Phase-Transformation Kinetics of TiO2 in TiO2/(O′+β′)-Sialon Multi-Phase Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 2318-2321
Author(s):  
Jian Yang ◽  
Xiang Xin Xue ◽  
Li Mei Pan ◽  
Mei Wang ◽  
Tai Qiu
Keyword(s):  
Phase Transformation ◽  
Kinetic Model ◽  
Raw Materials ◽  
Transformation Process ◽  
Transformation Kinetic ◽  
Order Kinetic ◽  
Weight Percentage ◽  
Tio2 Anatase ◽  
Additive Content ◽  
Kinetics Of

TiO2/(O′+β′)-Sialon multiphase ceramics with different phase composition of TiO2 were prepared by pressureless sintering under high-purity N2 atmosphere with (O′+β′)-Sialon powder and nano TiO2 (anatase) powder as raw materials, Yb2O3 or Tb2O3 as additive. For each sample, the weight percentage of anatase in TiO2 was calculated from XRD data and the kinetics of anatase-rutile transformation was investigated, wherein the emphasis was placed on the influence of Yb2O3 and Tb2O3. The results indicate that the added Tb2O3 and Yb2O3 serve the significant function of inhibition and promotion on the phase transformation, and the effects are enhanced and attenuated with increasing additive content, respectively. For the sample without additive, the transformation process follows apparent first-order kinetic model. The addition of Yb2O3 or Tb2O3 results in completely different transformation kinetic law. For the samples with Yb2O3 added, the transformation is an apparent second-order reaction, whereas a unique kinetic model, CA=kt1/2+C, is valid for the samples containing Tb2O3. In the two cases, the effect of the additive content on the transformation can be perfectly reflected by the apparent rate constant.

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.

Development of an Activity Based Kinetic Model for an Esterification Process with Indion 180 Catalyst

2019 ◽  
Vol 17 (9) ◽  
Author(s):  
Mekala Mallaiah ◽  
Chimmiri Venkateswarlu
Keyword(s):  
Kinetic Model ◽  
Reaction Rate ◽  
Experimental Results ◽  
Catalyst Loading ◽  
Esterification Reaction ◽  
Order Kinetic ◽  
Kinetic Rate ◽  
Model Predictions ◽  
Effects Of Temperature ◽  
Kinetics Of

Abstract The kinetics of esterification reaction between acetic acid and methanol was studied with the Indion 180 catalyst in the temperature range between 323.15 and 353.15K, and the catalyst loading between 0.01 g/cc to0.05 g/cc. The effects of temperature, catalyst loading, size of the catalyst and agitation speed on the reaction rate were investigated. The experimental results have shown the negligible effect of mass transfer resistances on the reaction rate. A second order kinetic rate expression was used to correlate the experimental data. An activity based kinetic model was also developed for the esterification process, which was validated against experimental results. The activity based model is found advantageous as it involves only two reaction rate parameters which were determined based on the kinetic rate parameters of the concentration based model. The comparison of the model predictions with the experimental results for different temperature and catalyst loading conditions has shown the better suitability of the activity based kinetic model for the esterification process with Indion 180 catalyst.

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.

Kinetics of Reductive Dechlorination of DDT in Soil with Zero-Valent Iron

2011 ◽  
Vol 295-297 ◽  
pp. 1236-1239
Author(s):  
Yin Hai Lang ◽  
Min Jie Wang ◽  
Nan Nan Wang
Keyword(s):  
Kinetic Model ◽  
Reductive Dechlorination ◽  
Reaction Rate ◽  
Zero Valent Iron ◽  
Order Kinetic ◽  
First Order ◽  
Reaction Rate Constants ◽  
Order Kinetic Model ◽  
Pseudo First Order ◽  
Kinetics Of

In this study, reductive dechlorination of DDT compounds by zero-valent iron in Jiangxi red soil was investigated. DDT compounds were effectively dechlorinated by zero-valent iron. The pseudo-first-order kinetic model for 2,4¢-DDT and 4,4¢-DDT reduction with zero-valent iron was proposed. The reaction rate constants for 2,4¢-DDT and 4,4¢-DDT were 1.19´10-2(min-1) and 1.44´10-2(min-1), respectively. The dechlorination of 2,4¢-DDT and 4,4¢-DDT were mainly affected by the specific surface area of iron. The data from the variable-pH experiments (between 3.6 and 8.8) suggested that pH does not play a role in the rate-determination step.

