Homogeneous oxidation of phenols in aqueous solution with hydrogen peroxide and ferric ions

1997 ◽  
Vol 36 (2-3) ◽  
pp. 151-154 ◽  
Author(s):  
H. Grigoropoulou ◽  
C. Philippopoulos
Keyword(s):  
Hydrogen Peroxide ◽  
Ferrous Sulphate ◽  
Ph Control ◽  
Chemical Oxidation ◽  
Ferric Ions ◽  
Experimental Conditions ◽  
Oxidation Rates ◽  
Homogeneous Oxidation ◽  
Oxidation Of Phenol ◽  
Ferrous Ammonium

The chemical oxidation of phenol and chlorophenols with hydrogen peroxide in the presence of soluble iron can be economically attractive at low oxidant consumption, leading then to intermediates that are more easily biodegradable. The homogeneous oxidation of phenol and chlorophenols in aqueous solutions with hydrogen peroxide is studied at oxidant : phenol ratio of about 4:1 and 16:1 (mol/mol) at various catalyst concentrations, at ambient temperature without pH control. Ferric chloride, ferric and ferrous sulphate and ferrous ammonium sulphate are used as oxidation catalysts. Ferric salts induce higher oxidation rates than ferrous ones and the nature of the anions present does not affect reaction rate. 4-Chlorophenol is found to be most resistant to oxidation and 2,4,6-Trichlorophenol is not attacked by hydrogen peroxide in the presence of ferric ions at the experimental conditions studied.

Stabilization of electroluminescence and photoluminescence of porous n-silicon by chemical oxidation in H2O2

1994 ◽  
Vol 358 ◽  
Author(s):  
F. Kozlowski ◽  
W. Wagenseil ◽  
P. Steiner ◽  
W. Lang
Keyword(s):  
Hydrogen Peroxide ◽  
Porous Silicon ◽  
Chemical Oxidation ◽  
Time Stability ◽  
Initial Value ◽  
Experimental Conditions ◽  
Long Time ◽  
Pl Intensity ◽  
High Level ◽  
Long Time Stability

ABSTRACTWe have oxidized porous (n-)silicon samples in solutions of H202 and have found that PL can be stabilized at a high level. The PL intensity of as prepared samples (PL quantum efficiencies in the range of 5 %) degrades to about 1/3 of the initial value in some ten minutes (the exact value depends on the experimental conditions). After having treated the samples for about 30 - 45 minutes in hydrogen peroxide it can be observed that bright PL remains stable for hours. These results confirm similar experiments performed with porous silicon made from p-substrates1. While red electroluminescing samples have shown long time stability for about 100 hours2, samples with blue-green electroluminescence have a lifetime of about 20 - 40 minutes. Oxidizing electroluminescent samples as described above results in a stabilization of electroluminescence for more than 7 hours.

CHEMICAL OXIDATION OF TREATED TEXTILE EFFLUENT BY HYDROGEN PEROXIDE AND FENTON PROCESS

2010 ◽  
Vol 9 (3) ◽  
pp. 351-360 ◽  
Author(s):  
Abdelnaser Omran ◽  
Hamidi Abdul Aziz ◽  
Marniyanti Mamat Noor
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Oxidation ◽  
Textile Effluent ◽  
Fenton Process

TREATABILITY OF 2,4-D PRODUCTION WASTEWATERS

1994 ◽  
Vol 30 (3) ◽  
pp. 73-78 ◽  
Author(s):  
O. Tünay ◽  
S. Erden ◽  
D. Orhon ◽  
I. Kabdasli
Keyword(s):  
Hydrogen Peroxide ◽  
Activated Sludge ◽  
Partial Oxidation ◽  
Chloride Concentration ◽  
Chemical Oxidation ◽  
Cod Removal ◽  
Optimum Conditions ◽  
Organic Loading ◽  
Activated Sludge System ◽  
Biological Treatability

This study evaluates the characterization and treatability of 2,4-D production wastewaters. Wastewaters contain 20000-40000 mg/l COD, 17000-30000 mg/l chloride and pH is around 1.0. Chemical oxidation with hydrogen peroxide provided almost complete COD removal. The optimum conditions are 3:1 H2O2/COD oxidant dosage, 3000 mg/l Fe3+ as catalyst and pH 3. Partial oxidation at 0.5:1 H2O2//COD ratio is also effective providing 67% COD removal. A batch activated sludge system is used for biological treatability. Dilution is needed to maintain a tolerable chloride concentration which increases through COD removal. pH also increased during COD removal. 85% COD removal is obtained for the 50% dilution at an organic loading of 0.3 day‒1 on a COD basis. Completely and partially oxidized wastewaters are also treated in the activated sludge down to 30 mg/l BOD5.

scholarly journals Ferroxidase activity of ferritin: effects of pH, buffer and Fe(II) and Fe(III) concentrations on Fe(II) autoxidation and ferroxidation

1999 ◽  
Vol 338 (3) ◽  
pp. 615-618 ◽  
Author(s):  
Xiaoke YANG ◽  
N. Dennis CHASTEEN
Keyword(s):  
Ph Control ◽  
Alternative Mechanism ◽  
Experimental Conditions ◽  
Iron Storage ◽  
Ferroxidase Activity ◽  
Effects Of Ph ◽  
Ph Stat ◽  
Ph Buffer ◽  
Horse Spleen Ferritin

It is widely accepted that iron deposition in the iron storage protein ferritin in vitro involves Fe(II) oxidation, and that ferritin facilitates this oxidation at a ferroxidase site on the protein. However, these views have recently been questioned, with the protein ferroxidase activity instead being attributed to autoxidation from the buffer alone. Ligand exchange between another protein with ferroxidase activity and ferritin has been proposed as an alternative mechanism for iron incorporation into ferritin. In the present work, a pH stat apparatus is used to eliminate the influence of buffers on iron(II) oxidation. Here we show that the recent experiments questioning the ferroxidase activity of ferritin were flawed by inadequate pH control, that buffers actually retard rather than facilitate iron(II) oxidation, and that horse spleen ferritin has ferroxidase activity when measured under proper experimental conditions. Furthermore, high pH (7.0), a high Fe(II) concentration and the presence of Fe(III) all favour Fe(II) autoxidation in the presence or absence of ferritin.

