Solid peroxides in Fenton-like reactions at near neutral pHs: Superior performance of MgO2 on the accelerated reduction of ferric species
Graphical abstract
Introduction
Fenton based advanced oxidation technologies (AOTs) have been widely applied for the removal of recalcitrant organic contaminants in wastewater (Yang et al., 2019; Zhang et al., 2019; Zhu et al., 2019; Zhou et al., 2020). In these reactions, highly active hydroxyl radicals can be produced by using iron containing substance and H2O2, and the mechanism can be described by Haber-Weiss reactions (R1 and R2) (Lin and Gurol, 1998; Xing et al., 2018). However, these processes are limited by the narrow applicable pH range and the sluggish reduction of ferric to ferrous ions (R2, k = ) (Lin and Gurol, 1998). Chelating agents (EDTA, citric acid, etc.) or immobilized iron containing materials were employed to widen the pH range by avoiding the precipitation of iron hydroxides at near neutral pHs (Ling et al., 2014; He et al., 2015; Zhou et al., 2017). Several strategies were also proposed to target the kinetic problems, including the introduction of external energy like UV or visible light (Zou et al., 2018; Liu et al., 2018; Serna-Galvis et al., 2018), electricity (Ganiyu et al., 2018) and ultrasound (Hassani et al., 2018; Wei et al., 2019a), the addition of organic reductants (e.g., ascorbic acid, hydroxylamine) (Qin et al., 2015; Hou et al., 2016), and employing nanomaterials like molybdenum disulfide (Zhu et al., 2020) and crystal boron (Zhou et al., 2020). However, it is still a challenge to develop facile and efficient strategies to accelerate the slow redox cycles of Fe(III)/Fe(II) and to make the reaction kinetics meet the applications’ requirements.
Generally, OH and are dominant radicals in Fenton or Fenton-like systems (Fu et al., 2016; Hayyan et al., 2016; Vione and Scozzaro, 2019; Zhu et al., 2019). Superoxide radical () is one typical reactive oxygen species (ROS), while the chemical generation of by the reaction between ferric ion and H2O2 (R2) is slow. In fact, the reaction rate constant of Fe(III) reduction by is very high (R3, ∼) (Li et al., 2016). Thus, the Fe(III)/Fe(II) cycles can be efficiently accelerated by enhancing production. The increased generation of can be realized by several methods, such as increasing H2O2 concentrations (Hayyan et al., 2016), using alkali metal superoxide (e.g. KO2) as oxidants (Smith et al., 2004), or catalyzing H2O2 decomposition by birnessite (γ-MnO2) (Furman et al., 2009) or Mn2+ ions (Li et al., 2016). Recently, we found that when using CaO2 as the oxidant, the generation rate of in the Fenton-like system of CaO2/Fe(III)-EDTA was about four orders of magnitude higher than that in the H2O2 system (Pan et al., 2018). On the other hand, is a relatively unreactive radical, and its reactivity depends greatly on the generation method, cosolvent polarity, contaminant type, and surface area of materials in the heterogeneous systems (Smith et al., 2004; Hayyan et al., 2016; Zhao et al., 2020). Therefore, simultaneous increasing of the reactivity and production rate of would be a feasible strategy to improve the removal of organic contaminates in Fenton or Fenton-like systems.
Solid peroxides, like CaO2, were frequently used as the alternative sources of H2O2 in Fenton based AOTs (Northup and Cassidy, 2008; Goi et al., 2011; Lu et al., 2017; Mosmeri et al., 2018; Xue et al., 2019; Wu et al., 2019; Yuan et al., 2019). The advantages of solid peroxides over liquid H2O2 are the more convenience and safety in storage and transportation, and to initiate Fenton-like oxidation within a wider pH range by utilizing the slowly released H2O2 in water. Apart from the most frequently studied CaO2, other solid peroxides, such as ZnO2, MgO2 and urea hydrogen peroxide (UHP) were also investigated in the Fenton-like reactions. A nano-ZnO2/Fe2+ system showed high efficiency in removal of Rhodamine B under faintly acidic conditions (Prasanna and Vijayaraghavan, 2017). High-purity MgO2 nanoparticles were synthesized and successfully applied for methylene blue degradation by using ferric ions as catalysts (Wu et al., 2019). Both MgO2 and CaO2 performed well in the remediation of oil-contaminated soil by using natural minerals as catalysts (Goi et al., 2011). A microwave assisted UHP/Fe2+ system was used for decontamination of halogenated aromatics polluted soil (Cravotto et al., 2007), and a couple of UHP and Fe impregnated biochar was used to reduce fumigant emission in soil (Qin et al., 2020). However, the distinctions among these solid peroxides as Fenton-like oxidants have not been studied yet, especially the reactivity and generation rate of from the solid peroxides.
