Kinetics of Acid Hydrolysis of Arabinogalactans

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Bright T Kusema ◽  
Chunlin Xu ◽  
Päivi Mäki-Arvela ◽  
Stefan Willför ◽  
Bjarne Holmbom ◽  
...  
Keyword(s):  
Acid Hydrolysis ◽  
Acid Concentration ◽  
Batch Reactor ◽  
Average Molecular Weight ◽  
Hydrolysis Rate ◽  
Order Kinetic ◽  
First Order ◽  
Order Kinetic Model ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the acid hydrolysis of arabinogalactans (AG) was studied isothermally in a batch reactor. AG was hydrolyzed with hydrochloric acid and the main parameters established were the acid concentration (pH), temperature and AG concentration. The hydrolysis rate increased with the acid concentration (pH) and temperature. Complete hydrolysis of AG to arabinose and galactose was achieved at 90°C and pH 1 without any further degradation of the sugars. A first-order kinetic model including two simultaneous reactions for the formation of arabinose and galactose was successfully fitted to the experimental data. The rate constants and activation energies were calculated from the model. The decrease of the average molecular weight was also explained by the model.

Evidence for the formation of lignin-hexenuronic acid-xylan complexes during modified kraft pulping processes

Holzforschung ◽  
2006 ◽  
Vol 60 (2) ◽  
pp. 137-142 ◽  
Author(s):  
Zhi-Hua Jiang ◽  
Jean Bouchard ◽  
Richard Berry
Keyword(s):  
Acid Hydrolysis ◽  
Kraft Pulp ◽  
Kraft Pulping ◽  
Order Kinetic ◽  
Kraft Pulps ◽  
First Order ◽  
Pseudo First Order ◽  
Hexenuronic Acid ◽  
Kinetics Of ◽  
Hydrolysis Of

Abstract The finding that hexenuronic acid (HexA) groups can be selectively removed from kraft pulps by acid hydrolysis has provided an opportunity to reduce bleaching chemicals. However, there is evidence that the acid hydrolysis is not uniform. In this report, we evaluate the kinetics of acid hydrolysis of HexA in a xylan sample enriched with HexA, a conventional kraft pulp, and three modified kraft pulps: anthraquinone pulp (Kraft-AQ), polysulfide pulp (PS), and polysulfide-anthraquinone pulp (PS-AQ). We found that HexA present in the xylan and conventional kraft pulp behaved similarly toward the acid hydrolysis throughout. On the other hand, HexA present in the Kraft-AQ, PS-AQ and PS pulps was heterogeneous toward acid hydrolysis and the reaction can be separated into two pseudo-first-order kinetic phases, each of which has a different rate constant. The kinetic data provide evidence for the formation of lignin-HexA-xylan complexes during modified kraft pulping processes.

Kinetics of bioactive compounds in functional spice Jiangpo during thermal processing

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Xiaoyan Dai ◽  
Chenhuan Yu ◽  
Qiaofeng Wu
Keyword(s):  
Kinetic Parameters ◽  
Bioactive Compounds ◽  
Thermal Processing ◽  
Order Rate Constant ◽  
Heat Processing ◽  
Order Kinetic ◽  
Time Intervals ◽  
First Order ◽  
Order Kinetic Model ◽  
Kinetics Of

Abstract Jiangpo is an increasingly popular East Asian spice which is made from Mangnolia officinalis bark and ginger juice. Since it induces bioactive compounds decomposition and has influence on final flavor and fragrance, cooking is regarded as the key operation in preparation of Jiangpo. To evaluate the bioactive compounds content changes of Jiangpo during thermal processing, kinetic parameters including reaction order, rate constant, T1/2 and activation energy of bioactive markers namely honokiol, magnolol and curcumin were determined. Cooking was set at temperatures 60, 90 and 120 °C for selected time intervals. Results displayed the thermal kinetic characteristics of the three compounds. Thermal degradation of Honokiol and magnolol both followed first order kinetic model and the loss of curcumin fitted second order. A mathematical model based on the obtained kinetic parameters has also been developed to predict the degradation of honokiol, magnolol and curcumin in non-isothermal state. All the information in this paper could contribute necessary information for optimizing the existing heat processing of Jiangpo.

