Mesoporous activated carbon from grass waste via H3PO4-activation for methylene blue dye removal: modelling, optimisation, and mechanism study

摘要

ABSTRACT The grass (G) biomass waste in this work was used as an alternative source for producing high-quality mesoporous activated carbon (AC) via H3PO4 activation.The developed G-based activated carbon by phosphoric (H3PO4) acid activation (GAC-PA) was characterised via various analytical techniques. The surface area property represents a high surface area (756.3 m2/g) and mesoporous structure (mean pore diameter of 11.3?nm) of GAC-PA. The adsorptive property of GAC-PA towards the methylene blue (MB) dye uptake was optimised via a response surface methodology with Box–Behnken design (RSM-BBD). The equilibrium adsorption fitted well with the Langmuir and Temkin isotherm models, and the qm value for the MB dye was 241.3 mg/g at 45°C. The MB dye adsorption mechanism on the GAC-PA surface indicates various dye–adsorbent interactions, such as electrostatic, π–π, and H-bonding. This study demonstrates the applicability of G waste as a promising candidate for developing desirable AC materials with high surface area and mesoporosity for cationic dye adsorption.