scholarly journals Degradation of Norfloxacin in an Aqueous Solution by the Nanoscale Zero-Valent Iron-Activated Persulfate Process

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yanchang Zhang ◽  
Lin Zhao ◽  
Yongkui Yang ◽  
Peizhe Sun
Keyword(s):  
Degradation Process ◽  
High Reactivity ◽  
Degradation Efficiency ◽  
Zero Valent Iron ◽  
Order Kinetic ◽  
Paramagnetic Resonance ◽  
Promising Alternative ◽  
Quenching Effect ◽  
Nanoscale Zero Valent Iron ◽  
Initial Ph

In this study, nanoscale zero-valent iron (nZVI) was synthesized and used to activate persulfate (PS) for the degradation of norfloxacin (NOR). The nZVI/PS system exhibited a high reactivity towards NOR, and the degradation efficiency of NOR (100 mg/L) reached 93.8% with 0.1 g/L nZVI, 12 mM PS, and an initial pH of 7.0 within 7 min. The NOR degradation followed a pseudo-first-order kinetic model, and the effects of parameters such as nZVI dosage, PS concentration, initial pH, and temperature were investigated systematically. Overloading of nZVI lowered the degradation efficiency owing to the quenching effect of excessive Fe2+. The higher PS concentration and temperature favored the degradation of NOR. The influence of pH was not obvious, and the degradation was effective in a wide pH range. In addition, the radical quenching experiments and electron paramagnetic resonance (EPR) indicated that both sulfate radical (SO4⋅-) and hydroxyl radical (OH⋅) were the dominant radicals in the degradation process, in which the latter played a more important role. Finally, three degradation pathways were proposed based on the result of intermediates identified by liquid chromatography-mass spectrometry. Overall, this study indicated that the nZVI/PS system could provide a promising alternative for NOR wastewater treatment.

scholarly journals Fenton-Like Oxidation of Antibiotic Ornidazole Using Biochar-Supported Nanoscale Zero-Valent Iron as Heterogeneous Hydrogen Peroxide Activator

2020 ◽  
Vol 17 (4) ◽  
pp. 1324 ◽  
Author(s):  
Yanchang Zhang ◽  
Lin Zhao ◽  
Yongkui Yang ◽  
Peizhe Sun
Keyword(s):  
Oxidation Process ◽  
Zero Valent Iron ◽  
Order Kinetic ◽  
Mass Ratio ◽  
Promising Alternative ◽  
Nanoscale Zero Valent Iron ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
H2o2 System

Biochar (BC)-supported nanoscale zero-valent iron (nZVI-BC) was investigated as a heterogeneous Fenton-like activator to degrade the antibiotic ornidazole (ONZ). The characterization of nZVI-BC indicated that BC could enhance the adsorption of ONZ and reduce the aggregation of nZVI. Thus, nZVI-BC had a higher removal efficiency (80.1%) than nZVI and BC. The effects of parameters such as the nZVI/BC mass ratio, pH, H2O2 concentration, nZVI-BC dose, and temperature were systematically investigated, and the removal of ONZ followed a pseudo-second-order kinetic model. Finally, possible pathways of ONZ in the oxidation process were proposed. The removal mechanism included the adsorption of ONZ onto the surface of nZVI-BC, the generation of •OH by the reaction of nZVI with H2O2, and the oxidation of ONZ. Recycling experiments indicated that the nZVI-BC/H2O2 system is a promising alternative for the treatment of wastewater containing ONZ.

scholarly journals Efficient Sequestration of Hexavalent Chromium by Graphene-Based Nanoscale Zero-Valent Iron Composite Coupled with Ultrasonic Pretreatment

2021 ◽  
Vol 18 (11) ◽  
pp. 5921
Author(s):  
Haiyan Song ◽  
Wei Liu ◽  
Fansheng Meng ◽  
Qi Yang ◽  
Niandong Guo
Keyword(s):  
Aqueous Solution ◽  
Removal Efficiency ◽  
Inhibitory Effect ◽  
Ultrasonic Cavitation ◽  
Zero Valent Iron ◽  
Ultrasonic Pretreatment ◽  
Nanoscale Zero Valent Iron ◽  
Passivation Layers ◽  
Initial Ph ◽  
Two Phases

