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1.
J Hazard Mater ; 444(Pt A): 130394, 2023 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-36403446

RESUMO

As two important components of dissolved organic matter (DOM), dissolved black carbon (DBC) and humic acid (HA) possess different chemical and structural properties, which might influence their activities like metal complexation and mediating electron transfer. In this study, a series of coprecipitates of iron oxides (FeOx) and DOM (HA or DBC) having different C/Fe molar ratios (0.2-3.0) was prepared under ambient conditions, which exhibited excellent catalytic efficiencies upon Fenton-like degradation of norfloxacin (NOR). Pseudo-first-order rate constant of NOR oxidation catalyzed by DBC-FeOx (C/Fe=3.0, 1.13 h-1) was 30.5, 4.3-14.2, and 1.3-15.7 folds higher than those mediated by FeOx alone, HA-FeOx and DBC-FeOx coprecipitates having C/Fe molar ratios of 0.2 and 1.6, respectively. Due to the higher concentrations of surface-bound Fe(III)/Fe(II) in the DBC-FeOx mediated systems, improved Fe(III)/Fe(II) cycling rates, •OH accumulation and NOR degradation were observed as compared with those of counterpart systems mediated by HA-FeOx. Besides functioning in Fe-C complexation to accelerate FeOOH cleavage, carbonyl/carboxyl groups of the coprecipitates also serve as electron shuttles, both of which improved Fe(III)/Fe(II) cycling and •OH production. Our findings emphasized the influence of DOM source and compositions on Fe(III)/Fe(II) cycling and provided a facile approach of preparing Fe-C catalyst for contaminants elimination.


Assuntos
Compostos Férricos , Norfloxacino , Matéria Orgânica Dissolvida , Fuligem , Compostos Ferrosos , Óxidos , Ferro
2.
Water Res ; 228(Pt A): 119386, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36427462

RESUMO

Fe(II) and silicate can form Si-Fe(II) co-precipitates in anoxic groundwater and sediments, but their phase composition and reactivity towards subsurface pollutants are largely unknown. Three types of Si-Fe(II) co-precipitations with the same chemical composition, namely Si-Fe(II)-I, Si-Fe(II)-II, and Si-Fe(II)-III, have been synthesized by different hydroxylation sequences in this work. It was found that Si-Fe(II)-III reduce carbon tetrachloride (CT) much faster (k1=0.04419 min-1) than Si-Fe(II)-I (0 min-1) and Si-Fe(II)-II (7.860 × 10-4 min-1). XRD results show that the main component of Si-Fe(II)-III is ferrous silicate (FeSiO3), which is quite different from that of Si-Fe(II)-I and Si-Fe(II)-II. The unique arrangement of hydroxyl coordination, the less distorted octahedral structure, the polyhedral morphology and the absence of Si-A center vacancies in Si-Fe(II)-III are responsible for its high reductive dehalogenation reactivity. The highest redox activity of Si-Fe(II)-III was shown by electrochemical characterization. The [FeII-O-Si]+ in Si-Fe(II)-III may stabilize the dichlorocarbene anion (˸CCl2-), which favors the transformation of CT to methane (9.2%). The Si-Fe(II) co-precipitates consist of countless internal electric fields, and the transformation of hydroxyl and CT both consumed electrons. The coexistence of hydroxyl and CT increases the electron density in the electron-rich region due to their electronegativity, enhancing their electron-accepting capabilities. This study deepens our understanding of the phase composition and electronic structure of Si-Fe(II) co-precipitates, which fills the gap in the reductive dehalogenation of halides by Si-Fe(II) co-precipitates.


Assuntos
Eletricidade , Água Subterrânea , Tetracloreto de Carbono , Elétrons , Radical Hidroxila , Compostos Ferrosos
3.
Sci Total Environ ; 858(Pt 2): 159884, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36334665

