Optimization of electrospun polyethyleneimine/polystyrene nanofibers for CO2 capture
摘要
The composition and operating conditions of electrospun polyethyleneimine (PEI)/polystyrene (PS) composite nanofibers were optimized for CO2 adsorption. A maximum capacity of 1.16 mmol CO2/g was achieved at a 60 °C isotherm using 20 wt% PEI with respect to PS. This adsorption capacity is comparable to that of many PEI-impregnated nanofibers and porous sorbents. Despite the exothermic nature of CO2 adsorption, operating at higher temperatures (up to 60 °C) increased the adsorption capacity. Thermal pre-treatment of PEI/PS nanofibers showed a similar trend, with nanofibers pre-treated at increasing temperatures (up to 60 °C) exhibiting greater capacity when operated at 30 °C. Pre-treatment at 60 °C led to similar capacities for isotherms at 30 °C and 60 °C, suggesting that temperature-induced changes to the nanofibers increased the capacity. Kinetic analysis of all PEI/PS nanofibers showed that pre-treatment did not affect the CO2 adsorption mechanism. However, pre-treatment above 60 °C decreased capacity, showing the thermal sensitivity of these materials. Temperature swing cycle testing (30 °C adsorption, 70 °C desorption) found desorption to be 6 times slower than adsorption, showing the constraints of operating within the fiber’s small range of thermal stability.