Direct capture of low concentration CO2 using tetraethylenepentamine-grafted polyacrylonitrile hollow fibers

This work demonstrated the fabrication of an efficient CO2 sorbent by grafting amines on the highly porous matrix of polyacrylonitrile (PAN) hollow fibers for CO2 capture from low concentration sources. Tetraethylenepentamine-grafted polyacrylonitrile ([email protected]) hollow fibers were characterized by Fourier transform infrared spectroscopy (FT-IR), scan electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) methods. Their CO2 adsorption capacities at low concentrations (470–5000 ppm) were also investigated, indicating the values ranged from 1.70 to 3.66 mmol g−1. The CO2 adsorption capacities fitted well with Langmuir isotherm model. The adsorption kinetic study was performed by using two kinetic models, and pesudo-second model was found fitting better with experimental data. In consideration of their real applications to capture CO2 from confined space, [email protected] hollow fibers were employed to adsorb CO2 directly from atmosphere (25 °C, 470 ppm, RH 25%), and their CO2 adsorption capacity reached up 2.03 mmol g−1. The used [email protected] hollow fibers after CO2 adsorption can be regenerated by temperature swing process. 20 adsorption-desorption cyclic tests were carried out, and no obvious decrease in CO2 adsorption capacity was observed. Owing to their favorable characteristics for CO2 adsorption from low concentrations, [email protected] hollow fiber may be a promising and cost effective sorbent for CO2 removal from confined space or ambient air.