SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Xianfa Zhang,Mingzhao Huang,Zuoming Zhou,Xiaodan Zhao,Guohua Jing
Sulfite activation with iron-based heterogeneous activators is a promising technology for the removal of organic contaminants from water. However, the slow valence transformation of >Fe(II)/>Fe(III) compromises sulfite activation efficiency. Regarding that the oxygen vacancy (Vo) can modulate the charge distribution and thus enhance >Fe(II)/>Fe(III) valence transformation via rapid electron transfer, Vo-enriched γ-Fe 2 O 3 is constructed for sulfite activation (simplified as the γ-Fe 2 O 3 -Vo/sulfite system). The γ-Fe 2 O 3 -Vo/sulfite system exhibits excellent abatement performance for iohexol (IOX) with the efficiency as high as 90.2 % within 1 h of reaction at pH 8.5, in which sulfate radicals (SO 4 •− ) and hydroxyl radicals (HO • ) are the major species. Electrochemical and DFT calculations reveal that Vo-enriched γ-Fe 2 O 3 possesses lower electrical impedance and the concomitant higher electron transfer efficiency. According to a series of characterizations, the enhance >Fe(II)/>Fe(III) valence transformation is confirmed to contribute to sulfite activation via the regulation of the electronic structure by the Vo. In addition, the degradation pathways of IOX are proposed by analyzing the degradation products of IOX by UPLC-QTOF-MS. Finally, the effects of different influencing factors on the degradation of IOX and the cyclic performance suggest the system shows strong resistance to interference and reusability, exhibiting superior application potential.
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Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Haishuo Wang,Jie Zhang,Zhichun Li,Bin Shi,Shiyin Li,Heyong Huang
Microcystin-LR (MCLR) is a highly toxic pollutant widely distributed in eutrophic waters. The interplay between dissolved organic matter (DOM) and metal ions has been extensively reported; however, the impact of DOM-metal complexes on MCLR remains to be thoroughly studied. In this research, equilibrium dialysis was employed to study the kinetics and isotherms of MCLR adsorption by DOM, meanwhile the Density functional theory (DFT) calculations provided insights into the theoretical mechanisms of Fe(II)/Mn(II) involvement in the adsorption process. The adsorption kinetics revealed that the process is physicochemical, with chemisorption being the critical factor controlling the adsorption rate. The adsorption isotherms confirmed that Fe(II) alters the spatial arrangement of adsorption sites on the superficies of DOM, with the complexes of Fe(II) and DOM from the macrophyte-dominated regions of Lake Taihu (MDR-Fe(II)) showing the uppermost adsorption capacity of 6193.965 µg/g among all combinations. The influence of different cations (K + , Ca 2+ , Na + , Mg 2+ ) on the adsorption of MCLR to DOM is divergent, with metals either reducing MCLR adsorption through competition for adsorption sites or increasing it by forming ternary complexes. The pH decrease reduced the affinity of DOM to metal ions while simultaneously enhancing MCLR adsorption through changes in its ionization state. DFT calculations demonstrated that Fe(II)/Mn(II) reduces the resistance to interaction between functional groups on DOM and MCLR, with carboxyl-Fe(II)-carboxyl interactions showing the highest binding energy (ΔG = −7.253 eV). Overall, Fe(II)/Mn(II) enhances the adsorption of MCLR via altering the structure and surface electrostatic potential distribution of DOM. This research indicates that the ultimate fate of MCLR in aquatic ecosystems is affected by DOM and metal ions.
