Eco-friendly removal of methylene blue from aqueous solutions using bark of mimosa caesalpiniifolia from Northeast Brazil

Abstract The research aims to use sabiá bark as a biosorbent for removing methylene blue dye from aqueous solutions. The sabiá bark was acquired from Fazenda Ipê, in the municipality of Governador Dix-Sept Rosado, in the state of Rio Grande do Norte, Brazil. It was crushed, macerated, and sieved for particle size standardization. The bark powder underwent extraction removal both hot and cold. The biosorbent was characterized using Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and Zero Charge Potential. Adsorption tests involving pH effects, kinetic studies, and isothermal studies were conducted. The results showed higher efficiency in alkaline medium. Equilibrium was reached in 60 min, and the Pseudo-2nd order kinetic model provided the best fit to the experimental data. Among the isothermal models, the Langmuir isotherm had the best fit at all three investigated temperatures, with 28 ºC providing the best fit with a maximum adsorption capacity of 99.080 mg g −1 . Thus, the biosorbent from sabiá bark demonstrated promising results in removing methylene blue dye. Graphical Abstract