Nanoscale zero-valent iron (nZVI) has attracted considerable attention for its potential to sequestrate and immobilize heavy metals such as Cr(VI) from an aqueous solution. However, nZVI can be easily oxidized and agglomerate, which strongly affects the removal efficiency. In this study, graphene-based nZVI (nZVI/rGO) composites coupled with ultrasonic (US) pretreatment were studied to solve the above problems and conduct the experiments of Cr(VI) removal from an aqueous solution. SEM-EDS, BET, XRD, and XPS were performed to analyze the morphology and structures of the composites. The findings showed that the removal efficiency of Cr(VI) in 30 min was increased from 45.84% on nZVI to 78.01% on nZVI/rGO and the removal process performed coupled with ultrasonic pretreatment could greatly shorten the reaction time to 15 min. Influencing factors such as the initial pH, temperature, initial Cr(VI) concentration, and co-existing anions were studied. The results showed that the initial pH was a principal factor. The presence of HPO42−, NO3−, and Cl− had a strong inhibitory effect on this process, while the presence of SO42− promoted the reactivity of nZVI/rGO. Combined with the above results, the process of Cr(VI) removal in US-nZVI/rGO system consisted of two phases: (1) The initial stage is dominated by solution reaction. Cr(VI) was reduced in the solution by Fe2+ caused by ultrasonic cavitation. (2) In the following processes, adsorption, reduction, and coprecipitation coexisted. The addition of rGO enhanced electron transportability weakened the influence of passivation layers and improved the dispersion of nZVI particles. Ultrasonic cavitation caused pores and corrosion at the passivation layers and fresh Fe0 core was exposed, which improved the reactivity of the composites.

scholarly journals Removal efficiency of hexavalent chromium from wastewater using starch-stabilized nanoscale zero-valent iron

2019 ◽  
Vol 80 (6) ◽  
pp. 1076-1084 ◽  
Author(s):  
Hualin Chen ◽  
Huajun Xie ◽  
Jiangmin Zhou ◽  
Yueliang Tao ◽  
Yongpu Zhang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Reactivity ◽  
Zero Valent Iron ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Reduction ◽  
Nanoscale Zero Valent Iron ◽  
Removal Efficiencies ◽  
Ph Range ◽  
Uniform Particle Size

Abstract In this study, starch-stabilized nanoscale zero-valent iron (S-nZVI) was produced using the liquid-phase reduction method. It was used to remove chromium from wastewater, and compared to a commercial nanoscale zero-valent iron (C-nZVI). Both nZVIs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The characterization results showed that S-nZVI had smaller particles and a more uniform particle size distribution than C-nZVI. Both nZVIs showed a core-shell structure with the Fe0 core prominently surrounded by less iron oxides of Fe2+ and Fe3+. The optimal application methods to remove Cr(VI) from wastewater were also explored. The results showed that both the removal efficiencies of total Cr and Cr(VI) increased with increases in the addition of nZVIs, while the removal efficiencies of total Cr and Cr(VI) by S-nZVI were clearly higher than that of C-nZVI, especially in a low pH range (pH = 1.0–6.0). This research indicated that starch-stabilized nanoscale zero-valent iron is a valuable material to remove heavy metals from wastewater due to its stability and high reactivity.

scholarly journals Well-Dispersed Nanoscale Zero-Valent Iron Supported in Macroporous Silica Foams: Synthesis, Characterization, and Performance in Cr(VI) Removal

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Chaoxia Zhao ◽  
Jie Yang ◽  
Yihan Wang ◽  
Bo Jiang
Keyword(s):  
Removal Efficiency ◽  
Shell Structure ◽  
Zero Valent Iron ◽  
Core Shell ◽  
Ambient Atmosphere ◽  
Order Kinetic ◽  
Macroporous Silica ◽  
X Ray ◽  
Nanoscale Zero Valent Iron ◽  
Core Shell Structure

Well-dispersed nanoscale zero-valent iron (NZVI) supported inside the pores of macroporous silica foams (MOSF) composites (Mx-NZVI) has been prepared as the Cr(VI) adsorbent by simply impregnating the MOSF matrix with ferric chloride, followed by the chemical reduction with NaHB4 in aqueous solution at ambient atmosphere. Through the support of MOSF, the reactivity and stability of NZVI are greatly improved. Transmission electron microscopy (TEM) results show that NZVI particles are spatially well-dispersed with a typical core-shell structure and supported inside MOSF matrix. The N2 adsorption-desorption isotherms demonstrate that the Mx-NZVI composites can maintain the macroporous structure of MOSF and exhibit a considerable high surface area (503 m2·g−1). X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD) measurements confirm the core-shell structure of iron nanoparticles composed of a metallic Fe0 core and an Fe(II)/Fe(III) species shell. Batch experiments reveal that the removal efficiency of Cr(VI) can reach 100% when the solution contains 15.0 mg·L−1 of Cr(VI) at room temperature. In addition, the solution pH and the composites dosage can affect the removal efficiency of Cr(VI). The Langmuir isotherm is applicable to describe the removal process. The kinetic studies demonstrate that the removal of Cr(VI) is consistent with pseudo-second-order kinetic model.

