scholarly journals Degradation kinetics of DDT in tropical soils: A proposed multi-phase zero order kinetic model that takes into account evaporation, hydrolysis, photolysis, microbial degradation and adsorption by soil particulates.

2020 ◽  
Vol 9 ◽  
pp. e00467
Author(s):  
Mark F. Zaranyika ◽  
Edmore Matimati ◽  
Paul Mushonga
Keyword(s):  
Kinetic Model ◽  
Microbial Degradation ◽  
Degradation Kinetics ◽  
Tropical Soils ◽  
Zero Order ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
Multi Phase ◽  
Kinetics Of

scholarly journals The effect of microwave pre-treatment of rapeseed on the degradation kinetics of lipophilic bioactive compounds of the oil during storage

2018 ◽  
Vol 69 (1) ◽  
pp. 233 ◽  
Author(s):  
A. Rękas ◽  
A. Siger ◽  
M. Wroniak
Keyword(s):  
Antioxidant Capacity ◽  
Degradation Kinetics ◽  
Storage Period ◽  
Zero Order ◽  
Order Kinetic ◽  
Carotenoid Concentration ◽  
Capacity Degradation ◽  
Order Kinetic Model ◽  
Pre Treatment ◽  
Kinetics Of

This study examined the storage stability of tocochromanols and carotenoids in the oils prepared from microwave pre-treated (MV) rapeseeds (2-10 min, 800W) during storage at 20 °C for 12 months. In line with lipophilic antioxidant degradation throughout the storage period, changes in the antioxidant capacity of the oil were monitored. Microwaving significantly affected the concentration of lipophilic antioxidants in the oil. After 10 min of MV pre-treatment the highest content of total tocochromanols (76.64 mg/100g) was achieved, whereas a maximum carotenoid concentration (861.28 μg/100g) was obtained following 6 min seed MV pre-treatment. The degradation kinetics for the tocochromanols and carotenoids followed a zero-order kinetic model. From the kinetic analysis, it was shown that the degradation rate constant (k) of both tocochromanols and carotenoids decreased with longer seed exposure to MV radiation. The kinetics of antioxidant capacity degradation during the storage of oils followed a zero-order reaction. The rate of antioxidant capacity degradation in the control oil was higher (k=9.1 x 10-2 mmol TEAC/l/month) compared with oils prepared from MV pre-treated seeds (k=6.8-8.0 x 10-2 mmol TEAC/l/month).

scholarly journals Kinetic Modeling of a Heterogeneous Fenton Oxidative Treatment of Petroleum Refining Wastewater

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Diya'uddeen Basheer Hasan ◽  
Abdul Aziz Abdul Raman ◽  
Wan Mohd Ashri Wan Daud
Keyword(s):  
Kinetic Model ◽  
Direct Conversion ◽  
Order Kinetic ◽  
Initial Oxidation ◽  
Oxidation Step ◽  
Kinetic Rate Constants ◽  
Order Kinetic Model ◽  
Generalized Kinetic Model ◽  
Petroleum Refinery Effluent ◽  
Kinetics Of

The mineralisation kinetics of petroleum refinery effluent (PRE) by Fenton oxidation were evaluated. Within the ambit of the experimental data generated, first-order kinetic model (FKM), generalised lumped kinetic model (GLKM), and generalized kinetic model (GKM) were tested. The obtained apparent kinetic rate constants for the initial oxidation step (k2′), their final oxidation step (k1′), and the direct conversion to endproducts step (k3′) were 10.12, 3.78, and 0.24 min−1for GKM; 0.98, 0.98, and nil min−1for GLKM; and nil, nil, and >0.005 min−1for FKM. The findings showed that GKM is superior in estimating the mineralization kinetics.

