Hollow sea-urchin-shaped carbon-anchored single-atom iron as dual-functional electro-Fenton catalysts for degrading refractory thiamphenicol with fast reaction kinetics in a wide pH range

Narrow pH application range and tepid reaction kinetics greatly hinder the efficacy of heterogeneous Fenton and electro-Fenton technologies. Herein, a hollow sea-urchin-shaped carbon-anchored single-atom iron (SAFe@HSC) derived from metal organic framework has been developed as a dual-functional electro-Fenton catalyst for O-2 reduction to H2O2 followed by in situ activation to center dot OH. Benefited by the unique structure and atomically dispersed iron, the electro-Fenton system exhibits fast reaction kinetics in a wide pH range from 3 to 11. For instance, 120.7 mmol g(catalyst)(-1) (7.5 mol g(Fe)(-1)) H2O2 and 50.7 mmol g(catalyst)(-1) (3.1 mol g(Fe)(-1)) center dot OH can be detected simultaneously at 60 min (20 mA cm(-2) and pH 7). As a result, the mass kinetic constants of refractory thiamphenicol (TAP) degradation are as high as 4506 min(-1) g(Fe)(-1) (pH 3), 4099 min(-1) g(Fe)(-1) (pH 5), 4037 min(-1) g(Fe)(-1) (pH 7), 2974 min(-1) g(Fe)(-1) (pH 9), and 2595 min(-1) g(Fe)(-1) (pH 11). The TAP removal efficiency in static flow process achieves nearly 100% within 40 min, showing a high total organic carbon (TOC) removal of 85% in 2 h (pH 7, 20 mA cm(-2), C-0 = 20 mg L-1, 1.5 mg of catalyst). It is the highest electro-Fenton activity among the reported catalysts for pollutant degradation at pH above 5. Furthermore, the TAP removal keeps 97% and the TOC removal reaches as high as 82.2% in the continuous-flow process (C-0 = 20 mg L-1, pH 7, 20 mA cm(-2), flow rate = 2 mL min(-1)). Moreover, only 1.5% Fe is leaked within 6 h. This study develops a highly efficient electro-Fenton catalyst for the treatment of organic wastewater.

Automated summary

A novel and highly efficient electro-Fenton catalyst SAFe@HSC was developed, exhibiting fast reaction kinetics in a wide pH range and effectively degrading refractory pollutants in organic wastewater.