Selective Catalytic Oxidation of Organic Sulfides to Sulfoxides without Forming
Sulfones over Solid Molybdenum Blue: Kinetic and Thermodynamic Studies

The present investigation reports studies on the selective catalytic oxidation of organic sulfide substrates over molybdenum blue catalyst supported on boron phosphate. The catalyst was synthesized through partial precipitation method and characterized by XRD, FTIR and SEM techniques. The sulfoxidation was carried out in a batch reactor using benzyl phenyl sulfide as the substrate over the present catalyst and the reaction parameters were varied and optimized. The results were compared with the MoO3 impregnated boron phosphate. The catalyst was also studied for its performance over other sulfide substrates and the results were compared with available studies in literature. The reaction followed pseudo first-order kinetics and rate of the reaction under optimized condition was 10.1 × 10-3 min-1, with energy of activation of 29.3 kJ/mol. The Mo-O-Mo bridging and -Mo=O bonds present in molybdenum blue were participating in the reaction and possible mechanism has been proposed. The 100% selectivity of the product towards sulfoxide has been attributed to the big-wheel structure of molybdenum blue as it sterically hinders further reaction of sulfoxides formed to sulfones.

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The Continuous Decolorization of Reactive Yellow Dye using Advanced Oxidation Reactors

Iraqi Journal of Chemical and Petroleum Engineering ◽

10.31699/ijcpe.2020.2.1 ◽

2020 ◽

Vol 21 (2) ◽

pp. 1-6

Author(s):

Noor Abdul Ameer Mohammed ◽

Abeer I. Alwared ◽

Mohammed S. Salman

Keyword(s):

Batch Reactor ◽

Low Cost ◽

Advanced Oxidation ◽

Chemical Degradation ◽

Continuous Reactor ◽

Flow Rates ◽

First Order ◽

First Order Kinetics ◽

Pseudo First Order ◽

Maximum Removal

The reactive yellow azo dye (λmax = 420 nm) is widely utilized for textile coloring due to its low-cost stability and tolerance properties. Treatment of dye-containing wastewater by traditional methods is usually inadequate because of its resistance to biological and chemical degradation. From this research, the continuous reactor of an advanced oxidation method supported the use of H2O2/TiO2/UV to remove the coloration of the reactive yellow dye from the discharge. At constant best conditions obtained from the batch reactor tests pH=7, H2O2 dosage = 400 mg/l and TiO2=25mg/l , the aqueous solutions were tested in the continuous reactor at different dye concentration and different flow rates . The maximum removal efficiency was found to be 91.552% obtained at the flow rate 5 l/h, also the results of decomposition information proved that method was pseudo-first-order kinetics.

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Modelling of activated sludge acclimisation to a non-ionic surfactant

Water Science & Technology ◽

10.2166/wst.2001.0377 ◽

2001 ◽

Vol 43 (7) ◽

pp. 9-17 ◽

Cited By ~ 10

Author(s):

G. Carvalho ◽

I. Nopens ◽

J. M. Novais ◽

P. A. Vanrolleghem ◽

H. M. Pinheiro

Keyword(s):

Carbon Source ◽

Activated Sludge ◽

Model Building ◽

Batch Reactor ◽

Ionic Surfactant ◽

Software Environment ◽

First Order ◽

First Order Kinetics ◽

Best Fitting ◽

Fitting Model

A model is proposed to describe activated sludge acclimatisation to a non-ionic surfactant. The model was calibrated automatically, using WEST, a specific software environment for wastewater treatment model building, simulation and parameter estimation. The assays have been performed in a sequencing-batch reactor (SBR), using a non-ionic surfactant as sole carbon source and non-acclimatised sludge. The best fitting model was based on the assumption of three sequentially degraded COD fractions, where the second fraction is a metabolite of the original molecule and the third fraction is a more slowly biodegradable metabolite resulting from the secondary degradation. For primary degradation, hydrolysis with no associated growth was assumed. The growth of microorganisms responsible for degradation of the second and third COD fractions was presumed to follow Haldane and first order kinetics, respectively. The model was able to fit four consecutive assays of the same acclimatisation process, using Brij 30 as carbon source, with different food/microorganism ratios. The parameters obtained showed that the (self-)inhibition of the growth on the second COD fraction decreased along acclimatisation.

