A critical review on the mechanisms of persulfate activation by iron-based materials: Clarifying some ambiguity and controversies

Hou, Kunjie; Pi, Zhoujie; Yao, Fubing; Wu, Bo; He, Li; Li, Xiaoming; Wang, Dongbo; Dong, Haoran; Yang, Qi

doi:10.1016/j.cej.2020.127078

Cited by 126 publications

(21 citation statements)

References 126 publications

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“…nFe 3 O 4 showed a higher catalytic activity on PS activation for BTEX degradation than commercial Fe 3 O 4 (Figure 3a). The main reason was that this heterogeneous catalytic process had a crucial weakness, that is, the corrosion products (Hou et al, 2021). The reaction intermediates and the over‐oxidation products on the surface of Fe 3 O 4 inhibited the further activation to PS (Hung et al, 2016).…”

Section: Resultsmentioning

confidence: 99%

l‐cysteine‐modified Fe₃O₄ nanoparticles as a novel heterogeneous catalyst for persulfate activation on BTEX removal

Sun

Lyu

2021

Water Environment Research

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l‐cysteine‐modified Fe3O4 nanoparticles (l‐cys@nFe3O4) were synthesized successfully and used as catalyst to activate persulfate (PS) for benzene, toluene, ethylbenzene, and xylenes (BTEX) degradation. The composite was fully characterized, and the l‐cys@nFe3O4 had more protrusions and l‐cys was combined on the surface of nFe3O4. The removals of BTEX were 78.2%, 85.1%, 85.3%, 81.2%, respectively, in PS/l‐cys@nFe3O4 system, while only 52.7% 57.8%, 60.8%, and 56.3% of BTEX removals reached under the same condition for nFe3O4 chelated with l‐cys in 48 h. Four successive cycles of BTEX degradation were completed in PS/l‐cys@nFe3O4 system. The synergistic mechanisms of BTEX degradation in PS/l‐cys@nFe3O4 system were investigated by electron paramagnetic resonance (EPR), benzoic acid (BA) probe and X‐ray photoelectron spectroscopy (XPS) tests. SFe bond in l‐cys‐Fe complexes promoted the electron transfer between nFe3O4 core and the solution, iron and iron at the interface, thereby promoting the Fe3+/Fe2+ cycle and the catalytic capacity of nFe3O4. The optimal pH of PS/l‐cys@nFe3O4 system was 3, while HCO3− and Cl− exhibited negative influences on BTEX degradation. Only 14.2%, 15.5%, 15.9%, and 15.6% BTEX had been removed in the presence of 0.12‐M PS and 8.0 g/L l‐cys@nFe3O4 under the actual groundwater condition. However, expanding the dosage of PS and l‐cys@nFe3O4 was an effective strategy to overcome the adverse effect. Practitioner Points L‐cys@nFe3O4 were synthesized successfully and used as catalyst to activate PS for BTEX degradation. Four successive cycles of BTEX degradation were completed in PS/L‐cys@nFe3O4 system. lS―Fe bond in L‐cys@nFe3O4 promoted the electron transfer between PS and nFe3O4 core.

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Section: Resultsmentioning

confidence: 99%

l‐cysteine‐modified Fe₃O₄ nanoparticles as a novel heterogeneous catalyst for persulfate activation on BTEX removal

Sun

Lyu

2021

Water Environment Research

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“…Computational Methodology. DFT calculations were performed using the DMol 3 (version 2018). The generalized gradient approximation of the Perdew−Wang (PW91) functional was employed for exchange−correlation potential.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Persulfate-based advanced oxidation processes (PDS-AOPs) have been generally acknowledged as an effective method for pollutant degradation in water purification. , Among the numerous approaches for PDS activation to produce highly oxidative species (e.g., radicals, high-valent metal ions, and singlet oxygen), transition-metal-based activation was the most viable one owing to its low energy requirement, operational convenience, and high effectiveness. − Heterogeneous transition-metal oxides (M x O y ) have the advantages of low metal ion leaching and easy postreaction recovery as compared to the homogeneous metal ions (e.g., Fe 2+ and Cu 2+ ions), which showed potential applications for contaminant degradation in real water. − However, lower PDS-activation efficiency of M x O y compared to the homogeneous analogues remains challenging, and the limited understanding of the PDS activation mechanism at the molecular level poses a huge obstacle to the rational design of highly efficient M x O y catalysts.…”

Section: Introductionmentioning

confidence: 99%

In Situ-Formed Phenoxyl Radical on the CuO Surface Triggers Efficient Persulfate Activation for Phenol Degradation

Huang

Han

Xiang

et al. 2021

Environ. Sci. Technol.