scholarly journals Degradation of the antibiotic ornidazole in aqueous solution by using nanoscale zero-valent iron particles: kinetics, mechanism, and degradation pathway

RSC Advances ◽  
2018 ◽  
Vol 8 (61) ◽  
pp. 35062-35072 ◽  
Author(s):  
Yanchang Zhang ◽  
Lin Zhao ◽  
Yongkui Yang ◽  
Peizhe Sun
Keyword(s):  
Aqueous Solution ◽  
Degradation Process ◽  
Degradation Pathway ◽  
Zero Valent Iron ◽  
Main Mechanism ◽  
Iron Particles ◽  
Nanoscale Zero Valent Iron ◽  
Nitro Reduction

The whole possible process of ONZ removal by nZVI. The reduction on the surface of nZVI was the main mechanism. A potential pathway including dechlorination, nitro reduction, N-denitration, and cleavage was proposed for the degradation process.

Performance of Nano Zero-Valent Iron Derived from the Decomposition of Siderite in the Removal of Phosphate

2021 ◽  
Vol 21 (1) ◽  
pp. 623-631
Author(s):  
Yueling Zhao ◽  
Haibo Liu ◽  
Tianhu Chen ◽  
Dong Chen ◽  
Chen Chen ◽  
...  
Keyword(s):  
Orthogonal Experiment ◽  
Zero Valent Iron ◽  
Raw Material ◽  
Order Kinetic ◽  
Experimental Conditions ◽  
P Concentration ◽  
Initial Ph ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Nano Zero Valent Iron

Natural siderite was selected as a raw material for preparing nano zero-valent iron (nZVI). The efficiency of the as-synthesized nZVI for PO3−4–P removal was investigated, and the effects of the annealing temperature, pH, initial PO3−4–P concentration, adsorption temperature and oxygen were investigated. The results indicated that after annealing at 550 °C, nZVI exhibited an average crystal size of 56.3 nm and a surface area of 14.1 m2/g. A decrease in pH and an increase in oxygen availability enhanced the removal efficiency. The adsorption process, which was spontaneous and exothermic according to the thermodynamic analysis, agreed well with the pseudo-second-order kinetic model. Based on the Langmuir equilibrium isotherms, the capacity of nZVI to adsorb phosphorus was determined to be 33.18 mg/L. The optimized conditions for the experimental conditions were defined by an orthogonal experiment as follows: initial P concentration 2 mg/L, initial pH 4, iron dose 2 g/L, adsorption time 60 min. The experimental results suggested that the as-prepared nZVI was a promising adsorbent for the removal of phosphate.

Degradation of bromamine acid by nanoscale zero-valent iron (nZVI) supported on sepiolite

2012 ◽  
Vol 66 (12) ◽  
pp. 2539-2545 ◽  
Author(s):  
Xuening Fei ◽  
Lingyun Cao ◽  
Lifeng Zhou ◽  
Yingchun Gu ◽  
Xiaoyang Wang
Keyword(s):  
Ph Value ◽  
Energy Dispersive Spectrometer ◽  
Zero Valent Iron ◽  
Mass Ratio ◽  
Initial Concentration ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Nanoscale Zero Valent Iron ◽  
Initial Ph ◽  
Set Up

Sepiolite, a natural nano-material, was chosen as a carrier to prepare supported nanoscale zero-valent iron (nZVI). The effects of preparation conditions, including mass ratio of nZVI and activated sepiolite and preparation pH value, on properties of the supported nZVI were investigated. The results showed that the optimal mass ratio of nZVI and sepiolite was 1.12:1 and the optimal pH value was 7. The supported nZVI was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS), and furthermore an analogy model of the supported nZVI was set up. Compared with the nZVI itself, the supported nZVI was more stable in air and possessed better water dispersibility, which were beneficial for the degradation of bromamine acid aqueous solution. The degradation characteristics, such as effects of supported nZVI dosage, initial concentration and initial pH value of the solution on the decolorization efficiency were also investigated. The results showed that in an acidic environment the supported nZVI with a dosage of 2 g/L showed high activity in the degradation of bromamine acid with an initial concentration of 1,000 mg/L, and the degree of decolorization could reach up to 98%.

