Valorization of hydrolyzed banana peel into activated carbons for methylene blue and malachite green removal—equilibrium and kinetic studies

This study investigated the potential of hydrolyzed banana peel, a by-product of subcritical water pectin extraction, as a precursor of activated carbons for the removal of malachite green (MG) and methylene blue (MB) dyes from aqueous solutions. The phosphoric acid activation was performed to produce activated carbons by varying the impregnation ratios where its effect on the physical properties and adsorption capacity were studied. The experimental data were fitted to isotherm and kinetic models to determine the adsorption mechanisms. The results showed that the activated carbon with a surface area of 879 m²/g exhibits high capacities of 145 mg/g and 228 mg/g for MB and MG, respectively and the adsorption process followed the Redlich-Peterson model. The kinetic adsorption on the other hand was found to be varied depending on the initial concentration of the dye. This study provides valuable insights into the use of low-cost and sustainable materials to produce effective adsorbents for the removal of dyes from wastewater.