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Study on Kinetic and Optimization of Continuous Advanced Oxidative Decolorization of Brilliant Reactive Red Dye

Iraqi Journal of Chemical and Petroleum Engineering ◽

10.31699/ijcpe.2019.1.2 ◽

2019 ◽

Vol 20 (1) ◽

pp. 9-14

Author(s):

Forqan M. Hameed ◽

Khalid M. Mousa

Keyword(s):

Batch Reactor ◽

Low Cost ◽

Complete Removal ◽

Chemical Degradation ◽

Continuous Reactor ◽

First Order ◽

First Order Kinetics ◽

Optimum Ph ◽

Red Dye ◽

Effective Conditions

The azo dye brilliant reactive red K-2BP (λmax = 534 nm) is widely used for coloring textiles because of its low-cost and tolerance fastness properties. Wastewaters treatment that contains the dye by conventional ways is usually inadequate due to its resistance to biological and chemical degradation. During this study, the continuous reactor of an advanced oxidation method supported the use of H2O2/sunlight, H2O2/UV, H2O2/TiO2/sunlight, and H2O2/TiO2/UV for decolorization of brilliant reactive red dye from the effluent. The existence of an optimum pH, H2O2 concentration, TiO2 concentration, and dye concentration was taken from the batch reactor experiments. The best conditions were pH=3, H2O2 dosage = 500 ppm, TiO2=100ppm and dye concentration=15 ppm .Under the most effective conditions, complete removal of the dye solution was achieved with different flow rates (10, 30, 60) ml/min. At flow rate of 10 ml/min, the percentage of decolorization were (80.47%, 84.65%, 89.42%, 77.5%) and at 60 mL/min (65.19%, 68.26%, 70.01%, 56.8%) for H2O2/sunlight, H2O2/UV, H2O2/TiO2/sunlight and H2O2/TiO2/UV respectively. Results of degradation information showed that the decolorization method was pseudo-first-order kinetics.

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Investigation of the effect of operational parameters and SnO2-coupling on the photocatalytic activity of TiO2

Global NEST Journal ◽

10.30955/gnj.000755 ◽

2013 ◽

Vol 15 (4) ◽

pp. 551-559

Keyword(s):

Hydrogen Peroxide ◽

Photocatalytic Activity ◽

Light Intensity ◽

Model Compound ◽

Batch Reactor ◽

Coupled System ◽

Operational Parameters ◽

First Order ◽

First Order Kinetics ◽

Pseudo First Order

<p>The effect of different operational parameters in UV/TiO2 process, such as initial dye concentration (20-50 mg l-1), light intensity (8-45 W m-2), pH (2.83-10.22), hydrogen peroxide concentration (100-500 mg l-1), temperature (21-45 ˚C) and photocatalyst concentration (150-900 mg l-1) were investigated on the decolorization of Acid Yellow 23 as a model compound from monoazo textile dyes. The apparent first-order rate constants (kap) were evaluated which confirms pseudo first-order kinetics. kap increased with the enhancement of pH, light intensity and temperature. A desired concentration found for hydrogen peroxide (400 mg l-1) and photocatalyst concentration (750 mg l-1). The SnO2 photocatalyst was not as effective as TiO2 but had the same desired concentration (750 mg l-1). Then TiO2+SnO2 suspensions (375+375 mg l-1) as photocatalysts were employed for decolorization at different solution thicknesses. The results showed that the coupled particles were not much different from single TiO2 system at the solution thickness of 4.5 cm in a batch reactor. But the coupled system was more effective when the solution thickness was reduced to 2.5 cm. Over 90% of decolorization occurs at the solution thickness of 1.1 cm after 30 min of irradiation while 90% decolorization takes place at the solution thickness of 4.5 cm after 100 min of irradiation.</p>

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Facile Fabrication of g-C3N4/Fe3O4 Photocatalyst with Enhanced Visible-Light Photocatalytic Activity towards the Degradation of Tartrazine Dye

Asian Journal of Chemistry ◽

10.14233/ajchem.2021.23305 ◽

2021 ◽

Vol 33 (10) ◽

pp. 2293-2300

Author(s):

S. Nikhil ◽

R. Arunadevi ◽

Krishna Veni ◽

C. Sudhakar ◽

A. Karthika ◽

...

Keyword(s):

Photocatalytic Performance ◽

Precipitation Method ◽

Electron Hole ◽

First Order ◽

First Order Kinetics ◽

Electron Hole Pair ◽

Facile Fabrication ◽

Pair Generation ◽

Ft Ir ◽

Co Precipitation

The removal of tartrazine dye from aqueous solution using g-C3N4/Fe3O4 nanocomposites was studied. The g-C3N4/Fe3O4 nanocomposites were synthesized using simple co-precipitation method. The synthesized nanocomposites were characterized by spectral (UV-Vis DRS, FT-IR) and analytical (PXRD, SEM, EDAX, HRTEM) techniques. Photodegradation of tartrazine dye using the synthesized catalyst was studied. The g-C3N4/Fe3O4 nanocomposites exhibited excellent photocatalytic performance by degrading tartrazine (90%) at 0.1 g/L of catalyst and 20 μM initial dye concentration at pH 3. The excellent performance by the catalyst was attributed to the highest electron hole pair generation. The kinetic study revealed that the photodegradation of tartrazine obeyed pseudo first-order kinetics.

