scholarly journals Advanced oxidation processes for decolorization of aqueous solution containing acid red G azo dye

2004 ◽  
Vol 2 (4) ◽  
pp. 573-588 ◽  
Author(s):  
Mioara Surpăţeanu ◽  
Carmen Zaharia
Keyword(s):  
Hydrogen Peroxide ◽  
Azo Dye ◽  
Catalytic Effect ◽  
Dye Decolorization ◽  
Alkaline Media ◽  
Ferrous Ions ◽  
Oxidant Concentration ◽  
Wide Range ◽  
Neutral Media ◽  
Acid Red G

AbstractSome investigations concerning the decolorization of Acid Red G azo dye by photooxidation with hydrogen peroxide were performed. The influences of pH, oxidant concentration, and the presence of Fe2+ or other metal ions (Co2+, Cu2+, Ni2+, Mn2+) as potential catalysts, were investigated. The best results were obtained in the presence of ferrous ions in acid and neutral media. The other ions are not as effective as Fe2+ for dye decolorization. Co2+ and Cu2+ ions have a catalytic action, at low concentration, within a wide range of pH. Ni2+ and Mn2+ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid Ni2+ and Mn2+ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid pH values, but show a weak action in alkaline media.

scholarly journals Aqueous photocatalytic oxidation of lignin and humic acids with supportedTiO2

2006 ◽  
Vol 2006 ◽  
pp. 1-7 ◽  
Author(s):  
Elina Portjanskaja ◽  
Sergei Preis ◽  
Juha Kallas
Keyword(s):  
Hydrogen Peroxide ◽  
Humic Acids ◽  
Photocatalytic Oxidation ◽  
Radical Formation ◽  
Ion Concentration ◽  
Alkaline Media ◽  
Radical Mechanism ◽  
Ferrous Ions ◽  
Glass Plates ◽  
Oxidation Efficiency

The photocatalytic oxidation (PCO) of UV-irradiated aqueous solutions containing humic acids and lignin was studied. The photocatalystTiO2was attached to buoyant hollow glass microspheres and glass plates. A maximum oxidation efficiency as low as1.1and2.54mgW−1h−1for humic acids and lignin, respectively, was achieved in neutral and alkaline media with 25gm−2of the buoyant catalyst. In acidic media, efficiency was even lower. The photocatalytic efficiency with the photocatalyst attached to glass plates was about 3 to 4 times higher than that for the buoyant catalyst. Ferrous ions added to acidic solutions did not increase the rate of PCO of humic acids. However the addition ofFe2+ions, up to 0.05 mM, to the lignin solution leads to a dramatic increase, about 25%, in PCO efficiency. A further increase in ferrous ion concentration results in a decrease in the PCO efficiency of lignin. Proceeding most likely by a radical mechanism, the efficiency of PCO of humic acids did not benefit from an excessive presence of hydroxyl radical promoters, such as hydrogen peroxide, although the reaction rate increased. However, PCO of lignin in the acidic medium, where OH.-radical formation is suppressed, benefited from the introduction of hydrogen peroxide due to promoted radical formation.

scholarly journals Treatment of Sulfonated Azo Dye Reactive Red 198 by UV/H2O2

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Jefferson P. Ribeiro ◽  
Juliene T. Oliveira ◽  
André G. Oliveira ◽  
Francisco W. Sousa ◽  
Eliezer F. Abdala Neto ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Azo Dye ◽  
Oxygen Demand ◽  
Sharp Decrease ◽  
Dye Decolorization ◽  
Color Removal ◽  
Process Efficiency ◽  
Reactive Red 198 ◽  
Ph Increase ◽  
Sulfonated Azo Dye

UV/H2O2system was tested on the color removal of sulfonated azo dye Reactive Red 198 (RR), which is widely used in textile process. The effects of hydrogen peroxide concentration, temperature, pH, and the in-line addition of hydrogen peroxide on high color and chemical oxygen demand (COD) removals were investigated. The kinetic of dye decolorization was also determined. The results showed that 2% H2O2decreased the process efficiency, while 1% H2O2solution led to a better performance of the system. Despite the fact that the pH increase had small effect on color removal, it affects positively COD removals. The same behavior was found for temperature increase. A high temperature resulted in a slight decrease in color removal and a sharp decrease for COD removal. In addition the H2O2in-line provided a small improvement in both color and COD removals. UV/1% H2O2treatment was the most efficient, the good performance was linked to higher amount of hydroxyl radicals formed.