scholarly journals Stability of tetracycline residues in honey

2012 ◽  
Vol 77 (7) ◽  
pp. 879-886 ◽  
Author(s):  
Cara Cristina ◽  
Dumitrel Gabriela-Alina ◽  
Glevitzky Mirel ◽  
Perju Delia
Keyword(s):  
Life Time ◽  
Order Kinetic ◽  
First Order ◽  
Reaction Rate Constants ◽  
Veterinary Medicines ◽  
West Region ◽  
Tetracycline Degradation ◽  
Order Kinetic Model ◽  
Tetracycline Residues ◽  
Kinetics Of

The problem of availability of veterinary medicines to treat honeybees is discussed extensively worldwide. An uncontrolled administration of antibiotics may lead to contamination of beehive products and contributes to the problem of food safety. In this study, the kinetics of tetracycline (TC) degradation in honey was studied for samples provided by four sideline beekeepers located in the west region of Romania. The samples of honey were stored in the dark at room temperature for 30 days and subsamples were analyzed every 3 days by Elisa method. The results of the study revealed that the level of tetracycline decreases in time for all honey samples. The tetracycline degradation follows a first-order kinetic model with reaction rate constants between 1.2?10-3 - 2?10-3 days-1. The half-life time of tetracycline in monofloral honeys: acacia and lime was 251 and 232 days respectively. Tetracycline degradation in polyfloral honey was accelerated since ?1/2 of TC was 151 days.

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.

Complexes of Nickel(II) and Copper(II) With 5,5,7-Trimethyl-1,4-Diazepane. Preparation and Kinetics of Acid-Hydrolysis

1986 ◽  
Vol 39 (2) ◽  
pp. 239 ◽  
Author(s):  
NF Curtis
Keyword(s):  
Acid Hydrolysis ◽  
Acid Concentration ◽  
Reaction Rates ◽  
Borohydride Reduction ◽  
Kinetics Of Hydrolysis ◽  
Rapid Reaction ◽  
Kinetics Of ◽  
Hydrolysis Of

The cyclic diamine 5,5,7-trimethyl-1,4-diazepane, tmdz, is formed by borohydride reduction of 5,7,7-trimethyl-2,3,6,7-tetrahydro-1H-1,4- diazepine , which is formed by a rapid reaction between ethanediamine and 4-methylpent-3-en-2-one. Salts of the cations [Ni( tmdz )2]2+ and [Cu( tmdz )2]2+ were prepared, and their properties are reported. The kinetics of hydrolysis of [Ni( tmdz )2]2+ and [Cu( tmdz )2]2+ and bis (1,4- diazepane )nickel(II), [Ni( dach )2]2+, in aqueous HCl/NaCl media have been studied. Reaction rates are independent of acid concentration over the ranges used . Ni2+,0.1-1 mol l-1 H+ in 1 mol l-1 Cl -, kobs(25°C) = 9.1(1)×10-7 s-1, kobs(50°C) = 2.0(1)×10-5 s-1,ΔH‡96(2)kJ mol-1,0.08-4 mol l-1, H+ in 4 mol l-1 Cl -, kobs (25°pC) = 2.0(3)°10-7 s-1. Cu2+, 0.04-1 mol l-1 H+, 1 mol l-1 Cl -, kobs (25°C) = 0.028(2) s-1, for the displacement of the second ligand . [Ni( dach )2]2+, 0.1-1 mol l-1 H+, 1 mol l-1 Cl -, kobs (25°C) = 0.051(2) s-1. [Ni( tmdz )2]2+ reacts more rapidly with NaOH/edta : 1 mol l-1 NaOH , 0.1 mol l-1, Na2(edtaH2), kobs (25°C) = 7.3(3)×10-3 s-1, 0.5 mol l-1 NaOH , 0.1 mol l-1 Na2(edtaH2), kobs (25°C) = 4.5(3)×10-3 s-1.

