Activation Of Pitch Carbon Fiber And Carbon Fiber Composites In Molten KOH To Produce Activated Carbon Fibers

Activated Carbon Fibers (ACF) is a new generation of porous carbon material,which developed based on the technology of carbon fiber and activated carbon. ACFs are usually used as adsorption material due to their high specific surface area, large pore volume and lots of oxygen containing functional groups, which are easily reacted with organic compounds on their surface. ACF can be processed into the forms of fabrics, mats, non-woven fabrics, paper and honeycomb, etc. These characteristics together with large adsorption capacity and fast adsorption rate facilitate the use of ACF for purifying water and removing contaminants from air. ACF can be applied in food, chemical and other industriesdue to its strong adsorption capacity with organic compounds. However, high manufacturing cost and discontinuous operation limit its application. Here, we report the activation of waste carbon fiber reinforced epoxy resin composites in molten KOH at relatively lower temperatures.Pitch carbon fiber and carbon fiber reinforced epoxy resin composites were used as raw materials, respectively. ACF was preparedin molten KOH. The effects of activation temperature and time on the morphology, surface properties were studied.The morphology of ACF was characterized by Scanning Electronic Microscopy(SEM). The surface area and porous texture were characterized by N2 adsorption system. The adsorption of methylene blue by ACF was investigated. The pyrolysis products from epoxy resin were also analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS).At first, ACFs were prepared in molten KOH using pitch carbon fiber. When the activation temperature increased from 350 ? to 550 ?, the surface area increased.Especially when the temperature reached 550 ? the surface area of micropores increased obviously. ACF-550 ?-1 h had the highest microporous surface area and smallest pore diameter. The surface of the ACF was smooth at relative low temperatures. Pitched ACF has a good adsorption performance for methylene blue.The maximum adsorption, qm calculated as 278 mg/g by Langmuir equation fitting.The adsorption equilibriumcan be quickly reached.ACF was prepared in molten KOH from carbon fiber reinforced epoxy resin composites. ACF was produced when the reaction temperature increased to 550 ?.The main gas products were hydrogen (82.2-87.1 vol%) andmethane (12.0-16.3 vol%).And the composition of the gas was relatively stable while the amount of the gas increased sharply with increasing temperature. The main liquid degradation products were aniline and 4,4'-methylenebis(N,N-dimethylaniline). These compounds were cleaved from crosslinked structures between bisphenol A and 4,4-Diaminodiphenyl methane (DDM). We provided a kind of semi-continuous method for the production of ACF using waste composites as feedstock in molten KOH. This method provides a possibility to transform waste material into high-value added materials.