Evaluation of microporous acrylic-based activated carbon fibers as novel adsorbents for methylene blue removal

A novel microporous activated carbon fiber was prepared through thermal stabilization and chemical activation of acrylic fibers. BET, FESEM, and FTIR analysis were used to study different characteristics of the obtained adsorbent. Also, the iodine number, pH at point zero charge, and the mechanical properties of the samples were presented. The potential of this new adsorbent for removal of methylene blue (MB) from aqueous solution was studied in the batch experiments and the influence of main operating parameters including pH, initial dye concentration and adsorption time was studied. Relatively complete removal (about 95%) of MB dye was achieved at the pH of 12 and initial dye concentration of 100 mg/L. Moreover, it was revealed that the experimental data could be expressed well by the Langmuir and pseudo-second-order model, such that the maximum amount of monolayer adsorption was about 324.83 mg/g. The spontaneous and endothermic nature of the adsorption process was proved by thermodynamic parameters. This research revealed that, along with the pore filling mechanism, as the significant mechanism, the adsorption may have occurred via hydrogen bonding, n-pi, pi-pi, and electrostatic interaction. Moreover, the desorption characteristics of the adsorbent were studied and about 86% desorption was achieved after three cycles. According to the results, the mechanical properties and adsorption/desorption capacity of this novel fabricated activated carbon fiber are relatively better than other adsorbents.