scholarly journals New Insight on the Study of the Kinetic of Biobased Polyurethanes Synthesis Based on Oleo-Chemistry

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4332 ◽  
Author(s):  
Julien Peyrton ◽  
Clémence Chambaretaud ◽  
Luc Avérous
Keyword(s):  
Methyl Oleate ◽  
Tertiary Amine ◽  
Large Range ◽  
Kinetic Studies ◽  
Polyurethane Foams ◽  
First Order ◽  
Model Molecule ◽  
Specific Order ◽  
Unsaturated Triglycerides ◽  
Kinetics Of

Nowadays, polyols are basic chemicals for the synthesis of a large range of polymers, such as polyurethane foams (PUF), which are produced with several other compounds, such as polyisocyanates. During the last decades, the oleo-chemistry has developed several routes from glycerides to polyols for the polyurethanes (PU) industry to replace mainly conventional fossil-based polyols. A large range of biobased polyols can be now obtained by epoxidation of the double bonds and ring-opening (RO) of the subsequent epoxides with different chemical moieties. In preliminary studies, the RO kinetics of an epoxidized model molecule (methyl oleate) with ethanol and acetic acid were investigated. Subsequently, polyols that were derived from unsaturated triglycerides were explored in the frame of e.g., PUF formulations. Different associations were studied with different mono-alcohols derived from epoxidized and ring-opened methyl oleate while using several ring-openers to model such systems and for comparison purposes. Kinetic studies were realized with the pseudo-first-order principle, meaning that hydroxyls are in large excess when compared to the isocyanate groups. The rate of isocyanate consumption was found to be dependent on the moiety located in β-position of the reactive hydroxyl, following this specific order: tertiary amine >> ether > ester. The tertiary amine in β-position of the hydroxyl tremendously increases the reactivity toward isocyanate. Consequently, a biobased reactive polyurethane catalyst was synthesized from unsaturated glycerides. These approaches offer new insights regarding the replacement of current catalysts often harmful, pungent, and volatile used in PU and PUF industry, in order to revisit this chemistry.

scholarly journals Kinetics of K release from soils of Brazilian coffee regions: effect of organic acids

2008 ◽  
Vol 32 (2) ◽  
pp. 533-540 ◽  
Author(s):  
Vladimir Antônio Silva ◽  
Giuliano Marchi ◽  
Luiz Roberto Guimarães Guilherme ◽  
José Maria de Lima ◽  
Francisco Dias Nogueira ◽  
...  
Keyword(s):  
Release Kinetics ◽  
Kinetic Studies ◽  
Release Rates ◽  
First Order ◽  
Potassium Release ◽  
Minas Gerais State ◽  
Soil Clay ◽  
Extractant Solution ◽  
Kinetics Of ◽  
K Release

Kinetic studies on soil potassium release can contribute to a better understanding of K availability to plants. This study was conducted to evaluate K release rates from the whole soil, clay, silt, and sand fractions of B-horizon samples of a basalt-derived Oxisol and a sienite-derived Ultisol, both representative soils from coffee regions of Minas Gerais State, Brazil. Potassium was extracted from each fraction after eight different shaking time periods (0-665 h) with either 0.001 mol L-1 citrate or oxalate at a 1:10 solid:solution ratio. First-order, Elovich, zero-order, and parabolic diffusion equations were used to parameterize the time dependence of K release. For the Oxisol, the first-order equation fitted best to the experimental data of K release, with similar rates for all fractions and independent of the presence of citrate or oxalate in the extractant solution. For all studied Ultisol fractions, in which K release rates increased when extractions were performed with citrate solution, the Elovich model described K release kinetics most adequately. The highest potassium release rate of the Ultisol silt fraction was probably due to the transference of "non-exchangeable" K to the extractant solution, whereas in the Oxisol exchangeable potassium represented the main K source in all studied fractions.

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.

