Enhanced molybdenum(VI) removal using sulfide-modified nanoscale zerovalent iron: kinetics and influencing factors

Abstract The overall goal of this study is to investigate the effect of sulfidated nanoscale zerovalent iron (S-nZVI) on the removal of hexavalent molybdate (MoO42-) under different aquatic chemistry conditions. Surface analysis suggests that Mo(VI) is removed mainly by adsorption and co-precipitation onto the surface of S-nZVI and a small amount of Mo(VI) can be reduced to Mo(V) species. The results of batch tests show that Mo(VI) removal by S-nZVI are well described with the pseudo-second order adsorption model. The removal rate increases with a decrease in solution pH (4.0–9.0) and significantly affected by the S/Fe ratio of S-nZVI with the optimal S/Fe ratio of 0.5. The presence of anions WO42- or CrO42- can reduce the Mo(VI) removal, which is likely due to that they compete for adsorption sites on the solid surfaces. The divalent cations Ni2+, Cu2+ and Co2+ also inhibit the removal of Mo(VI) whereas Zn2+, Ca2+ and Mg2+ enhance it. After aged for 35 d in water, S-nZVI still exhibits high reactivity towards Mo(VI) removal (57.39%). The study demonstrate that S-nZVI can be used as an environmentally friendly material for effectively removing Mo(VI) from contaminated water.

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Adsorptive and Reductive Removal of Chlorophenol from Wastewater by Biomass-Derived Mesoporous Carbon-Supported Sulfide Nanoscale Zerovalent Iron

Nanomaterials ◽

10.3390/nano9121786 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1786 ◽

Cited By ~ 3

Author(s):

Hui Wang ◽

Sixiang Cai ◽

Liang Shan ◽

Min Zhuang ◽

Nan Li ◽

...

Keyword(s):

Synergistic Effect ◽

Mesoporous Carbon ◽

Removal Rate ◽

Water Environment ◽

Surface Oxidation ◽

Zerovalent Iron ◽

Adsorption Model ◽

Biomass Waste ◽

Nanoscale Zerovalent Iron ◽

Pseudo Second Order

Chlorinated compounds in a water environment pose serious threats to humanity. A nanoscale zerovalent iron (nZVI) has desirable properties for water dichlorination, but its reactivity is still limited by agglomeration and oxidation. In this study, the mesoporous carbon (MC) derived from biomass waste was prepared for immobilizing nZVI, and the nZVI@MC was further modified by sulfur (S-nZVI@MC) to relieve surface oxidation. The synergistic effect between nZVI and surface modification, the reaction conditions and the removal mechanism were investigated systematically. The characterization results showed nZVI was successfully loaded on the surface of MC, and the aggregation of nZVI was prevented. Moreover, sulfidation modification resulted in the formation of FeS on the surface of nZVI, which effectively alleviated surface oxidation of nZVI and promoted the electron transfer. Batch experiments demonstrated S-nZVI@MC had greatly enhanced reactivity towards 2,4,6-trichlorphenol (TCP) as compared to MC and nZVI, and the removal rate could reach 100%, which was mainly attributed to the significant synergistic effect of MC immobilization and sulfidation modification. Furthermore, the TCP removal process was well described by a Langmuir adsorption model and pseudo-second-order model. The possible mechanism for enhanced removal of TCP is the fast adsorption onto S-nZVI@MC and effective reduction by S-nZVI. Therefore, with excellent reducing activity and antioxidation, S-nZVI@MC has the potential as a pollutant treatment.

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Synthesis of Nanoscale Zerovalent Iron (nZVI) Supported on Biochar for Chromium Remediation from Aqueous Solution and Soil

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16224430 ◽

2019 ◽

Vol 16 (22) ◽

pp. 4430 ◽

Cited By ~ 5

Author(s):

Haixia Wang ◽

Mingliang Zhang ◽

Hongyi Li

Keyword(s):

