Dissolved oxygen triggers a low concentration of H₂O₂ conversion over carbon-supported nanoscale zero-valent iron for fluoroquinolone degradation

Abstract

Achieving satisfactory micropollutant oxidation with a low hydrogen peroxide (H₂O₂) concentration is vital for advanced oxidation processes to improve catalytic efficiency and reduce resource consumption. Herein, the efficient conversion of low-concentration H₂O₂ (20 μmol/L) triggered by dissolved oxygen (DO) over carbon-supported nanoscale zero-valent iron prepared in this study (nZVI–C) for efficient contaminant degradation is achieved. The experimental results revealed that 1) H₂O₂-DO systems promoted electron transfer between nZVI–C and iron species, followed by the generation of more abundant reactive oxygen species, which was quite different from the alone H₂O₂ or DO systems mostly their-self function for limited reactive oxygen species generation; 2) The in-situ generation of H₂O₂ via DO activation played a significant role. The H₂O₂–DO system effectively degraded ofloxacin (OFL), norfloxacin (NOR), and ciprofloxacin (CIP) degradation at low concentrations (5 μmol/L). With the addition of 10 mg/L nZVI–C and 20 μmol/L H₂O₂, the degradation rates of OFL, NOR, and CIP reached 93.25%, 90.71%, and 92.80%, respectively, within 15 min. DO activation and catalyst adsorption contributed 44.93%, 39.84%, and 36.19%, respectively. Theoretical calculation results further demonstrated the stretching of O–O bonds in O₂ and H₂O₂ molecules, indicating a possible homolytic reaction. This study elucidates the triggering role of low-concentration H₂O₂ in DO conversion over nZVI, providing an efficient strategy for the Fenton degradation of micropollutants with a low dosage of catalysts and oxidants.

Graphical abstract

Keywords

Dissolved oxygen (DO) / Micropollutant / Carbon-coated nanoscale zero-valent iron / Fenton-like reaction / In situ H₂O₂ generation

Highlight

	● A high-loading zero-valent iron catalyst with a unique topology was synthesised.
	● Fluoroquinolones were efficiently removed at micropollutant levels.
	● DO and H2O2 synergistically enhanced oxidant utilisation.
	● DO activation induced in situ H2O2 generation and reactive oxygen species.

References

[1] Barbosa M O , Moreira N F F , Ribeiro A R , Pereira M F R , Silva A M T . (2016). Occurrence and removal of organic micropollutants: an overview of the watch list of EU Decision 2015/495. Water Research, 94: 257–279

[2] Brumovský M , Oborná J , Micić V , Malina O , Kašlík J , Tunega D , Kolos M , Hofmann T , Karlický F , Filip J . (2022). Iron nitride nanoparticles for enhanced reductive dechlorination of trichloroethylene. Environmental Science & Technology, 56(7): 4425–4436

[3] Chen M J , Chu W . (2016). H₂O₂ assisted degradation of antibiotic norfloxacin over simulated solar light mediated Bi₂WO₆: kinetics and reaction pathway. Chemical Engineering Journal, 296: 310–318

[4] Chen X F , Su J , Meng Y , Yu M D , Zheng M X , Sun Y Y , Xi B D . (2023). Oxygen vacancy promoted heterogeneous Fenton-like degradation of sulfamethazine by chlorine-incorporated micro zero-valent iron. Chemical Engineering Journal, 463: 142360

[5] Chen Y J , Ji S F , Wang Y G , Dong J C , Chen W X , Li Z , Shen R A , Zheng L R , Zhuang Z B , Wang D S . et al. (2017). Isolated single iron atoms anchored on n-doped porous carbon as an efficient electrocatalyst for the oxygen reduction reaction. Angewandte Chemie International Edition, 56(24): 6937–6941

[6] Crane R A , Scott T B . (2012). Nanoscale zero-valent iron: future prospects for an emerging water treatment technology. Journal of Hazardous Materials, 211–212: 112–125

[7] Cui C N , Zhang H C , Luo Z X . (2020). Nitrogen reduction reaction on small iron clusters supported by N-doped graphene: a theoretical study of the atomically precise active-site mechanism. Nano Research, 13(8): 2280–2288

[8] Du J K , Bao J G , Fu X Y , Lu C H , Kim S H . (2016). Mesoporous sulfur-modified iron oxide as an effective Fenton-like catalyst for degradation of bisphenol A. Applied Catalysis B: Environmental, 184: 132–141