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Cyanide Containing Wastewater Treatment by Ozone Enhanced Catalytic Oxidation over Diatomite Catalysts

MATEC Web of Conferences ◽

10.1051/matecconf/201814201003 ◽

2018 ◽

Vol 142 ◽

pp. 01003

Author(s):

Mingguo Lin ◽

Qiyuan Gu ◽

Xinglan Cui ◽

Xingyu Liu

Keyword(s):

Catalytic Oxidation ◽

Advanced Oxidation Process ◽

Oxidation Process ◽

Removal Rate ◽

Order Rate Constant ◽

Alkaline Condition ◽

First Order ◽

First Order Kinetics ◽

Initial Ph ◽

The One

Cyanide containing wastewater that discharged from gold mining process creates environmental problems due to the toxicity of cyanide. As one of the promising advanced oxidation process, catalytic oxidation with ozone is considered to be effective on the purification of cyanide. Diatomite, a natural mineral, was used as catalyst in this study. The effect of O3 dosage, salinity, initial cyanide concentration and initial pH condition were investigated. It was observed that the removal rate of cyanide was much higher in the catalytic oxidation with ozone process than the one in zone alone process. Alkaline condition was especially favorable for cyanide in catalytic oxidation with ozone. The ozone and catalytic oxidation with ozone were simulated by pseudo-first-order kinetics model. The apparent first-order rate constant contribution of the diatomite catalyst was 0.0757 min-1, and the contribution percentage was 65.77%.

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Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽

10.32964/tj17.03.167 ◽

2018 ◽

Vol 17 (03) ◽

pp. 167-178 ◽

Cited By ~ 2

Author(s):

Xin Tong ◽

Jiao Li ◽

Jun Ma ◽

Xiaoquan Chen ◽

Wenhao Shen

Keyword(s):

Degradation Rate ◽

Southern China ◽

Catalytic Degradation ◽

Pulp And Paper ◽

Gaseous Pollutants ◽

Pulp And Paper Mills ◽

Paper Mills ◽

Initial Concentration ◽

First Order ◽

First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

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Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

10.31221/osf.io/m9g7p ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Methyl Orange ◽

Solution Ph ◽

Vanadium Concentration ◽

Limiting Behavior ◽

First Order ◽

First Order Kinetics ◽

Ph Range ◽

Kinetic Pattern ◽

Triton X ◽

Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

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Biodegradation rates of aromatic contaminants in biofilm reactors

Water Science & Technology ◽

10.2166/wst.1995.0027 ◽

1995 ◽

Vol 31 (1) ◽

pp. 117-128 ◽

Cited By ~ 8

Author(s):

Jean-Pierre Arcangeli ◽

Erik Arvin

Keyword(s):

Aromatic Hydrocarbons ◽

Competitive Inhibition ◽

Removal Rate ◽

First Order ◽

Biofilm Reactors ◽

First Order Kinetics ◽

Reducing Conditions ◽

Low Concentrations ◽

Degradation Rates ◽

Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

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In-vitro Kinetic Hydrolysis Study of Metronidazole Derivatives with Carvacrol and Eugenol Using Validated RP-HPLC Method

Current Pharmaceutical Analysis ◽

10.2174/1573412916999200529123151 ◽

2020 ◽

Vol 16 ◽

Author(s):

M. Alarjah

Keyword(s):

Half Life ◽

Hplc Method ◽

Hydrolysis Rate ◽

First Order ◽

First Order Kinetics ◽

Rp Hplc ◽

Pharmacokinetic Properties ◽

Pseudo First Order ◽

Kinetic Hydrolysis

Background: Prodrugs principle is widely used to improve the pharmacological and pharmacokinetic properties of some active drugs. Much effort was made to develop metronidazole prodrugs to enhance antibacterial activity and or to improve pharmacokinetic properties of the molecule or to lower the adverse effects of metronidazole. Objective: In this work, the pharmacokinetic properties of some of monoterpenes and eugenol pro metronidazole molecules that were developed earlier were evaluated in-vitro. The kinetic hydrolysis rate constants and half-life time estimation of the new metronidazole derivatives were calculated using the validated RP-HPLC method. Method: Chromatographic analysis was done using Zorbbax Eclipse eXtra Dense Bonding (XDB)-C18 column of dimensions (250 mm, 4.6 mm, 5 μm), at ambient column temperature. The mobile phase was a mixture of sodium dihydrogen phosphate buffer of pH 4.5 and methanol in gradient elution, at 1ml/min flow rate. The method was fully validated according to the International Council for Harmonization (ICH) guidelines. The hydrolysis process carried out in an acidic buffer pH 1.2 and in an alkaline buffer pH 7.4 in a thermostatic bath at 37ºC. Results: The results followed pseudo-first-order kinetics. All metronidazole prodrugs were stable in the acidic pH, while they were hydrolysed in the alkaline buffer within a few hours (6-8 hr). The rate constant and half-life values were calculated, and their values were found to be 0.082- 0.117 hr-1 and 5.9- 8.5 hr., respectively. Conclusion: The developed method was accurate, sensitive, and selective for the prodrugs. For most of the prodrugs, the hydrolysis followed pseudo-first-order kinetics; the method might be utilised to conduct an in-vivo study for the metronidazole derivatives with monoterpenes and eugenol.

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