Aqueous Solution ◽

Photoelectron Spectroscopy ◽

Zero Valent Iron ◽

Zerovalent Iron ◽

X Ray ◽

Nanoscale Zerovalent Iron ◽

Before And After ◽

Pseudo Second Order ◽

Xrd Patterns ◽

Co Precipitation

Maize straw biochar-supported nanoscale zero-valent iron composite (MSB-nZVI) was prepared for efficient chromium (Cr) removal through alleviating the aggregation of zero-valent iron particles. The removal mechanism of MSB-nZVI was investigated by scanning electron microscopy with energy dispersive X-ray (SEM-EDX), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). Cr(VI) removal from aqueous solution by MSB-nZVI was greatly affected by pH and initial concentration. The removal efficiency of Cr(VI) decreased with increasing pH, and the removal kinetics followed the pseudo-second-order model. XRD patterns of MSB-nZVI before and after reaction showed that reduction and precipitation/co-precipitation (FeCr2O4, Fe3O4, Fe2O3) occurred with the conversion of Cr(VI) to Cr(III) and Fe(0) to Fe(II)/Fe(III). The produced precipitation/co-precipitation could be deposited on the MSB surface rather than being only coated on the surface of nZVI particles, which can alleviate passivation of nZVI. For remediation of Cr(VI)-contaminated saline–alkali soil (pH 8.6–9.0, Cr 341 mg/kg), the released amount of Cr(VI) was 70.7 mg/kg, while it sharply decreased to 0.6–1.7 mg/kg at pH 4.0–8.0, indicating that the saline–alkali environment inhibited the remediation efficiency. These results show that MSB-nZVI can be used as an effective material for Cr(VI) removal from aqueous solution and contaminated soil.

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Effect of Water Chemistry on Antimony Removal by Chemical Coagulation: Implications of ζ-Potential and Size of Precipitates

International Journal of Molecular Sciences ◽

10.3390/ijms20122945 ◽

2019 ◽

Vol 20 (12) ◽

pp. 2945 ◽

Cited By ~ 2

Author(s):

Muhammad Ali Inam ◽

Rizwan Khan ◽

Muhammad Akram ◽

Sarfaraz Khan ◽

Ick Tae Yeom

Keyword(s):

Water Chemistry ◽

Divalent Cations ◽

Chemical Properties ◽

Point Of Zero Charge ◽

Hydrodynamic Diameter ◽

Alkaline Ph ◽

Solution Ph ◽

Ζ Potential ◽

Wide Group ◽

Co Precipitation

The process of coagulation and precipitation affect the fate and mobility of antimony (Sb) species in drinking water. Moreover, the solubility and physico-chemical properties of the precipitates may be affected by the media chemistry. Accordingly, the present study aimed to investigate the removal of Sb(III, V) species by ferric chloride coagulation under various water chemistry influences with a particular focus on the role of the properties of the precipitates. The results indicated that the amount of Sb(III) removed increased with increasing solution pH, showing the insignificant effects of the hydrodynamic diameter (HDD) and ζ-potential of the precipitates. However, no Sb(V) removal occurred at alkaline pH values, while a highly negative ζ-potential and the complete dissolution of precipitates were observed in the aqueous solution. The solution pH was also useful in determining the dominant coagulation mechanisms, such as co-precipitation and adsorption. The Fe solubility substantially affects the Sb removal at a certain pH range, while the HDD of the precipitates plays an insignificant role in Sb removal. The presence of divalent cations brings the ζ-potential of the precipitates close to point of zero charge (pzc), thus enhancing the Sb(V) removal at alkaline pH conditions. Pronounced adverse effects of humic acid were observed on Sb removal, ζ-potential and HDD of the precipitates. In general, this study may provide critical information to a wide group of researchers dealing with environmental protection from heavy metal pollution.

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Removal of Different Kinds of Heavy Metals by Novel PPG-nZVI Beads and Their Application in Simulated Stormwater Infiltration Facility

Applied Sciences ◽

10.3390/app9204213 ◽

2019 ◽

Vol 9 (20) ◽

pp. 4213

Author(s):

Xiaoran Zhang ◽

Lei Yan ◽

Junfeng Liu ◽

Ziyang Zhang ◽

Chaohong Tan

Keyword(s):

Metal Ions ◽

Adsorption Process ◽

Guar Gum ◽

Removal Rate ◽

Zerovalent Iron ◽

Contaminated Water ◽

Maximum Adsorption Capacity ◽

Covalent Bonds ◽

Nanoscale Zerovalent Iron ◽

Stormwater Infiltration

Polyvinyl alcohol and pumice synthetized guar gum-nanoscale zerovalent iron beads (PPG-nZVI beads) were synthesized, and their adsorption towards Pb2+, Cu2+, and Zn2+ ions was evaluated. The adsorption kinetics of metal ions was well fitted by the pseudo-second-order model. The adsorption rate decreased followed in the order of Cu2+ > Pb2+ > Zn2+, consistent with the reduction potential of the ions. The sorption isotherm was well fitted by Langmuir model. The maximum adsorption capacity decreased followed in the order of Pb2+ > Cu2+ > Zn2+, which suggested that the strength of covalent bonds between the metal ions and surface functional groups substituted to the beads is one of the major factors in the adsorption process. Adsorption increased with the increase of pH and the largest sorption occurred at pH 5.5, while ionic strength did not significantly influence the adsorption process. The application of PPG-nZVI beads as filling materials in the simulated stormwater infiltration facility shows good removal efficiency in treating the contaminated water containing Pb2+, Cu2+, Zn2+, Cr6+, and Cd2+ and the removal rate was more than 65% at least. The results indicated that the PPG-nZVI beads could be applied as promising sorbents for purification of heavy metal contaminated water.

