scholarly journals Enhanced removal of selenate from mining effluent by H2O2/HCl-pretreated zero-valent iron

2018 ◽  
Vol 78 (11) ◽  
pp. 2404-2413 ◽  
Author(s):  
Bing Wu ◽  
Huichao Jia ◽  
Zhe Yang ◽  
Chao Shan ◽  
Jingxia Weng ◽  
...  
Keyword(s):  
Passive Layer ◽  
Zero Valent Iron ◽  
Mining Effluent ◽  
Acid Washing ◽  
Initial Ph ◽  
Wide Ph Range ◽  
Adsorption Reduction ◽  
Ph Range ◽  
Co Precipitation ◽  
Direct Use

Abstract Direct use of zero-valent iron (ZVI) in reductive removal of selenate (Se(VI)) is inefficient due to the intrinsic passive layer of ZVI. Here we observed that ZVI pretreated with H2O2 (P-ZVI-O) performs much better in Se(VI) removal from a mining effluent than other three modes of ZVI alone, acid washing ZVI (P-ZVI-A), and simultaneous addition of H2O2 and ZVI (ZVI-O) as well. The P-ZVI-O exhibits exceptionally high Se(VI) removal at a low dosage, wide pH range, with Se dropping down from 93.5 mg/L to <0.4 μg/L after 7-h reaction. Interestingly, the initial pH (2–6) of the mining effluent exerted little influence on the final Se(VI) removal. H2O2/HCl pretreatment results in the formation of various reducing corrosion products (e.g. Fe3O4, FeO and Fe2+), which greatly favors the efficient Se(VI) removal. In addition, surface-bound Fe2+ ions participated in the reduction of Se(VI). Combined with the influence of Se valence as well as pH and Fe2+ (whether dissolved or surface bound), it is deduced that the P-ZVI-O mode induced efficient Se(VI) removal via the adsorption-reduction and/or co-precipitation. This study demonstrates that H2O2/HCl pretreatment of ZVI is a very promising option to enhance the efficiency of reductive removal of Se(VI) from real effluents.

scholarly journals Arsenic removal from water by Zr-γ- FeOOH nanoparticles

2019 ◽  
Vol 2 (1) ◽  
pp. 112-120
Author(s):  
Nguyen Dinh Trung ◽  
Le Thi Ha Lan
Keyword(s):  
Ammonium Chloride ◽  
Arsenic Removal ◽  
Precipitation Method ◽  
Freundlich Isotherms ◽  
Langmuir And Freundlich Isotherms ◽  
Adsorption Data ◽  
Wide Ph Range ◽  
Ph Range ◽  
Co Precipitation ◽  
Competitive Ions

Zr-γ-FeOOH nanoparticle adsorbent for As(V) and As(III) removal was prepared by a chemical co-precipitation method. Compared with γ-FeOOH, the addition of Zr enhanced the adsorptive capacities of As(V) and As(III). The maximum adsorptive capacities for As(V) and As(III) were 69.81 and 94.25 mg/g, respectively (rate Fe:Zr =1:0.5) at pH= 7.0. The adsorption data accorded with Langmuir and Freundlich isotherms. The adsorption of As(III) by Zr- γ-FeOOH was found to be effective in wide pH range of 6–8. Competitive ions hindered the adsorption according to the decreasing sequence phosphate, sulfate, ammonium, chloride, magnesium and calcium. The high adsorptive capability and good performance on other aspects make the Zr-γ- FeOOH nanorods a promissing adsorbent for the removal of As(V) and As(III) from groundwater.

Influence of pH and Incubation Time on Ochratoxin A Production by Aspergillus carbonarius in Culture Media

2005 ◽  
Vol 68 (7) ◽  
pp. 1435-1440 ◽  
Author(s):  
A. ESTEBAN ◽  
M. L. ABARCA ◽  
M. R. BRAGULAT ◽  
F. J. CABAÑES
Keyword(s):  
Ochratoxin A ◽  
Culture Media ◽  
Aspergillus Carbonarius ◽  
Yeast Autolysate ◽  
Initial Ph ◽  
Wide Ph Range ◽  
Ph Range ◽  
Incubation Temperatures ◽  
Influence Of Ph ◽  
Czapek Yeast Autolysate Agar

