Abstract

The increasing discharge of pharmaceutical contaminants, particularly antibiotics like metronidazole (MNZ), into water systems poses significant ecological and public health risks due to their high solubility and low biodegradability. This study developed and characterized a highly porous activated carbon derived from maize cob (MC-AC). The synthesized material was characterized using FTIR, FESEM, PXRD, HRTEM, and BET analysis. Batch adsorption experiments were conducted, and the removal efficiency of MC-AC for MNZ was 98.6%. Optimization and modeling of the process variables of pH (3–11), contact time (0–75 min), concentration (0–70 mg/L), temperature (25–35 °C), and adsorbent dosage (0.5–1.5 g/L) were investigated using the Box–Behnken design (BBD) of response surface methodology, and 29 runs were obtained. The BBD model determined an optimal removal efficiency of 94.6 for metronidazole. Furthermore, non-linearized kinetic and isotherm models were used to determine the adsorption mechanism and mode of metronidazole from water. From the investigation, it was observed that both the Freundlich and pseudo-second-order models exhibited high correlation coefficients. The models with the best performance and low error metrics were determined by R2, MSE, RMSE, SAE, and SSE. Therefore, the adsorption mode was multilayer heterogeneous, and the mechanism was chemisorption. Therefore, this study provides a unique alternative for using the Box–Behnken design, kinetic, and isotherm models to understand the removal of metronidazole from water using maize cob-activated carbon.

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