Adsorption Kinetics and Performance of Methylene Blue onto Alkali-Treated Sugarcane Bagasse Biochar

Abstract

Sugarcane bagasse (SCB), an abundant agricultural byproduct, was utilized to synthesize an effective biochar adsorbent via NaOH pretreatment and muffle furnace pyrolysis at 500 °C for the removal of methylene blue (MB) dye from aqueous solutions. Surface characterization using Fourier-Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and Elemental Analysis (EA) confirmed significant structural transformations, including increased carbonization and the development of a well-defined porous network. Batch adsorption experiments demonstrated rapid adsorption kinetics, achieving an equilibrium dye removal efficiency of approximately 95% within 30 min with an equilibrium capacity (qe) of 14.5584 mg/g. Kinetic modelling revealed that the adsorption process strongly followed the pseudo-second-order model (R2=0.9997, k2=0.0676 g/mg.min) significantly outperforming the Langmuir (R2=0.1806) and Lagergren pseudo-first order (R2= 0.3713). These results confirm that chemisorption involving electron sharing or exchange between MB molecules and biochar surface active sites is the dominant rate-controlling mechanism10. This study demonstrates the potential of value-added sugarcane bagasse biochar as a sustainable and cost-effective material for industrial dye wastewater remediation.