Comparative analysis of penetrant diffusion in gas separation membranes through FTIR Spectroscopy

FTIR spectroscopy is widely used in fields such as pharmaceuticals, material science, environmental monitoring, and quality control to identify both organic and inorganic compounds. This sensitive and non-destructive technique utilizes infrared electromagnetic waves to analyze molecular vibrations, particularly focusing on functional groups. By interpreting these vibrations, the molecular composition of a sample can be determined, as well as any structural changes over time. In this study, two FTIR techniques—Attenuated Total Reflection (ATR) and Transmission Tests—are employed to analyze diffusion in membrane materials. The objective is to examine the diffusion of specific gases or gas mixtures in three types of membranes, considering variations in their structure and external factors like temperature, humidity, and gas composition. The first membranes analyzed are supported liquid membranes made of ionic liquids, which vary in charge density and hydrophilicity. The study investigates whether increased humidity (water in the methane stream) creates a barrier effect in more hydrophilic membranes due to water uptake. The second type includes polymers of intrinsic microporosity, tested with CO2 in transmission cells to study the diffusion coefficient's variation at different CO2 concentrations. , the study examines amine-based facilitated transport membranes, used for CO2 capture. These membranes operate via two mechanisms: facilitated transport at low CO2 partial pressures, and solution-diffusion at higher pressures. The goal is to identify differences in membrane spectra when exposed to diluted versus undiluted CO2, providing insights into the mechanisms behind facilitated transport.