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WATER RESEARCH
·
2024
·
IF 11.4
Fangyuan Meng,Hui Tong,Chunhua Feng,Ziyuan Huang,Pan Wu,Jimei Zhou,Jian Hua,Fei Wu,Chengshuai Liu
Magnetite is a reductive Fe(II)-bearing mineral, and its reduction property is considered important for degradation of contaminants in groundwater and anaerobic subsurface environments. However, the redox condition of subsurface environments frequently changes from anaerobic to aerobic owing to natural and anthropogenic disturbances, generating reactive oxygen species (ROS) from the interaction between Fe(II)-bearing minerals and O 2 . Despite this, the mechanism of ROS generation induced by magnetite under aerobic conditions is poorly understood, which may play a crucial role in As(III) oxidation. Herein, we found that magnetite could activate O 2 and induce the oxidative transformation of As(III) under aerobic conditions. As(III) oxidation was attributed to the ROS generated via structural Fe(II) within the magnetite octahedra oxygenation. The electron paramagnetic resonance and quenching tests confirmed that O 2 •− , H 2 O 2 , and •OH were produced by magnetite. Moreover, density function theory calculations combined with experiments demonstrated that O 2 •− was initially formed via single electron transfer from the structural Fe(II) to the adsorbed O 2 ; O 2 •− was then converted to •OH and H 2 O 2 via a series of free radical reactions. Among them, O 2 •− and H 2 O 2 were the primary ROS responsible for As(III) oxidation, accounting for approximately 52 % and 19 % of As(III) oxidation. Notably, As(III) oxidation mainly occurred on the magnetite surface, and As was immobilized further within the magnetite structure. This study provides solid evidence regarding the role of magnetite in determining the fate and transformation of As in redox-fluctuating subsurface environments.
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ACS ES&T Engineering
·
2025
·
IF 6.7
Xiaoyu Teng,Peng Zhang,Songhu Yuan
Air sparging (AS) normally removes volatile chlorinated solvents in aquifers by stripping. Here, we found that oxygen (O2) supplied by AS could be transformed to hydroxyl radicals (•OH) by aquifer Fe(II) and led to a significant degradation of contaminants. In a simulated two-dimensional (2D) sand-filling aquifer contaminated with 22 μM trichloroethylene (TCE), long-term groundwater circulation subsequent to short-term AS was applied to facilitate the dissolving and mass transport of O2, and dissolved Fe(II) in the form of TPP–Fe(II) complex was added as the source of Fe(II). With the addition of 1.6 mM TPP–Fe(II), TCE removal increased from 52.9 to 89.0% with the increase in air flow rate from 20 to 120 L/h, and degradation contributed to over 89% of the total removals. TCE degradation also increased significantly with the increase in TPP–Fe(II) concentration. Degradation played a much more significant role than stripping for TCE removal in the sequential process. Temporal and spatial distributions of dissolved O2, dissolved Fe(II), and TCE corroborated the predominant contribution of the O2–Fe(II) interaction for TCE degradation due to •OH production. This study demonstrates the important role of oxidation in air sparging and provides a new strategy for applying O2–Fe(II)-driven oxidation by O2 in aquifer treatment.
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Environmental Science-Processes & Impacts
·
2025
·
IF 3.9
Rong Peng,Qi Zhu,Shuang Li,Hui Liu
The bacterium Comamonas terrigena strain HJ-2 has been reported as a nitrate-dependent iron-oxidizing bacterium, surprisingly with Fe(III) reduction ability. The control of iron redox cycling by the strain HJ-2 in the Fe(II)-Fe(III) co-existing system is mysterious and worthy of exploration. The present study demonstrates that HJ-2 utilizes nitrate as an electron acceptor to rapidly oxidize Fe(II), with negligible Fe(III) reduction, under neutral anaerobic conditions in a co-existing Fe2+ and ferrihydrite system. Nitrate significantly influences the iron transformation mediated by HJ-2. The final conversion ratio of Fe(II) increased from 27.94% to 96.67%, and the bio-oxidation rate of Fe(II) escalated from 0.000143 to 0.013 h⁻¹ as nitrate concentrations rose from 0.1 to 10 mM. X-ray diffraction results indicated that in the absence of HJ-2, goethite was the sole product, regardless of the nitrate concentration. While in the presence of HJ-2, the minerals formed transitioned from crystalline goethite and lepidocrocite to amorphous or weakly crystalline minerals with increasing nitrate concentration. Scanning electron microscopy and energy-dispersive X-ray spectroscopy showed that the morphology of the final mineral formed under high nitrate conditions resembled ferrihydrite, with higher carbon content on the mineral surface at elevated nitrate concentrations, suggesting enhanced production of bio-iron oxides and increased adsorption capacity for aqueous Fe(II). X-ray photoelectron spectroscopy results confirmed higher Fe(II) content on the amorphous minerals surface than goethite. This work provides new insights into microbial-mediated Fe-N cycling in natural environments, highlighting the significance of nitrate in driving iron redox processes and the iron mineral transformation by strain HJ-2.
