Kinetics of pyrite, pyrrhotite, and chalcopyrite dissolution byAcidithiobacillus ferrooxidans

2016 ◽  
Vol 62 (8) ◽  
pp. 629-642 ◽  
Author(s):  
Ayse Tuba Kocaman ◽  
Mustafa Cemek ◽  
Katrina Jane Edwards
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Dissolution Kinetics ◽  
The Other ◽  
Mineral Surfaces ◽  
Dissolution Rates ◽  
Ion Concentrations ◽  
Ph Changes ◽  
Kinetics Of Dissolution ◽  
Kinetics Of ◽  
Number Of Cells

The main objective of this study was to investigate the dissolution kinetics of pyrite, pyrrhotite, and chalcopyrite. Crushed minerals were reacted with Acidithiobacillus ferrooxidans (25 °C). The kinetics of dissolution was investigated by monitoring pH and Fe2+and Fe3+ion concentrations in the leaching solutions. Pyrite, pyrrhotite, and chalcopyrite dissolution by A. ferrooxidans was found to be a chemically controlled process. With bacteria, the dissolution rates of the minerals increased in the order of pyrrhotite, pyrite, and chalcopyrite. The number of cells attached to mineral surfaces increased in the same order. Acidithiobacillus ferrooxidans was found to enhance the dissolution rates of the minerals. The acid-insoluble trait of pyrite and acid-soluble trait of the other 2 minerals affected the pH changes in the leaching solutions.

scholarly journals The initial dissolution rates of simulated UK Magnox–ThORP blend nuclear waste glass as a function of pH, temperature and waste loading

2015 ◽  
Vol 79 (6) ◽  
pp. 1529-1542 ◽  
Author(s):  
N. Cassingham ◽  
C.L. Corkhill ◽  
D.J. Backhouse ◽  
R.J. Hand ◽  
J.V. Ryan ◽  
...  
Keyword(s):  
Dissolution Kinetics ◽  
Intrinsic Rate ◽  
Waste Glass ◽  
High Level Waste ◽  
Dissolution Mechanism ◽  
Dissolution Rates ◽  
Forward Rates ◽  
Glass Dissolution ◽  
High Level ◽  
Kinetics Of

AbstractThe first comprehensive assessment of the dissolution kinetics of simulant Magnox–ThORP blended UK high-level waste glass, obtained by performing a range of single-pass flow-through experiments, is reported here. Inherent forward rates of glass dissolution were determined over a temperature range of 23 to 70°C and an alkaline pH range of 8.0 to 12.0. Linear regression techniques were applied to the TST kinetic rate law to obtain fundamental parameters necessary to model the dissolution kinetics of UK high-level waste glass (the activation energy (Ea), pH power law coefficient (η) and the intrinsic rate constant (k0)), which is of importance to the post-closure safety case for the geological disposal of vitreous products. The activation energies based on B release ranged from 55 ± 3 to 83 ± 9 kJ mol–1, indicating that Magnox–THORP blend glass dissolution has a surface-controlled mechanism, similar to that of other high-level waste simulant glass compositions such as the French SON68 and LAW in the US. Forward dissolution rates, based on Si, B and Na release, suggested that the dissolution mechanism under dilute conditions, and pH and temperature ranges of this study, was not sensitive to composition as defined by HLW-incorporation rate.

scholarly journals Kinetics of carbonate mineral dissolution in CO2-acidified brines at storage reservoir conditions

2016 ◽  
Vol 192 ◽  
pp. 545-560 ◽  
Author(s):  
Cheng Peng ◽  
Benaiah U. Anabaraonye ◽  
John P. Crawshaw ◽  
Geoffrey C. Maitland ◽  
J. P. Martin Trusler
Keyword(s):  
Kinetic Model ◽  
Carbonic Acid ◽  
Dissolution Kinetics ◽  
Carbonate Reservoir ◽  
Mineral Dissolution ◽  
Direct Reaction ◽  
Carbonate Mineral ◽  
Dissolution Rates ◽  
Saturated Water ◽  
Kinetics Of

We report experimental measurements of the dissolution rate of several carbonate minerals in CO2-saturated water or brine at temperatures between 323 K and 373 K and at pressures up to 15 MPa. The dissolution kinetics of pure calcite were studied in CO2-saturated NaCl brines with molalities of up to 5 mol kg−1. The results of these experiments were found to depend only weakly on the brine molality and to conform reasonably well with a kinetic model involving two parallel first-order reactions: one involving reactions with protons and the other involving reaction with carbonic acid. The dissolution rates of dolomite and magnesite were studied in both aqueous HCl solution and in CO2-saturated water. For these minerals, the dissolution rates could be explained by a simpler kinetic model involving only direct reaction between protons and the mineral surface. Finally, the rates of dissolution of two carbonate-reservoir analogue minerals (Ketton limestone and North-Sea chalk) in CO2-saturated water were found to follow the same kinetics as found for pure calcite. Vertical scanning interferometry was used to study the surface morphology of unreacted and reacted samples. The results of the present study may find application in reactive-flow simulations of CO2-injection into carbonate-mineral saline aquifers.

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.

