Application of Chemically-Activated Recycled Carbon Fibres for Aqueous-Phase Adsorptions - Part I: Optimisation of Activation Process

Abstract

Carbon fibre reinforced polymers (CFRPs) are an attractive and versatile material, owing to their low weight and high mechanical stability, among other characteristics. This has led to a rapid increase in their use across many industries, particularly the aviation and automotive sectors. However, large quantities of waste are being generated when CFRPs reach their end-of-life (EoL) due to limited recycling and reuse pathways. To create a circular economy for CFRPs, alternative, high-value EoL pathways for recycled carbon fibres (rCFs) are needed. At present, very few studies investigate the activation of rCFs, particularly for applications as adsorbents. Developing on from the authors’ previous study, where rCFs were shown to be a promising precursor for the development of carbonaceous adsorbents, for applications in aqueous-phase, this work has focused on optimising the chemical activation procedure via a box Behnken design-response surface methodology (BBD-RSM) approach, with an aim to maximise product yield and methylene blue adsorption capacity, using virgin carbon fibres (vCFs) as proof of concept. The optimum activated rCFs achieved an adsorption capacity of 454.55 mg/L; a significant increase of 715% when compared to the previous study. While the optimum activated vCF counterpart achieved a maximum adsorption capacity 344.83 mg/L.

Keywords: recycled carbon fibre, chemical activation, optimisation, design of experiment, adsorption