Amoxicillin degradation using green synthesized iron oxide nanoparticles: Kinetics and mechanism analysis

Abstract Beta-lactam antibiotic amoxicillin (AMX) removal in aqueous solution using green synthesized iron oxide nanoparticles (gINPs) from Carob pod ( Ceratonia siliqua ) was studied. The characterization analyses of the gINPs were performed by TEM, SEM, EDX, XRD, BET, FESEM and Raman spectroscopy. The nanoparticles were found as oxide forms with the spherical shape at an average of 7 ± 5 nm dimensions with 7.67 m 2 /g surface area. The experimental analysis revealed that the amoxicillin removal efficiency depends on the initial pH, AMX concentration, temperature, and gINPs dose. High removal efficiency (99%) was obtained at a molar ratio of 1:50 AMX/gINPs in 200 min at pH 2. The removal of amoxicillin was investigated by the kinetic studies for the adsorption and degradation mechanisms. The kinetic analysis showed that the adsorption is a physical process with an activation energy of 30 kJ.mol −1 . The removal process was determined as the pseudo-first-order following a chemically surface-controlled reaction due to the high activation energy of 87 kJ.mol −1 . The occurrence of AMX degradation products was detected by UV–vis and HPLC/MS analyses. The potential degradation pathway of AMX using gINPs was determined as physical adsorption onto the iron corrosion products, and then reduction on the surface of gINPs.