Kinetic Study of the Adsorption of Dye onto Cotton in SDS-CTAB Reverse Micelles

2015 ◽  
Vol 723 ◽  
pp. 591-595
Author(s):  
Zu Lan Liu ◽  
Lan Qian Li ◽  
Yi Ping Liu ◽  
Ming Lu
Keyword(s):  
Kinetic Study ◽  
Adsorption Kinetics ◽  
Reverse Micelles ◽  
Adsorption Kinetic ◽  
Order Kinetic ◽  
First Order ◽  
Reactive Blue 19 ◽  
Order Kinetic Model ◽  
Pseudo First Order ◽  
Kinetics Of

Adsorption kinetic study of C.I. reactive blue 19 onto cotton was carried out in SDS-CTAB reverse micelles. The data of adsorption kinetics were examined using pseudo first-and second-order kinetic models. It was found that the adsorption kinetics of dye on cotton with diffusion controlling follows the pseudo first-order kinetic model.

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 MODELAMIENTO DE LA CINÉTICA DE HIDRÓLISIS ENZIMÁTICA DE PROTEÍNAS DEL PLASMA BOVINO (MODELING OF THE KINETICS OF ENZYMATIC HYDROLYSIS OF BOVINE PLASMA PROTEINS)

Revista EIA ◽  
2013 ◽  
Vol 9 (17) ◽  
pp. 71
Author(s):  
Omar Alfredo Figueroa ◽  
José Édgar Zapata ◽  
Gail Albeiro Gutiérrez
Keyword(s):  
Kinetic Model ◽  
Plasma Proteins ◽  
Batch Reactor ◽  
Degree Of Hydrolysis ◽  
Order Kinetic ◽  
Enzyme Substrate ◽  
Bovine Plasma ◽  
Order Kinetic Model ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Se utilizó un modelo cinético para estudiar la velocidad de reacción en la hidrólisis de proteínas de plasma de bovino con alcalasa 2,4 L en un reactor batch. Se estudió la influencia de variables como la concentración inicial de sustrato y enzima sobre el grado de hidrólisis y se determinaron los parámetros cinéticos de la ecuación de velocidad, analizando su relación con las variables de trabajo. Se ajustó un modelo cinético de orden cero y desactivación enzimática por sustrato, de segundo orden, así como la relación directa entre la fracción enzima-sustrato y la tasa de formación de productos de hidrólisis.Abstract: A kinetic model was used to study the reaction rate of hydrolysis of bovine plasma proteins and alcalase 2.4 L, in a batch reactor. The influence of variables, such as the concentration of initial enzyme substrate and the degree of hydrolysis was studied, and kinetic parameters of the rate equation were determined by analyzing its relationship with the work variables. A zero-order kinetic model and enzyme deactivation by substrate was found, as well as the direct relationship between the fraction of enzyme-substrate and the rate of formation of hydrolysis products.

scholarly journals Optimization of Ethanol Production Process from Cassava Starch by Surface Response

2019 ◽  
Vol 54 (4) ◽  
Author(s):  
Leticia López Zamora ◽  
José Amir González Calderón ◽  
Evangelina Trujillo ◽  
Eusebio Bolaños Reynoso
Keyword(s):  
Acid Hydrolysis ◽  
Ethanol Concentration ◽  
Continuous Process ◽  
Cassava Starch ◽  
Average Error ◽  
Order Kinetic ◽  
Quadratic Regression ◽  
Statistical Software ◽  
First Order ◽  
Order Kinetic Model

This work shows the study of the optimization process for producing ethanol from cassava starch based on 22 experimental designs with three central points and using statistical software. This methodology was applied to the stage of saccharification of cassava starch by acid hydrolysis as well as to the stage of fermentation using Saccharomyces cerevisiae. From the experimental data of acid hydrolysis, we proposed a first-order kinetic model which presented an average error of 1.87 % compared to the quadratic regression obtained. The development of a semi-continuous process showed a 89.84 % conversion of starch initially considered, yielding an ethanol concentration of 49.76 % Alc/vol.

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