Journal
JOURNAL OF HAZARDOUS MATERIALS
Volume 416, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.jhazmat.2021.125768
Keywords
Flow-through electrode; Graphite felt; Electroreduction; Hexavalent chromium
Categories
Funding
- National Key Research and Development Program of China (Developing Highly Efficient Means of Water Utilization) [2019YFC0408202]
- National Natural Science Foundation of China (NSFC) [21876050]
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Flow-through electrodes with commercial graphite felt as cathode showed high reduction efficiency for Cr(VI) in acidic conditions. The porous structure allowed sufficient contact surface, while slow flow rate and high current promoted electroreduction. Competing metal ions at fast flow rates decreased Cr(VI) reduction efficiency.
Flow-through electrodes generally outcompete traditional parallel-plate electrodes in current efficiency and mass transfer. High-performance electrode materials can be costly and complicated to fabricate, hindering their wide application. In this study, we used commercial graphite felt (GF) as the cathode of a flow-through electrochemical cell to investigate its potential in treating Cr(VI) solution through electroreduction. The flow-through design with the porous GF electrode allowed sufficient contact surface with Cr(VI) and single-pass tests demonstrated a high reduction efficiency (95-100%) [117 mg/L-3 mg/L Cr(VI)] under acidic conditions. Slow flow rate and high current promoted electroreduction of Cr(VI). The presence of other metal ions could further improve Cr(VI) reduction at low flow rates due to enhanced conductivity in dilute solutions and generation of low valent ions as reducing agents. At fast flow rates, competition of these ions for reduction decreased Cr(VI) reduction efficiency. Moreover, an acidic environment prevented the coating of an insoluble layer on the GF surface and promoted durable performance, with a lower energy consumption [0.46 kWh for treating 100 L 117 mg/L Cr(VI) solution per unit area of GF]. This work demonstrated the potential of Cr(VI) detoxification using GF cathodes in flow-through electrochemical cell.
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