Electrochemical oxidation of ofloxacin using a TiO2-based SnO2-Sb/polytetrafluoroethylene resin-PbO2 electrode: Reaction kinetics and mass transfer impact

Abstract

Electrochemical oxidation has been proposed for the destruction of organic contaminants; however, this process is hampered by low oxidation efficiency and high energy cost. Accordingly, we developed a TiO2-based SnO2-Sb/polytetrafluroethylene resin (FR)-PbO2 electrode that was based on TiO2 nanotubes. We tested the performance of the electrode on an antibiotic, ofloxacin, and identified the major pathway of ofloxacin oxidation. We found growing TiO2 nanotubes on Ti material increased current efficiency, and the electrical efficiency per order (EE/O, kWh/m 3) for oxidation was decreased by 16.2%. Our electrode requires a large overpotential before electrons flow, which minimizes oxygen evolution, reduces hydrogen peroxide and ozone generation, and favors hydroxyl radicals (HO•) production. We found the electron efficiency (EE) during oxidation was as high as 88.45%. In other words, 88.45% of the electrons that flow out of the electrode cause oxidation. The effects of current density, initial concentration, pH value and electrolyte concentration were investigated. A differential column batch reactor (DCBR) was used to simulate the performance of continuous plug flow reactor and we found that the destruction of ofloxacin followed pseudo-first order model. We also evaluated the impact of mass transfer on electrochemical performance. The effects of fluid velocity and electrode spacing on oxidation rate were evaluated by determining the mass transfer coefficient and the effectiveness factor Ω (between 0-1). Our experiments and calculations indicated that the mass transfer reduced oxidation rate by more than 55% (Ω<0.45) for an electrode spacing of 1 cm at a fluid velocity of 0.033 m/s. Unlike studies carried out using completely mixed batch reactor, the DCBR can simulate the flow conditions in pilot or full scale reactors; consequently, observed pseudo-first order rate constants in the DCBR can be used for preliminary design.

Degradation of Atenolol with Electrochemical Oxidation at Mixed Metal Oxide Electrodes Assisted by UV Photolysis

“…Moreover, the EE/ O total decreased from 14.8 to 7.6 kW m −3 and then increased to 8.2 kW m −3 when the applied current densities increased from 5 to 10 and 15 mA cm −2 (Table ). The EE/ O total values obtained were in the same magnitude with the results reported by other researches . In this study, the optimal current density for the lowest EE/ O total was 10 mA cm −2 during the photo‐electrolysis process.…”

Photocatalytic Degradation of Atenolol by TiO2 Irradiated with an Ultraviolet Light Emitting Diode: Performance, Kinetics, and Mechanism Insights

“…(5) The highest ATL degradation efficiency was achieved at an optimal TiO 2 catalyst dosage of 2.0 g/L in the photocatalytic system, inducing complete degradation of ATL in 60 min. (6) The pH significantly affects the protonation and charge of semiconductor TiO 2 , leading to a fluctuation of hydroxyl radical concentrations in the reaction system. The ATL degradation efficiency increased with increasing pH, with complete degradation within 30 min at pH 11.0.…”

“…PPCPs and their metabolites are now regularly reported in the aquatic environment worldwide and as most PPCP substances are quite stable with complex structures, they cannot be easily absorbed and digested by biological organisms, resulting in environmental persistence and an increased potential hazard to both human and environmental health [2,3]. The enrichment of these chemical contaminants in aquatic environments may also contribute to antibiotic resistance and the spread of resistance genes, which potentially poses a serious threat to the whole ecosystem [4][5][6]. Therefore, it is imperative to remove PPCPs from the aquatic environment, to reduce the risk they pose to all biota.…”

“…Therefore, it is important to develop an environmentally friendly and effective technology for ATL degradation or removal from aquatic systems. which potentially poses a serious threat to the whole ecosystem [4][5][6]. Therefore, it is imperative to remove PPCPs from the aquatic environment, to reduce the risk they pose to all biota.…”

A short review of bioaerosol emissions from gas bioreactors: Health threats, influencing factors and control technologies

“…To evaluate the inactivation performance of different technologies on bioaerosol, the EE/O calculation was used in this study to characterize the energy efficiency of the technologies according to the following equation (Xie et al, 2017;Chen et al, 2019).…”