Correlations Between Alkali and Crystallinity in lyocell-Based ACF Probed with X-Ray Diffraction

Abstract

This study examined the effect of alkalis on lyocell-based activated carbon fibres (ACFs) with high Brunauer-Emmett-Teller (BET) surface areas, using X-ray diffraction (XRD). Here, alkali treatments were conducted using 10 ~ 25 % NaOH and KOH on lyocell samples for 3 h at ambient room temperature. A secondary treatment with 4 % each of KOH and H3PO4 for an additional 3 h followed. An activated form of the samples was prepared by oxidation (stabilisation), carbonisation, and activation. The final ACF form of the samples showed a porous structure with high BET surface areas (> 1,000 m² g^-1). A 25 % dosage of NaOH produced the highest BET surface area compared to other samples. In terms of crystallinity, a 15 % dosage of KOH was found to be the optimum dosage to secure the highest degree of crystallinity among all samples. Meanwhile, the NaOH was successfully shifted the samples into the most distinct form of cellulose II. 15 % NaOH was found to secure the most stable thermal characteristics, as determined via thermo-gravimetric analysis. The present work demonstrates the various physio-chemistries of ACFs prepared with different proportions and types of alkalis, leading to intriguing potential applications.