scholarly journals Kinetic Studies and Mechanism of Hydrogen Peroxide Catalytic Decomposition by Cu(II) Complexes with Polyelectrolytes Derived from L-Alanine and Glycylglycine

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Spyridon Skounas ◽  
Constantinos Methenitis ◽  
George Pneumatikakis ◽  
Michel Morcellet
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Rate ◽  
Aqueous Media ◽  
Catalytic Efficiency ◽  
Catalytic Decomposition ◽  
Kinetic Studies ◽  
Side Chain ◽  
First Order ◽  
Redox Pair ◽  
Ph Increase

The catalytic decomposition of hydrogen peroxide by Cu(II) complexes with polymers bearing L-alanine (PAla) and glycylglycine (PGlygly) in their side chain was studied in alkaline aqueous media. The reactions were of pseudo-first order with respect to [H2O2] and [L-Cu(II)] (L stands for PAla or PGlygly) and the reaction rate was increased with pH increase. The energies of activation for the reactions were determined at pH 8.8, in a temperature range of 293–308 K. A suitable mechanism is proposed to account for the kinetic data, which involves the Cu(II)/Cu(I) redox pair, as has been demonstrated by ESR spectroscopy. The trend in catalytic efficiency is in the order PGlygly>PAla, due to differences in modes of complexation and in the conformation of the macromolecular ligands.

Photocatalysed Oxidation of Toxic Organics

1987 ◽  
Vol 19 (3-4) ◽  
pp. 381-390 ◽  
Author(s):  
M. Brett Borup ◽  
E. Joe Middlebrooks
Keyword(s):  
Hydrogen Peroxide ◽  
Ultraviolet Radiation ◽  
Organic Compounds ◽  
Hydroxyl Radicals ◽  
Reaction Rate ◽  
Oxidation Process ◽  
Dimethyl Phthalate ◽  
First Order ◽  
Toxic Organics ◽  
Catalyzed Oxidation

The feasibility of treating water contaminated by two toxic organic compounds with an ultraviolet light catalyzed oxidation process using hydrogen peroxide as an oxidant is investigated. In this process hydrogen peroxide is decomposed by ultraviolet radiation producing hydroxyl radicals. The hydroxyl radicals will then oxidize organic compounds via a complex chain of radical reactions. Tests showed that this photooxidation process could successfully remove isophorone and dimethyl phthalate from contaminated waters. A reaction rate expression which adequately describes the process was developed. The reaction rate was found to be first order with respect to hydrogen peroxide concentration, zero order with respect to organic concentration and a function of ultraviolet radiation intensity. The reaction did not exhibit autocatalytic characteristics.

Kinetics of the Ozonation of Tetrabromobisphenol-A in Wastewater

2011 ◽  
Vol 383-390 ◽  
pp. 2945-2950 ◽  
Author(s):  
Jie Zhang ◽  
Shi Long He ◽  
Mei Feng Hou ◽  
Li Ping Wang ◽  
Li Jiang Tian
Keyword(s):  
Rate Constants ◽  
Apparent Rate Constant ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Kinetic Studies ◽  
Tetrabromobisphenol A ◽  
First Order ◽  
Reaction Rate Constants ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of TBBPA degradation by ozonation in semi-batch reactor was studied. The reaction rate constants of TBBPA with O3 and •OH were measured by means of direct ozone attack and competition kinetics, and the values of which were 6.10 l/(mol•s), 4.8×109 l/(mol•s), respectively. Results of kinetic studies showed that TBBPA degradation by ozonation under the different conditions tested followed the pseudo-first-order. The values of apparent rate constant of TBBPA degradation increased with the increase of ozone dosage and pH, but decreased with the increase of initial TBBPA concentration.

Green Synthesis of CoFe2O4 and Investigation of its Catalytic Efficiency for Degradation of Dyes in Aqueous Medium

2018 ◽  
Vol 232 (3) ◽  
pp. 359-371 ◽  
Author(s):  
Muhammad Saeed ◽  
Asim Mansha ◽  
Muhammad Hamayun ◽  
Aziz Ahmad ◽  
Atta Ulhaq ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Green Synthesis ◽  
Aqueous Medium ◽  
Heterogeneous Catalysts ◽  
Aqueous Media ◽  
Catalytic Efficiency ◽  
Catalytic Wet Oxidation ◽  
Simple Method ◽  
Langmuir Hinshelwood Mechanism ◽  
Bimetallic Oxides

AbstractThe catalytic wet oxidation is one the methods used for elimination of dyes from aqueous medium in which various metal based materials can be used as heterogeneous catalysts. Bimetallic oxides as heterogeneous catalysts have gained much attention as bimetallization improve the catalytic properties of the resulting particles. The biosynthetic green method is the most viable and simple method for synthesis of bimetallic oxides nanoparticles. Here, we report the green synthesis of CoFe2O4particles usingAzadirachata indicaleaves extract as reducing and stabilizing agent. The synthesized particles were characterized using X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared spectroscopy and scanning electron microscopy. The synthesized CoFe2O4particles were tested as a catalyst for mineralization of rhodamine B and methylene blue dyes in the presence of hydrogen peroxide in aqueous media. More than 95% dyes degraded in 120 min. The reaction kinetics was described in terms of Langmuir–Hinshelwood mechanism which suggests that molecules of dye and hydrogen peroxide adsorbed surface of CoFe2O4and then react together.