RESUMO

Iron (Fe)-manganese (Mn) minerals formed in situ can be used for the natural remediation of the primary poor-quality groundwater with coexistence of arsenite [As(III)], Mn(II), and Fe(II) (PGAMF). However, the underlying mechanisms of immobilization and coupling of As, Mn, and Fe during in-situ formation of Fe-Mn minerals in PGAMF remains unclear. The simultaneous immobilization and coupling of arsenic (As), Mn, and Fe in PGAMF during in-situ formation of biogenic Fe-Mn minerals induced by O2 perturbations and indigenous bacteria (Comamonas sp. RM6) were investigated at the different molar ratios of Fe(II):Mn(II) (1:1, 2:1, and 3:1). Compared with systems without Fe(II) in the presence of Mn(II), the coexisted Fe(II) significantly enhanced Mn(II) bio-oxidation and mineral precipitation, resulting in As immobilization increased by 5, 7, and 7 times at initial Fe(II) concentration of 0.3, 0.6, and 0.9 mM, respectively. Moreover, the As(III) immobilization efficiencies in Mn(II) and Fe(II) mixed system at initial Fe(II) concentration of 0.3, 0.6, and 0.9 mM were 73%, 91%, and 92%, respectively, that were significantly higher than those of single Fe(II) system (30%, 59%, and 74%) and those of single Mn(II) system (12%), indicating that Fe(II) and Mn(II) oxidation synergically enhanced As(III) immobilization. This was mainly attributed to the formation and As adsorption capacity of biogenic Fe-Mn minerals (BFMM). The formed BFMM significantly facilitated simultaneous immobilization of Fe, Mn, and As in PGAMF by oxidation, adsorption, and precipitation/coprecipitation, a coupling of biological, physical, and chemical processes. Fe component was mainly responsible for As fixation, and Mn component dominated As(III) oxidation. Based on the results from this work, biostimulation and bioaugmentation techniques can be developed for in-situ purification and remediation of PGAMF. This work provides insights into the simultaneous immobilization of pollutants in PGAMF, as well as promising strategies for in-situ purification and remediation of PGAMF.


Assuntos
Arsênio , Água Subterrânea , Poluentes Químicos da Água , Manganês , Oxigênio , Ferro , Minerais , Bactérias , Oxirredução , Compostos Ferrosos
4.
Sci Total Environ ; 858(Pt 1): 159721, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36306837

RESUMO

As a newly identified nitrogen loss pathway, the nitrate-dependent ferrous oxidation (NDFO) process is emerging as a research hotspot in the field of low carbon to nitrogen ratio (C/N) wastewater treatment. This review article provides an overview of the NDFO process and summarizes the functional microorganisms associated with NDFO from different perspectives. The potential mechanisms by which external factors such as influent pH, influent Fe(II)/N (mol), organic carbon, and chelating agents affect NDFO performance are also thoroughly discussed. As the electron-transfer mechanism of the NDFO process is still largely unknown, the extensive chemical Fe(II)-oxidizing nitrite-reducing pathway (NDFOchem) of the NDFO process is described here, and the potential enzymatic electron transfer mechanisms involved are summarized. On this basis, a three-stage electron transfer pathway applicable to low C/N wastewater is proposed. Furthermore, the impact of Fe(III) mineral products on the NDFO process is revisited, and existing crusting prevention strategies are summarized. Finally, future challenges facing the NDFO process and new research directions are discussed, with the aim of further promoting the development and application of the NDFO process in the field of nitrogen removal.


Assuntos
Desnitrificação , Compostos Ferrosos , Compostos Ferrosos/metabolismo , Compostos Férricos , Elétrons , Estudos Prospectivos , Nitratos/metabolismo , Óxidos de Nitrogênio , Oxirredução , Nitrogênio , Águas Residuárias , Carbono , Reatores Biológicos
5.
Sci Total Environ ; 855: 159003, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36155041

RESUMO

A majority of clay minerals contain Fe, and the redox cycling of Fe(III)/Fe(II) in clay minerals has been extensively studied as it may fuel the biogeochemical cycles of nutrients and govern the mobility, toxicity and bioavailability of a number of environmental contaminants. There are three types of Fe in clay minerals, including structural Fe sandwiched in the lattice of clays, Fe species in interlayer space and adsorbed on the external surface of clays. They exhibit distinct reactivity towards contaminants due to their differences in redox properties and accessibility to contaminant species. In natural environments, microbially driven Fe(III)/Fe(II) redox cycling in clay minerals is thought to be important, whereas reductants (e.g., dithionite and Fe(II)) or oxidants (e.g., peroxygens) are capable of enhancing the rates and extents of redox dynamics in engineered systems. Fe(III)-containing clay minerals can directly react with oxidizable pollutants (e.g., phenols and polycyclic aromatic hydrocarbons (PAHs)), whereas structural Fe(II) is able to react with reducible pollutants, such as nitrate, nitroaromatic compounds, chlorinated aliphatic compounds. Also structural Fe(II) can transfer electrons to oxygen (O2), peroxymonosulfate (PMS), or hydrogen peroxide (H2O2), yielding reactive radicals that can promote the oxidative transformation of contaminants. This review summarizes the recent discoveries on redox reactivity of Fe in clay minerals and its links to fates of environmental contaminants. The biological and chemical reduction mechanisms of Fe(III)-clay minerals, as well as the interaction mechanism between Fe(III) or Fe(II)-containing clay minerals and contaminants are elaborated. Some knowledge gaps are identified for better understanding and modelling of clay-associated contaminant behavior and effective design of remediation solutions.