Kinetic Modelling of Phenol Oxidation in a Bioremediation Medium Using Fenton's Reagent

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Pardeep Kumar ◽  
Hossein Nikaktari ◽  
Mehdi Nemati ◽  
Gordon A. Hill
Keyword(s):  
Kinetic Modeling ◽  
Rate Constants ◽  
Maleic Acid ◽  
Kinetic Modelling ◽  
Pure Water ◽  
Chemical Oxidation ◽  
Phenol Oxidation ◽  
Oxidation Products ◽  
Increase With Increase ◽  
Oxidation Of Phenol

The present study is aimed at kinetic modeling of phenol oxidation using Fenton’s reagent in a medium suitable for bioremediation of organic pollutants. Batch experiments were conducted to study the effects of H2O2 concentration (29.26 to 146.31 mM), temperature (5 to 35°C), and to compare the oxidation of phenol in a bioremediation medium to that in pure water. The reaction mechanism used for kinetic modeling is based on the intermediate oxidation products identified in this study using LC-MS and ion chromatography. Progress of the chemical oxidation by Fenton’s reagent was monitored by determining the residual phenol concentration and concentrations of evolved intermediate compounds (catechol and hydroquinone) at regular time intervals. The rate of phenol oxidation and ultimate conversion of phenol were found to increase with increase in hydrogen peroxide concentration. The increase in temperatures has a positive effect on phenol oxidation and the rate of phenol oxidation was found to increase with temperature in the range of 5-35°C. Kinetic parameters, namely rate constants and activation energies for reactions involved, were determined by best-fitting the experimental data to the proposed reaction model. The values of the rate constants for oxidation of phenol and intermediate compounds, k1 (phenol to catechol), k2 (phenol to hydroquinone), k3 (catechol to maleic acid), k4 (hydroquinone to maleic acid) at 25°C were found to be 7.02x10-5±4.63x10-5, 7.22x10-4±6.09x10-4, 1.82x10-4±1.08x10-4, 1.68x10-3±1.29x10-3 L/mM min, respectively.

Impacts of Changing Operational Parameters of In Situ Chemical Oxidation (ISCO) on Removal of Aged PAHs from Soil

2012 ◽  
Vol 15 (2) ◽  
Author(s):  
Paula Cajal-Mariñosa ◽  
Ruth G. de la Calle ◽  
F. Javier Rivas ◽  
Tuula Tuhkanen
Keyword(s):  
Hydrogen Peroxide ◽  
Removal Efficiency ◽  
Contaminated Soil ◽  
Chemical Oxidation ◽  
Contaminant Removal ◽  
Operational Parameters ◽  
In Situ Chemical Oxidation ◽  
Different Types ◽  
Wood Impregnation

AbstractThe removal efficiency of two different types of peroxide addition, catalyzed hydrogen peroxide (CHP) and sodium percarbonate (SPC) were compared on a highly PAH-contaminated soil from a wood impregnation site. In an attempt to simulate real in situ reagents delivery, experiments have been carried out in acrylic columns. The main parameters affecting contaminant removal were the reagent’s temperature and the total addition of peroxide (g

scholarly journals Impact of two disinfectants on detachment of Enterococcus faecalis from polythene in aquatic microcosm

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
C. Lontsi Djimeli ◽  
A. Tamsa Arfao ◽  
V Rossi ◽  
N Nsulem ◽  
V Raspal ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Adhesion ◽  
Enterococcus Faecalis ◽  
Sodium Hypochlorite ◽  
Growth Phases ◽  
Planktonic Cells ◽  
Stationary Growth ◽  
Experimental Conditions ◽  
The Impact ◽  
Aquatic Microcosm

<p><strong>After cell adhesion processes in microcosm, the impact of sodium hypochlorite (NaOCl) and hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) on the detachment of <em>Enterococcus faecalis </em>from polythene fragments immersed in water under stationary and dynamic conditions was assessed. The abundance of planktonic cells was also evaluated. The density of <em>E. faecalis</em> adhered in absence of disinfectant fluctuated between 2 and 4 units (Log CFU/cm<sup>2</sup>). </strong><strong>After living in disinfected water, </strong><strong>the density of <em>E. faecalis</em> remained adhered to polythene sometimes reached 2 units (Log CFU/Cm<sup>2</sup>)</strong><strong>. </strong><strong>This highest abundance of cells remained adhered was recorded with cells coming from the lag, exponential and stationary growth phases in water treated with 0.5‰ NaOCl. In H<sub>2</sub>O<sub>2</sub> disinfected water, the highest value was recorded at all cells growth phases with 5‰ H<sub>2</sub>O<sub>2 </sub>concentration. Adhered <em>E. faecalis</em> cells have been sometimes completely or partially decimated respectively by NaOCl and H<sub>2</sub>O<sub>2</sub> treated water. Considering separately each experimental condition, it was noted that increasing the concentration of disinfectant caused a significant decrease (P≤0.01) in abundance of cells stay adhered after living in water disinfected by the two disinfectants. Changes in disinfectant concentrations in different experimental conditions had an impact on the detachment of <em>E. faecalis</em> cells from the substrates. </strong></p>

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