Surface Modification of Graphite Support as an Effective Strategy to Enhance the Electro-Fenton Activity of Fe₃O₄/Graphite Composites in Situ Fabricated from Acid Mine Drainage Using an Air-Cathode Fuel Cell

Abstract

Air-cathode fuel cell (AC-FC) technology provides a facile way for fabricating Fe3O4/graphite composite by in situ utilizing the FeII in acid mine drainage (AMD). Herein, surface modification of the graphite support is suggested to be an effective strategy to enhance electro-Fenton (EF) catalytic activity of the Fe3O4/graphite composite prepared from AMD. Four surface modification methods, including H2O2 treatment, electro-oxidation treatment, KOH treatment, and N2H4 treatment, are applied on commercial graphite felt (GF). Structures and properties of the modified GFs are characterized, and EF catalytic activities of corresponding Fe3O4/GF composites prepared from synthetic AMD are evaluated. The results demonstrate that surface modification of GF not only improves the electro-oxidation of FeII in AC-FC but also promotes the electro-generation of H2O2 in the heterogeneous EF process. Notably, the concentration of H2O2 generated on N2H4-treated GF (GF-N2H4) is more than three times that generated on unmodified GF (GF-Raw), and iron content in the prepared Fe3O4/GF-N2H4 composite is more than twice that in the Fe3O4/GF-Raw composite. Application of GF-N2H4 to the treatment of real AMD greatly enhances the recovery efficiency of FeII as Fe3O4. The Fe3O4/GF-N2H4 composite prepared from real AMD displays high catalytic activity and good stability in the heterogeneous EF process for mineralizing a variety of refractory organic contaminants.

Hierarchical Iron Phosphides Composite Confined in Ultrathin Carbon Layer as Effective Heterogeneous Electro‐Fenton Catalyst with Prominent Stability and Catalytic Activity

“…[8] Within this context, the heterogeneous EF catalysts require considerable activity for both H 2 O 2 generation and decomposition, [9][10][11] which consequently increase the difficulty in catalyst design and fabrication due to the higher structural complexity of the catalyst. Currently, carbon matrix (C) supported transition metal (TM) materials (TM/C) still majored in the preparation of heterogeneous EF catalyst , [12][13][14] where TM and carbon matrix could serves as the heterogeneous Fenton and 2e − oxygen reduction reaction (ORR) actives sites, [15] respectively. Besides, the carbon matrix could also support the TM particles and promote its electron transfer.…”

Selective Cleavage of C–O Bond in Diaryl Ether Contaminants via Anodic Oxidation

“…Both TCS and RhB are removed more effectively on the functionalized MWCNTs; thus, the catalytic role of surface oxygenated groups in the anodic oxidation process was confirmed. Surface oxygenated groups can improve the hydrophilicity of the carbon electrode, favoring mass transfer of the water and reactants to the electrode surface to perform electrochemical oxidation reaction . In addition, once combined with the diaryl ether reactant, the electrophilic surface oxygenated groups would facilitate the acquisition of hydroxyl groups from water.…”

“…Surface oxygenated groups can improve the hydrophilicity of the carbon electrode, favoring mass transfer of the water and reactants to the electrode surface to perform electrochemical oxidation reaction. 45 In addition, once combined with the diaryl ether reactant, the electrophilic surface oxygenated groups 46 would facilitate the acquisition of hydroxyl groups from water. Notably, the highest TCS and RhB removal rates are observed on carboxylated MWCNTs, suggesting very high catalytic activity of the CO group.…”

Trace FeCu@PC Derived from MOFs for Ultraefficient Heterogeneous Electro-Fenton Process: Enhanced Electron Transfer and Bimetallic Synergy

“…Electro-Fenton (EF) is a prominent member among electrochemical advanced oxidation processes (EAOPs) that are highly efficient process for the removal of different class of organic contaminants. − The nonrecyclability of used catalyst is one of challenges in homogeneous EF (Homo-EF) process. , To meet this challenge, homogeneous catalysts can be replaced by heterogeneous catalysts. , In the traditional heterogeneous electro-Fenton (Hetero-EF) process, how to improve the activation efficiency of H 2 O 2 and promote the cycle of Fe 3+ /Fe 2+ is the core issue. Currently, many methods have been proposed to solve these problems, such as introducing additional electrons, adjusting the morphologies and exposed crystal planes, and coupling with light irradiation …”