The effect of pH (2 to 10) and temperature (15 and 30°C) on growth and production of ochratoxin A (OTA) of six strains of Aspergillus carbonarius was studied in two culture media: Czapek yeast autolysate agar and yeast extract sucrose agar. Isolates were selected by their different source and different reported ability to produce OTA. Regardless of the initial pH or the temperature tested, Czapek yeast autolysate agar has been shown to be the best culture medium for OTA production by A. carbonarius. In this medium, OTA was produced from pH 2 to 10 at the two incubation temperatures tested. The results obtained show the ability of A. carbonarius to not only grow but also produce OTA over a wide pH range at high or low temperatures. This may help explain why this species is considered the main OTA source in some substrata.

Preparation and Analysis of Magnetic Nanoparticles Used as Highly Active Catalysts over a Wide pH Range

2012 ◽  
Vol 424-425 ◽  
pp. 1057-1061
Author(s):  
Wei Wang ◽  
Tie Long Li ◽  
Ying Liu
Keyword(s):  
Magnetic Nanoparticles ◽  
Precipitation Method ◽  
Fe3o4 Magnetic Nanoparticles ◽  
Ph Adjustment ◽  
Highly Active ◽  
Wide Range ◽  
Iron Leaching ◽  
Wide Ph Range ◽  
Ph Range ◽  
Co Precipitation

In this work, Fe3O4 magnetic nanoparticles with high peroxidase-like catalytic activity and spontaneous pH adjustment ability were successfully prepared by co-precipitation method followed by appropriate thermal treatment. Key synthesis factors were identified and adjusted to tailor the crystallinity, chemical composition and then catalytic property. The crystal structure and Fe (II) content of the catalyst strongly affected its degradation efficiency. Phenol was completely removed by the optimal magnetic nanoparticles under a wide range of pH from 3.0 to 8.0. Additionally, this catalyst exhibited low iron leaching, good reusability and excellent potential to eliminate various organic pollutants from waste water. The reaction mechanism was discussed in terms of the formation of HO• and O2•−/HO2• radicals.

Photocatalytic mineralisation of perchloroethylene using titanium dioxide

1995 ◽  
Vol 31 (9) ◽  
pp. 47-54 ◽  
Author(s):  
Hani Gupta ◽  
Shuzo Tanaka
Keyword(s):  
Titanium Dioxide ◽  
Lag Time ◽  
Order Reaction ◽  
Co2 Production ◽  
First Order ◽  
Tio2 Particles ◽  
Initial Ph ◽  
Wide Ph Range ◽  
Catalyst Dosage ◽  
Ph Range

The photocatalytic mineralisation of perchloroethylene (PCE) is demonstrated mainly in terms of CO2 formation to investigate the effects of various factors such as dissolved oxygen (DO), titanium dioxide semiconductor (TiO2) catalyst dosage, PCE concentration and pH on PCE photocatalysis. PCE was rapidly adsorbed onto the TiO2 particles followed by its gradual degradation, and CO2 production started after a short lag time that corresponded to the adsorption phase. The rate of CO2 formation increased with increasing DO, TiO2 dosage and PCE concentration. There was no significant effect of initial pH on the CO2 production rate over a wide pH range. The dependence of the CO2 formation on PCE concentration was found to obey the Langmuir-Hinshelwood model. No intermediates were detected during PCE degradation and PCE degradation followed a first-order reaction.

scholarly journals Enhanced As(III) sequestration using nanoscale zero-valent iron modified by combination of loading and sulfidation: characterizations, performance, kinetics and mechanism

2021 ◽  
Author(s):  
Shun Cheng ◽  
Hong Liu ◽  
Emmanuella Anang ◽  
Chunxia Li ◽  
Xianyuan Fan
Keyword(s):  
Arsenic Removal ◽  
Average Particle Size ◽  
Zero Valent Iron ◽  
Maximum Adsorption Capacity ◽  
Average Particle ◽  
Order Kinetic ◽  
Arsenic Adsorption ◽  
Nanoscale Zero Valent Iron ◽  
Wide Ph Range ◽  
Co Precipitation