Herein, four solid peroxides (MgO2, CaO2, ZnO2 and UHP) including both metallic and non-metallic peroxides were selected. They are common oxidants that have been frequently employed in Fenton and Fenton-like reactions. Their performance on Fenton-like reactions for phenol degradation at near neutral pHs were investigated. Based on mechanistic analyses, the intrinsic differences on the generation rates and reactivity of were discussed, and a strategy to accelerate the Fenton-like reactions and to improve utilization efficiency of active oxygen was proposed.
Section snippets
Materials
MgO2 was synthesized by a modified method based on previous reports (Navik et al., 2017). Other materials were commercially purchased, and details can be found in Text S1 and S2. All other chemicals were of the highest grade and used without purification.
Release of H2O2
The release of H2O2 from the solid peroxides were measured at the pHs of 5 or 7 by using phosphate buffers (0.05 M). Specifically, a certain amount of solid peroxide was added into the buffered aqueous solution, which was magnetically stirred
Active oxygen contents of peroxides and H2O2 release
The active oxygen contents (wt%) and purities of the four solid peroxides, MgO2, CaO2, ZnO2 and UHP, were determined. Theoretically, MgO2 has the highest active oxygen content (28.4 wt%), which was about twice of that in the commercial 30 wt% H2O2 solution. As shown in Table S1, the measured active oxygen contents were 13.0 ± 0.34%, 12.8 ± 0.19%, 8.22 ± 0.16% and 16.4 ± 0.08% for MgO2, CaO2, ZnO2 and UHP, respectively. According to the ratio of the measured active oxygen to the theoretical
Conclusions
In summary, according to a comparison of four solid peroxides, MgO2 displayed a superior performance to CaO2 and ZnO2 in the generation rate and reactivity of , which resulted in accelerated Fe(III) reduction and organic degradation in the Fenton-like reactions. UHP behaved like H2O2 due to the instant release of H2O2 and the absence of precipitates. Although currently the cost of MgO2 is higher than H2O2, MgO2 has advantages over H2O2 in the convenience and safety of transportation and
Credit author statement
Yitong Zhu: Data curation, Methodology, Investigation, Visualization, Writing-original draft. Jiaolong Qin: Resources, Investigation, Methodology. Shuqi Zhang: Investigation, Methodology. Adi Radian: Validation, Methodology, Writing - review & editing. Mingce Long: Conceptualization, Supervision, Funding acquisition, Resources, Writing - review & editing.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This work was supported by the National Key Research and Development Program of China (2017YFE0195800), the National Natural Science Foundation of China (21876108) and Shanghai Municipal International Cooperation Foundation (19230713800). The authors also acknowledge the experimental support of the BET-BJH analysis from Ms. Jie Zhang of Instrumental Analysis Center of Shanghai Jiao Tong University.
References (60)
- et al.
Decontamination of soil containing POPs by the combined action of solid Fenton-like reagents and microwaves
Chemosphere
(2007) - et al.
Role of the intermediates in the degradation of phenolic compounds by Fenton-like process
J. Hazard Mater.
(2006) - et al.
Enhanced degradation of benzene in aqueous solution by sodium percarbonate activated with chelated-Fe(II)
Chem. Eng. J.
(2016) - et al.
Heterogeneous electro-Fenton and photoelectro-Fenton processes: a critical review of fundamental principles and application for water/wastewater treatment
Appl. Catal. B Environ.
(2018) - et al.
Polychlorinated biphenyls-containing electrical insulating oil contaminated soil treatment with calcium and magnesium peroxides
Chemosphere
(2011) - et al.
Enhanced removal of basic violet 10 by heterogeneous sono-Fenton process using magnetite nanoparticles
Ultrason. Sonochem.
(2018) - et al.
EDTA enhanced heterogeneous Fenton oxidation of dimethyl phthalate catalyzed by Fe3O4: kinetics and interface mechanism
J. Mol. Catal. Chem.
(2015) - et al.
