scholarly journals Remediation of arsenic(III) from aqueous solutions using zero-valent iron (ZVI) combined with potassium permanganate and ferrous ions

2017 ◽  
Vol 77 (2) ◽  
pp. 375-386 ◽  
Author(s):  
Wenna Deng ◽  
Zimai Zhou ◽  
Xuan Zhang ◽  
Yilin Yang ◽  
Yanqiu Sun ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Potassium Permanganate ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Order Reaction ◽  
Zerovalent Iron ◽  
Isotherm Models ◽  
Heterogeneous Structure ◽  
Pseudo First Order Reaction ◽  
Wide Range

Abstract A system of zerovalent iron combined with potassium permanganate and ferrous irons (Fe(II)-KMnO4-ZVI) was used to remove As(III), one of the most poisonous wastewater pollutants. The Fe(II)-KMnO4-ZVI system was characterized by using X-ray photoelectron spectroscopy and scanning electron microscopy. The As(III) removal efficiency by the Fe(II)-KMnO4-ZVI system under different conditions was investigated and the experimental data were fitted to adsorption kinetics and isotherm models. As(III) could be removed by both physisorption and chemisorption through mixing adsorbents in a very short time (minute scale) with high removal ratios (more than 99.5%) over a wide range of pH (1–9) and concentration (20–100 mg/L). The removal of As(III) by the Fe(II)-KMnO4-ZVI system agreed well with pseudo-first-order reaction kinetics and pseudo-second-order reaction kinetics. The Freundlich isotherm provided a good model of the adsorption system, indicating that the Fe(II)-KMnO4-ZVI system has heterogeneous structure. The results show that the Fe(II)-KMnO4-ZVI system exhibited a high removal efficiency for As(III), which suggested that it might be an effective material for As(III) remediation.

scholarly journals Optimization and Kinetics of Bioadsorption of Aqueous Potassium Permanganate in Charred Cacao Shells

KIMIKA ◽  
2020 ◽  
Vol 31 (2) ◽  
pp. 80-90
Author(s):  
Cyrus Ariel D.R. Fornoles ◽  
Naela V. Delmo ◽  
Alvin Manuel M. Traje ◽  
Sheryl Lozel B. Arreola ◽  
Amelia B. Hizon-Fradejas ◽  
...  
Keyword(s):  
Potassium Permanganate ◽  
Removal Efficiency ◽  
Order Reaction ◽  
Pseudo First Order Reaction ◽  
Adsorption Parameters ◽  
First Order ◽  
Kinetics Studies ◽  
Adsorption Data ◽  
Other Substances ◽  
Kinetics Of

In this study, charred cacao shells were tested for their capability as bioadsorbent for aqueous potassium permanganate. Optimization of adsorption parameters showed that the best amount of adsorbent is 0.5% w of cacao biochar/v of 0.005 N aqueous KMnO4 with a removal efficiency of 98.79%, and the optimum particle size is 212 mm, with a corresponding removal efficiency of 99.76%. Kinetics studies showed that the adsorption fits a pseudo-first order reaction with R2 = 0.9833. Lastly, the adsorption data fits the Elovich isotherm with R2 = 0.9712, which strongly suggests a multi-layer chemisorption on a heterogenous surface. Conclusively, the charred cacao shells were found to be effective as an adsorbent of aqueous potassium permanganate. Furthermore, the resulting product of adsorption can be used to study adsorption of other substances due to its multi-layer nature.

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

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.

