Efficient electrochemical oxidation of COVID-19 treatment drugs favipiravir by a novel flow-through Ti/TiO2-NTA/Ti4O7 anode.

• A flow-through Ti/TiO 2 -NTA/Ti 4 O 7 was modified by TiO 2 nanotube array. • The flow-through mode is significantly superior to the traditional flow-by mode. • Favipiravir removal ratio was as high as 93.4% at Ti/TiO 2 -NTA/Ti 4 O 7 anode. • A high removal ratio of 87.7% for favipiravir can be achieved in actual wastewater. In this study, TiO 2 nanotube arrays (TiO 2 -NTA) were used as an intermediate layer to provide effective electrocatalytic activity and stability for Ti/TiO 2 -NTA/Ti 4 O 7 anode. Compared with Ti/Ti 4 O 7 anode, Ti/TiO 2 -NTA/Ti 4 O 7 anode exhibited higher oxygen evolution potential (2.40 V), larger active specific surface areas (1.81 m2 g−1), stronger radical generation capacity (64.42 μM), longer accelerated service life (56.0 h), and superior favipiravir removal ratio. The flow-through electrochemical reaction system was constructed by using the porous Ti/TiO 2 -NTA/Ti 4 O 7 anode. The removal ratio, TOC removal ratio and mineralization current efficiency of favipiravir in the flow-by electrochemical system were significantly improved and the energy consumption was reduced compared with the conventional flow-by electrochemical system, verifying the superiority of the porous flow-through Ti/TiO 2 -NTA/Ti 4 O 7 anode. The effects of operating parameters on the removal of favipiravir in the flow-through electrochemical reaction system were investigated. The degradation mechanisms of favipiravir are the synergetic effects of the free radical (·OH and SO 4 −·) and the direct electron transfer. Ti/TiO 2 -NTA/Ti 4 O 7 anode displayed excellent stability in five consecutive cycles, exhibited significant removal ratio (87.7%) of favipiravir from actual wastewater, and remained efficient and versatile for a wide range of typical PPCPs pollutants. Therefore, Ti/TiO 2 -NTA/Ti 4 O 7 is a promising porous anode material in the engineering application. [Display omitted] [ABSTRACT FROM AUTHOR]