Experimental and Theoretical Study of Antibiotics Removal via an Electrolytic Carbon: Statistical Physics Modeling and DFT Calculations

The widespread use of antibiotics has globally become a significant concern due to their health and environmental impacts. Since the usual wastewater treatment methods are often ineffective for removing the majority of antibiotic residuals, other treatments are gaining considerable attention. This innovative study applies two theoretical approaches based on statistical physics modeling and density functional theory (DFT) to microscopically interpret the removal of amoxicillin (AXC) and sulfachloropyridazine (SCP) from aqueous solutions using an electrolytic carbon (EC) sample for water detoxification. Experimental data points are analyzed within the framework of two distinct theoretical models: real and ideal gas monolayer models. Based on modeling findings, model parameters have been successfully estimated and applied to investigate the details of the docking process of these antibiotics on EC at four temperatures (25, 35, 45, and 55 °C). Stereographic analysis revealed that the adsorbent pores preferentially capture the attached species with n > 1 at specific temperatures, suggesting a multimolecular mechanism with significant aggregation. The saturation adsorbed quantities of the EC adsorbent, determined by the monolayer models, are found to be 49.58-65.87 mg/g for amoxicillin and 33.28-71.52 mg/g for sulfachloropyridazine. These findings suggest that the adsorption performance of EC for the tested antibiotics is highly temperature-dependent, where the adsorbed quantities increase with the increase of this operating variable. Energetic analysis confirms the physisorption mechanism and the exothermic nature of the AXC/SCP on the EC surface, considering that the removal of these contaminants involves physical interactions. Both statistical physics and DFT theories show that at high temperatures the interactions of EC with SCP are higher than those with AXC. Overall, applying both theoretical approaches provides a consistent interpretation of the mechanism of adsorption at high temperatures.