High-Efficient Generation of H₂O₂ by Aluminum-Graphite Composite through Selective Oxygen Reduction for Degradation of Organic Contaminants

Abstract

Hydrogen peroxide (H2O2) is an effective green oxidant, which has been widely applied for environmental remediation. Here, we prepared a novel aluminum-graphite (Al-Gr) composite, which was capable of high-efficient production of H2O2 through selective O2 reduction via a two-electron pathway. We discovered the production of H2O2 at a wide pH range, which could be enhanced by optimizing Al-Gr synthesis conditions. Poly­(ethylene glycol) (PEG) addition could promote the formation of a welding interface and porous structure between Al and Gr in the Al-Gr composite, which enhanced the galvanic corrosion of Al0, the selectivity of oxygen reduction via the two-electron pathway, and the mass transfer of O2 in the Al-Gr/O2 system. The formation of Al4C3 could be regulated by sintering temperature and sintering time, which could promote the intergranular corrosion of Al0 and enhance the mass transfer of O2 by reaction with water to generate the porous structure in the Al-Gr composite. The concentration of H2O2 reached 777.5 mg/L at an initial pH of 9.0, an Al-Gr dosage of 8 g/L, and an O2 gas flow rate of 400 mL/min. The possible mechanisms of Al-Gr synthesis and H2O2 production in the Al-Gr/O2 system were proposed. The Al-Gr composite was effective for the in situ production of H2O2, which could be further decomposed into a hydroxyl radical (•OH) by Al0 in the Al-Gr composite. This composite could be used not only to decolorize the Rhodamine B dye but also to degrade various organic contaminants in different water matrices, indicating its environmental significance.

Selective Removal of Phenolic Compounds by Peroxydisulfate Activation: Inherent Role of Hydrophobicity and Interface ROS

“…Advanced oxidation processes (AOPs) including photochemical oxidization, , ozonation, and Fenton oxidation , have been widely reported for environmental remediation. Among these technologies, persulfate-based AOP (PS-AOP) involving peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation has attracted increasing attention due to its high removal efficiency, simple operation, and versatility. − However, PS-AOP-based technology still faces challenges such as low selectivity in removing target pollutants and difficulty in catalyst recovery, − which limit the practical applications of PS-AOP. Therefore, highly selective and efficient PS-AOP systems are urgently needed to remove target pollutants in the presence of coexisting substances or interference chemicals, which will undoubtedly broaden the application prospects of PS-AOP.…”

Facilitating Redox Cycles of Copper Species by Pollutants in Peroxymonosulfate Activation

“…Water pollution caused by the discharge of nonbiodegradable organic contaminants has become a serious global environmental problem. − Peroxymonosulfate (PMS) activation is one of the most effective advanced oxidation processes owing to the generated reactive oxygen species (ROS) with high oxidation capacity, such as hydroxyl radicals (•OH), sulfate radicals (SO 4 •– ), and singlet oxygen ( 1 O 2 ). , Generally, electron transfer from the metal active centers of catalysts to PMS is prerequisite for generating •OH and SO 4 •– upon the cleavage of the O–O bond in PMS molecules . On the other hand, PMS oxidation on the metal sites leads to the formation of SO 5 •– .…”

An assessment of the UV/nFe0/H2O2 system for the removal of refractory organics in the effluent produced by the biological treatment of landfill leachate

“…Increasing the H 2 O 2 dosage over a particular range could significantly improve the removal efficiency of organic matter. This was because, under the activation of nFe 0 , H 2 O 2 could produce more • OH with a high redox potential to rapidly destroy the chemical structure of organics and even mineralize refractory macromolecular organic matter (Equations 3-6) (Liu et al, 2020). However, excessive amounts of H 2 O 2 had a quenching effect on the • OH generated in the system (Equations 7-8) (Li & Goel, 2010).…”