[9] Du P H , Sun P Z , Wang J J , Mo X H , Yao L L , Yang X , Chow A T S . (2026). Concentration-dependent kinetics of micropollutant oxidation: revealing the hidden role of long-lived reactive species. Environmental Science & Technology, 60(8): 6534–6545

[10] Fu F L , Dionysiou D D , Liu H . (2014). The use of zero-valent iron for groundwater remediation and wastewater treatment: a review. Journal of Hazardous Materials, 267: 194–205

[11] Gao X Y , Lin H L , Li Y , Nie Y L , Yang C , Shi J B . (2025). Insights into the restoration of micropolluted groundwater by pyrite: the contribution of Fe(IV) and outer-sphere electron transfer. Environmental Science & Technology, 59(13): 6872–6880

[12] Hong P D, Wu Z J, Yang D D, Zhang K S, He J Y, Li Y L, Xie C, Yang W, Yang Y, Kong L T, et al. (2021). Efficient generation of singlet oxygen (¹O₂) by hollow amorphous Co/C composites for selective degradation of oxytetracycline via Fenton-like process. Chemical Engineering Journal, 421(Pt 1): 129594

[13] Hou C , Zhao J , Yang L B , Chen J B , Xia X F , Zhou X F , Zhang Y L . (2023). A single-atom Fe-N-C catalyst with superior Fenton-like reaction performance prepared facilely using microalgae: key roles of oxygen and interactions between Fe-N_x and Fe/Fe compounds. Applied Catalysis B: Environmental, 339: 123135

[14] Hug S J , Leupin O . (2003). Iron-catalyzed oxidation of arsenic(III) by oxygen and by hydrogen peroxide: pH-dependent formation of oxidants in the Fenton reaction. Environmental Science & Technology, 37(12): 2734–2742

[15] Jawad A , Zhan K , Wang H B , Shahzad A , Zeng Z H , Wang J , Zhou X Q , Ullah H , Chen Z L , Chen Z Q . (2020). Tuning of persulfate activation from a free radical to a nonradical pathway through the incorporation of non-redox magnesium oxide. Environmental Science & Technology, 54(4): 2476–2488

[16] Jin Z Y , Li P P , Meng Y , Fang Z W , Xiao D , Yu G H . (2021). Understanding the inter-site distance effect in single-atom catalysts for oxygen electroreduction. Nature Catalysis, 4(7): 615–622

[17] Khan E , Wirojanagud W , Sermsai N . (2009). Effects of iron type in Fenton reaction on mineralization and biodegradability enhancement of hazardous organic compounds. Journal of Hazardous Materials, 161(2−3): 1024–1034

[18] Lai C , Yang L , Li L , Ma D S , Cheng M , Liu S Y , Zhang M M , Yan H C , Tang L S , Chen Z X . et al. (2023). Design of a highly efficient Cu-based catalyst with two functional areas: the role of Cu⁰ and oxygen vacancies in Fenton-like system. Chemical Engineering Journal, 464: 142420

[19] Li J Z , Zhang H G , Samarakoon W , Shan W T , Cullen D A , Karakalos S , Chen M J , Gu D M , More K L , Wang G F . et al. (2019). Thermally driven structure and performance evolution of atomically dispersed FeN₄ sites for oxygen reduction. Angewandte Chemie International Edition, 58(52): 18971–18980

[20] Li X , Zhou M H , Pan Y W , Xu L T , Tang Z X . (2017). Highly efficient advanced oxidation processes (AOPs) based on pre-magnetization Fe⁰ for wastewater treatment. Separation and Purification Technology, 178: 49–55

[21] Li X N , Huang X , Xi S B , Miao S , Ding J , Cai W Z , Liu S , Yang X L , Yang H B , Gao J J . et al. (2018). Single cobalt atoms anchored on porous N-doped graphene with dual reaction sites for efficient Fenton-like catalysis. Journal of the American Chemical Society, 140(39): 12469–12475

[22] Li Y R , Zhao H P , Zhu L Z . (2021). Remediation of soil contaminated with organic compounds by nanoscale zero-valent iron: a review. Science of the Total Environment, 760: 143413

[23] Li Z W , Liang L Y , Tan W , Liu Y , Pan H H , Shi Q , Zhao C Q , Huang S Y , Liu X X . (2025). Insight into in-situ Fenton-like catalysis by iron-rich sludge-derived iron-carbon composites: molecular oxygen activation driven by electron transfer in Fe-C structure. Journal of Environmental Chemical Engineering, 13(3): 116683

