Plane trees’ bark–derived porous biochar for efficient methylene blue biosorption

The increasing demand for textile products has led to a significant rise in wastewater discharge, posing environmental and health risks due to the presence of dyes like methylene blue. This article presents a novel approach to wastewater treatment using biochar derived from plane tree bark, a renewable and cost-effective biomass source. The biochar is activated using potassium carbonate, resulting in a porous structure with a high specific surface area, making it an excellent adsorbent for methylene blue. The study investigates the effects of various parameters, such as annealing temperature, mass ratio of activators, adsorption time, and initial concentration, on the adsorption performance. The adsorption process is found to follow pseudo-second-order kinetics and is best described by the Freundlich isotherm model, indicating multilayer adsorption on a heterogeneous surface. The plane tree bark biochar demonstrates a high adsorption capacity of 1123 mg/g, outperforming many other biochar adsorbents. The article also explores the potential reuse of the biochar and discusses the underlying adsorption mechanisms, including hydrogen bonding, π-π* stacking, electrostatic interaction, and pore filling. Furthermore, the characterization of the biochar using techniques like SEM, XRD, XPS, and FTIR provides insights into its structural and chemical properties, contributing to its excellent adsorption performance. The findings of this study offer a promising solution for the efficient removal of methylene blue from wastewater, with potential applications in other dye removal processes.