STUDYING THE KINETIC CHARACTERISTICS OF THE EXTRACTION OF ANTHOCYANINS FROM THE SQUEEZE OF KRASNOSTOP ZOLOTOVSKY

2020 ◽  
Author(s):  
M.A. Egyan ◽  
Keyword(s):  
Reaction Rate ◽  
Sugar Content ◽  
Extraction Process ◽  
Efficiency Coefficient ◽  
Kinetic Characteristics ◽  
Reaction Rate Constants ◽  
Solids Content ◽  
Kinetics Of ◽  
Process Speed

The article shows studies characterizing the quality of the squeeze: the mechanical composition of the squeeze is determined, the structural moisture of each component is determined, the sugar content in the formed process of sedimentation of the juice and its acidity are determined refractometrically. The kinetics of anthocyanins extraction was determined in two ways, the solids content in the extract was calculated, and the reaction rate constants of the extraction process and the efficiency coefficient of ultrasonic amplification of the extraction process speed were calculated.

Effects of Carrageenan and Chitosan as Coating Materials on the Thermal Degradation of Microencapsulated Phycocyanin from Spirulina sp.

2019 ◽  
Vol 15 (5-6) ◽  
Author(s):  
H. Hadiyanto ◽  
Marcelinus Christwardana ◽  
Meiny Suzery ◽  
Heri Sutanto ◽  
Ayu Munti Nilamsari ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Thermal Degradation ◽  
Rate Constants ◽  
Reaction Rate ◽  
Order Reaction ◽  
Coating Materials ◽  
First Order ◽  
Reaction Rate Constants ◽  
Kinetics Of

AbstractPhycocyanin is a natural substance that can be used as an antioxidant and food colorant. The quality of phycocyanin deteriorates when it is exposed to heat, and such deterioration is evidenced by decreases in its antioxidant activity and color. Encapsulation, which introduces a coating material over a substance of interest, has been applied to prevent changes in substance quality. The objective of the present research is to evaluate the kinetics of thermal degradation of phycocyanin coated with carrageenan or chitosan. Encapsulated phycocyanin samples were exposed to temperatures of 40, 50, or 60 °C for 90 min, and kinetics of the resulting degradation was evaluated to determine changes in sample quality. The results showed that the thermal degradation of encapsulated phycocyanin at 40–60 °C follows first-order reaction kinetics with reaction rate constants (k) of 4.67–9.17 × 10–5 s-1 and 3.83–7.67 × 10–5 s-1 for carrageenan and chitosan, respectively, and that the k of encapsulated phycocyanin is slower than that obtained from samples without the coating materials (control). Encapsulation efficiencies (EE) of 68.66 % and 76.45 %, as well as loading capacities of 45.28 % and 49.16 %, were, respectively, obtained for carrageenan and chitosan.

scholarly journals Kinetic Monte Carlo simulation of the growth of CdSe nanocrystals

2021 ◽  
Vol 134 (1) ◽  
pp. 7-23
Author(s):  
S.M. Asadov ◽  
Keyword(s):  
Monte Carlo ◽  
Rate Constants ◽  
Reaction Rate ◽  
Kinetic Monte Carlo ◽  
Cdse Nanocrystals ◽  
Modified Model ◽  
Early Maturation ◽  
Reaction Rate Constants ◽  
Colloidal Crystallization ◽  
Kinetics Of

This article is devoted to modeling the kinetics of colloidal crystallization of cadmium selenide (CdSe) nanoparticles (NPs). The kinetic equation is modified, considering the contributions of the reaction rate constants of individual stages. It includes the reaction rate constants, thermodynamic and calculated parameters, and physical properties. There is used modified kinetic model based on the crystallization equation. There are considered the contributions of adsorption, desorption, and migration of nucleated particles at different times. Modified model assumes that, upon crystallization of NPs CdSe, monomer units depend on the frequency of attachment and detachment transitions of the monomer–CdSe complex. In this case, the transformation of the precursor into a monomer, the formation of an effective monomer and nucleation pass into the growth stage of (NC CdSe) nanocrystals with a seeded mass. In the process, the resulting nanocluster will continue to grow due to early maturation, aging, and subsequent growth into larger NC CdSe. The Kinetic Monte Carlo method (KMC) is used to approximate the model of the nucleation–growth of NC considering different contributions to the reaction rate constants. The modified model with the use of KMC allows to describe the dependences of the kinetic rate constants on the average radius of nanoparticles as a function of time, concentration, and distribution of NC CdSe at a given time. There are described conditions for the formation of NPs CdSe with an evolutionary distribution function of NC CdSe in size space. The results of modeling the kinetics of colloidal crystallization of CdSe can be used to control nucleation rate and growth of NPs CdSe, as well as similar systems in the formation of high-quality NC.