KINETIC STUDIES OF METHYL-BIS-β-CHLOROETHYLAMINE: III. THE KINETICS OF THE DIMERIZATION IN METHANOL

1948 ◽  
Vol 26b (2) ◽  
pp. 175-180 ◽  
Author(s):  
C. A. Winkler ◽  
A. W. Hay ◽  
A. L. Thompson
Keyword(s):  
Rate Constants ◽  
Initial Rate ◽  
Kinetic Studies ◽  
First Order ◽  
Rate Expression ◽  
Principal Reaction ◽  
Kinetics Of ◽  
Rate Controlling Step

The principal reaction of methyl-bis-β-chloroethylamine in methanol is dimerization, which results in one chlorine from each molecule becoming ionic, but this is accompanied by slight alcoholysis. The rate-controlling step is believed to be the first order formation of an ethylenimonium ion which reacts rapidly with one of its kind to form dimer. The rate expression as calculated from initial rate constants is k (initial) = 4.0 × 1013e−19600/RThr.−1.

scholarly journals Reactivity and kinetic studies of benzofuran hydrodeoxygenation over a Ni2P-O/MCM-41 catalyst

2019 ◽  
Vol 44 (4) ◽  
pp. 307-315 ◽  
Author(s):  
Xueya Dai ◽  
Hua Song ◽  
Hualin Song ◽  
Jing Gong ◽  
Feng Li ◽  
...  
Keyword(s):  
Kinetic Studies ◽  
Time Analysis ◽  
Liquid Ratio ◽  
Order Model ◽  
Free Products ◽  
First Order ◽  
Reaction Rate Constants ◽  
Different Temperatures ◽  
Kinetics Of ◽  
Mcm 41

A nickel phosphide hydrodeoxygenation catalyst (Ni2P-O/MCM-41) was prepared using a new synthetic method. The as-prepared catalyst was evaluated in the hydrodeoxygenation of benzofuran, and the effects of reaction temperature, pressure, and the H2/liquid ratio were investigated. A pseudo first-order model was employed to describe the reaction kinetics of benzofuran hydrodeoxygenation over the Ni2P-O/MCM-41 catalyst. The reaction rate constants ( k1– k5) at different temperatures were determined according to this model. At 533 K, the conversion of 2-ethylphenol in to ethylbenzene began to increase dramatically, and the yield of O-free product, ethylcyclohexane, started to increase rapidly. At 573 K, 3.0 MPa, and a H2/liquid ratio of 500 (V/V), the conversion of benzofuran over Ni2P-O/MCM-41 reached 93%, and the combined yield of O-free products was 91%. Contact time analysis indicated that demethylation was not favored over the Ni2P-O/MCM-41 catalyst.

KINETIC STUDIES ON THE HYDROLYSIS OF BENZOYLCHOLINE BY HUMAN SERUM CHOLINESTERASE

1956 ◽  
Vol 34 (1) ◽  
pp. 637-653 ◽  
Author(s):  
W. Kalow ◽  
K. Genest ◽  
N. Staron
Keyword(s):  
Kinetic Studies ◽  
Reaction Rates ◽  
Serum Cholinesterase ◽  
Initial Reaction ◽  
Ultraviolet Spectrophotometry ◽  
First Order ◽  
Low Concentrations ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Substrate Concentrations

Benzoylcholine stands out from other known substrates of serum cholinesterase because of its high apparent affinity for this enzyme combined with a rapid rate of destruction. The reaction kinetics of the hydrolysis of benzoylcholine can be studied by ultraviolet spectrophotometry, since the absorbance decreases in proportion to the concentration of substrate. Kinetic data obtained by measuring initial reaction rates, and by analyzing continuous hydrolysis curves, are the same within the range of experimental error. The enzymatic data are compatible with the assumption that in the presence of high substrate concentrations a complex consisting of esterase and two substrate molecules is formed. This complex is hydrolyzed more slowly than the complex containing one molecule of substrate which is formed at low concentrations of benzoylcholine. Alkaline hydrolysis of benzoylcholine follows the kinetics of a first order reaction.