Browning Reaction Kinetics of High Hydrostatic Pressure-Treated Peach Puree during Storage

2011 ◽  
Vol 7 (4) ◽  
Author(s):  
Thamer Abdul Kadir Khalil ◽  
Mazin Ibrahem Al-Zubaidy ◽  
Omer Fawzi Abdulaziz
Keyword(s):  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Temperature Scale ◽  
Zero Order ◽  
Order Kinetic ◽  
Browning Reaction ◽  
Color Development ◽  
Order Kinetic Model ◽  
Pressure Scale ◽  
Kinetics Of

Kinetics of browning color development, described as browning index (BI), of peach puree subjected to high hydrostatic pressure (HHP) treatments (400, 500, and 600 MPa/1 and 3 min) during 6 weeks of storage at 4 and 20°C were investigated. This research was conducted to modify the use of pressure scale instead of temperature scale in calculating the kinetic parameters of BI values in peach puree samples. The increase in BI values followed the zero-order kinetic model. The highest activation energy (Ea) was experienced with HHP treatment (400, 500, and 600 MPa/3 min) of peach puree samples stored at 4°C.

scholarly journals CHARACTERISTICS OF ASCORBIC ACID RELEASE FROM TPP-CROSSLINKED CHITOSAN/ALGINATE POLYELECTROLYTE COMPLEX MEMBRANES

2018 ◽  
Vol XXIII ◽  
pp. 76-87 ◽  
Author(s):  
Magdalena Gierszewska ◽  
Jadwiga Ostrowska-Czubenko ◽  
Ewelina Chrzanowska
Keyword(s):  
Ascorbic Acid ◽  
Kinetic Model ◽  
Polyelectrolyte Complex ◽  
Zero Order ◽  
Order Kinetic ◽  
Initial Burst ◽  
First Order ◽  
Order Kinetic Model ◽  
Acid Release ◽  
Release Data

Chitosan/alginate polyelectrolyte complex membranes (Ch/Alg) additionally cross-linked with tripolyphosphate (TPP) and containing ascorbic acid (AA) were prepared. The dynamic swelling behaviour of Ch/Alg/TPP and ascorbic acid release from the membrane were characterised in different buffer solutions. It has been found that the pH of the buffer solution affects the swelling and release behaviour of AA. Ascorbic acid release, observed over a period of 360 min, exhibited a biphasic pattern, characterised by a fast initial burst release, followed by a slow, sustained release. Different mathematical models were used to study the kinetics and transport mechanism of AA from Ch/Alg/TPP hydrogels. Drug release data were fitted to the zero order kinetic model and first order kinetic model. To characterise the drug mechanism, the release data were fitted to the Higuchi and Korsmeyer-Peppas equations. The initial burst AA release followed zero order kinetics and was quasi-Fickian in nature. The second step of AA release followed first order kinetics.

scholarly journals Thermal Stability and Degradation Kinetics of Patulin in Highly Acidic Conditions: Impact of Cysteine

Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 662
Author(s):  
Enjie Diao ◽  
Kun Ma ◽  
Hui Zhang ◽  
Peng Xie ◽  
Shiquan Qian ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Degradation Kinetics ◽  
Correlation Coefficients ◽  
Degradation Process ◽  
Weibull Model ◽  
Degradation Efficiency ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
Acidic Conditions ◽  
Kinetics Of

The thermal stability and degradation kinetics of patulin (PAT, 10 μmol/L) in pH 3.5 of phosphoric-citric acid buffer solutions in the absence and presence of cysteine (CYS, 30 μmol/L) were investigated at temperatures ranging from 90 to 150 °C. The zero-, first-, and second-order models and the Weibull model were used to fit the degradation process of patulin. Both the first-order kinetic model and Weibull model better described the degradation of patulin in the presence of cysteine while it was complexed to simulate them in the absence of cysteine with various models at different temperatures based on the correlation coefficients (R2 > 0.90). At the same reaction time, cysteine and temperature significantly affected the degradation efficiency of patulin in highly acidic conditions (p < 0.01). The rate constants (kT) for patulin degradation with cysteine (0.0036–0.3200 μg/L·min) were far more than those of treatments without cysteine (0.0012–0.1614 μg/L·min), and the activation energy (Ea = 43.89 kJ/mol) was far less than that of treatment without cysteine (61.74 kJ/mol). Increasing temperature could obviously improve the degradation efficiency of patulin, regardless of the presence of cysteine. Thus, both cysteine and high temperature decreased the stability of patulin in highly acidic conditions and improved its degradation efficiency, which could be applied to guide the detoxification of patulin by cysteine in the juice processing industry.

