scholarly journals Dissolution kinetics of Amazonian metakaolin in nitric acid

Cerâmica ◽  
2018 ◽  
Vol 64 (369) ◽  
pp. 86-90 ◽  
Author(s):  
P. E. A. Lima ◽  
R. S. Angélica ◽  
R. F. Neves
Keyword(s):  
Nitric Acid ◽  
Flat Plate ◽  
Acid Leaching ◽  
Dissolution Kinetics ◽  
Regression Coefficients ◽  
First Order ◽  
Constant Size ◽  
Shrinking Core ◽  
Leaching Reaction ◽  
Kinetics Of

Abstract The kinetic study of Amazon metakaolin dissolution was performed with the application of the shrinking core model for spherical and ‘flat plate’ particles with constant size. The Amazon kaolin was calcinated at 700 ºC in order to produce metakaolin. This metakaolin was leached with 5% excess nitric acid at 70, 80 and 95±3 ºC for 3 h. Samples were collected every 15 min and subjected to aluminum analysis. The acid leaching was a chemically controlled process. The spherical morphology showed better fit than the flat plate particles when taking into account the regression coefficients. 91.58 kJ/mol of activation energy was found as well as an aluminum leaching reaction of the first order. The results found in this work using 5% excess acid and Amazon kaolin were consistent with previous research results using excess acid above 50% and standard kaolin.

Dissolution kinetics of Amazonian metakaolin in hydrochloric acid

Clay Minerals ◽  
2017 ◽  
Vol 52 (1) ◽  
pp. 75-82 ◽  
Author(s):  
Paula E.A. Lima ◽  
Rômulo S. Angélica ◽  
Roberto F. Neves
Keyword(s):  
Hydrochloric Acid ◽  
Dissolution Kinetics ◽  
Regression Coefficients ◽  
Shrinking Core Model ◽  
First Order ◽  
Constant Size ◽  
Shrinking Core ◽  
Kinetics Of Dissolution ◽  
Leaching Reaction ◽  
Kinetics Of

AbstractThe kinetics of dissolution of Amazonian metakaolin in hydrochloric acid (HCl) was studied using the ‘Shrinking Core Model’ for spherical and ‘flat plate’ particles of constant size. The Amazonian kaolin was calcined at 700°C for 2 h. The calcined samples (metakaolins) were leached in an HCl solution with 5% excess at 70, 80 and 95 ± 3°C for 3 h. Samples were collected every 15 min and subjected to Al analysis by the EDTA titrimetric method. Experimental data showed that the spherical morphology produced a better fit with respect to the regression coefficients. The activation energy of the reaction was 90.6 kJ/mol. The chemical process is a first-order leaching reaction. The results of the present study are consistent with those from previous research on this topic, which used HCl with an excess of >90%.

scholarly journals Acidic leaching of iron from Kaoje Goethite ore by hydrochloric acid: Kinetics modelling

2020 ◽  
Vol 39 (3) ◽  
pp. 800-806
Author(s):  
K.I. Ayinla ◽  
A.A. Baba ◽  
S. Girigisu ◽  
O.S. Bamigboye ◽  
B.C. Tripathy ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Acid Leaching ◽  
Dissolution Kinetics ◽  
Second Phase ◽  
Low Grade ◽  
Iron And Steel ◽  
Kinetics Modelling ◽  
Shrinking Core ◽  
Hcl Concentration ◽  
Kinetics Of

Considering the recent focus of the Nigeria Government to grow and develop the nation’s economy through the solid minerals sector reform, this study has been devoted to the kinetics of a Nigerian goethite ore by hydrochloric acid leaching for improved iron and steel industries applications. This study was performed in three different phases. In the first phase, acidic leaching of iron from a goethite ore was examined and the influence of the operating variables including: HCl concentration, leaching temperature, stirring speed and particle sizes was examined experimentally. The optimum condition was found to be HCl concentration of 1.81M, temperature of 80°C, 200 rpm stirring speed and particle size 0.09 μm for iron in the range of investigated parameters. Under those conditions, the highest iron recovery was obtained to be 95.67 %. In the second phase, the dissolution kinetics of iron was evaluated by the shrinking core models. The finding reveals that diffusion through the fluid was the leaching kinetics rate controlling step of the iron. The activation energy (Ea) was found to be 14.54 kJmol-1 for iron. Equation representing the leaching kinetic of iron was achieved to be 1−2/3α - (1 − x)2/3 = 0.7272 × e−38.29/8.314×T × t. The final stage of the experiment was carried out by characterizing the leached residues by X-ray diffractometer (XRD) and scanning electron microscopy (SEM), the result showed majorly the presence of rutile (TiO2), anglesite (PbSO4), and traces of iron-silicate face like pyrite (FeS), quartz (SiO2). Keywords: kinetics modelling, leaching, low-grade, recovery, shrinking core

Kinetics of Alumina Removal from a Calcined Kaolin with Nitric, Sulphuric and Hydrochloric Acids