scholarly journals Evidence for a close similarity in the catalytic sites of papain and ficin in near-neutral media despite differences in acidic and alkaline media. Kinetics of the reactions of papain and ficin with chloroacetate

1982 ◽  
Vol 201 (1) ◽  
pp. 101-104 ◽  
Author(s):  
K Brocklehurst ◽  
S M Mushiri ◽  
G Patel ◽  
F Willenbrock
Keyword(s):  
Catalytic Triad ◽  
Interactive Systems ◽  
Alkaline Media ◽  
Active Centre ◽  
Wide Range ◽  
Catalytic Sites ◽  
Rate Maximum ◽  
Neutral Media ◽  
Acidic And Alkaline Media ◽  
Kinetics Of

1. The pH-dependences of the second-order rate constants (k) for the alkylation by chloroacetate of the active-centre thiol groups of papain (EC 3.4.22.2) and ficin (EC 3.4.22.3) were determined over a wide range of pH at 25 degrees C at I 0.1. 2. The main feature of both pH-k profiles is a striking rate maximum at pH6 (characterizing parameters in both cases pKI approx. 3.5, pKII approx. 8.4 and pH-independent rate constant approximately kXH 2.5-3.0 M-1 . s-1). 3. The profile for the ficin reaction contains a plateau at high pH, with approximately kX 0.10 M-1 . s-1; if an analogous plateau exists in the papain reaction, approximately kX ix much lower, less than 0.02 M-1 . s-1. 4. Both enzymes appear to contain closely similar thiolate-imidazolium interactive systems at pH6, but differences in their behaviour in more-acidic media and in alkaline media suggest differences in interaction with the postulated carboxylate component of the putative catalytic triad.

scholarly journals The reaction of methane and oxygen sensitized by nitrogen peroxide. Part I—Thermal ignition

1934 ◽  
Vol 145 (854) ◽  
pp. 307-321 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Monoxide ◽  
Ignition Temperature ◽  
Catalytic Effect ◽  
Thermal Ignition ◽  
Slow Reaction ◽  
Wide Range ◽  
Branching Chains ◽  
Oxygen Reaction

Nitrogen peroxide has been shown to be effective in lowering the ignition temperature of several gases in air. Dixon found that 1% nitrogen peroxide gave a maximum lowering of the ignition temperature of methane in air, whilst only a trace of the peroxide lowered the ignition temperature of hydrogen in oxygen by as much as 200°C. This effect in the hydrogen-oxygen reaction has been studied by Dixon, Hinshelwood, and their co-workers, and by Norrish and Griffiths, and in the carbon monoxide-oxygen reaction by Semenoff. Gibson and Hinshelwood and Thompson and Hinshelwood working with hydrogen-oxygen mixtures found that over a wide range of temperature there are two pressures of nitrogen peroxide between which there is an explosion and above and below which there is a very slow reaction. Thus for small increasing pressures of nitrogen peroxide the reaction is catalysed, but beyond a certain concentration the nitrogen peroxide acts as an anti-catalyst; consequently the graph of ignition temperature against pressure of nitrogen peroxide showed a minimum. The catalytic effect was explained by Thompson and Hinshelwood as due to the initiation of chains by reaction between molecules of hydrogen and nitrogen peroxide to give ultimately activated molecules of hydrogen peroxide and branching chains leading to explosion; the inhibition was explained as being due to the breaking of the chains by the deactivation of the hydrogen peroxide molecules by collision with nitrogen peroxide molecules.

Origin and Use of Hydrogen Peroxide in Neurosurgery

Neurosurgery ◽  
2021 ◽  
Author(s):  
David Bailey ◽  
Elias B Rizk
Keyword(s):  
Hydrogen Peroxide ◽  
Hemostatic Agent ◽  
Medical Field ◽  
Wide Range ◽  
Actual Effectiveness ◽  
Fatal Complications