Assuntos
Poluentes Ambientais , Ferro , Argila , Ferro/química , Peróxido de Hidrogênio , Minerais/química , Oxirredução , Compostos Ferrosos/química , Compostos Férricos/química
6.
J Hazard Mater ; 441: 129885, 2023 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-36115095

RESUMO

The hydroxylamine-enhanced Fe(II)/peracetic acid (PAA) process is a promising advanced oxidation process (AOP) with the generation of reactive species (RS) including RO•, •OH and Fe(IV). Nevertheless, it is still challenging to identify which RS is the major intermediate oxidant, and the reasons why the optimal condition is pH 4.5 rather than 3.0 are also unclear. Herein, the generation of RS and their contribution to the degradation of three micro-pollutants were explored. The quenching experiments and pseudo first-order kinetic model demonstrated that RO• rather than the other two RS were predominant. Then the overall generation and evolution pathways of RS were depicted. The elevation of pH (3.0-4.5) would accelerate the Fe(II)/Fe(III) redox cycle through the enhanced reduction of Fe(III) by hydroxylamine and induce the conversion of Fe(IV) to RO•, which benefited naproxen degradation. While the adverse Fe(III) precipitation would dominate the reduced degradation performance with the solution pH higher than 4.5. The elevation of PAA and Fe(II) dosages sped up the PAA activation, while excess hydroxylamine could consume the formed RS and exhibited an inhibitory effect. This study helps further understand the role of HA and differentiate the contribution of RS in the emerging PAA-based AOPs.


Assuntos
Poluentes Ambientais , Poluentes Químicos da Água , Compostos Férricos , Compostos Ferrosos , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Hidroxilamina , Hidroxilaminas , Ferro , Naproxeno , Oxidantes , Oxirredução , Ácido Peracético
7.
J Environ Sci (China) ; 124: 688-698, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36182174

RESUMO

It has been documented that organic contaminants can be degraded by hydroxyl radicals (•OH) produced by the activation of H2O2 by Fe(II)-bearing clay. However, the interfacial electron transfer reactions between structural Fe(II) and H2O2 for •OH generation and its effects on contaminant remediation are unclear. In this study, we first investigated the relation between •OH generation sites and sulfamethoxazole (SMX) degradation by activating H2O2 using nontronite with different reduction extents. SMX (5.2-16.9 µmol/L) degradation first increased and then decreased with an increase in the reduction extent of nontronite from 22% to 62%, while the •OH production increased continually. Passivization treatment of edge sites and structural variation results revealed that interfacial electron transfer reactions between Fe(II) and H2O2 occur at both the edge and basal plane. The enhancement on basal plane interfacial electron transfer reactions in a high reduction extent rNAu-2 leads to the enhancement on utilization efficiencies of structural Fe(II) and H2O2 for •OH generation. However, the •OH produced at the basal planes is less efficient in oxidizing SMX than that of at edge sites. Oxidation of SMX could be sustainable in the H2O2/rNAu-2 system through chemically reduction. The results of this study show the importance role of •OH generation sites on antibiotic degradation and provide guidance and potential strategies for antibiotic degradation by Fe(II)-bearing clay minerals in H2O2-based treatments.


