The usage of different forms of ferrate (VI) ion for amoxicillin and ciprofloxacin removal: density functional theory based modelling of redox decomposition

Abstract

BACKGROUND: Decomposition of amoxicillin (AMX) and ciprofloxacin (CIP) in aqueous suspensions by two forms of ferrate (VI) were investigated. The effect of the initial concentration of antibiotics, pH, and ferrate (VI) dosage were examined. Model calculations were made by the Density Functional Theory (DFT) method (RB3LYP) taking into account the environmental parameters. LanL2DZ and 6-311G(++)(d, p) were taken as basic functions for the calculations. This was followed by analysis of two redox decomposition mechanisms of the ferrate ion, with the O-2 molecule formation and electron density distribution, and the reaction mechanism of superoxide particle formation, which participates in the AMX and CIP oxidation process. RESULTS: Ferrate (VI) degraded CIP more effciently than AMX in both forms. Electrogenerated ferrate (VI) was more efficient than direct use of its solid form. The removal efficiencies of CIP and AMX by electrogenerated ferrate (VI) were 80.9% and 63.7%, respectively. CONCLUSION: This study demonstrates that ferrate (VI), with its high oxidizing capacity and coagulation effect, could be applied to the removal of antibiotics in wastewater treatment. The results of the AMX and CIP electron structure calculations demonstrate that electron transfer to the molecules leads to the formation of meta-stable states and causes the molecules to fragment. (C) 2014 Society of Chemical Industry