Abstract Hydrogen peroxide (H2O2) is a chemical with a wide range of applications. This includes its use in the medical field, in which its use has been ubiquitous but is most useful as an antiseptic and in achieving hemostasis. Neurosurgeons have been using H2O2 for well over a century, primarily for its hemostatic and antiseptic effects. This is in spite of the fact that the actual effectiveness of H2O2 as an antiseptic is questionable, and its use, in general, may be more dangerous than it appears. We review the application of H2O2 in medicine generally and, more specifically, in neurosurgery. This review outlines the reasoning behind the use of H2O2 as an antiseptic and details why it may not be as effective as one might think. We also detail its use as a hemostatic agent in neurosurgery, reviewing a number of techniques in which it has been useful in this role. Finally, we review the documented cases of complications associated with the use of H2O2 in neurosurgery. Ultimately, we conclude that the use of H2O2 in neurosurgery be reconsidered because of its lack of effectiveness as an antiseptic and potentially fatal complications.

scholarly journals Reactivity and Chemical Sintering of Carey Lea Silver Nanoparticles

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1525
Author(s):  
Sergey Vorobyev ◽  
Elena Vishnyakova ◽  
Maxim Likhatski ◽  
Alexander Romanchenko ◽  
Ivan Nemtsev ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Silver Nanoparticles ◽  
Flexible Electronics ◽  
Photoelectron Spectroscopy ◽  
Colloidal Solutions ◽  
Ag Nps ◽  
Wide Range ◽  
Carboxylic Groups ◽  
The Media ◽  
Sulfide Ions

Carey Lea silver hydrosol is a rare example of very concentrated colloidal solutions produced with citrate as only protective ligands, and prospective for a wide range of applications, whose properties have been insufficiently studied up to now. Herein, the reactivity of the immobilized silver nanoparticles toward oxidation, sulfidation, and sintering upon their interaction with hydrogen peroxide, sulfide ions, and chlorocomplexes of Au(III), Pd(II), and Pt(IV) was investigated using SEM and X-ray photoelectron spectroscopy (XPS). The reactions decreased the number of carboxylic groups of the citrate-derived capping and promoted coalescence of 7 nm Ag NPs into about 40 nm ones, excluding the interaction with hydrogen peroxide. The increased nanoparticles form loose submicrometer aggregates in the case of sulfide treatment, raspberry-like micrometer porous particles in the media containing Pd(II) chloride, and densely sintered particles in the reaction with inert H2PtCl6 complexes, probably via the formation of surface Ag-Pt alloys. The exposure of Ag NPs to HAuCl4 solution produced compact Ag films along with nanocrystals of Au metal and minor Ag and AgCl. The results are promising for chemical ambient temperature sintering and rendering silver-based nanomaterials, for example, for flexible electronics, catalysis, and other applications.

Application of eco-friendly natural dye obtained from Spathodea campanulata on silk using combination of mordants

2016 ◽  
Vol 27 (1) ◽  
pp. 15-21 ◽  
Author(s):  
M Kumaresan
Keyword(s):  
Large Scale ◽  
Potassium Dichromate ◽  
Ferrous Sulphate ◽  
Research Work ◽  
Natural Dye ◽  
Alkaline Media ◽  
Silk Fabric ◽  
Content Type ◽  
Wide Range ◽  
New Research

Purpose – The purpose of this paper is to extract the eco-friendly natural dye obtained from the flower of Spathodea campanulata and apply on silk fabric using combination of mordants. The fastness properties of the flower of Spathodea campanulata dyed silk fabric have been studied using different combination (1:3, 1:1 and 3:1) of various mordants, such as myrobolan: nickel sulphate, myrobolan: aluminium sulphate, myrobolan: potassium dichromate, myrobolan: ferrous sulphate and myrobolan: stannous chloride. The wash, rub, light and perspiration fastness of the dyed samples have been evaluated. Design/methodology/approach – For dyeing there are three methods are used. They are Pre mordanting, Simultaneous mordanting and Post mordanting methods. Dyed silk materials are tested by using wash fastness, rub fastness, light and perspiration fastness methods. Findings – It is found that Spathodea campanulata dye can be successfully used for the dyeing of silk to obtain a wide range colours by using various combinations of mordants. With regards to colour fastness, test samples exhibit excellent fastness to washing, rubbing, except for pre-mordanting using myrobolan: potassium dichromate combination; and good to excellent fastness to perspiration in both acidic and alkaline media. Originality/value – Availability of literature related to this work is not available. The study of combination of mordants of this natural dye on silk is a new research work and the large scale preparation is definitely very useful to the society.

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