Clay Minerals ◽  
1970 ◽  
Vol 8 (3) ◽  
pp. 337-345 ◽  
Author(s):  
S. F. Hulbert ◽  
D. E. Huff
Keyword(s):  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Kinetic Data ◽  
Acid Leaching ◽  
Normal Reaction ◽  
Reaction Equation ◽  
Experimental Conditions ◽  
Image Position ◽  
Calcined Kaolin ◽  
Kinetics Of

AbstractAn investigation of the acid-leaching of a calcined kaolin was made to compare the reaction kinetics of hydrochloric, nitric, and sulphuric acids. The acid concentrations used were 5·9 and 8·6 normal. Reaction temperatures used were 95°, 80° and 60° C.Particular attention was given to finding a reaction equation which would mathematically represent the kinetic data. A nucleation rate equation of the general form, was found to represent these data. Values of m varied from 1·10 to 1·55 depending on the experimental conditions.Under the conditions employed the rate of alumina leaching is fastest with hydrochloric acid, slower with sulphuric acid, and slowest with nitric acid. The rate controlling steps are proposed from the experimental evidence.

Correlation analysis of reactivity in the addition of substituted benzylamines to β-nitrostyrene

1996 ◽  
Vol 74 (4) ◽  
pp. 625-629 ◽  
Author(s):  
Neeta Jalani ◽  
Seema Kothari ◽  
Kalyan K. Banerji
Keyword(s):  
Activation Energy ◽  
Correlation Analysis ◽  
Rate Constant ◽  
Steric Hindrance ◽  
Nucleophilic Addition ◽  
Regression Coefficients ◽  
Nucleophilic Attack ◽  
Arrhenius Activation Energy ◽  
First Order ◽  
Kinetics Of

The kinetics of addition of a number of ortho-, meta-, and para-substituted benzylamines to β-nitrostyrene (NS) in acetonitrile have been studied. The reaction is first order with respect to NS. The order with respect to the amine is higher than one. It has been shown that the reaction follows two mechanistic pathways, uncatalyzed and catalyzed by the amine. The Arrhenius activation energy for the catalyzed path is negative, indicating the presence of a pre-equilibrium (k1, k−1) leading to the formation of a zwitterion. The values of the rate constant, k1, for the nucleophilic attack have been determined for 28 benzylamines. The rate constant k1 was subjected to correlation analysis using Charton's LDR and LDRS equations. The polar regression coefficients are negative, indicating the formation of a cationic species in the transition state. The reaction is subject to steric hindrance by ortho substituents. Key words: nucleophilic addition, benzylamines, correlation analysis, kinetics, alkene.

scholarly journals Application of the Shrinking-Core Models for Determination of Dissolution Kinetics of Mn and Zn from Spent Zinc–Carbon Battery Powder in Organic Acid Solution

2019 ◽  
Vol 27 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Tevfik Agacayak ◽  
Hasan Ali Taner
Keyword(s):  
Acetic Acid ◽  
Acid Solution ◽  
Acetic Acid Solution ◽  
Dissolution Kinetics ◽  
Kinetic Studies ◽  
Product Layer ◽  
Different Temperatures ◽  
Shrinking Core ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

Abstract In this study, dissolution kinetics of manganese and zinc from spent zinc–carbon batteries in acetic acid solution was investigated. To determine the kinetics of dissolution of manganese and zinc, shrinking core model was applied to dissolution recoveries obtained at different temperatures. As a result of kinetic studies, it was determined that manganese and zinc were dissolved in acetic acid solution by diffusion from product layer and then activation energies (Ea) were calculated.

Comparison of different models for describing gypsum dissolution kinetics in different aqueous salt solutions

Soil Research ◽  
1990 ◽  
Vol 28 (6) ◽  
pp. 947 ◽  
Author(s):  
H Singh ◽  
MS Bajwa
Keyword(s):  
Dissolution Kinetics ◽  
Sodium Adsorption Ratio ◽  
Standard Errors ◽  
Salt Solutions ◽  
Order Model ◽  
Gypsum Dissolution ◽  
First Order ◽  
Aqueous Salt Solutions ◽  
Elovich Equation ◽  
Kinetics Of

Gypsum dissolution as a function of time was measured in solutions having a sodium adsorption ratio (SAR) of 7.5, 14 and 27 (mmol(+) kg-1)1/2 and an electrical conductivity (EC) of 1 5 and 3.1 dS m-1. The amount of gypsum dissolved increased with increases in the SAR and EC values of the different equilibrating solutions. The rate of gypsum dissolution was higher initially but declined with increasing time of equilibration. Of the total amount of gypsum dissolved in 40 h, about 60-70% dissolution occurred during the first 5 min. Comparisons of coefficients of determination (r2) and standard errors of estimate indicated that, in addition to the most widely used linear form of the first-order model, other models such as the power function, empirical (modified from first-order) and the Elovich equation, can also be used to describe the kinetics of gypsum dissolution in aqueous solutions varying in SAR and EC.

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