Electro-induced carbon black particle electrodes for sustainable tetracycline degradation

Abstract

For the purpose of degrading tetracycline (TC), a three-dimensional electro-oxidation (3D EO) system using particle electrodes of carbon black (CB) and polytetrafluoroethylene (PTFE) was developed. The CB-PTFE particles fabricated at a CB/PTFE mass ratio of 3:2 and calcination time of 60 min exhibited the high performance for TC removal, as well as low energy consumption and high mechanical strength. TC removal efficiency reached 95% within 15 minutes, driven by a pseudo-first-order reaction with a rate constant of 0.20 min−1. The process incurred an energy consumption of 20.31 kWh/m3. The surface characterizations indicated that the CB-PTFE particles possessed excellent catalytic properties for H2O2 production. Despite the substantial influence of voltage and particle dosage on performance, the system demonstrated consistently high efficiency in TC removal regardless of solution pH within the range of 3–11. Quenching experiments and probe experiments using benzoate suggested that the surface-bound hydroxyl radicals (•OH (ads)) dominated (64.7%) the oxidation of TC in the 3D CB-PTFE EO system. The •OH (ads) was produced by the reduction of H2O2 on the particle surface. Products examination by LC-MS-MS confirmed a degradation pathway of TC by •OH attacking. These findings indicate that the CB-PTFE EO system has unique advantages and potentials in treating antibiotics due to its high oxidizing capacity, a wide range of applicable pH, no chemical adding, and self-cleaning.