Anaerobic degradation kinetics of a cholesteryl ester

2003 ◽  
Vol 48 (6) ◽  
pp. 141-147
Author(s):  
S. Gutiérrez ◽  
M. Viñas
Keyword(s):  
Palmitic Acid ◽  
Anaerobic Degradation ◽  
Drop Size ◽  
Degradation Kinetics ◽  
Relative Rate ◽  
Hydrolysis Rate ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
The Difference ◽  
Kinetics Of

The most important components of wool scouring effluent grease are esters of sterols. Cholesteryl palmitate (CP) is the main ester in this grease. In this paper, the influence of the ester concentration in the anaerobic digestion and the relative rate of the different degradation steps, are studied. The experiment was carried out to measure methane production in the anaerobic degradation of acetate, palmitic acid (PA) and CP. A first-order kinetic model was assumed for hydrolysis and Monod models were assumed for both the methanogenic and acetogenic steps. Maximum hydrolysis rate was found to be around 20 times faster than the maximum methanogenic reaction rate during the experience. The lanolin emulsion drop size effect was also evaluated employing fine and coarse stock lanolin emulsions and no adapted sludge. Concentrations of 13.7 to 4.6 gCOD.l-1 were employed. In a previous study, the effect of palmitic acid emulsion size was found important when similar sludge was tested. When esters are degraded, a significant effect of drop size on the degradation rate was not found. The difference between CP and PA emulsions behavior could be due to the fact that cholesterol produced during the ester degradation has a protective effect on the sludge.

Note. Hydrolysis of Onion and Kinetics of Non-Enzymatic Browning of its Hydrolysate

2004 ◽  
Vol 10 (1) ◽  
pp. 41-44 ◽  
Author(s):  
J. M. Kim ◽  
K. S. Ra ◽  
H. J. Suh
Keyword(s):  
Zero Order ◽  
Total Sugar ◽  
Effect Of Temperature ◽  
Enzymatic Browning ◽  
Order Kinetic ◽  
Arrhenius Model ◽  
Browning Index ◽  
Order Kinetic Model ◽  
Kinetics Of ◽  
Hydrolysis Of

Enzymatic hydrolysis of onion was performed by three different commercial enzyme products (Econase, Rapidase and Viscozyme) for preparation of onion hydrolysates. The hydrolysis yield was determined through the analysis of reducing and total sugar contents in final hydrolysates. Total sugar contents after 2 h-hydrolysis with Econase, Rapidase and Viscozyme were 59.6, 64.1 and 62.2 mg/mL, respectively, and reducing sugar contents of 28.5, 42.7 and 35.9 mg/mL in the same order. According to these results Rapidase was more suitable for the hydrolysis of onion than the other enzymatic products. The effect of temperature on non-enzymatic browning reaction kinetics of the onion hydrolysate was determined. The browning index variation was adequately described by both the first- and the zero-order kinetic. However, the zero-order kinetic model was preferred because its fitting was higher. The values of kinetic constants were 0.081 (60 C), 0.185 (70 C), 0.270 (80 C) and 0.377 (90 C). According to the Arrhenius model, the activation energy for browning index in the range 60–90 C was 21.9 kJ/mol.

scholarly journals Fractional kinetics of photocatalytic degradation

2018 ◽  
Vol 08 (05) ◽  
pp. 1850034 ◽  
Author(s):  
C. L. Wang
Keyword(s):  
Kinetic Model ◽  
Photocatalytic Degradation ◽  
Degradation Process ◽  
Order Kinetic ◽  
Material Parameters ◽  
First Order ◽  
Fractional Kinetics ◽  
Order Kinetic Model ◽  
Kinetics Of ◽  
Degradation Time

In this paper, photocatalytic degradation processes of different materials are fitted to the first-order kinetic model, second-order kinetic model and fractional first-order kinetic model. Deterministic coefficients are calculated for the evaluation of the validity of these models. The fitting results show clearly that the degradation process can fit the fractional first-order kinetic model in a very good manner. In this way, two material parameters can be well defined. One is the degradation time, which can be used to describe the photocatalytic degradation process quantitatively. Another is the order of the derivative, which could be related to the material’s microstructure.

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