Adsorption of Carbon Dioxide with Ni-MOF-74 and MWCNT Incorporated Poly Acrylonitrile Nanofibers

Abstract

Among the new adsorbent forms, nanofiber structures have attracted extra attention because of features such as high surface area, controllable properties, and fast kinetics. The objective of this study is to produce the polyacrylonitrile (PAN) electrospun nanofibers loaded with Ni-MOF-74/MWCNT to obtain maximum CO2 adsorption. The prepared PAN/MWCNT/MOF nanofiber based on the Box–Behnken design (BBD) model suggests the CO2 adsorption of about 1.68 mmol/g (at 25 °C and 7 bar) includes 14.61 w/v%, 1.43 w/w%, and 11.9 w/w% for PAN, MWCNT, and MOF, respectively. The results showed the effective CO2 adsorption of about 1.65 ± 0.03 mmol/g (BET = 65 m2/g, pore volume = 0.08 cm3/g), which proves the logical outcomes of the chosen model. The prepared PAN/MWCNT/MOF nanofiber was characterized using different analyzes such as SEM, TEM, TG, XRD, FTIR, and N2 adsorption–desorption isotherms. More MOF mass loading on the nanofiber surface via secondary growth method resulted in 2.83 mmol/g (BET = 353 m2/g, pore volume = 0.22 cm3/g, 43% MOF mass loading) and 4.35 mmol/g (BET = 493 m2/g, pore volume = 0.27 cm3/g, 65% MOF mass loading) CO2 adsorption at 7 bar for the first and second growth cycles, respectively. This indicates that secondary growth is more effective in the MOF loading amount and, consequently, adsorption capacity compared to the MOF loading during electrospinning.