Abstract Nanoscale zero-valent iron (nZVI) and sulfides have been confirmed to be effective in arsenic sequestration from aqueous solution. In this study, attapulgite supported and sulfide-modified nanoscale zero-valent iron (S-nZVI@ATP) are synthesized to realize the superposition effect of enhanced arsenic sequestration. The results indicated that nZVI clusters were well disaggregated and the BET specific surface area increased from 19.61 m2·g−1 to 46.04 m2·g−1 of S-nZVI@ATP, resulting in an enhanced removal efficiency of arsenic from 51.4% to 65.1% at 20 min. The sulfides in S-nZVI@ATP mainly exists as mackinawite (FeS) and causes the spherical nanoparticles exhibiting a larger average particle size (94.6 nm) compared to bare nZVI (66.0 nm). In addition, S-nZVI@ATP exhibited a prominent ability for arsenic sequestration over a wide pH range of 3.0–6.0. The presence of anions SO42− and Cl− can enhance the arsenic removal whereas HCO3− inhibited it. The arsenic adsorption by S-nZVI@ATP could be explained by the pseudo-second-order kinetic model and the Langmuir model, with the maximum adsorption capacity of 193.8 mg·g−1. The mechanism of As(III) sequestration by S-nZVI@ATP involved multiple processes, mainly including precipitation conversion from FeS to As2S3, surface-complexation adsorption and co-precipitation.

scholarly journals Synergistic degradation of PNP via coupling H2O2 with persulfate catalyzed by nano zero valent iron

RSC Advances ◽  
2019 ◽  
Vol 9 (35) ◽  
pp. 20323-20331 ◽  
Author(s):  
Jiangkun Du ◽  
Yang Wang ◽  
Faheem Faheem ◽  
Tiantian Xu ◽  
Han Zheng ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Zero Valent Iron ◽  
Sulfate Radicals ◽  
Initial Ph ◽  
Nano Zero Valent Iron ◽  
Simultaneous Activation ◽  
Synergistic Degradation ◽  
Ph Range

Simultaneous activation of H2O2 and persulfate by nanoscaled Fe0 shows synergistic effect for degradation of p-nitrophenol with generating both hydroxyl and sulfate radicals in a wide initial pH range.

scholarly journals Strong adsorption of phosphate by amorphous lanthanum carbonate nano-adsorbents

2021 ◽  
Vol 83 (7) ◽  
pp. 1605-1618
Author(s):  
Yifan Lu ◽  
Huawei Wu ◽  
Yan Xia ◽  
Mei Huang
Keyword(s):  
Lanthanum Carbonate ◽  
Batch Adsorption ◽  
Maximum Adsorption Capacity ◽  
Water Matrix ◽  
Wide Range ◽  
Initial Ph ◽  
Wide Ph Range ◽  
Equilibrium Data ◽  
Ph Range ◽  
P Removal

Abstract Phosphorus removal is a crucial aspect of controlling water pollution and eutrophication. In this study, the preparation of lanthanum carbonate (LC) nano-adsorbents for the efficient removal of phosphate (P) from water and wastewater was investigated. Results from XRD, SEM and Zeta potential analyses revealed that addition of magnesium ions and adjustment of the reaction temperature could control the morphology and microstructure of LC. Effects of initial pH, adsorbent dosage, contact time, and the water matrix on P adsorption were investigated. Batch adsorption experiments revealed that LC showed strong performance on P removal over a wide pH range (3.0 to 11.0). The kinetic data followed a pseudo-second-order model, and equilibrium data were well fitted by the Langmuir model with a maximum adsorption capacity of 112.9 mg P/g. Adsorption thermodynamics showed that the adsorption process was exothermic and spontaneous. Results of a monolayer model for single adsorption indicated that P could completely interact with two or more functional groups from the LC surface. In the presence of competing ions (F−, Cl−, SO42−, NO3−, and HCO3−), LC maintained high selectivity for phosphate. For a real effluent, the P concentration was efficiently reduced from 3.2 mg P/L to below 0.5 mg P/L at a dose of 0.5 g/L LC. All the results suggested that LC can serve as a promising adsorbent for P removal in a wide range of pH, and thus could meet the stricter discharge regulations from actual wastewater.

scholarly journals Novel nanostructured Fe–Cu–Al trimetal oxide for enhanced antimony(V) removal: synthesis, characterization and performance

