Boosting the oxidative capacity of the Fe(0)/O2 system via an air-breathing cathode

作者：Lei, Zhenchao; Huang, Ziyuan; Lin, Yimin; Liu, Yuwei; Yan, Zhang; Zheng, Wenxiao; Ma, Huanxin; Dang, Zhi; Feng, Chunhua^*

来源：Journal of Hazardous Materials, 2022, 438: 129552.

DOI：10.1016/j.jhazmat.2022.129552

• Acid waste water treatment
• Iron-air fuel cell
• Oxidative degradation
• Oxygen activation
• Zero-valent iron

The corrosion of Fe(0) in the presence of O-2 in nature can lead to the oxidation of organic compounds, but the efficiency is very limited. Herein, attempts were made to establish a galvanic system that separates the anodic Fe(0) oxidation reaction and the cathodic O-2 reduction reaction using an air-breathing cathode. Compared with the chemical Fe(0)/O-2 system, it exhibited a substantially higher capability of destroying a variety of pollutants, such as organic dyes (12 types), phenol, nitrobenzene, acetaminophen, phenol, and ethylenediaminetetraacetic acid. The degradation rate constant of a model dye (i.e., Rhodamine B) increased from 0.047 min(-)(1) (chemical) to 1.412 min(-1) (galvanic) under the passive air-breathing condition. The electric circuit design promoted Fe(0) dissolution to Fe(II) and triggered electron transfer that drives O-2 reduction to H2O2, two important species responsible for the generation of HO center dot at high abundance. In addition, the galvanic Fe(0)/O-2 system produces electricity while destroying pollutants. Tests with real Ni plating wastewater further demonstrated the capability of the system to oxidize complexed organics and phosphite. This study provides a new strategy for boosting the oxidative capacity of the Fe(0)/O-2 system, which shows promise for acid wastewater treatment.