Assuntos
Peróxido de Hidrogênio , Sulfametoxazol , Antibacterianos , Argila , Elétrons , Compostos Ferrosos , Minerais/química , Oxirredução , Sulfametoxazol/química
8.
J Environ Sci (China) ; 124: 89-97, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36182191

RESUMO

In situ and simultaneous remediation of a variety of pollutants in sediments remains a challenge. In this study, we report that the combination of electrocoagulation (EC) and electrooxidation (EO) is efficient in the immobilization of phosphorus and heavy metals and in the oxidation of ammonium and toxic organic matter. The integrated mixed metal oxide (MMO)/Fe anode system allowed the facile removal of ammonium and phosphorus in the overlying water (99% of 10 mg/L NH4+-N and 95% of 10 mg/L P disappeared in 15 and 30 min, respectively). Compared with the controls of the single Fe anode and single MMO anode systems, the dual MMO/Fe anode system significantly improved the removal of phenanthrene and promoted the transition of Pb and Cu from the mobile species to the immobile species. The concentrations of Pb and Cu in the toxicity characteristic leaching procedure extracts were reduced by 99% and 97% after an 8 hr operation. Further tests with four real polluted samples indicated that substantial proportions of acid-soluble fraction Pb and Cu were reduced (30%-31% for Pb and 16%-23% for Cu), and the amounts of total organic carbon and NH4+-N decreased by 56%-71% and 32%-63%, respectively. It was proposed that the in situ electrogenerated Fe(II) at the Fe anode and the active oxygen/chlorine species at the MMO anode are conducive to outstanding performance in the co-treatment of multiple pollutants. The results suggest that the EC/EO method is a powerful technology for the in situ remediation of sediments contaminated with different pollutants.


Assuntos
Compostos de Amônio , Poluentes Ambientais , Metais Pesados , Fenantrenos , Poluentes Químicos da Água , Carbono , Cloro , Eletrocoagulação , Compostos Ferrosos , Sedimentos Geológicos , Chumbo , Metais Pesados/análise , Óxidos , Fósforo , Espécies Reativas de Oxigênio , Água , Poluentes Químicos da Água/análise
9.
Chemosphere ; 310: 136693, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36202380

RESUMO

The potassium-doped magnetic biochar (KMBC) preparation was inevitably introduced the different anions in the process of modifying magnetic biochar (MBC) with different potassium salts, but the effect and mechanism of different anion on KMBC activation properties has not been reported. Therefore, in this paper, five different KMBCs were prepared using several common potassium salts under the same dosage of K+ and Fe2+, and then was added in the presence of persulfate (PS) for the removal of metronidazole (MNZ). The removal rate of metronidazole was ordered as KMBCK2SO4 (98.40%) > KMBCKNO3 (76.84%) > KMBCKCl (20.79%) > KMBCK2CO3 (19.02%) > KMBCK2C2O4 (14.23%). However, the semi-quantitative of Fe(II) experiments results confirmed that the effectively increase of Fe(II) content by potassium salts modification played the dominant role in improvement of KMBC activation performance. The Fe(II) content of KMBC were ordered as KMBCK2CO3 > KMBCK2SO4 > KMBCKNO3 > KMBCKCl > KMBCK2C2O4, with the Fe(II) content of KMBC of 36.74, 17.70, 8.79, 5.24 and 4.85 mg/g, respectively. The indicated that the introduction of different anions would lead to different optimal Fe(Ⅱ) content in KMBC modified with different potassium salts, which was most directly reflected in 1O2 content in different KMBC/PS systems, and account for the difference in MNZ degradation efficiency. Meanwhile, when the Fe(II) content in KMBC reached the range of 13.7-28.8 mg/g, KMBC had the better performance of activating PS.


Assuntos
Metronidazol , Poluentes Químicos da Água , Sais , Oxirredução , Potássio , Ânions , Compostos Ferrosos , Fenômenos Magnéticos , Poluentes Químicos da Água/análise
10.
Chemosphere ; 310: 136852, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36241115

RESUMO

Iron (Fe) salt was applied extensively to remove phosphorus (P) in wastewater treatment plants (WWTPs). Exploring the formation mechanism of iron-phosphorus compounds (FePs) during the chemical P removal (CPR) process is beneficial to P recovery. In this study, the performance of P removal, FePs speciation analysis and the kinetics of P removal under different conditions (pH, Fe/P molar ratio (Fe/Pmol), type of Fe salt, dissolved organic matters) were comprehensively investigated. More than 95% of P was removed under the optimal conditions with pH = 4.7, Fe/Pmol = 2, FeCl3 or polymeric ferric sulfate (PFS) as the coagulant. The FePs formation mechanism was considerably influenced by reaction conditions. Iron-phosphate compounds were the dominant FePs species (>76%) at pH < 6.2, while more iron oxides were formed at pH ≥ 6.2 with decreased P removal efficiency. When the initial Fe/Pmol was 2, iron-phosphate compound was the only product that was formed by the reaction between PO43- and Fe(III) or Fe(II) ions directly. More iron oxides were generated when the initial Fe/Pmol was 1 or 3. At Fe/Pmol = 1, the Fe(III) was hydrolyzed to form iron oxides and trapped PO43-, while at Fe/Pmol = 3, iron-phosphate compounds were produced firstly and the remaining Fe(III) was hydrolyzed to form iron oxides. The pseudo-second-order kinetic model simulated the chemical P removal process well. The reaction rate of P with Fe(II) was slower than that with Fe(III), but complete removal was still achieved when the reaction time was more than 30 min. Poly-Fe salt exhibited a fast P removal rate, while the removal efficiency depended on its iron content. Organic matters in wastewater with large molecular weight and multiple functional groups (such as humic acids) inhibited P removal rate but hardly affect the removal amount. This study provides an insight into CPR by Fe salts and is beneficial for P recovery in WWTPs.