Fate of nitrogen species in nitrate reduction by nanoscale zero valent iron and characterization of the reaction kinetics

2010 ◽  
Vol 61 (3) ◽  
pp. 705-712 ◽  
Author(s):  
Y. H. Hwang ◽  
D. G. Kim ◽  
Y. T. Ahn ◽  
C. M. Moon ◽  
H. S. Shin
Keyword(s):  
Nitrate Reduction ◽  
Chemical Reduction ◽  
Reduction Rate ◽  
Zero Valent Iron ◽  
Ammonium Ion ◽  
Alkaline Condition ◽  
Order Kinetic ◽  
Nitrogen Species ◽  
Nanoscale Zero Valent Iron ◽  
Fate Of Nitrogen

This study investigates the fate of nitrogen species during nitrate reduction by nanoscale zero valent iron (NZVI) as well as the related kinetics. The NZVI used for the experiments was prepared by chemical reduction without a stabilizing agent. The pseudo first order kinetic constant of nitrate reduction at 30°C with an NZVI/nitrate ratio of 1.25:1, which were the reference conditions of this study, was 4.08 h−1 (R2 = 0.955). A nitrogen mass balance was established by quantitative analysis of aqueous-phase and gas-phase nitrogen species. The results confirm that the nitrate was converted to ammonium ion, that ammonia stripping subsequently occurred under a strong alkaline condition, and that the total amount of aqueous nitrogen was consequently reduced. The nitrate reduction rate also increased with a lower pH and a higher temperature when microscale ZVI was used. However, in contrast to the reaction by microscale ZVI, the nitrate reduction rate by NZVI was higher for an unbuffered condition, possibly due to the abundance of surface atoms and the smaller size.

scholarly journals Preparation of Nanosized Zero-Valent zinc (Zn0) Immobilized on ZnO as Redox Nanocomposite for Degradation of Methyl Orange from Aqueous Solution

2019 ◽  
Author(s):  
Samira Taherkhani ◽  
Ali Khani
Keyword(s):  
Aqueous Solution ◽  
Methyl Orange ◽  
Gas Flow ◽  
Degradation Process ◽  
Degradation Efficiency ◽  
Effect Of Temperature ◽  
Order Kinetic ◽  
Zno Nanopowder ◽  
Order Kinetic Model ◽  
Degradation Of Methyl Orange

Introduction: In this study, nanosized zero-valent zinc (Zn0) as a reducing agent, simultaneously synthesized and immobilized on an oxidizing agent, ZnO photocatalyst for degradation of methyl orange (MO) from the aqueous solution. Materials and Methods: The prepared redox nanocomposite (nZn0-ZnO) was characterized by the XRD and SEM techniques. The prepared sample was separated by centrifuging. The preparation process of nZn0-ZnO including synthesis-immobilization, washing, and drying carried out under Argon gas flow. Moreover, the effect of temperature and kinetics reaction was studied. Results: The results showed that degradation efficiency of prepared redox nanocomposite was increased compared to each ZnO nanopowder and Zn0 under the same operational condition. The calculated activation energy for the degradation process was 4.05 KJ.mol-1. Finally, the results showed that the degradation processes followed pseudo first order kinetic model in the basic condition by the relative deviation modulus. Conclusion: As compared to ZnO nanopowder and Zn0, the prepared redox nanocomposite showed high degradation efficiency for the removal of methyl orange from the aqueous solution.

scholarly journals Thermal Stability and Degradation Kinetics of Patulin in Highly Acidic Conditions: Impact of Cysteine

Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 662
Author(s):  
Enjie Diao ◽  
Kun Ma ◽  
Hui Zhang ◽  
Peng Xie ◽  
Shiquan Qian ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Degradation Kinetics ◽  
Correlation Coefficients ◽  
Degradation Process ◽  
Weibull Model ◽  
Degradation Efficiency ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
Acidic Conditions ◽  
Kinetics Of

The thermal stability and degradation kinetics of patulin (PAT, 10 μmol/L) in pH 3.5 of phosphoric-citric acid buffer solutions in the absence and presence of cysteine (CYS, 30 μmol/L) were investigated at temperatures ranging from 90 to 150 °C. The zero-, first-, and second-order models and the Weibull model were used to fit the degradation process of patulin. Both the first-order kinetic model and Weibull model better described the degradation of patulin in the presence of cysteine while it was complexed to simulate them in the absence of cysteine with various models at different temperatures based on the correlation coefficients (R2 > 0.90). At the same reaction time, cysteine and temperature significantly affected the degradation efficiency of patulin in highly acidic conditions (p < 0.01). The rate constants (kT) for patulin degradation with cysteine (0.0036–0.3200 μg/L·min) were far more than those of treatments without cysteine (0.0012–0.1614 μg/L·min), and the activation energy (Ea = 43.89 kJ/mol) was far less than that of treatment without cysteine (61.74 kJ/mol). Increasing temperature could obviously improve the degradation efficiency of patulin, regardless of the presence of cysteine. Thus, both cysteine and high temperature decreased the stability of patulin in highly acidic conditions and improved its degradation efficiency, which could be applied to guide the detoxification of patulin by cysteine in the juice processing industry.

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