Kinetic studies of Dakin oxidation of o- and p-hydroxyacetophenones

1977 ◽  
Vol 55 (1) ◽  
pp. 102-110 ◽  
Author(s):  
M. B. Hocking ◽  
J. H. Ong
Keyword(s):  
Hydrogen Peroxide ◽  
Fractional Order ◽  
Rate Constants ◽  
Kinetic Studies ◽  
Second Order ◽  
Simple Test ◽  
Alkaline Hydrogen Peroxide ◽  
Para Isomer ◽  
First Order ◽  
Pseudo First Order

Rates of oxidation of aqueous o-, and p-hydroxyacetophenone with alkaline hydrogen peroxide to yield catechol and hydroquinone, respectively, have been followed spectrophotometri-cally. Both ketones showed smooth pseudo first-order behaviour, the ortho isomer yielding rate constants in the range 2.6 to 6.6 × 10−2 min−1 at 0 °C, and the para isomer of 0.73 to 7.10 × 10−2 min−1 at 35 °C for the concentrations of hydrogen peroxide and base used. The order in hydrogen peroxide was, unexpectedly, found to be 1.4. A simple test established that this fractional order was probably not the result of hydrogen peroxide involvement in simultaneous first- and second-order processes of differing rates. Other plausible pathways to explain this are proposed.

scholarly journals Evaluation of combined radiation for the treatment of lamivudine and zidovudine via AOP

2021 ◽  
pp. 29-29
Author(s):  
Alex Leandro Lucena ◽  
Rayany Magali da Rocha Santana ◽  
Marcos André Oliveira ◽  
Luciano Costa Almeida ◽  
Marta Maria Bezerra Duarte Duarte ◽  
...  
Keyword(s):  
Advanced Oxidation Processes ◽  
Environmental Problem ◽  
Aqueous Media ◽  
Kinetic Studies ◽  
Toxicity Tests ◽  
Operational Conditions ◽  
Oxidation Processes ◽  
First Order ◽  
Uv C ◽  
By Products

The presence of pharmaceutical contaminants in nature is an environmental problem generating increasing concerns. Due to this, it is necessary to evaluate treatments that are capable of degrading these contaminants, such as the advanced oxidation processes (AOP). In this work, the photoperoxidation and photo-Fenton AOP were applied to degrade a mixture of the drugs lamivudine and zidovudine, in aqueous medium and synthetic effluent (SE). To this end, a bench reactor (UV-C; UV-A and sunlight irradiations) was built. The AOP treatments efficiency was evaluated by ultraviolet/visible spectrophotometry. The tests involved the application of the irradiations individually and combined. The best operational conditions were [H2O2] of 600 mg.L-1 and [Fe] of 0.5 mg.L-1, for both matrices, with degradations of 90.53% and 89.32% for the photoperoxidation and photo-Fenton processes in aqueous media and 88.69% and 85.79% in SE. Kinetic studies showed a good fit for two pseudo-first order models with R2 > 0.93. Toxicity tests involving the application of lettuce, carrot, and tomato seeds showed an inhibition for the three seeds when submitted to solutions after treatment, for both matrices, this fact is corroborated by the HPLC analysis, in which the formation of small peaks was verified, suggestive of the formation of by-products. Thus, it can be affirmed that both photo-Fenton and photoperoxidation processes are efficient to degrade the drug mixture when applying UV-C radiation.

scholarly journals Kinetic studies with the use of proton-magnetic-resonance spectroscopy of the specific α-deuteration of amino acids by Escherichia coli aspartate aminotransferase

1978 ◽  
Vol 171 (3) ◽  
pp. 719-723 ◽  
Author(s):  
E Gout ◽  
S Chesne ◽  
C G Beguin ◽  
J Pelmont
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Aspartate Aminotransferase ◽  
Proton Magnetic Resonance ◽  
Reaction Rate ◽  
Kinetic Studies ◽  
Bond Breaking ◽  
Resonance Spectroscopy ◽  
First Order ◽  
Reaction Rate Constants

Escherichia coli aspartate aminotransferase was exposed to aspartate or phenylalanine without oxo acid in buffered 2H2O. The alpha-hydrogen of the amino acids underwent first-order exchange with respect to both substrate and enzyme. P.m.r. spectroscopy gave consistent reaction-rate constants. The deuterium-exchange rate was only moderately increased by addition of oxo acids and was of the same order as the transamination rate. No beta-deuteration was observed. The C(alpha)-H-bond-breaking step is discussed as a part of the entire transamination mechanism.