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Degradation Kinetics of Methyl Orange Dye in Water Using Trimetallic Fe/Cu/Ag Nanoparticles

Catalysts ◽

10.3390/catal11040428 ◽

2021 ◽

Vol 11 (4) ◽

pp. 428

Author(s):

Masaku Kgatle ◽

Keneiloe Sikhwivhilu ◽

Gebhu Ndlovu ◽

Nosipho Moloto

Keyword(s):

Methyl Orange ◽

Ag Nanoparticles ◽

Azo Dye ◽

Degradation Kinetics ◽

Zerovalent Iron ◽

Solution Ph ◽

Nanoscale Zerovalent Iron ◽

Dye Pollutants ◽

Efficient Alternative ◽

Sodium Borohydride Reduction

The release of azo dye contaminants from textile industries into the environment is an issue of major concern. Nanoscale zerovalent iron (nZVI) has been extensively studied in the degradation of azo dye pollutants such as methyl orange (MO). In this study, iron was coupled with copper and silver to make trimetallic Fe/Cu/Ag nanoparticles, in order to enhance the degradation of MO and increase reactivity of the catalyst by delaying the rate of oxidation of iron. The synthesis of the trimetallic nanoparticles (Fe/Cu/Ag) was carried out using the sodium borohydride reduction method. The characterization of the particles was performed using XRD, XPS, EDX, and TEM. The analyses confirmed the successful synthesis of the nanoparticles; the TEM images also showed the desired structures and geometry of the nanoscale zerovalent iron particles. The assessment of the nanoparticles in the degradation of methyl orange showed a notable degradation within few minutes into the reaction. The effect of parameters such as nanoparticle dosage, initial MO concentration, and the solution pH on the degradation of MO using the nanoparticles was investigated. Methyl orange degradation efficiency reached 100% within 1 min into the reaction at a low pH, with lower initial MO concentration and higher nanoparticle dosage. The degradation rate of MO using the nanoparticles followed pseudo first-order kinetics and was greatly influenced by the studied parameters. Additionally, LC-MS technique confirmed the degradation of MO within 1 min and that the degradation occurs through the splitting of the azo bond. The Fe/Cu/Ag trimetallic nanoparticles have proven to be an appropriate and efficient alternative for the treatment of dye wastewater.

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Heterogeneous Fenton Catalytic Removal of Organic Pollutant in Aqueous Solution by using Coal Gangue as a Catalyst

Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) ◽

10.2174/2405520412666190806120033 ◽

2019 ◽

Vol 12 (4) ◽

pp. 312-325

Author(s):

Jiwei Zhang ◽

Jingjing Xu ◽

Shuaixia Liu ◽

Baoxiang Gu ◽

Feng Chen ◽

...

Keyword(s):

Aqueous Solution ◽

Hydrogen Peroxide ◽

Hydroxyl Radical ◽

Removal Rate ◽

Organic Pollutant ◽

Coal Gangue ◽

Ion Leakage ◽

Heterogeneous Fenton ◽

Solution Ph ◽

X Ray

Background: Coal gangue was used as a catalyst in heterogeneous Fenton process for the degradation of azo dye and phenol. The influencing factors, such as solution pH gangue concentration and hydrogen peroxide dosage were investigated, and the reaction mechanism between coal gangue and hydrogen peroxide was also discussed. Methods: Experimental results showed that coal gangue has the ability to activate hydrogen peroxide to degrade environmental pollutants in aqueous solution. Under optimal conditions, after 60 minutes of treatment, more than 90.57% of reactive red dye was removed, and the removal efficiency of Chemical Oxygen Demand (COD) up to 72.83%. Results: Both hydroxyl radical and superoxide radical anion participated in the degradation of organic pollutant but hydroxyl radical predominated. Stability tests for coal gangue were also carried out via the continuous degradation experiment and ion leakage analysis. After five times continuous degradation, dye removal rate decreased slightly and the leached Fe was still at very low level (2.24-3.02 mg L-1). The results of Scanning Electron Microscope (SEM), energy dispersive X-Ray Spectrometer (EDS) and X-Ray Powder Diffraction (XRD) indicated that coal gangue catalyst is stable after five times continuous reuse. Conclusion: The progress in this research suggested that coal gangue is a potential nature catalyst for the efficient degradation of organic pollutant in water and wastewater via the Fenton reaction.

