Kinetic Model for the Reaction of Cobalt Porphyrins with Olefins under Free Radical Conditions1

1996 ◽  
Vol 15 (1) ◽  
pp. 222-235 ◽  
Author(s):  
Alexei A. Gridnev ◽  
Steven D. Ittel ◽  
Michael Fryd ◽  
Bradford B. Wayland
Keyword(s):  
Free Radical ◽  
Kinetic Model ◽  
Cobalt Porphyrins

A Comprehensive Kinetic Model for the Free-Radical Polymerization of Vinyl Chloride in the Presence of Monofunctional and Bifunctional Initiators

2004 ◽  
Vol 43 (20) ◽  
pp. 6382-6399 ◽  
Author(s):  
Apostolos Krallis ◽  
Costas Kotoulas ◽  
Stratos Papadopoulos ◽  
Costas Kiparissides ◽  
Jacques Bousquet ◽  
...  
Keyword(s):  
Free Radical ◽  
Kinetic Model ◽  
Radical Polymerization ◽  
Vinyl Chloride ◽  
Free Radical Polymerization ◽  
Bifunctional Initiators

scholarly journals New Semi-IPN Hydrogels Based on Cellulose for Biomedical Application

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
S. K. Bajpai ◽  
M. P. Swarnkar
Keyword(s):  
Free Radical ◽  
Kinetic Model ◽  
Water Uptake ◽  
Diffusion Coefficients ◽  
Biomedical Application ◽  
Paper Industry ◽  
Swelling Behavior ◽  
Late Time ◽  
Cellulose Pulp ◽  
Uptake Data

Cellulose pulp, obtained from a paper industry, has been dissolved in PEG/NaOH system and the resulting solution has been polymerized in the presence of monomer acrylic acid (AA) and crosslinker N,N′ methylene bisacrylamide via free radical polymerization. The Cell/PEG/poly (SA) ternary semi-IPN hydrogel, so prepared, was characterized by FTIR and TG analysis. The dynamic water uptake of various hydrogels, having different compositions, was investigated in the physiological buffer of pH 7.4 at 37°C. The various hydrogels exhibited chain-relaxation controlled swelling behavior. The uptake data was best interpreted by Schott kinetic model. The various diffusion coefficients, that is, initial (Di), average (Dave), and late time (DL), were also calculated using the dynamic water uptake data. The hydrogels showed fair pH and salt-dependent swelling behavior.

scholarly journals Modeling the Mineralization Kinetics of Visible Led Graphene Oxide/Titania Photocatalytic Ozonation of an Urban Wastewater Containing Pharmaceutical Compounds

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1256
Author(s):  
Fernando J. Beltrán ◽  
Manuel Checa ◽  
Javier Rivas ◽  
Juan F. García-Araya
Keyword(s):  
Free Radical ◽  
Kinetic Model ◽  
Hydroxyl Radical ◽  
Reaction Kinetics ◽  
Hydroxyl Radicals ◽  
Reaction Rate ◽  
Pharmaceutical Compounds ◽  
Urban Wastewater ◽  
Photocatalytic Ozonation ◽  
Liquid Reaction

In a water ozonation process, dissolved organics undergo two reactions at least: direct ozone attack and oxidation with hydroxyl radicals generated from the ozone decomposition. In the particular case of urban wastewater contaminated with pharmaceuticals, competition between these two reactions can be studied through application of gas–liquid reaction kinetics. However, there is a lack in literature about kinetic modeling of ozone processes in water specially in photocatalytic ozonation. In this work, lumped reactions of ozone and hydroxyl radicals with total organic carbon have been proposed. Urban wastewater containing a mixture of eight pharmaceutical compounds has been used to establish the kinetic model that simulates the mineralization process. The kinetic model is based on a mechanism of free radical and molecular reactions and the knowledge of mass transfer, chemical reaction rate constants, and radiation transfer data. According to the model, both single ozonation and photocatalytic ozonation present two distinct reaction periods characterized by the absence and presence of dissolved ozone. In the first period (less than 10 min), pharmaceuticals mainly disappear by direct ozone reactions and TOC variation due to these compounds has been modeled according to gas–liquid reaction kinetics through a lumped ozone-pharmaceutical TOC fast second order reaction. The corresponding rate constant of this reaction was found to change with time from 3 × 105 to 200 M−1 s−1 with Hatta values higher than 0.3. In the second period (nearly 5 h), competition between direct and hydroxyl radical reactions takes place and a kinetic model based on a direct and free radical reaction mechanism is proposed. Main influencing parameters to be known were: Direct ozone reaction rate constant, catalyst quantum yield, and hydroxyl radical scavengers. The first two take values of 0.5 M−1 s−1 and 5 × 10−4 mol·photon−1, respectively, while a fraction of TOC between 10% and 90% that changes with time was found to possess hydroxyl radical scavenger nature.

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