Ascorbic acid/Fe@Fe2O3: a highly efficient combined Fenton reagent to remove organic contaminants
J. Hazard Mater.
(2016) - et al.
Enhanced persulfate oxidation of organic pollutants and removal of total organic carbons using natural magnetite and microwave irradiation
Chem. Eng. J.
(2020) - et al.
Generation and transformation of ROS on g-C3N4 for efficient photocatalytic NO removal: a combined in situ DRIFTS and DFT investigation
Chin. J. Catal.
(2018)
Degradation of naphthalene with magnetic bio-char activate hydrogen peroxide: synergism of bio-char and Fe−Mn binary oxides
Water Res.
Mn2+-mediated homogeneous Fenton-like reaction of Fe(III)-NTA complex for efficient degradation of organic contaminants under neutral conditions
J. Hazard Mater.
Magnetically separable core-shell structural gamma-Fe2O3@Cu/Al-MCM-41 nanocomposite and its performance in heterogeneous Fenton catalysis
J. Hazard Mater.
Insight into electro-Fenton and photo-Fenton for the degradation of antibiotics: mechanism study and research gaps
Chem. Eng. J.
Application of calcium peroxide in water and soil treatment: a review
J. Hazard Mater.
Calcium peroxide (CaO2) for use in modified Fenton chemistry
J. Hazard Mater.
CaO2 based Fenton-like reaction at neutral pH: accelerated reduction of ferric species and production of superoxide radicals
Water Res.
Coupled use of Fe-impregnated biochar and urea-hydrogen peroxide to simultaneously reduce soil-air emissions of fumigant and improve crop growth
J. Hazard Mater.
Photoinduced disinfection in sunlit natural waters: measurement of the second order inactivation rate constants between E. coli and photogenerated transient species
Water Res.
Efficient bifunctional piezocatalysis of Au/BiVO4 for simultaneous removal of 4-chlorophenol and Cr(VI) in water
Appl. Catal. B Environ.
2020 roadmap on pore materials for energy and environmental applications
Chin. Chem. Lett.
Highly pure MgO2 nanoparticles as robust solid oxidant for enhanced Fenton-like degradation of organic contaminants
J. Hazard Mater.
Metal sulfides as excellent co-catalysts for H2O2 decomposition in advanced oxidation processes
Inside Chem.
Insight into CaO2-based Fenton and Fenton-like systems: strategy for CaO2-based oxidation of organic contaminants
Chem. Eng. J.
Enhancing CaO2 fenton-like process by Fe(II)-oxalic acid complexation for organic wastewater treatment
Water Res.
Synergistic effect of artificial enzyme and 2D nano-structured Bi2WO6 for eco-friendly and efficient biomimetic photocatalysis
Appl. Catal. B Environ.
A review on Fenton process for organic wastewater treatment based on optimization perspective
Sci. Total Environ.
Robust photocatalytic benzene degradation using mesoporous disk-like N-TiO2 derived from MIL-125(Ti)
Chin. J. Catal.
Chelating agents enhanced CaO2 oxidation of bisphenol A catalyzed by Fe3+ and reuse of ferric sludge as a source of catalyst
Chem. Eng. J.
Strategies for enhancing the heterogeneous Fenton catalytic reactivity: a review
Appl. Catal. B Environ.
Cited by (17)
A critical review of solid peroxides in environmental remediation and water purification: From properties to field applications
2023, Chemical Engineering JournalInsight into H<inf>2</inf>O<inf>2</inf>-mediated catalytic ozonation of cyclophosphamide by zinc peroxide
2023, Journal of Environmental Chemical EngineeringOxygen-Rich Graphene/ZnO<inf>2</inf>-Ag nanoframeworks with pH-Switchable Catalase/Peroxidase activity as O<inf>2</inf> Nanobubble-Self generator for bacterial inactivation
2023, Journal of Colloid and Interface ScienceBromine functionalized Fe/Cu bimetallic MOFs for accelerating Fe(III)/Fe(II) cycle and efficient degradation of phenol in Fenton-like system
2023, Colloids and Surfaces A: Physicochemical and Engineering AspectsDegradation of 1,2,3-trichloropropane by pyrite activating sodium percarbonate and the implications for groundwater remediation
2023, Journal of Environmental Chemical Engineering