Removal of amoxicillin and tetracycline antibiotics using high surface area activated carbon derived from petroleum residues

Abstract Asphaltenes are petroleum wastes that are soluble in aromatic solvents and insoluble in aliphatic solvents. Since they form scales and deposits, they are responsible for major expenditures in the form of maintenance, handling, and disposal. In addition, asphaltenes are rich in carbon and form solid waste; hence, a strategy to use these asphaltenes was explored. In this work, the asphaltene-derived activated carbon (AC) was prepared via chemical activation and used to remove antibiotics-tetracycline (TC) and amoxicillin (AMX)-from simulated wastewater. Material characterization included BET surface area analysis, FE-SEM, EDX, XRD, and FT-IR, while residual antibiotic concentrations were analyzed using UV-Visible spectroscopy. The residual antibiotics were estimated using UV-visible spectroscopy. The AC exhibited a high surface area of 1800 m 2 g −1 and a pore volume of 1.8 ×10 −6 m 3 g −1 . Batch adsorption studies were performed and analyzed using Langmuir, Freundlich, Temkin, and Redlich-Peterson adsorption isotherms. In addition, adsorption kinetics data were obtained from kinetics studies and were fit to Pseudo first-order (PFO) and Pseudo second-order (PSO) adsorption kinetics models, with the PSO model providing the best fit to the experimental data. Additionally, the maximum monolayer adsorption capacity ( q m ) was determined using the Langmuir isotherm. The prepared AC showed a higher affinity for TC ( q m = 746 mg g −1 ) compared to AMX ( q m = 412 mg g −1 ). Furthermore, thermodynamic studies indicated that the adsorption process was spontaneous in both cases, with a chemisorption-driven mechanism for AC-TC and physisorption governing the AC-AMX adsorption. However, the column studies showed a high removal percentage for both antibiotics (84% for AMX and 76% for TC). This study promotes the use of petroleum solid waste, contributing to the circular economy, as well as the removal of emerging pollutants, thereby supporting environmental remediation.