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.

scholarly journals Detection of L-Proline-Catalyzed Michael Addition Reaction in Model Biomembrane

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Masanori Hirose ◽  
Shigenori Sugisaki ◽  
Keishi Suga ◽  
Hiroshi Umakoshi
Keyword(s):  
Michael Addition ◽  
Reaction Rate ◽  
Phase State ◽  
Addition Reaction ◽  
Michael Addition Reaction ◽  
Membrane Systems ◽  
Liposome Membrane ◽  
Reaction Rate Constants ◽  
Plausible Model ◽  
Kinetics Of

A method to detect the L-proline- (L-Pro-) catalyzed Michael addition reaction in model biomembranes has been established, using N-[p(2-benzimidazolyl)phenyl]maleimide and acetone as reactants. The effect of liposome membranes on this reaction was kinetically analyzed using fluorescence spectroscopy. The kinetics of the reaction were different from those of the constituent lipids of the liposomes. Zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine liposome, which is in the solid-ordered phase, had a better value of reaction rate, suggesting that the reaction rate constants of this reaction in liposome membrane systems could be regulated by the characteristics of the liposome membrane (i.e., the phase state and surface charge). Based on the results obtained, a plausible model of the L-Pro-catalyzed Michael addition reaction was discussed. The obtained results provide us with an easily detectable method to assess the reactivity of L-Pro in biological systems.

Carbohydrates in alkaline systems. II. Kinetics of the transformation and degradation reactions of cellobiose, cellobiulose, and 4-O-β-D-glucopyranosyl-D-mannose in 1 M sodium hydroxide at 22 °C

1969 ◽  
Vol 47 (21) ◽  
pp. 3957-3964 ◽  
Author(s):  
Donald J. MacLaurin ◽  
John W. Green
Keyword(s):  
Sulfuric Acid ◽  
Sodium Hydroxide ◽  
Column Chromatography ◽  
Rate Constants ◽  
Reaction Rate ◽  
Reaction System ◽  
Reaction Rate Constants ◽  
Degradation Reactions ◽  
Fructose 2 ◽  
Kinetics Of

Rates of isomerization, epimerization, and degradation reactions were measured for cellobiose (7), cellobiulose (8), and 4-O-β-D-glucopyranosyl-D-mannose (9) at 0.001 M in 1 M NaOH under N2 in the dark at 22 °C. Reaction system resolution was by column chromatography on anion resins in the borate form. Assay for D-glucose (1), D-fructose (2), D-mannose (3), and 7,8, and 9 was by continuous automated colorimetry of column effluent with orcinol–sulfuric acid as reagent. Reaction rate constants (h−1) found: k78 0.078, k79 0.0005, k7,10 0.002, k87 0.022, k89 0.003 k81 0.065, k8,12 0.023, k97 0.002, k98 0.013, k9,11 0.006 where 10,11, and 12 are other products than 1,2,3,7,8, and 9. Details for preparation of 8 and 9 are given.

scholarly journals Investigation of CO2 capture systems, Lewis acid-base pairs, and oscillating reactions with electronic structure theory and kinetics-based approaches

2020 ◽  
Author(s):  
◽  
Joseph Schell
Keyword(s):  
Lewis Acid ◽  
Rate Constants ◽  
Reaction Rate ◽  
Hysteresis Loops ◽  
Reaction Energy ◽  
Acid Base ◽  
Oscillating Reactions ◽  
Reaction Rate Constants ◽  
Delta G