[24] Liu W , Li Y Y , Liu F Y , Jiang W , Zhang D D , Liang J L . (2019). WITHDRAWN: visible-light-driven photocatalytic degradation of diclofenac by carbon quantum dots modified porous g-C₃N₄: mechanisms, degradation pathway and DFT calculation. Water Research, 150: 431–441

[25] Liu X C , Pan Y S , Yao Y , Chen S X , Chen B L , Chu C H . (2025). Accelerated pollutant degradation by UV/H₂O₂ at the air–water interface of microdroplets. Environmental Science & Technology, 59(10): 5406–5414

[26] Lu J , Wu J , Zhang C , Wang J H , He X . (2024). Occurrence and possible sources of antibiotic resistance genes in seawater of the South China Sea. Frontiers of Environmental Science & Engineering, 18(9): 108

[27] Mohammadi M , Pakizeh E . (2023). Adsorption of SO, CO, O₂, and N₂ on the most stable small Fe clusters. Materials Science and Engineering: B, 297: 116752

[28] Nidheesh P V . (2015). Heterogeneous Fenton catalysts for the abatement of organic pollutants from aqueous solution: a review. RSC Advances, 5(51): 40552–40577

[29] Nidheesh P V , Gandhimathi R , Ramesh S T . (2013). Degradation of dyes from aqueous solution by Fenton processes: a review. Environmental Science and Pollution Research, 20(4): 2099–2132

[30] Niu H Y , Yang Y L , Zhao W J , Lv H Z , Zhang H , Cai Y Q . (2021). Single-crystalline Fe₇S₈/Fe₃O₄ coated zero-valent iron synthesized with vacuum chemical vapor deposition technique: enhanced reductive, oxidative and photocatalytic activity for water purification. Journal of Hazardous Materials, 401: 123442

[31] Nosaka Y , Nosaka A Y . (2017). Generation and detection of reactive oxygen species in photocatalysis. Chemical Reviews, 117(17): 11302–11336

[32] Pan Y W , Zhang Y , Zhou M H , Cai J J , Tian Y S . (2019). Enhanced removal of antibiotics from secondary wastewater effluents by novel UV/pre-magnetized Fe⁰/H₂O₂ process. Water Research, 153: 144–159

[33] Pignatello J J , Oliveros E , MacKay A . (2006). Advanced oxidation processes for organic contaminant destruction based on the Fenton reaction and related chemistry. Critical Reviews in Environmental Science and Technology, 36(1): 1–84

[34] Pouran S R , Raman A A A , Daud W M A W . (2014). Review on the application of modified iron oxides as heterogeneous catalysts in Fenton reactions. Journal of Cleaner Production, 64: 24–35

[35] Qu J H , Li Z R , Bi F X , Zhang X B , Zhang B , Li K G , Wang S Q , Sun M Z , Ma J , Zhang Y . (2023). A multiple Kirkendall strategy for converting nanosized zero-valent iron to highly active Fenton-like catalyst for organics degradation. Proceedings of the National Academy of Sciences of the United States of America, 120(39): e2304552120

[36] Sankar M S , Dash P , Singh S , Lu Y H , Mercer A E , Chen S . (2019). Effect of photo-biodegradation and biodegradation on the biogeochemical cycling of dissolved organic matter across diverse surface water bodies. Journal of Environmental Sciences, 77: 130–147

[37] Shi Y B , Wang X B , Liu X F , Ling C C , Shen W J , Zhang L Z . (2020). Visible light promoted Fe₃S₄ Fenton oxidation of atrazine. Applied Catalysis B: Environmental, 277: 119229

[38] Stadler N , Höfer M , Sigler K . (2001). Mechanisms of Saccharomyces cerevisiae PMA1 H⁺-ATPase inactivation by Fe²⁺, H₂O₂ and Fenton reagents. Free Radical Research, 35(6): 643–653

[39] Sudhakaran S , Maeng S K , Amy G . (2013). Hybridization of natural systems with advanced treatment processes for organic micro-pollutant removals: new concepts in multi-barrier treatment. Chemosphere, 92(6): 731–737

[40] Vadahanambi S , Lee S H , Kim W J , Oh I K . (2013). Arsenic removal from contaminated water using three-dimensional graphene-carbon nanotube-iron oxide nanostructures. Environmental Science & Technology, 47(18): 10510–10517