Assuntos
Compostos Férricos , Compostos de Ferro , Compostos Férricos/química , Fósforo/química , Ferro/química , Fosfatos , Compostos Ferrosos/química , Óxidos/química
11.
J Inorg Biochem ; 238: 112035, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36327499

RESUMO

Nitric oxide synthase (NOS) is a cytochrome P450-type mono­oxygenase that catalyzes the oxidation of L-arginine to nitric oxide. We previously observed that intramolecular electron transfer from biopterin to Fe2+-O2 in Deinococcus radiodurans NOS (DrNOS) using pulse radiolysis. However, the rate of electron transfer in DrNOS (2.2 × 103 s-1) contrasts with a reported corresponding rate (11 s-1) in a mammalian NOS determined using rapid freeze-quench (RFQ) EPR. We applied pulse radiolysis to Bacillus subtilis NOS (bsNOS) and to rat neural NOS oxygenase domain NOS (mNOS). Concurrently, RFQ EPR was used to trap a pterin radical during single-turnover enzyme reactions of the enzymes. By using the pulse radiolysis method, hydrated electrons (eaq-) reduced the heme iron of NOS enzymes. Subsequently, ferrous heme reacted with O2 to form a Fe2+-O2 intermediate. In the presence of pterin, the intermediate of bsNOS was found to convert to other intermediate in the time range of milliseconds. A similar process was determined to have occurred after pulse radiolysis of the pterin-bound mNOS, though the rate was much slower. The intermediates of all of the NOS enzymes further converted to the original ferric form in the time range of seconds. When using the RFQ method, pterin radicals were formed very rapidly in both DrNOS and bsNOS in the time range of milliseconds. In contrast, the pterin radical in mNOS was observed to form slowly, at a rate of ∼20 s-1.


Assuntos
Biopterina , Óxido Nítrico , Animais , Ratos , Arginina/metabolismo , Biopterina/metabolismo , Elétrons , Compostos Ferrosos , Heme/metabolismo , Ferro , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/metabolismo , Oxirredução , Pterinas , Bacillus subtilis/enzimologia
12.
J Environ Sci (China) ; 125: 470-479, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36375930

RESUMO

The flooding and drainage of paddy fields has great effects on the transformation of heavy metals, however, the transformation of Cr in basalt-derived paddy soil with high geological background values was less recognized. The typical basalt-derived paddy soil was incubated under alternating redox conditions. The Cr fractions and the dynamics of Fe/N/S/C were examined. The HCl-extractable Cr increased under anaerobic condition and then decreased during aerobic stage. The UV-vis spectra of the supernatant showed that amounts of colloids were released under anaerobic condition, and then re-aggregated during aerobic phase. The scanning transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) revealed that Fe oxides were reduced and became dispersed during anaerobic stage, whereas Fe(II) was oxidized and recrystallized under aerobic condition. Based on these results, a kinetic model was established to further distinguish the relationship between the transformation of Cr and Fe. During anaerobic phase, the reduction of Fe(III) oxides not only directly released the structurally bound Cr, but also enhanced the breakdown of soil aggregation and dissolution of organic matter causing indirect mobilization of Cr. During aerobic phase, the oxidation of Fe(II) and further recrystallization of newly formed Fe(III) oxides might induce the re-aggregation of soil colloids and further incorporation of Cr. In addition, the kinetic model of Cr and Fe transformation was further verified in the pot experiment. The model-based findings demonstrated that the Cr transformation in the basalt-derived paddy soil with high geological background values was highly driven by redox sensitive iron cycling.