Equilibrium is a key theme in chemistry education. Starting in high school and continuing in freshman general chemistry courses, STEM students have to learn the foundations of equilibria. What is the key concept of an equilibrium? How can we describe an equilibrium? The concept of an equilibrium constant K is introduced, and its relation to the Gibbs enthalpy [delta] G [superscript 0] is noted. The equilibrium constant K also is related in a straightforward manner to the forward and backward reaction rate constants. Usually, a few simple applications are discussed, primarily in the area of acid-base chemistry. The topic is revisited in organic chemistry and clarified conceptually with reaction energy diagrams. To study equilibrium as a student is one thing, and to study equilibrium problems as a researcher is quite another. How does one determine equilibrium constants and how does one determine reaction rate constants? What do we know about the accuracy of the experimental quantities reported in the literature? How does one deal with multi-equilibria? How does one account for non-ideal conditions and concentrated solutions? Over the last six years, I have learned how to approach and solve all of these issues. One of the most stunning insights was the realization that even so-called non-linear reactions can in fact be described in some cases by application of complicated systems of equilibrium reactions. The Glaser group very strongly believes that the interplay between experimental and theoretical work is vitally important to really understand a problem. This combination builds a strong focus on quantitative aspects and it often also leads to new insights that might not be attainable from experimentation or modeling alone. The five chapters presented here show that this two-pronged approach is widely applicable to several areas of chemistry. The two main topics of our studies have been carbon dioxide capture from air and reaction mechanisms of oscillating chemical systems. All of the chapters in my dissertation do have a very strong connection between theory and experimentation. I studied both aspects in most cases. Only in one case (Chapter 5) did I not perform the experiments, but even in this case, a very deep engagement with the experimental literature was required to solve a decades-long discrepancy. Chapter 1 is about the study of equilibria between different conformations of substrates and products and an evaluation of their effects on the overall reaction energy. Specifically, we studied the capture of CO2 by small alkylamines. The quality of that discussion was tested directly with the work described in Chapter 2. The work that led to Chapter 2 was an enormous learning experience; it was amazing to see all the pieces of the complicated multi-equilibrium system come together to determine the [delta] G [superscript 0] of the carbamylation of butylamine in aqueous solution. The interest in equilibria actually began with the quest of the non-linear dynamics group to understand oscillating chemical reactions. From the outset, this quest was pursued as an interdisciplinary project between chemistry and mathematics. My work with the dynamics group resulted in Chapters 3 and 4 of the present dissertation. Chapter 3 is a re-evaluation of the video-based kinetic analysis with high temporal resolution and over long timescales. The colorimetric studies revealed unexpected "hysteresis loops" in cerium-catalyzed Belousov-Zhabotinsky oscillating reactions. We studied the reaction progress in RGB space because we wanted to learn under what conditions the video-based analysis would allow for quantitative concentration determinations. The desire to assess the quality of the video-based analysis in RGB space, led to the serendipitous discovery of hysteresis loops. The origins of Chapter 4 had to do with the question as to whether accounting for ionic strength would be essential to obtain accurate simulations of BZ reactions. The goal of my work on phosphate buffers was an evaluation of the usefulness of Debye-Huckel theory to electrolyte solutions with highly-charged ions present in significant concentrations. The phosphate buffer systems are widely in use and outstanding experimental sets of pH values were available to really test the performance of the solution models. Many years of studies of the Lewis acid-base pair F3B[arrow]PH3 illustrate in a beautiful fashion what can go wrong when expertalists interpret their data based on inaccurate theory and when computational chemists do not seek consistency with existing experimental data published in the literature. A careful read of the literature clearly showed early on that experimental and theoretical reports on F3B[arrow]PH3 are entirely inconsistent. It took years to explain what was actually measured, namely the compound F2B-PH2, and to explain why many theoretical reports predicted the wrong dative-bonding geometry.

Effect of Extraction Solvent on Tannin-Formaldehyde Adhesives for Plywood Production

2018 ◽  
Vol 1 (2) ◽  
pp. 120-126 ◽  
Author(s):  
N.S.A. Derkyi
Keyword(s):  
Aqueous Ethanol ◽  
Sugar Content ◽  
Extraction Process ◽  
Poor Quality ◽  
Pine Bark ◽  
Formaldehyde Resin ◽  
Extraction Solvent ◽  
High Sugar Content ◽  
Very High

Pine bark is a good source of natural polyphenolic compounds for wood adhesives. The objective of this study was to obtainthe most suitable solvent for extracting pine tannins in the preparation of tannin-formaldehyde plywood adhesives. Aqueousacetone, aqueous ethanol, aqueous NaOH and water as solvents were used to obtain crude tannins from pine bark. Thetannin content, sugar content and Stiasny number of the extracts were determined. Using the extracts from the solventextractions, synthesis of tannin-formaldehyde resin was carried out. Plywood panels were made using the synthesized resinsand the quality of the resins in plywood application determined. The quality of tannin-formaldehyde resins produced from thetannins were generally in close agreement with the chemical characteristics of the extracts obtained from the various solventextractions. The aqueous NaOH extraction although gave very high tannin yield (16.1%), its associated high sugar content(33.8%) and very low Stiasny number (49) resulted in poor quality resin. Similarly, although aqueous extraction gave a veryhigh Stiasny number (91), its low tannin yield (8.7%) might not be of commercial interest. The extraction process that gave ahigh tannin yield (12.9%) and a very good Stiasny number (81.5) with a corresponding good quality resin (shear strength =1.9 MPa, 22% delamination) was found for 60% aqueous ethanol extraction.

