent γ-butyrolactone (GBL). Results show that mixing 75 wt % of DMF with 25 wt % GBL enhanced the membrane gas permeability toward hydrogen, methane, helium, carbon dioxide, and nitrogen. The overall permeability was increased by 9.6% compared to the permeability of the membrane made by 100 wt % DMF. Hydrogen-to-methane selectivity was also raised from 26.3 to 29.3.