[41] Wang J L , Wang S Z . (2020). Reactive species in advanced oxidation processes: formation, identification and reaction mechanism. Chemical Engineering Journal, 401: 126158

[42] Wang L , Guan J , Han H , Yao M Y , Kang J , Peng M , Wang D S , Xu J Y , Hao J M . (2022). Enhanced photocatalytic removal of ozone by a new chlorine-radical-mediated strategy. Applied Catalysis B: Environmental, 306: 121130

[43] Wei Y A, Wang B F, Cui X F, Muhammad Y, Zhang Y J, Huang Z Q, Li X S, Zhao Z X, Zhao Z X (2018). Highly advanced degradation of thiamethoxam by synergistic chemisorption-catalysis strategy using MIL(Fe)/Fe-SPC composites with ultrasonic irradiation. ACS Applied Materials & Interfaces, 10(41): 35260–35272

[44] Wu G, Chen Z W, Artyushkova K, Garzon F H, Zelenay P (2008). Polyaniline-derived non-precious catalyst for the polymer electrolyte fuel cell cathode. In: ECS Transactions [Proton Exchange Membrane Fuel Cells 8, pts 1 and 2]. 8th Symposium on Proton Exchange Membrane Fuel Cells. Honolulu, HI, USA, October 12–17, 2008; The Electrochemical Society: Pennington, NJ, 2008; pp 159–170

[45] Yang Z M , Ma Y P , Liu Y , Li Q S , Zhou Z Y , Ren Z Q . (2017). Degradation of organic pollutants in near-neutral pH solution by Fe-C micro-electrolysis system. Chemical Engineering Journal, 315: 403–414

[46] Yin J L , Zhang H , Luo M F , Zhao J , Zhou X , Wang F C , Zhou H Y , Yuan Y , Liu Y , Shi Y B . et al. (2025). Electro-Fenton process for wastewater treatment: from selective H₂O₂ generation to efficient ^•OH conversion. Chemical Engineering Journal, 507: 160709

[47] Yin Y , Lv R L , Li X Y , Lv L , Zhang W M . (2021). Exploring the mechanism of ZrO₂ structure features on H₂O₂ activation in Zr–Fe bimetallic catalyst. Applied Catalysis B: Environmental, 299: 120685

[48] Ying D W , Peng J , Xu X Y , Li K , Wang Y L , Jia J P . (2012). Treatment of mature landfill leachate by internal micro-electrolysis integrated with coagulation: a comparative study on a novel sequencing batch reactor based on zero valent iron. Journal of Hazardous Materials, 229–230: 426–433

[49] Zhang C W , Li T Y , Zhang J Y , Yan S , Qin C Y . (2019). Degradation of p-nitrophenol using a ferrous-tripolyphosphate complex in the presence of oxygen: the key role of superoxide radicals. Applied Catalysis B: Environmental, 259: 118030

[50] Zhang L , Wan S S , Li C X , Xu L , Cheng H , Zhang X Z . (2018). An adenosine triphosphate-responsive autocatalytic Fenton nanoparticle for tumor ablation with self-supplied H₂O₂ and acceleration of Fe(III)/Fe(II) conversion. Nano Letters, 18(12): 7609–7618

[51] Zhang L D , Huo S Y , Li W X , Song L Z , Fu W X , Li J , Gao M C . (2023). Improved heterogeneous photo-Fenton-like degradation of ofloxacin through polyvinylpyrrolidone modified CuFeO₂ catalyst: performance, DFT calculation and mechanism. Separation and Purification Technology, 311: 123261

[52] Zhang Y J , Huang G X , Winter L R , Chen J J , Tian L L , Mei S C , Zhang Z , Chen F , Guo Z Y , Ji R . et al. (2022). Simultaneous nanocatalytic surface activation of pollutants and oxidants for highly efficient water decontamination. Nature Communications, 13(1): 3005

[53] Zhao X , Liu W , Cai Z Q , Han B , Qian T W , Zhao D Y . (2016). An overview of preparation and applications of stabilized zero-valent iron nanoparticles for soil and groundwater remediation. Water Research, 100: 245–266

[54] Zou Y D , Wang X X , Khan A , Wang P Y , Liu Y H , Alsaedi A , Hayat T , Wang X K . (2016). Environmental remediation and application of nanoscale zero-valent iron and its composites for the removal of heavy metal ions: a review. Environmental Science & Technology, 50(14): 7290–7304

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