On the Chemical Reactivity of the Phytochrome Chromophore in the Pr and Pfr Form

1985 ◽  
Vol 40 (3-4) ◽  
pp. 215-218 ◽  
Author(s):  
Fritz Thümmler ◽  
Peter Eilfeld ◽  
Wolfhart Rüdiger ◽  
Doo-Khil Moon ◽  
Pill-Soon Song
Keyword(s):  
Reaction Kinetics ◽  
Rate Constants ◽  
Chemical Reactivity ◽  
Order Reaction ◽  
First Order Reaction ◽  
Limiting Factor ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Pseudo First Order ◽  
The Difference

The reactivity of the phytochrome chromophore and related tetrapyrroles towards ozone and tetranitromethane was investigated. Both oxidizing reagents cause bleaching of the main absorp­tion band of the pigment. The rate constants for this bleaching were determined under conditions of pseudo first order reaction kinetics. The rate constants for the reaction with ozone are similar for native phytochrome and for freely accessible tetrapyrroles (biliverdin, small chromopeptides from phytochrome) indicating that accessibility is not the limiting factor for the reaction with ozone. Under a variety of conditions, the Pfr chromophore reacts by about 10% faster than the Pr chromophore. This may reflect the true difference in reactivity. The rate constants for the reaction with tetranitromethane are much larger for biliverdin, bilirubin and small chromopeptides from phytochrome than for native phytochrome. The limiting factor for this reaction in native phytochrome therefore is the accessibility of the chromophore by the reagent. Previous conclusions on the difference in exposure of the tetrapyrrole chromophore in Pr and Pfr are confirmed.

Interactions of hypochlorite ion and humic acid: photolytic and photocatalytic pathways

2001 ◽  
Vol 44 (5) ◽  
pp. 205-210 ◽  
Author(s):  
D. Gonenç ◽  
M. Bekbolet
Keyword(s):  
Humic Acid ◽  
Reaction Kinetics ◽  
Removal Efficiency ◽  
Photocatalytic Oxidation ◽  
Removal Rate ◽  
Order Reaction ◽  
First Order Reaction ◽  
Acid Oxidation ◽  
First Order ◽  
Toc Removal

Photolytic and photocatalytic interactions of hypochlorite ion and humic acid are investigated under various conditions. Humic acid oxidation by aqueous chlorine under dark conditions are expressed in terms of first order reaction kinetics. Upon irradiation (300 nm < λ < 400 nm), photolysis of aqueous chlorine affect the removal efficiency of humic acid via oxidation. TiO2 sensitised photocatalytic oxidation conditions reveal an increase in the TOC removal rate of humic acid in the presence of aqueous chlorine. Under the specified conditions, increasing the photocatalyst loading up to 1.0 mg/mL markedly increase the TOC removal rate.

Pseudo-first order reaction kinetics and thermodynamic properties study of neem oil esterification using MgO grafted natural hydroxyapatite

RSC Advances ◽  
2016 ◽  
Vol 6 (11) ◽  
pp. 8892-8901 ◽  
Author(s):  
Himadri Sahu ◽  
Kaustubha Mohanty
Keyword(s):  
Thermodynamic Properties ◽  
Reaction Kinetics ◽  
Fish Bone ◽  
Order Reaction ◽  
Neem Oil ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Pseudo First Order ◽  
Natural Hydroxyapatite ◽  
Kinetics And Thermodynamic

In this work, waste fish bone was used as a source of natural hydroxyapatite which was later used for the preparation of a metal grafted catalyst.

Reduction of highly concentrated phosphate from aqueous solution using pectin-nanoscale zerovalent iron (PNZVI)

2016 ◽  
Vol 73 (11) ◽  
pp. 2689-2696 ◽  
Author(s):  
Hongyu Wang ◽  
Zhuocheng Zou ◽  
Xuelian Xiao ◽  
Dan Chen ◽  
Kai Yang
Keyword(s):  
Aqueous Solution ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Phosphate Removal ◽  
Zerovalent Iron ◽  
Phosphate Adsorption ◽  
Maximum Adsorption Capacity ◽  
Surface Areas ◽  
Nanoscale Zerovalent Iron ◽  
The Fourier Transform