2019 ◽  
Vol 79 (10) ◽  
pp. 1995-2004
Author(s):  
Jianyan Wang ◽  
Jing Chen ◽  
Qiumei Li ◽  
Gaosheng Zhang
Keyword(s):  
Toxic Metal ◽  
Point Of Zero Charge ◽  
Precipitation Method ◽  
Hydroxyl Groups ◽  
Adverse Health Effects ◽  
Ion Exchange Reaction ◽  
Wide Ph Range ◽  
And Performance ◽  
Ph Range ◽  
Co Precipitation

Abstract Given the adverse health effects of antimony (Sb), there is an increased focus on developing methods to remove this toxic metal from contaminated water bodies. To effectively remove Sb(V), a new nanostructured Fe–Cu–Al trimetal oxide was fabricated using co-precipitation method at ambient temperature. The Fe–Cu–Al trimetal oxide was very effective at removing Sb(V) from water; it had a maximal adsorption capacity of 169.1 mg/g at pH 7.0, a capacity that was competitive with most other reported adsorbents. The obtained amorphous oxide had a high pH point of zero charge (pHpzc = 8.8) and good adsorption Sb(V) efficiency over a wide pH range (4.0–8.0). Sb(V) uptake was achieved mainly through an ion-exchange reaction between Sb(V) ions and hydroxyl groups on the surface of the oxide. Given its good removal performance, high selectivity, and simple synthesis, this novel Fe–Cu–Al trimetal oxide offers a promising alternate for removing antimony contamination from aquatic environments.

scholarly journals Application of MIL-53(Fe) metal-organic framework material in catalytic wet oxidation of phenol

2021 ◽  
Vol 10 (1) ◽  
pp. 28-32
Author(s):  
Danh Huynh Thanh ◽  
Nghi Nguyen Huu ◽  
Du Pham Dinh
Keyword(s):  
Metal Organic Framework ◽  
Phenol Oxidation ◽  
Oxidation Reactions ◽  
Catalytic Wet Oxidation ◽  
X Ray Diffraction ◽  
Initial Ph ◽  
Wide Ph Range ◽  
Metal Organic ◽  
Ph Range ◽  
Organic Framework

In the present study, MIL-53(Fe) metal-organic framework material was applied as catalyst for phenol oxidation reaction in aqueous solution with H2O2 under UV radiation. The materials were characterized using X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FT-IR). The effects of reaction time, initial phenol concentration, and initial pH of the solution on phenol oxidation reactions were investigated. The results indicated that MIL-53(Fe) could work effectively in the wide pH range from 2 to 10. Phenol was quickly oxidized to form simple organic acids, including acetic acid, formic acid and oxalic acid.

The effects of pH and addition of an organic buffer (HEPES) on nitrate transformation in Fe0-water systems

1998 ◽  
Vol 38 (7) ◽  
pp. 107-115 ◽  
Author(s):  
Lara L. Zawaideh ◽  
Tian C. Zhang
Keyword(s):  
Nitrate Nitrogen ◽  
Batch Reactor ◽  
Nitrate Removal ◽  
Zero Valent Iron ◽  
Contaminated Water ◽  
Batch Reactors ◽  
Operational Parameters ◽  
Wide Ph Range ◽  
Effects Of Ph ◽  
Ph Range

The feasibility of using zero-valent iron (Fe0) powder to remediate nitrate-contaminated water was studied using bench-scale batch reactors. Operational parameters, such as Fe0 dosage (w/v), initial concentration of nitrate-nitrogen, pH, and the use of an organic buffer (HEPES) were studied, specifically focusing on the effects of pH and the addition of HEPES on nitrate transformation using zero-valent iron powder. Nitrate-nitrogen was removed by 94% when 0.01M of HEPES was added to a non-shaking batch reactor containing 20 mg/l nitrate-nitrogen and 4% (w/v) of Fe0. Shaking was proved to be more efficient than no shaking. Using the response surface methodology it was found that nitrate removal was closely related to pH. At low pH (e.g., pH < 2), the nitrate removal was fast and efficient (95% to 100%). At high pH (e.g., pH > 11), the transformation of nitrate was fast and efficient only for low concentration of nitrate in the Fe0-H2O system. At normal pH range (pH = 6 to 8), nitrate removal was usually lower than 50% without buffer treatment. The addition of the organic buffer (HEPES) could greatly enhance the nitrate transformation in a wide pH range (e.g., pH = 2 to 11).

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