Oil Palm Shell-Derived Activated Carbon: Adsorption Kinetics, Thermodynamics, and Interaction Mechanism for Lufenuron...

Activated carbon (AC) was synthesized from oil palm shell (OPS) through physical (AC-800-2 and AC-900-2) and chemical (AC-750-1.5-3:1 and AC-800-1-2:1) activation processes in a carbon dioxide atmosphere. KOH was used as an activating agent in the impregnation process in the case of chemical activation. The synthesized ACs were characterized by proximate and ultimate analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and textural properties of the samples. The tested properties, including surface area (S _BET), pore volume (V_T), and average pore size (S_P), were determined by the Brunauer-Emmet-Teller (BET) method and the Barrett-Joyner-Halenda (BJH) model. Lufenuron adsorption results demonstrated that AC-900-2 achieved the highest lufenuron removal yield of 96.9%. The samples were best represented overall by the pseudo-second-order kinetic model, with R ² values between 0.91 and 0.99. This suggests that the lufenuron adsorption process onto the activated carbons produced in this study was related to the chemisorption process. In addition, this adsorption process was spontaneous, exothermic, and exhibited a high probability of reversibility for samples AC-900-2, AC-750-1.5-3:1, and AC-800-1-2:1, with van der Waals forces and hydrogen bonds playing a significant role in the interaction between lufenuron and AC. In contrast, for sample AC-800-2, the adsorption process required an increase in temperature to become spontaneous, and the process was endothermic and irreversible. In general, the high percentages of adsorption observed in the AC produced by physical and chemical activation could be explained by the strong interactions of the surface functional groups with lufenuron. In the case of physically activated carbon, the high surface area provides more sites available for these interactions. In the case of chemically activated carbon , although the surface area is lower, the functional groups introduced using KOH improve the adsorption capacity.