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CHEMICAL GEOLOGY
·
2025
·
IF 3.6
Changjin Liang,Honghai Wu,Yaowei Li,Yufeng Guan
Ferrihydrite (Fh) can usually transform into phases with higher crystallinities. This may greatly alter Fh adsorption capacity for chromium ions, thereby affecting their immobilizations and fates. Foreign elements [e.g., lanthanum (La)] as impurities can become incorporated into Fh. Herein, the effect of La-substitution into Fh and the influence of the presence of Cr(VI) on Fh phase transformation and fate of Cr(VI) were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Electro-chemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) and other test methods were employed to probe phase changes after the Fe(II)-induced La-substituted Fh (La-Fh) transformations. At pH 5.5, no neoformed phase was observed until 7 d for La-Fh or pure Fh at 1 mM Fe(II) aq, but all La-Fh systems underwent transformations at 5 mM Fe(II)aq. A low pH and Fe(II)aq level favored lepidocrocite (Lp) to form, whereas goethite (Gt) was the predominant phase rather than Lp as pH increased to 7.2 with higher level Fe(II)aq. However, the La-substitution inhibits the La-Fh transformation rate and path. This made 5 % La-Fh transformed to Lp after 30 d at pH 7.2 and 1 mM Fe(II)aq. The La-release was present to some extent during the transformation process. Either the inhibition to La-Fh transformation or the La-slow release favors the retention of early-adsorbed Cr(VI) on iron-mineral surface. The added Cr(VI) might promote the La-Fh transformation even under a lower-level Fe(II), primarily attributed to the rapid reduction of Cr(VI) to Cr(III) by Fe(II), which produced more liable Fe(III) in addition to the Cr(III) that can improve the mineral conductivity, thereby enhancing the La-Fh transformation. Mechanisms responsible for the Fe(II)-induced La-Fh transformation companying the La slow-release are proposed to provide insights into the reduction and immobilization of Cr(VI) under anaerobic conditions, thus demonstrating that La-Fh is a promising material for application in Cr-contaminated site remediation.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2023
·
IF 22.1
Zixuan Zhang,Chenying Zhou,Yiming Sun,Peng Zhou,Yang Liu,Heng Zhang,Ye Du,Chuanshu He,Zhaokun Xiong,Bo Lai
Fenton oxidation technology is a widely-used advanced oxidation technology. However, the generation of hydroxyl radicals is restrained by the sluggish recovery of Fe(II), thus affecting its long-lasting performance for water decontamination. Here, a novel niobium carbide (Nb 2 C) MXene material was applied as a green co-catalyst. Nb 2 C MXene can significantly promote Fenton reactions to produce hydroxyl radicals for degrading dimethyl phthalate (DMP) with high efficiency and high stability for long-term operation, which outperforms than various reported co-catalysts. Meanwhile, the Nb 2 C/Fe(III)/H 2 O 2 system is capable of non-selectively degrading a wide spectrum of refractory pollutants. Mechanism investigation reveals that Nb 2 C MXene as an electron donor can straight reduce Fe(III), meanwhile mediate electron shuttle from Fe(II) to H 2 O 2 to strongly expedite the generation of hydroxyl radicals. In addition, four main degradation routes of DMP were proposed. Therefore, this study offers an updated and valid strategy for the refractory organic pollutants elimination by coupling Nb 2 C MXene and Fenton oxidation.