Pectin-nanoscale zerovalent iron (PNZVI) has been studied as an effective phosphate adsorption material to remove highly concentrated phosphate from aqueous solution. Batch phosphate removal and equilibrium experiments were conducted in order to evaluate the effects of environmental factors such as pH, coexisting anions and ionic strengths on phosphate removal by PNZVI. The scanning electron microscope images of nanoscale zerovalent iron (NZVI) and PNZVI demonstrated that PNZVI exhibited larger specific surface areas than NZVI so that PNZVI had higher phosphate removal efficiency than NZVI. Equilibrium experiments showed that phosphate adsorption by PNZVI was well fitted with the Freundlich and Langmuir models. In addition, the maximum adsorption capacity reached 277.38 mgP/gPNZVI. The ionic strengths and common anions showed no significant effects on the process of phosphate adsorption by PNZVI. The phosphate removal efficiency increased to a peak value with pH increased from 2.0 to 5.0, then decreased with pH further increased from 5.0 to 10.0. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses of PNZVI and P-loaded PNZVI indicated that adsorption, rather than redox reaction, was the dominant mechanism for the removal of phosphate by PNZVI.

Kinetic cooperativity of tyrosinase. A general mechanism.

2011 ◽  
Vol 58 (3) ◽  
Author(s):  
Jose Luis Muñoz-Muñoz ◽  
Francisco Garcia-Molina ◽  
Ramón Varon ◽  
Jose Tudela ◽  
Francisco Garcia-Cánovas ◽  
...  
Keyword(s):  
Methyl Ester ◽  
Order Reaction ◽  
General Mechanism ◽  
Slow Step ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Acid Type ◽  
Wide Range ◽  
Hydroxyphenylacetic Acid ◽  
Stable Product

Tyrosinase shows kinetic cooperativity in its action on o-diphenols, but not when it acts on monophenols, confirming that the slow step is the hydroxylation of monophenols to o-diphenols. This model can be generalised to a wide range of substrates; for example, type S(A) substrates, which give rise to a stable product as the o-quinone evolves by means of a first or pseudo first order reaction (α-methyl dopa, dopa methyl ester, dopamine, 3,4-dihydroxyphenylpropionic acid, 3,4-dihydroxyphenylacetic acid, α-methyl-tyrosine, tyrosine methyl ester, tyramine, 4-hydroxyphenylpropionic acid and 4-hydroxyphenylacetic acid), type S(B) substrates, which include those whose o-quinone evolves with no clear stoichiometry (catechol, 4-methylcatechol, phenol and p-cresol) and, lastly, type S(C) substrates, which give rise to stable o-quinones (4-tert-butylcatechol/4-tert-butylphenol).

scholarly journals Removal of Hexavalent Chromium From Wastewater by Cu/Fe Bimetallic Nanoparticles

2020 ◽  
Author(s):  
Jien Ye ◽  
Yi Wang ◽  
Qiao Xu ◽  
Hanxin Wu ◽  
Jianhao Tong ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Loading Rate ◽  
Bimetallic Nanoparticles ◽  
Particle Surface ◽  
Zerovalent Iron ◽  
Order Kinetic ◽  
Initial Concentration ◽  
First Order

Abstract BackgroundNanoscale zerovalent iron (nZVI) is a promising material for removing heavy metals from wastewater. However, passivation of nZVI hinders its efficiency in water treatment. 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. Purpose of this study was to clarify the effects and mechanisms of Cu loading on the removal efficiency of Cr(VI).ResultsThe 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. It was found that Cr(VI) removal followed a pseudo-first-order kinetic model. When the Cu loading rate was 3%, the initial concentration of Cr(VI) was 100 mg/L, the observed first-order rate coefficient (kobs) was 0.016 min-1 for Cu/Fe bimetallic nanoparticles at pH of 3.5, which was twice than that of nZVI (0.008 min-1). 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.ConclusionsIn this study, it was found that the loading of Cu can significantly increase the specific surface area and the Cr(VI) remove efficiency of nZVI, and the removal efficiency decreases with increasing pH and Cr(VI) initial concentration. Therefore, Cu loading can alleviate the passivation of nZVI effectively and can be beneficial for the application of iron-based nanomaterials in remediation of wastewater.

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