scholarly journals Kinetic studies of oxidized nicotinamide–adenine dinucleotide-facilitated reactions of d-glyceraldehyde 3-phosphate dehydrogenase

1974 ◽  
Vol 143 (2) ◽  
pp. 353-363 ◽  
Author(s):  
Patricia J. Harrigan ◽  
David R. Trentham
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Temperature Jump ◽  
Reaction Pathway ◽  
Kinetic Studies ◽  
Rate Equations ◽  
First Order ◽  
Diffusion Controlled ◽  
Relaxation Temperature ◽  
Pig Muscle ◽  
Kinetics Of

The kinetics of the acylation of d-glyceraldehyde 3-phosphate dehydrogenase from pig muscle by 1,3-diphosphoglycerate in the presence of NAD+ has been analysed by using the relaxation temperature-jump method. At pH7.2 and 8°C the rate of acylation of the NAD+-bound (or holo-) enzyme was 3.3×105m−1·s−1 and the rate of phosphorolysis, the reverse reaction, was 7.5×103m−1·s−1. After a temperature-jump perturbation the equilibrium of NAD+ binding to the acyl-enzyme was re-established more rapidly than that of the acylation. The rate of phosphorolysis of the apoacylenzyme from sturgeon muscle and of aldehyde release from the d-glyceraldehyde 3-phosphate–apoenzyme complex were ≤40m−1·s−1 and ≤12s−1 respectively at pH8.0 and 22°C, which means that both processes are too slow to contribute significantly to the reaction pathway of the reversible NAD+-linked oxidative phosphorylation of d-glyceraldehyde 3-phosphate. Phosphorolysis of both acyl-apoenzyme and acyl-holoenzyme was first-order in Pi up to 100mm-Pi and more. PO43− could be the reactive species of the phosphorolysis of the acyl-holoenzyme, in which case phosphorolysis is a diffusion-controlled reaction, although other kinetically indistinguishable rate equations for the reaction are possible.

scholarly journals Removal of methylene blue dye from aqueous solution using a superabsorbant hydrogel the polyacrylamide: isotherms and kinetic studies

2019 ◽  
Vol 9 (5) ◽  
pp. 337-346
Author(s):  
Imane Lebkiri ◽  
Brahim Abbou ◽  
Lamya Kadiri ◽  
Abdelkarim Ouass ◽  
Youness Essaadaoui ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Contact Time ◽  
Kinetic Studies ◽  
Organic Dye ◽  
Blue Dye ◽  
Methylene Blue Dye ◽  
Order Model ◽  
First Order ◽  
Kinetics Of ◽  
Maximal Capacity

The present work aims the elimination of an organic dye Methylene Blue (MB) by adsorption on the polyacrylamide (PAAM) hydrogel. Several experiments series were then carried out in order to study the influence on the adsorption capacity of certain parameters such as the mass of the adsorbent, the pH, the contact time, the initial dye concentration and the temperature. The maximal capacity is 1620 mg/g it was obtained at T = 25°C, pH = 6, [BM] = 200 ppm and 0.013g of the adsorbent. The adsorption kinetics of the dye on the support is well described by the first-order model. The adsorption isotherms of the adsorbent/adsorbate systems studied are satisfactorily described by the Langmuir mathematical model. On the other hand, the thermodynamic study revealed that adsorption is spontaneous and endothermic.

scholarly journals Kinetics and Mechanism of Oxidation oft-Butylbenzylamine by Diperiodatoargentate(III) in Aqueous Alkali