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ChemistrySelect
·
2026
·Vol. 11
·期 20
·e73532
·
IF 2.3
Siyu Mao,Yaqi Fu,Jiaxing Wei,Yichuan Wang,Wei Feng
Manganese superoxide dismutase (SOD) catalyzes the decomposition of hydrogen peroxide (H 2 O 2 ) to generate hydroxyl radicals (•OH). In this study, SOD was encapsulated via coordination with Cu(II), Fe(II), and phosphate in phosphate-buffered saline (PBS) to form a hybrid material denoted as SOD@Cu&Fe&PO 4 . Our study demonstrates that SOD and the coordinated Cu(II)/Fe(II) ions exert a synergistic catalytic effect on •OH generation during H 2 O 2 decomposition. This synergistic behavior stems from the dynamic interplay between the production and consumption of superoxide anion radicals (O 2 •− ). Specifically, O 2 •− is generated as an intermediate in the reactions of coordinated Cu(II) and Fe(II) with H 2 O 2 . The in situ generated O 2 •− is subsequently utilized by encapsulated SOD, which in turn reduces Mn 3 + at the enzyme's active site to Mn 2 + . A continuous supply of O 2 •− to SOD accelerates the Mn 3 + /Mn 2 + redox cycle at its active center. Concurrently, the timely removal of O 2 •− from the Cu(II)/Fe(II)–H 2 O 2 reaction system eliminates the potential inhibition of O 2 •− accumulation, thereby promoting the Fe(III)/Fe(II) and Cu(II)/Cu(I) redox cycles. As a result, SOD@Cu&Fe&PO 4 affords a significantly enhanced •OH generation capacity. Moreover, this hybrid material exhibits enhanced contaminant degradation efficiency and potent antibacterial activity against multidrug-resistant Escherichia coli (MDR E. coli ) and methicillin-resistant Staphylococcus aureus (MRSA). Graphical O 2 •− is generated as an intermediate in the reactions of coordinated Cu(II) and Fe(II) with H 2 O 2 . The in situ generated O 2 •− is subsequently utilized by encapsulated SOD, which in turn reduces Mn 3 + at the enzyme's active site to Mn 2 + . A continuous supply of O 2 •− to SOD accelerates the Mn 3 + /Mn 2 + redox cycle at its active center.
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Journal of Water Process Engineering
·
2025
·
IF 6.7
Jiangfu Zheng,Xiaoming Li,Jinglin Ding,Xingong Li
Research on peroxymonosulfate (PMS) activation via catalytic processes for degrading trace organic pollutants in aquatic environments has attracted considerable interest. Although iron is widely used in homogeneous advanced oxidation processes (AOPs), its effectiveness in activating PMS remains suboptimal. This study demonstrates that the environmentally benign chelating agent ethylenediamine- N , N ′-dibutyldicarboxylate (EDDS) markedly enhances iron-mediated PMS activation. With six coordination sites, EDDS forms stable five- and six-membered chelate rings with Fe(III)/Fe(II) ions, facilitating efficient PMS activation and leading to complete degradation of NTP. Beyond improving iron's catalytic performance, EDDS also inhibits iron disproportionation, thereby promoting PMS activation and facilitating NTP mineralization. Moreover, the system achieved removal efficiencies exceeding 96 % for tetracycline (TC), ciprofloxacin (CIP), sulfamethoxazole (SMX), and methylene blue (MB) within 35 min. Systematic experiments elucidated the critical role of the Fe(III)/Fe(II) redox cycle in the HeLDH/EDDS/PMS system, highlighting the central involvement of Fe(III) species in the regeneration of Fe(II). Multiple reactive oxygen species, including •OH, SO₄• − , RO•, O₂• − , and 1 O₂, were identified as contributors to NTP degradation. Transformation pathways and mechanistic details of NTP degradation were revealed via mass spectrometry, and toxicity evaluations confirmed a significant reduction in the ecotoxicity of oxidation products. The system also exhibited strong resistance to humic acid interference and effectively degraded multiple organic contaminants, underscoring its potential for sustainable water purification applications.
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WATER RESEARCH
·
2021
·
IF 11.236
Xiaoyu Liu,Shunke Ding,Pin Wang,Yuntao Hong,Hongying Zhao,Wenhai Chu
To remove disinfection by-product (DBP) precursors and mitigate odor compounds, peroxide (peroxymonosulfate and persulfate)/Fe(II)-based process was applied as a combination of coagulation and oxidation. Compared with traditional Fe-based salt coagulation (FeSO 4 and FeCl 3 ), peroxide/Fe(II)-based process was more efficient in dissolved organic carbon , UV 254 and turbidity removal, and peroxymonosulfate showed better performance than persulfate. The better coagulation performance arose from a combination of enhanced neutralization and different characteristics of flocs. Even though the combined process would increase the bromine substitution factor of DBPs, DBP formation and DBP-associated toxicity after peroxide/Fe(II)-based process were 9.2–38.8% and 5.2–27.2% lower than that after conventional Fe(III) coagulation. Both enhanced dissolved organic matter removal and oxidation of DBP precursors played vital roles in DBP control. Conventional Fe-based salt coagulation could hardly remove odor compounds (less than 10%, generally), whereas 28.2–84.9% of odor compounds were degraded during peroxide/Fe(II)-based process, due to free radical formation. This study demonstrated that PMS/Fe(II)-based process might be a promising treatment process for simultaneous DBP control and odor removal in source water.
