Adsorption mechanism of a pesticide/herbicide mixture on a new eco-friendly activated carbon of Ritama-Monosperma (L.) Boiss used DFT/B3LYP

The removal of the agricultural hazardous waste, 2,4-dichlorophenoxyacetic and 2,4,5-trichlorophenoxyacetic acids, from an aqueous solution in a batch method using a natural resource, was studied. The new bio-adsorbent prepared from Ritama-Monosperma (L.) Boiss powder, carbonized at 500 °C and activated with H3PO4, is characterized by different structural and textural characterization methods such as XRD, FTIR, SEM/EDX, Boehm titration, iodine value, and pHzpc. The influence of starting pH, temperature, and pesticide dose on the equilibrium, kinetics, and thermodynamics of adsorption was studied. Adsorption kinetics were tested using two simplified models, the pseudo-first-order kinetic model, and the pseudo-second-order kinetic model. The pseudo-second-order kinetic model best fits the adsorption of 2,4-D and 2,4,5-T on RMAC-P. On the other hand, in the concentration range examined, the equilibrium results reflect the Freundlich equilibrium model, with a maximum adsorption capacity of 69.44 mg/g for 2,4-D and 13.81 mg/g for 2,4,5-T.