scholarly journals KINETIKA PROSES AOPs UNTUK PENGHILANGAN WARNA AIR LIMBAH PRODUKSI BATIK

2018 ◽  
Vol 1 (3) ◽  
Author(s):  
Rudi Nugroho ◽  
Ikbal Mahmud
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Compounds ◽  
Azo Dyes ◽  
Reaction Rate ◽  
Pilot Scale ◽  
Colour Removal ◽  
First Order ◽  
Order Chemical Reaction ◽  
First Order Chemical Reaction ◽  
Long Chain

An experiment of Advanced Oxydation Processes (AOPs) was conducted in semi-pilot scale using ozon and hydrogen peroxide. The reaction of ozon and hydrogen peroxide  produce an active hydroxil which can crack a long-chain organic compounds such as azo dyes. A wastewater contains colour substances coming from batik industries in Jababeka was treated by AOPs. The reaction rate was affected by ozon concentration supplied to the wastewater. The more ozon concentration, the colour removal became faster.The colour removal using AOPs could be illustrated by first-order chemical reaction equation.The constant of reaction was calculated from experiment as high as 0,38 per hour.The cost for treating the wastewater using AOPs was  Rp.3.656,- for one cubic meter of wastewater. Key words:  AOPs, Colour Removal, Hydrogen Peroxide, Ozon,

scholarly journals Kinetics and Mechanism of the Oxidation of Lactic Acid and Mandelic Acid by Pyridinium Chlorochromate in Aqueous Acidic Medium

2009 ◽  
Vol 6 (1) ◽  
pp. 273-280
Author(s):  
Sapana Jain ◽  
B. L. Hiran ◽  
C. V. Bhatt
Keyword(s):  
Lactic Acid ◽  
Free Radical ◽  
Reaction Mechanism ◽  
Acidic Medium ◽  
Mandelic Acid ◽  
Reaction Rate ◽  
Kinetic Studies ◽  
Pyridinium Chlorochromate ◽  
First Order ◽  
Aqueous Acidic Medium

Pyridinium chlorochromate (PCC) act as two electron oxidant in kinetic studies of the oxidation of lactic and mandelic acid in acidic medium. The influence of several factors such as acidity, salts, solvent composition and temperature on the reaction rate has been studied. The reaction shows first order dependence with respect to [PCC] and [H+]. The various thermodynamic parameters have been evaluated. Products as oxoacids and absence of free radical were confirmed. Suitable reaction mechanism has been proposed.

Studies on sorption of cadmium (II) ions onto Haro river sand from aqueous media using radiotracer and voltammetric techniques

2006 ◽  
Vol 94 (8) ◽  
Author(s):  
Riaz Ahmed ◽  
Tayyaba Yamin ◽  
Muhammad S. Ansari ◽  
Syed Moosa Hasany
Keyword(s):  
Aqueous Media ◽  
Kinetic Studies ◽  
Order Rate Constant ◽  
River Sand ◽  
Radiotracer Technique ◽  
First Order ◽  
Ph Values ◽  
Voltammetric Techniques ◽  
Effects Of Ph ◽  
Intra Particle Diffusion

SummarySorption of Cd(II) ions on Haro river sand has been studied using radiotracer technique. The effects of pH and acid concentrations on the sorption were studied. The sorption increases with pH, reaches a maximum at pH7 and decreases at higher pH values. With acids, it was found that sorption decreases with increasing acid concentration, and for more oxidizing acids sorption was less. Kinetic studies indicate that mostly intra particle diffusion occurs with first order rate constant of 18.45 × 10

The influence of an illuminated mercury surface on the Franck-Cario reactions

1926 ◽  
Vol 23 (2) ◽  
pp. 162-171 ◽  
Author(s):  
Herbert Sim Hirst
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Monoxide ◽  
Catalytic Efficiency ◽  
Mercuric Oxide ◽  
Reaction Products ◽  
Marked Influence ◽  
Mercury Surface ◽  
First Order ◽  
Rate Of Reaction ◽  
Hydrogen Mixtures

It has been found that illumination of a mercury surface by ultraviolet light strong in the line λ=2536·7 Å., exerts a marked influence on the photochemical union of hydrogen andgases such as oxygen, ethylene, and carbon monoxide. The rate of reaction is proportional to the first order to the area of surface exposed.The formation of a mercuric oxide film has been shown to occur only in the presence of a mixture of hydrogen and oxygen, and alternative mechanisms for its formation are suggested.In the case of nitrogen-hydrogen mixtures, hydrazine and ammonia have been identified in the reaction products, and in the case of hydrogen and oxygen, hydrogen peroxide and water have been found, and it is suggested that the reactions proceed in steps.The catalytic efficiency of the surface depends on its cleanness and is cut down by poisons, such as the reaction products in the case of the combination of hydrogen and carbon monoxide.

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