Separation of carbon dioxide and nitrogen gases using novel composite membranes

Global warming is the major environmental issue caused by greenhouse gases, especially CO2. This demands urgent action to reduce or offset CO2 emission from power plants, which could be done using facilitated transport membranes (FTMs). In this context, CO2 selective carriers were prepared by blending polyvinyl alcohol (PVA) with three amines: ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetramine (TETA). Then, the composite membranes were prepared using PVA–amine blend as the separation layer and ceramic candle filters as the support layer. The fabricated membrane was characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Furthermore, the effect of amine species, effect of TETA concentration, cross-linking agent content, pressure difference, and the thickness of the membrane on the permeance and selectivity of CO2 over N2 were investigated. The permeance and selectivity of CO2 through the membranes were in the following order: TETA > DETA > EDA. This order is related to the number of nitrogen atoms per amine molecule, which can be correlated to loading capacity and, consequently, to amine reactivity with CO2. Under optimized conditions, for a pure gas experiment, the maximum permeance of 6.9 GPU for CO2 gas and selectivity of 50 over N2 was obtained, whereas in the CO2/N2 gas mixture, the maximum permeance of 8.6 GPU and selectivity of 98 was obtained. The membrane was found to be stable for 264 h.