2012 ◽  
Vol 9 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Mahantesh A. Angadi ◽  
Suresh M. Tuwar
Keyword(s):  
Kinetic Studies ◽  
Active Species ◽  
Alkali Concentration ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Middle Range ◽  
Wide Range ◽  
Rate Of Reaction ◽  
Mechanism Of Oxidation ◽  
Kinetics Of

t-Butylbenzylamine (t-BA) is used as a free base in the synthesis of salbutamol drug. Its mechanism of oxidation was proposed from kinetic studies. The kinetics of oxidation oft-butylbenzylamine by diperiodatoargentate(III) (DPA) was studied spectrophotometrically by monitoring decrease in absorbance of DPA. The reaction was found to be first order each in [DPA] and [t-BA]. The effect of alkali concentration in a wide range on rate of reaction was studied. The rate of reaction was found to be increased with increase in [OH–] in the lower range of [OH–], decreasing effect in the middle range and at higher range again increasing effect on rate of reaction was observed. The added periodate retarded the rate of reaction. The polymerization test revealed that oxidation was occurred with the intervention free radical. A suitable mechanism was proposed for a middle range of [OH–]. The active species of silver(III) periodate for all the three different stages of [OH–] are assayed. Rate law was derived and verified. The oxidative product oft-BA was characterized by LC-ESI-MS spectra.

Kinetic studies on the degradation of crystal violet by the Fenton oxidation process

2010 ◽  
Vol 62 (1) ◽  
pp. 1-7 ◽  
Author(s):  
H. Wu ◽  
M. M. Fan ◽  
C. F. Li ◽  
M. Peng ◽  
L. J. Sheng ◽  
...  
Keyword(s):  
Crystal Violet ◽  
Oxidation Process ◽  
Degradation Kinetics ◽  
Kinetic Studies ◽  
Fenton Oxidation ◽  
Dyeing Wastewater ◽  
First Order ◽  
Fenton Oxidation Process ◽  
System Variables ◽  
Kinetics Of

The degradation of dye crystal violet (CV) by Fenton oxidation process was investigated. The UV–Vis spectrogram has shown that CV can be degraded effectively by Fenton oxidation process. Different system variables namely initial H2O2 concentration, initial Fe2 +  concentration and reaction temperature, which have effect on the degradation of CV by Fenton oxidation process, have been studied systematically. The degradation kinetics of CV was also elucidated based on the experimental data. The degradation of CV obeys the first-order reaction kinetics. The kinetic model can be described as k = 1.5 exp(−(7.5)/(RT))[H2O2]00.8718[Fe2+]00.5062. According to the IR spectrogram, it is concluded that the benzene ring of crystal violet has been destroyed by Fenton oxidation. The result will be useful in treating dyeing wastewater containing CV by Fenton oxidation process.

Kinetic Studies on Oxidation of Veratryl Alcohol by Laccase-Mediator System. Part 1. Effects of Mediator Concentration

Holzforschung ◽  
2000 ◽  
Vol 54 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Mikhail Yu. Balakshin ◽  
Chen-Loung Chen ◽  
Josef S. Gratzl ◽  
Adrianna G. Kirkman ◽  
Harald Jakob
Keyword(s):  
Kinetic Studies ◽  
Veratryl Alcohol ◽  
Alcohol Oxidation ◽  
Order Rate Constant ◽  
Molar Ratio ◽  
Active Centers ◽  
First Order ◽  
System Part ◽  
Kinetics Of

Summary Kinetics of the laccase-catalyzed oxidation of veratryl alcohol with dioxygen in the presence of 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diamonium salt (ABTS), the mediator, were studied to elucidate the possible reaction mechanism and the role of the mediator in this reaction. The reaction follows a pseudo-first order reaction law. The first order rate constant (κ) is dependent on the Mediator/Substrate (M/S) ratio and has a maximum at M/S molar ratio of 0.15. The kinetic studies show that the mechanism of veratryl alcohol oxidation with dioxygen-laccase-ABTS is rather complex and includes different reaction pathways. The mediator is involved in competitive reactions. It has been suggested that at low mediator concentration, the veratryl alcohol is oxidized via the laccase redox cycle. The mediator acts mostly as a laccase activator at a M/S ratio lower than 0.15. With increasing ABTS concentration with respect to the substrate concentration, ABTS acts increasingly as a cosubstrate competing with the original substrate for active centers of the laccase. This results in inhibition of veratryl alcohol oxidation in the enzyme cycle and increases the role of substrate oxidation by an oxidized mediator.

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