Structural reasons for the formation of multicomponent products and the influence of high pressure

2021 ◽  
Vol 77 (3) ◽  
Author(s):  
Krzysztof A. Konieczny ◽  
Julia Bąkowicz ◽  
Damian Paliwoda ◽  
Mark R. Warren ◽  
Arkadiusz Ciesielski ◽  
...  
Keyword(s):  
High Pressure ◽  
Photochemical Reaction ◽  
Unit Cell Volume ◽  
Reaction Rate ◽  
Crystalline Form ◽  
Reaction Centre ◽  
High Elasticity ◽  
Reaction Proceeds ◽  
Kinetics Of

(S)-(−)-1-Phenylethanaminium 4-(2,4,6-triisopropylbenzoyl)benzoate (S-PEATPBB) undergoes a photochemical reaction in its crystalline form upon UV irradiation and forms three different products: the first product is the result of a Yang cyclization with the participation of the δ-H atom of o-isopropyl (product D) and the second and third products are obtained via a Norrish–Yang reaction with the involvement of the γ-H atom of 2-isopropyl (product P) and 6-isopropyl (product Z). These products are formed in different proportions (D > P >> Z). The path and kinetics of the reaction were monitored step-by-step using crystallographic methods, both under ambient and high-pressure conditions. The reactivity of S-PEATPBB depends strongly on the geometry of the reaction centre and the volume of the reaction cavity. Due to the geometrical preferences making the cyclization reaction easier to proceed, product D dominates over the other products, while the formation of product Z becomes difficult or almost impossible at high pressure. The reaction proceeds with an increase of the unit-cell volume, which, suppressed by high pressure, results in a significant decrease of the reaction rate. The crystal lattice of S-PEATPBB shows high elasticity. The quality of the partially reacted crystal remains the same after decompression from 0.75 GPa to 0.1 MPa.

scholarly journals Kinetics study of hydrazodicarbonamide synthesis reaction

2013 ◽  
Vol 19 (2) ◽  
pp. 273-279 ◽  
Author(s):  
Gh. Bakeri ◽  
M. Rahimnejad
Keyword(s):  
Reaction Rate ◽  
Second Step ◽  
Kinetics Study ◽  
Synthesis Reaction ◽  
Formation Reaction ◽  
Reaction Rate Constants ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting ◽  
Kinetics Of

In this study, the kinetics of hydrazodicarbonamide (HDCA) synthesis reaction was investigated. Hydrazodicarbonamide is prepared by reaction of urea and hydrazine in acidic medium. Synthesis of HDCA from urea and hydrazine is a two steps reaction. In the first step, semicarbazide is synthesized from the reaction of one mole of urea and one mole of hydrazine and in the second step, semicarbazide reacts with urea to produce hydrazodicarbonamide. By controlling the temperature and pH in the reaction, hydrazine concentration and the amount of produced hydrazodicarbonamide were measured and using these data, reaction rate constants were calculated. Based on this study, it was found that the semicarbazide formation reaction from hydrazine is the rate limiting step. Rate of semicarbazide synthesis is -r1 = 0.1396 [NH2NH2]0.5810 and the rate of hydrazodicarbonamide synthesis is -r2 = 0.7715 [NH2NHCONH2]0.8430.

Effects of pH value and temperature on the initiation, promotion, inhibition and direct reaction rate constants of natural organic matter in ozonation

RSC Advances ◽  
2016 ◽  
Vol 6 (22) ◽  
pp. 18587-18595 ◽  
Author(s):  
Ee Ling Yong ◽  
Yi-Pin Lin
Keyword(s):  
Natural Organic Matter ◽  
Organic Contaminants ◽  
Reaction Rate ◽  
Ph Value ◽  
Direct Reaction ◽  
Reaction Rate Constants ◽  
Effects Of Ph ◽  
Specific Reactions ◽  
Kinetics Of ◽  
Ozonation Process

pH and temperature affect the kinetics of specific reactions of NOM and influence organic contaminants removal in the ozonation process.

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