scholarly journals Minerals as Potential Catalysts in Heterogeneous Catalytic Ozonation: A Kinetic Study of p-CBA Degradation in Aqueous Solutions at pH 7

2021 ◽  
Vol 5 (1) ◽  
pp. 5
Author(s):  
Savvina Psaltou ◽  
Efthimia Kaprara ◽  
Manassis Mitrakas ◽  
Anastasios Zouboulis
Keyword(s):  
Kinetic Model ◽  
Kinetic Study ◽  
Raw Materials ◽  
Catalytic Ozonation ◽  
Second Order ◽  
Order Kinetic ◽  
First Order ◽  
Heterogeneous Catalytic ◽  
Order Kinetic Model ◽  
Pseudo Second Order

This study examines the removal of p-CBA via the application of heterogeneous catalytic ozonation in the presence of 13 minerals. The solids were used as raw materials or after hydrophilic/hydrophobic modification. The optimal minerals were zeolite, calcite, dolomite, and thermally treated talc. The kinetic study showed that the decomposition of ozone followed a first-order kinetic model for all ozonation systems, whereas the kinetic model of p-CBA removal depended on the materials that were applied. The catalytic degradation of p-CBA followed a second-order kinetic model, while in the presence of non-catalytic materials; the p-CBA abatement was in best agreement with the pseudo-second-order kinetic model, as single ozonation.

Phase Transformation Kinetics of TiSi2

1993 ◽  
Vol 311 ◽  
Author(s):  
R.R. Mann ◽  
L.L. Clevenger ◽  
Q.Q. Hong
Keyword(s):  
Phase Transformation ◽  
Effective Activation Energy ◽  
Single Crystal Silicon ◽  
Transformation Process ◽  
Silicon Substrates ◽  
Effective Activation ◽  
Transformation Kinetics ◽  
Crystal Silicon ◽  
Face Centered ◽  
Kinetics Of

ABSTRACTThe microstructure and kinetics of the polymorphic C49 to C54-TiSi2 phase transformation have been studied using samples prepared as in self-aligned silicide applications. For C49-TiSi2 thin films formed at temperatures of 600°C and 625°C on (100) single-crystal silicon substrates, the effective activation energy was 5.6 ± 0.3 and 5.7 ± 0.08 eV, respectively, for this phase transformation carried out in the temperature range of 600°C to 700°C. The transformation process was observed to occur by nucleation and growth of the orthorhombic face-centered (C54) phase from the as-formed orthorhombic base-centered (C49) phase.

Rehydration Capacity and Kinetics of Solar-Dried Carrot (Daucus carota) Slices as Affected by Blanching and Osmotic Pretreatments

2016 ◽  
Vol 12 (2) ◽  
pp. 203-210
Author(s):  
F. Teferra Tadesse ◽  
Solomon Abera ◽  
W. K. Solomon
Keyword(s):  
Kinetic Model ◽  
Hot Water ◽  
Soluble Solids ◽  
Order Kinetic ◽  
Salt Solutions ◽  
First Order ◽  
Treatment Conditions ◽  
Order Kinetic Model ◽  
Soluble Solid ◽  
Kinetics Of

Abstract This study investigated effects of pretreatments on rehydration characteristics of solar-dried carrot slices. Blanching at 55, 65 and 75°C for 45 minutes and osmotic dewatering in 5%, 10% and 15% salt solutions for 5 h were used as pretreatments. Rehydration capacity of the dried carrots was determined by soaking 20 g sample in hot water at 95°C for 10 min and rehydration kinetics was carried out by soaking 5 g samples at 75, 85 and 95°C. All the treatment conditions separately and in combination influenced the rehydration characteristics of the carrot slices. High values of rehydration capacity and low lixiviated soluble solids, which indicates better quality, were obtained for samples treated at the lower blanching temperature. Similarly the lower salt concentration resulted in higher rehydration capacity and lower lixiviated soluble solids. The interaction of the lower level of both pretreatments produced higher rehydration capacity and lower soluble solid losses. A first-order kinetic model was used to describe the rehydration kinetics. A better rehydration performance was observed for the samples subjected to the lower levels of pretreatments and rehydration conditions.

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