研究领域:
环境科学
·
水处理工程
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Journal of Cleaner Production
·
2020
·
IF 7.246
Peijie Li,Xiaoxiang Cheng,Weiwei Zhou,Congwei Luo,Fengxun Tan,Zixiao Ren,Lu Zheng,Xuewu Zhu,Daoji Wu
It remains challenging to efficiently mitigate membrane fouling caused by natural organic matter (NOM) for the widespread application of ultrafiltration process. In this study, sodium percarbonate activated with Fe(II) (Fe(II)/SPC) was proposed as a feedwater pretreatment strategy for membrane fouling control. Typical NOM fractions, i.e., humic acid (HA), bovine serum albumin (BSA) were employed as membrane foulants, as well as natural surface water. The results showed that Fe(II)/SPC pretreatment apparently alleviated membrane fouling by BSA and HA-BSA, and the performance outperformed Fe(II) pre-coagulation and SPC pre-oxidation alone. Considering HA fouling, more severe flux decline and increased reversible fouling resistance were obtained, while irreversible fouling was slightly mitigated. The filtration of HA-BSA was well fitted to intermediate blocking followed by cake filtration, and Fe(II)/SPC noticeably increased the filtration volume corresponding to the formation of cake filtration. With Fe(II)/SPC pretreatment, a sparser and more homogeneous foulant layer with lower resistances was observed on membrane surface, and Fourier transform infrared spectroscopy indicated that the peak intensities of major functional groups for organic pollutants were significantly decreased. In surface water treatment, Fe(II)/SPC could effectively improve membrane filtration behavior and pollutants removal, with a distinct decrease of both fluorescent fractions and different molecular weight organic compounds. It seemed that hydroxyl radical oxidation and coagulation with in-situ formed Fe(III) were the main mechanisms of contaminants removal and membrane fouling control. Overall, this combined process exhibited a great potential for actual application during drinking water treatment .
研究领域:
环境工程
·
水处理技术
·
膜科学
·
高级氧化工艺
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Yang Zhang,Zhenglei Li,Dongqing Yan,Hongxia Chen,Meng Zhang,Jun Wang,Guang Yang
In this work, Fe(II)/Peroxymonosulfate (PMS) treatment with dual functionality of pre-oxidation and coagulation was applied to enhance the removal of alkali lignin in water. The removal efficiency of alkali lignin (2 g/L) could reach ∼ 99% at an optimal dosage of [Fe(II)] = 2.4 mM and [PMS] = 7.8 mM, which was efficiently superior than that using ferric and polymeric coagulant individually. Pre-oxidation, involving hydroxyl radical (•OH) and sulfate radical (SO 4 •− ), has been demonstrated to play a crucial role in both oxidative degradation (∼30%) and reducing the molecular weight and hydrophilicity of lignin. Meanwhile, the formation of polynuclear Fe-hydroxide complexes was also fostered, which in turn greatly contribute to the removal of lignin through an enhanced coagulation mechanism. The reductive units present in alkali lignin was demonstrated to initiate a dynamic transition between Fe(III) and Fe(II) by donating electrons. This redox activity is anticipated to continuously promote the formation of electro-neutral and loose flocs, thereby resulting in an enhanced coagulation performance. Furthermore, ultrafiltration (UF) was also demonstrated as a viable liquid/solid separation method following Fe(II)/PMS treatment, effectively promoting membrane flux recovery rate to ∼90%. This highlights the remarkable potential of this method when combined with other treatment processes. This study aims to offer a complementary strategy for remediating alkali lignin wastewater while advancing the fundamental understanding of redox-reaction enhanced in-situ coagulation in water treatment applications.
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