Assuntos
Poluentes do Solo , Solo , Solo/química , Ferro/química , Cromo/análise , Poluentes do Solo/análise , Oxirredução , Óxidos/química , Compostos Ferrosos
13.
Spectrochim Acta A Mol Biomol Spectrosc ; 285: 121845, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36152503

RESUMO

This paper reports on a chemiluminescence (CL) probe consist of CsPbBr3 quantum dots (QDs) in organic phase together with Fe(II) and K2S2O8 in aqueous medium for the highly selective and sensitive determination of the antibiotic, cefazolin (CFZ). The CsPbBr3perovskite QDs prepared by the ligand assisted reprecipitation method, exhibit a narrow fluorescence at 533 nm under 460 nm excitation with a high quantum yield (42 %). The Fe(II) - S2O82- as an ultra-weak CL system is converted to a rather strong CL sensing platform in the presence of organic-phase CsPbBr3 QDs. It was observed that CFZ exerts an enhancement effect on the CL signal of the designed probe in the linear range of 25 - 300 nM, with a low limit of detection (9.6 nM). The introduced sensor has broad application prospects in biosensing, food detection, and other fields with recovery ranging from 94 to 106 %.


Assuntos
Pontos Quânticos , Luminescência , Cefazolina , Compostos Ferrosos
14.
Spectrochim Acta A Mol Biomol Spectrosc ; 285: 121943, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36209713

RESUMO

In this article, a novel metal-organic framework, namely MIL-101(FeII), was firstly synthesized via a facile method. In the presence of H2O2, MIL-101(FeII) possesses excellent peroxidase-like activity toward the classical chromogenic substrate, N,N-Diethyl-p-phenylenediamine sulfate salt (DPD). The substitution of Fe2+ enhances the construction of Fe(II)-oxo nodes and accelerates electrons transfer between DPD and H2O2, thereby improving the peroxidase-mimicking catalytic activity of MIL-101(FeII) nanoenzyme. Additionally, DPD molecules could be adsorbed readily onto the surface of the nanoparticles due to the π-π interaction. The study of Michaelis constant indicates that the MIL-101(FeII) exhibits a higher affinity towards DPD (0.16 mM) in contrast to horseradish peroxidase (0.78 mM). In view of the impressive catalytic performance of MIL-101(FeII), two reliable monitoring platforms for the rapid detection of H2O2 and glucose were established with extremely low detection limits of 18.04 nM and 0.87 µM in the ranges of 40-5000 nM and 1.2-300 µM, respectively. The study of the catalytic mechanism indicates that DPD oxidation is attributed to the hydroxyl radical (·OH) produced from the decomposition of H2O2 catalyzed by MIL-101(FeII). Furthermore, the developed sensor indicates high selectivity and stability and can be effectively appropriate for the detection of H2O2 and glucose in real samples. This work not only provides a novel nanozyme with superior catalytic performance for biological analysis, but also broadens the application field of MIL-101(FeII) material.


Assuntos
Estruturas Metalorgânicas , Estruturas Metalorgânicas/química , Peroxidase/química , Colorimetria/métodos , Glucose/análise , Peróxido de Hidrogênio/análise , Corantes , Compostos Ferrosos
15.
Chemosphere ; 311(Pt 1): 137009, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36326516

RESUMO

In this work, the different selectivity of SO4•- and •OH towards municipal solid waste incineration leachates (MSWILs) was studied by a comparative study of UV/persulfate (PS) and UV/H2O2. Results showed SO4•- preferentially mineralized carbon atoms of higher average oxidation state, while •OH showed a two-stage mechanism of partial oxidation and mineralization successively. Electron spin resonance (ESR) analysis showed SO4•- had superior selectivity towards MSWILs than •OH, and Fe(II) would significantly affect the selectivity via forming Fe-MSWILs complex. As the consequence, Fe(II) showed slightly negative effect on UV/PS, but greatly enhanced the performance of UV/H2O2/Fe(II). High concentration of Cl- affected the degradation of non-fluorescent substances by UV/PS, while SO42- and NO3- showed no effect. In contrast, anions showed no effect on UV/H2O2. In addition, •OH preferentially attacked large molecules, but SO4•- showed no selectivity. This study further revealed the selectivity of SO4•- and •OH in the treatment of hypersaline wastewater, and provided theoretical support for the development of targeted technology.