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Designing of a nanoscale zerovalent iron@fly ash composite as efficient and sustainable adsorbents for hexavalent chromium (Cr(VI)) from water

Environmental Science and Pollution Research ◽

10.1007/s11356-020-11692-1 ◽

2021 ◽

Author(s):

Shubhangi Madan ◽

Urvashi Thapa ◽

Sangeeta Tiwari ◽

Sandeep Kumar Tiwari ◽

Suresh Kumar Jakka ◽

...

Keyword(s):

Fly Ash ◽

Hexavalent Chromium ◽

Zerovalent Iron ◽

Nanoscale Zerovalent Iron

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Removal of hexavalent chromium from wastewater by Cu/Fe bimetallic nanoparticles

Scientific Reports ◽

10.1038/s41598-021-90414-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jien Ye ◽

Yi Wang ◽

Qiao Xu ◽

Hanxin Wu ◽

Jianhao Tong ◽

...

Keyword(s):

Hexavalent Chromium ◽

Removal Efficiency ◽

Photoelectron Spectroscopy ◽

Bimetallic Nanoparticles ◽

Chemical Reduction ◽

Particle Surface ◽

Zerovalent Iron ◽

Order Model ◽

X Ray ◽

Nanoscale Zerovalent Iron

AbstractPassivation of nanoscale zerovalent iron hinders its efficiency in water treatment, and loading another catalytic metal has been found to improve the efficiency significantly. In this study, Cu/Fe bimetallic nanoparticles were prepared by liquid-phase chemical reduction for removal of hexavalent chromium (Cr(VI)) from wastewater. Synthesized bimetallic nanoparticles were characterized by transmission electron microscopy, Brunauer–Emmet–Teller isotherm, and X-ray diffraction. The results showed that Cu loading can significantly enhance the removal efficiency of Cr(VI) by 29.3% to 84.0%, and the optimal Cu loading rate was 3% (wt%). The removal efficiency decreased with increasing initial pH and Cr(VI) concentration. The removal of Cr(VI) was better fitted by pseudo-second-order model than pseudo-first-order model. Thermodynamic analysis revealed that the Cr(VI) removal was spontaneous and endothermic, and the increase of reaction temperature facilitated the process. X-ray photoelectron spectroscopy (XPS) analysis indicated that Cr(VI) was completely reduced to Cr(III) and precipitated on the particle surface as hydroxylated Cr(OH)3 and CrxFe1−x(OH)3 coprecipitation. Our work could be beneficial for the application of iron-based nanomaterials in remediation of wastewater.

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Synthesis of Polymer-Based Magnetic Nanocomposite for Multi-Pollutants Removal from Water

Polymers ◽

10.3390/polym13111742 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1742

Author(s):

Fatimah Mohammed Alzahrani ◽

Norah Salem Alsaiari ◽

Khadijah Mohammedsaleh Katubi ◽

Abdelfattah Amari ◽

Faouzi Ben Rebah ◽

...

Keyword(s):

Adsorption Process ◽

Magnetic Composite ◽

Sample Treatment ◽

Water Type ◽

X Ray Diffraction ◽

Solution Ph ◽

Vibration Sample Magnetometer ◽

Pollutants Removal ◽

Co Precipitation ◽

Red Dye

A magnetic polymer-based nanocomposite was fabricated by the modification of an Fe3O4/SiO2 magnetic composite with polypyrrole (PPy) via co-precipitation polymerization to form PPy/Fe3O4/SiO2 for the removal of Congo red dye (CR) and hexavalent chromium Cr(VI) ions from water. The nanocomposite was characterized using various techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), vibration sample magnetometer, and thermogravimetric analysis (TGA). The results confirm the successful fabrication of the nanocomposite in the size of nanometers. The effect of different conditions such as the contact time, adsorbent dosage, solution pH, and initial concentration on the adsorption process was investigated. The adsorption isotherm suggested monolayer adsorption of both contaminants over the PPy/Fe3O4/SiO2 nanocomposite following a Langmuir isotherm, with maximum adsorption of 361 and 298 mg.g−1 for CR dye and Cr(VI), respectively. Furthermore, the effect of water type on the adsorption process was examined, indicating the applicability of the PPy/Fe3O4/SiO2 nanocomposite for real sample treatment. Interestingly, the reusability of the nanocomposite for the removal of the studied contaminants was investigated with good results even after six successive cycles. All results make this nanocomposite a promising material for water treatment.

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