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Transition-metal oxide (M x O y )-based persulfate (PDS) activation processes have demonstrated enormous potential for pollutant degradation in water purification. However, the mechanistic insight of PDS activation by a M x O y catalyst concerning the mediate role of the organic substrate remains obscure. Here, we demonstrated that the in situ-formed phenoxyl radical on the CuO surface can trigger efficient persulfate activation for phenol degradation. The formation of the phenoxyl radical was an innersphere process, which involved the successive steps of chemisorption through surface hydroxyl group substitution and the subsequent spontaneous electron transfer reaction from adsorbed phenol to CuO. The organic substrate phenol can be oxidized by the PDS molecule and surface-bound SO 4•− through the nonradical and free-radical pathways, respectively. Such a unique "half-radical" mechanism resulted in an extraordinarily high PDS utilization efficiency of 188.9%. More importantly, a general rule for phenoxyl radical formation was concluded; it can be formed in the cases of organic substrates with a Hammett constant σ + lower than −0.02 and metal ion of a 3d subshell between half-filled and fully filled. This study clarifies the mediate role of the organic substrate for interfacial PDS activation on M x O y and also gives new insights into the rational design of a highly efficient M x O y catalyst for selective phenolic/aniline pollutant degradation in wastewater.

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“…External energy activation is an efficient method; however, its high energy consumption and strict reaction conditions have hampered its large-scale application. , Transition-metal activation is a simple and efficient technique that does not require extra energy; the process mainly exhibits changes in the valence, chemistry states, and unoccupied orbits of the catalysts, which are accountable for electron transfer during the activation of PS with the production of active radicals. , However, a main disadvantage to using metal activation is the potential for secondary contamination due to the leaching of toxic metal. In addition, the change in the valence state of the oxidation–reduction center necessarily alters the chemical properties of the relevant metals, including the number of coordination sites, the geometry, and the crystal structure .…”

Section: Overviewmentioning

confidence: 99%

Structure–Function Correlations of Carbonaceous Materials for Persulfate-Based Advanced Oxidation

Zhao

Wang

2021

Langmuir

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Carbonaceous materials (CMs), as high-efficiency activators in a persulfatebased advanced oxidation process (PS-AOP), are attracting increasing attention for environmental remediation due to their high efficiency, low toxicity, and environmental friendliness. The correlations between the structural and surface properties of carbonaceous materials and the catalytic reaction efficiency in PS-AOP have been focused on experimentally and theoretically. In this Perspective, we discuss the effect of the microstructure of carbonaceous materials on the catalytic reaction efficiency, which can depend on the reaction pathways, including adsorption, free-radical routines, and non-free-radical pathways. Various features of carbonaceous materials, covering the dimensionality, pristine carbon configuration, crystallinity, defects, porosity, chemically active groups, and heterogeneous doping, can be involved. Those characteristics mainly affect the electronic process and mass transfer during the whole PS-AOP. An important target in the field is how to rationally regulate the intrinsic properties of carbonaceous substances to control both the reaction pathways and catalytic efficiency. Therefore, we conclude with a critical discussion and presentation of future challenges.

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A critical review on the mechanisms of persulfate activation by iron-based materials: Clarifying some ambiguity and controversies

Cited by 126 publications

References 126 publications

l‐cysteine‐modified Fe₃O₄ nanoparticles as a novel heterogeneous catalyst for persulfate activation on BTEX removal

l‐cysteine‐modified Fe₃O₄ nanoparticles as a novel heterogeneous catalyst for persulfate activation on BTEX removal

In Situ-Formed Phenoxyl Radical on the CuO Surface Triggers Efficient Persulfate Activation for Phenol Degradation

Structure–Function Correlations of Carbonaceous Materials for Persulfate-Based Advanced Oxidation

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A critical review on the mechanisms of persulfate activation by iron-based materials: Clarifying some ambiguity and controversies

Cited by 126 publications

References 126 publications

l‐cysteine‐modified Fe3O4 nanoparticles as a novel heterogeneous catalyst for persulfate activation on BTEX removal

l‐cysteine‐modified Fe3O4 nanoparticles as a novel heterogeneous catalyst for persulfate activation on BTEX removal

In Situ-Formed Phenoxyl Radical on the CuO Surface Triggers Efficient Persulfate Activation for Phenol Degradation

Structure–Function Correlations of Carbonaceous Materials for Persulfate-Based Advanced Oxidation

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l‐cysteine‐modified Fe₃O₄ nanoparticles as a novel heterogeneous catalyst for persulfate activation on BTEX removal

l‐cysteine‐modified Fe₃O₄ nanoparticles as a novel heterogeneous catalyst for persulfate activation on BTEX removal