Effect of heat treatment on surface properties of polyacrylonitrile-based activated carbon fibres

摘要

Due to their excellent surface properties, high adsorption capacity and great flexibility for conversion into a wide variety of textile forms, such as tow, fabric and felt, activated carbon fibres (ACFs) have recently attracted increasing attention [1-3]. Poly-acrylonitrile (PAN) based fibre has been one of the precursors for manufacturing activated carbon fibres [4-6]. Conversion of activated carbon fibres from PAN-based fibres usually includes three steps: (1) oxidative stabilization transforms the linear structure of PAN fibres into a partially cyclized ladder structure; (2) higher temperature carbonization develops a consolidated, graphite-like carbon structure; and (3) activation treatment creates porosity within the material. Due to the interaction of activating agents during the activation treatment, the surface properties of carbon fibres were significantly varied. These surface properties, e.g. surface area, surface microstructure and chemical structure, have significant effects on the efficiency and potential of ACFs in their application areas. So it seems important to understand the variation of surface properties of fibres during their transition from precursor to final product. This study developed ACFs from PAN-based precursor fibres using thermal stabilization, carbonization and steam activation treatment. Then the ACFs were successively subjected to a heat treatment in vacuum, and a reactivation treatment, respectively. Variations in the surface properties - surface area, bulk and surface composition - were monitored during these heat treatment processes, along with the surface Raman spectra.