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 Comparative studies of the kinetics of dissolution of medicines on the basis of clopidogrel

2021 ◽  
pp. 26-34
Author(s):  
O. P. Baula ◽  
O. O. Saliy ◽  
V. I. Bessаrabov ◽  
A. М. Gerasimchuk
Keyword(s):  
Comparative Studies ◽  
Generic Drugs ◽  
Dissolution Kinetics ◽  
Dissolution Test ◽  
Generic Medicines ◽  
Dissolution Medium ◽  
Clopidogrel Bisulfate ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

Generic medicines occupy dominant positions both in the pharmaceutical market of Ukraine and in industrial production by domestic pharmaceutical enterprises. The use of generic drugs in medical practice is of significant medical and social importance for expanding the accessibility of the general population to essential drugs. In Ukraine, more than twenty generic medicines based on clopidogrel, both foreign and domestic, are registered. All generic drugs containing clopidogrel bisulfate must comply with pharmaceutical bisulfate must comply with pharmaceutical equivalence, the kinetics of release of the active pharmaceutical ingredient using the Dissolution test in vitro, and pharmacokinetic parameters in vivo. The aim of the work was to carry out comparative studies of the dissolution kinetics of four samples of generic drugs based on clopidogrel with the dissolution kinetics of the original drug Plavix®, to evaluate the similarity factor of dissolution profiles and to determine the effect of biopharmaceutical factors on the equivalence of generics. Comparative studies of the kinetics of dissolution were carried out by the in vitro method according to the «Dissolution» test using a device with a blade with a rotation speed of 50 rpm, a dissolution medium with a pH value of 2.0 in a volume of 900 ml at a temperature of 37 ± 1 °C. The determination of the quantitative content of clopidogrel, which passed into the dissolution medium, was carried out by the method of adsorption spectrophotometry in the ultraviolet region at a wavelength of about 240 ± 2 nm. Based on the data obtained, the dissolution profiles of the original drug Plavix® and the studied samples of generic drugs were constructed, the similarity of which was assessed by the value of the similarity factor. According to the research results, it was found that one sample of the generic drug proved its equivalence by the in vitro method to Plavix®, and three other samples of generics had differences in dissolution kinetics in comparison with the original drug. Biopharmaceutical factors were analyzed that could affect the dissolution kinetics of the studied generic drugs, from which the physicochemical characteristics of clopidogrel bisulfate, the qualitative and quantitative composition of excipients and the features of the technological process were determined. Thus, on the basis of the comparative studies of the dissolution kinetics of drugs based on clopidogrel, generics were found that did not correspond to the in vitro equivalence according to the Dissolution test to the original drug, which could be due to the influence of a combination of biopharmaceutical factors.

scholarly journals Kinetics of dissolution of calcium phosphate (Ca-P) bioceramics

2008 ◽  
Vol 2 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Lukas Brazda ◽  
Dana Rohanova ◽  
Ales Helebrant
Keyword(s):  
Calcium Phosphate ◽  
Dissolution Rate ◽  
Dissolution Kinetics ◽  
Weight Changes ◽  
Enhanced Dissolution ◽  
Different Temperatures ◽  
Sbf Solution ◽  
Kinetics Of Dissolution ◽  
Unexpected Findings ◽  
Kinetics Of

Hydroxyapatite (HAp) and ?-tricalcium phosphate (?-TCP) are widely used bioceramics for surgical or dental applications. This paper is dealing with dissolution kinetics of synthetically prepared ?-TCP and four types of HAp granules. Two groups of HAp, treated at different temperatures, each of them with two different granule sizes, were tested. Three corrosive solutions with different pH and simulated body fluid (SBF) were used for immersing of the samples. Changes in concentrations of calcium and phosphate ions, pH level and weight changes of the samples were observed. It was found that presence of TRIS buffer enhanced dissolution rate of the ?-TCP approximately two times. When exposed to SBF solution, calcium phosphate (most probably hydroxyapatite) precipitation predominates over ?-TCP dissolution. Results from HAp samples dissolution showed some unexpected findings. Neither heat treatment nor HAp particle size made any major differences in dissolution rate of the same mass of each HAp sample.

Calorimetric Studies of Dissolution Kinetics of Ni2(Cr,Mo) Phase in Ni-Cr-Mo Alloys Using Non-Isothermal Approach

2008 ◽  
Vol 279 ◽  
pp. 111-116 ◽  
Author(s):  
H.C. Pai ◽  
Bikas C. Maji ◽  
A. Biswas ◽  
Madangopal Krishnan ◽  
M. Sundararaman
Keyword(s):  
Activation Energy ◽  
Dissolution Kinetics ◽  
Scanning Calorimetry ◽  
Alloy Matrix ◽  
Nickel Chromium ◽  
Chromium Alloys ◽  
Kinetics Of Dissolution ◽  
Calorimetric Studies ◽  
Kinetics Of ◽  
Complex Nickel

The kinetics of dissolution of ordered phase with Pt2Mo structure has been studied in two nickel chromium alloys – one without molybdenum and another with molybdenum - using differential scanning calorimetry. The activation energy for dissolution, determined using three nonisothermal approaches was found to be ~ 418 kJ /mole for both the alloys. This value agreed very well with the activation energy for coarsening of g″ precipitates in Ni-Cr-Mo matrix and is close to activation energy for mobility of chromium and molybdenum in complex nickel alloy matrix.

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