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.

Decomposition of meta- and para-phenylphenol during ozonation process

2013 ◽  
Vol 67 (9) ◽  
Author(s):  
Magdalena Olak-Kucharczyk ◽  
Jacek Miller ◽  
Stanisław Ledakowicz
Keyword(s):  
Decay Rate ◽  
Rate Constants ◽  
Reaction Rate ◽  
Homogeneous System ◽  
Liquid System ◽  
Second Order ◽  
Direct Reaction ◽  
Reaction Parameters ◽  
Reaction Rate Constants ◽  
Ozonation Process

AbstractThe decomposition of meta-phenylphenol (m-PP) and para-phenylphenol (p-PP) in a heterogeneous gas-liquid system using ozone was investigated. The influence of different reaction parameters such as ozone and PP isomers concentration as well as pH and temperature of the reaction mixture on the PP decay rate was determined. The second-order rate constants for the direct reaction of molecular ozone, determined in a homogeneous system, were (5.85 ± 0.35) × 102 M−1 s−1 and (8.90 ± 0.33) × 102 M−1 s−1 for m-PP and p-PP, respectively. The rate constants for the reaction of m-PP and p-PP with ozone increased with increasing pH. The reaction rate constants with ozone were found to be (1.75 ± 0.02) × 109 M−1 s−1 and (1.86 ± 0.02) × 109 M−1 s−1 for m-PP and p-PP anions, respectively.

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.

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.

Photocatalytic Oxidation of Toluene in Water From an Algae Pond With High Dissolved Oxygen Content

Solar Energy ◽  
2002 ◽  
Author(s):  
Sanjay Vijayaraghavan ◽  
D. Y. Goswami
Keyword(s):  
Dissolved Oxygen ◽  
Organic Contaminants ◽  
Photocatalytic Oxidation ◽  
Reaction Rate ◽  
Expected Improvement ◽  
Solar Ultraviolet Radiation ◽  
Reaction Rate Constants ◽  
Batch Type ◽  
Water Ph ◽  
Contaminant Destruction

Water in well-mixed ponds containing photosynthetic algae has been observed to have an extremely high Dissolved Oxygen (DO) content. Up to four times saturation levels of DO have been recorded. Since DO is known to have an important role in the photocatalytic oxidation of organic contaminants in water, it was hypothesized that a faster rate of contaminant destruction would be observed in water drawn from algae ponds supersaturated with DO. In order to verify this hypothesis a bench scale, batch type photoreactor was constructed. Some baseline tests were performed to investigate the influence of UV intensity, water pH and DO content on the photocatalytic destruction of toluene in water. An array of ultraviolet “blacklight” lamps in a lamp box was used to simulate solar ultraviolet radiation. First-order reaction rate constants were calculated from the destruction data, using a kinetic model proposed earlier. The reaction was found to proceed forward equally fast at pH 4 and 10. A power law relation was derived for the reaction rate dependence on UV intensity. Presence of DO in the water was found to be required for the reaction to go forward. Water from an algae pond, supersaturated with dissolved oxygen was spiked with toluene and destruction tests were then conducted in the same reactor. These tests did not show the expected improvement in destruction rates.

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 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.

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