Metal oxides incorporated polyacrylonitrile-based activated carbon nanofibers on methane adsorption

Abstract

This study aims to investigate the effects of incorporation metal oxide in PAN-based activated carbon nanofibers (ACNFs) and its physicochemical properties and gas adsorption capabilities. The nanofibers (NFs) were fabricated via electrospinning process by preparing the polymer solution of polyacrylonitrile (PAN) with different concentrations of manganese dioxide (MnO2) and magnesium oxide (MgO) in N, N-dimethylformamide solvent and were further activated through pyrolysis process under optimum conditions. The effects of incorporating different weight ratio of metal oxide into PAN- based ACNFs (0 to 15% relative to PAN wt.) were evaluated based on the chemical and physical morphologies as well as its adsorption performance. Results showed that the ACNFs blended with MnO2 and MgO possess a specific surface area (SSA) up to 430.87 and 1893.09 m2/g, respectively with higher microporous structure. The Fourier transform infrared spectrum indicated that the MnO2 and MgO bonds can be detected at 547 and 476 cm-1, respectively. The x-ray diffraction elucidated both crystalline structure and crystallite sizes of ACNFs are loaded with MnO2 and MgO. The diameter of the resultant ACNFs is inversely proportional to the concentrations of the metal oxide as shown by scanning electron microscopy micrograph. The addition of metal oxides up to 15% (relative to PAN wt.) in polymer solution significantly increased the SSA of the NFs to about four times as compared to metal oxide-free ACNFs; however, the methane (CH4) uptake up to 2.39 mmol/g was attained for ACNFs containing both metal oxides from the static volumetric test. This study suggested that the addition of metal oxide in PAN-based ACNFs would produce a new modified gas adsorbent with higher SSA and excellent porosity with increasing adsorption capacity of CH4.