Enhancement of adsorption capacity of Methylene blue, Malachite green, and Rhodamine B onto KOH activated carbon derived from oil palm empty fruit bunches

Enhancement adsorption capacity of Methylene blue (MeB), Malachite green (MaG), and Rhodamine B (RhoB) onto activated carbon derived from oil palm empty fruit bunches (Biochar). The activated carbon was produced by pyrolysis with impregnation in KOH solution. To enhance its efficiency, the activation process was performed twice, yielding the adsorbents 1KAC and 2KAC. The adsorption capacity and equilibrium of the three dyes onto the biochar and activated carbon samples were determined by examining the removal efficiency, capacity, kinetics and isotherm models. The pseudo-second-order model performed better than the pseudo-first-order model in terms of adsorption kinetics. The Langmuir model fits well for all three dye molecules with high correlation coefficient values, suggesting that the activated carbon surface is homogeneous and characterized by a finite number of identical sites. The maximum adsorption capacity was 1123.57, 1315.36, and 982.87 mg/g for MeB, MaG, and RhoB, respectively. This founding indicated a high potential adsorbent more than among KOH activated carbon reported in the literature. The study provides valuable insights into the use of activated carbon derived from oil palm empty fruit bunches for the removal of dyes from wastewater.