Assuntos
Resíduos Sólidos , Poluentes Químicos da Água , Peróxido de Hidrogênio , Incineração , Raios Ultravioleta , Oxirredução , Compostos Ferrosos , Sulfatos
16.
J Hazard Mater ; 441: 129917, 2023 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-36099737

RESUMO

Quick and precise recovery of palladium (Pd) from electronic waste remains a serious task, owing to the strong acid and complexity of chemical compounds in leachate. Here, bioinspired construction of magnetic nano stirring rod with radially aligned dual mesopores and abundant 8-aminoquinoline (MNSR-DM-AQ) is proposed for selective and rapid extraction of Pd(II) from highly acidic sample solutions. Benefit from the unique dual mesoporous (12.4 nm and 3.6 nm) and the stirring motion under an external magnetic field, MNSR-DM-AQ possesses enhanced adsorption capacity and kinetics, achieving 11.62 mg g-1 (97.2 % of the maximum adsorption capacity) in 15 min. Distribution coefficient (KD = 299.0 mL g-1), separation factor (α above 25.54) and concentration factor (CF = 230.2 mL g-1) reveal the excellent selectivity of MNSR-DM-AQ towards Pd(II) when comparing with the coexisting ions (Ca(II), Co(II), Cu(II), Fe(II), Mg(II), Ni(II), Pb(II), Zn(II)). The adsorption mechanisms of MNSR-DM-AQ are ion exchange and chelation due to a strong affinity between Pd(II) and N. Meanwhile, 96.82 % of the captured Pd(II) can be easily eluted within 15 min, and the adsorption capacity remains stable after five adsorption-desorption cycles. It is worthwhile to mention that MNSR-DM-AQ exhibits a high adsorption capacity of 8.39 mg g-1 from leachate of abandoned high-voltage patch capacitor, which is greatly desired in Pd(II) extraction from electronic waste.


Assuntos
Paládio , Poluentes Químicos da Água , Ácidos/química , Adsorção , Compostos Ferrosos , Concentração de Íons de Hidrogênio , Íons , Cinética , Chumbo , Fenômenos Magnéticos , Paládio/química , Poluentes Químicos da Água/química
17.
Dalton Trans ; 51(46): 17753-17761, 2022 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-36346270

RESUMO

We have performed and analyzed the first combined 151Eu and 57Fe nuclear resonant vibrational spectroscopy (NRVS) for naturally abundant KEu(III)[Fe(II)(CN)6] and Eu(III)[Fe(III)(CN)6] complexes. Comparison of the observed 151Eu vs.57Fe NRVS spectroscopic features confirms that Eu(III) in both KEu(III)[Fe(II)(CN)6] and Eu(III)[Fe(III)(CN)6] occupies a position outside the [Fe(CN)6] core and coordinates to the N atoms of the CN- ions, whereas Fe(III) or Fe(II) occupies the site inside the [Fe(CN)6]4- core and coordinates to the C atoms of the CN- ions. In addition to the spectroscopic interest, the results from this study provide invaluable insights for the design and evaluation of the nanoparticles of such complexes as potential cellular contrast agents for their use in magnetic resonance imaging. The combined 151Eu and 57Fe NRVS measurements are also among the first few explorations of bi-isotopic NRVS experiments.


Assuntos
Compostos Ferrosos , Ferro , Ferro/química , Análise Espectral
18.
J Am Chem Soc ; 144(45): 20641-20652, 2022 11 16.
Artigo em Inglês | MEDLINE | ID: mdl-36382466

RESUMO

The new nonheme iron complexes FeII(BNPAPh2O)(N3) (1), FeIII(BNPAPh2O)(OH)(N3) (2), FeII(BNPAPh2O)(OH) (3), FeIII(BNPAPh2O)(OH)(NCS) (4), FeII(BNPAPh2O)(NCS) (5), FeIII(BNPAPh2O)(NCS)2 (6), and FeIII(BNPAPh2O)(N3)2 (7) (BNPAPh2O = 2-(bis((6-(neopentylamino)pyridin-2-yl) methyl)amino)-1,1-diphenylethanolate) were synthesized and characterized by single crystal X-ray diffraction (XRD), as well as by 1H NMR, 57Fe Mössbauer, and ATR-IR spectroscopies. Complex 2 was reacted with a series of carbon radicals, ArX3C· (ArX = p-X-C6H4), analogous to the proposed radical rebound step for nonheme iron hydroxylases and halogenases. The results show that for ArX3C· (X = Cl, H, tBu), only OH· transfer occurs to give ArX3COH. However, when X = OMe, a mixture of alcohol (ArX3COH) (30%) and azide (ArX3CN3) (40%) products was obtained. These data indicate that the rebound selectivity is influenced by the electron-rich nature of the carbon radicals for the azide complex. Reaction of 2 with Ph3C· in the presence of Sc3+ or H+ reverses the selectivity, giving only the azide product. In contrast to the mixed selectivity seen for 2, the reactivity of cis-FeIII(OH)(NCS) with the X = OMe radical derivative leads only to hydroxylation. Catalytic azidation was achieved with 1 as catalyst, λ3-azidoiodane as oxidant and azide source, and Ph3CH as test substrate, giving Ph3CN3 in 84% (TON = 8). These studies show that hydroxylation is favored over azidation for nonheme iron(III) complexes, but the nature of the carbon radical can alter this selectivity. If an OH· transfer pathway can be avoided, the FeIII(N3) complexes are capable of mediating both stoichiometric and catalytic azidation.


Assuntos
Azidas , Ferro , Ferro/química , Catálise , Espectroscopia de Ressonância Magnética , Carbono , Compostos Ferrosos/química , Isotiocianatos , Ligantes
19.
J Am Chem Soc ; 144(47): 21512-21520, 2022 11 30.
Artigo em Inglês | MEDLINE | ID: mdl-36395461

RESUMO

Non-heme iron enzymes are versatile catalysts in the biosynthesis of medicinal natural products and have attracted increasing attention as practical catalytic tools in chemical synthesis due to their ability to perform chemically challenging transformations. The Fe(II)/α-ketoglutarate-dependent oxygenase TqaL catalyzes unusual aziridine formation from l-Val via cleavage of the unactivated Cß-H bond. However, the mechanistic details as well as the synthetic potential of TqaL-catalyzed ring closure remain unclear. Herein, we show that the TqaL-catalyzed aziridination of l-Val proceeds with an atypical, mixed stereochemical course involving both the retention and inversion of the C3(Cß) stereocenter. It is also demonstrated that TqaL accepts l-Ile and l-allo-Ile to generate the same diastereomeric pairs of aziridine products via an enzyme-controlled, stereoconvergent process. Our mutagenesis studies reveal that the reaction type (aziridination versus hydroxylation) and the stereochemical outcome are regulated by Ile343 and Phe345. Proper substitutions of Ile343 or Phe345 also make TqaL highly active toward the oxidation of α-amino acid substrates. This work provides mechanistic insights into the stereoselectivity and substrate specificity of the TqaL reactions.


Assuntos
Aziridinas , Ácidos Cetoglutáricos , Oxigenases , Especificidade por Substrato , Compostos Ferrosos
20.
Water Res ; 227: 119351, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36399840

RESUMO

The incorporation of secondary metal atoms into iron oxyhydroxides may regulate the surface chemistry of mediating electron transfer (ET) and, therefore, the biogeochemical pollutant processes such as arsenic (As) in the subsurface and soils. The influence of incorporating two typical metals (Cu and Zn) into a specific {001} hematite facet on O2 activation by surface-bound Fe(II) was addressed. The results showed that Cu-incorporated hematite enhances As(III) oxidation in the presence of Fe(II) under oxic conditions and increases with increasing Cu content. Conversely, Zn incorporation leads to the opposite trend. The As(III) oxidation induced by surface-bound Fe(II) is positively related to the Fe(II) content and is favorable under acidic conditions. Reactive oxygen species (ROS), such as superoxide (·O2-) and H2O2, predominantly contribute to As(III) oxidation as a result of 1-electron transfer from bound Fe(II) to surface O2 on hematite and radical propagation. Electrochemical analysis demonstrates that Cu incorporation significantly lower the oxidation potential of Fe(II) on hematite, whereas Zn led to a higher reaction potential for Fe(II) oxidation. Subsequently, distinct surface reactivities of hematite for the activation of O2 to form ROS by surface-bound Fe(II) are evidenced by metal incorporation. Our study provides a new understanding of the changes in the surface chemistry of iron oxyhydroxides because of incorporating metals (Zn and Cu), and therefore impact the biogeochemical processes of pollutants in soils and subsurface environments.


Assuntos
Arsênio , Oxigênio , Peróxido de Hidrogênio , Espécies Reativas de Oxigênio , Metais , Solo , Ferro/química , Compostos Ferrosos/química
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