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.

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.

scholarly journals Torrefaction Thermogravimetric Analysis and Kinetics of Sorghum Distilled Residue for Sustainable Fuel Production

2021 ◽  
Vol 13 (8) ◽  
pp. 4246
Author(s):  
Shih-Wei Yen ◽  
Wei-Hsin Chen ◽  
Jo-Shu Chang ◽  
Chun-Fong Eng ◽  
Salman Raza Naqvi ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Pso Algorithm ◽  
Nitrogen Atmosphere ◽  
Computational Method ◽  
Weight Changes ◽  
Design And Optimization ◽  
Thermogravimetric Analyzer ◽  
Model Free ◽  
Different Temperatures ◽  
Kinetics Of

This study investigated the kinetics of isothermal torrefaction of sorghum distilled residue (SDR), the main byproduct of the sorghum liquor-making process. The samples chosen were torrefied isothermally at five different temperatures under a nitrogen atmosphere in a thermogravimetric analyzer. Afterward, two different kinetic methods, the traditional model-free approach, and a two-step parallel reaction (TPR) kinetic model, were used to obtain the torrefaction kinetics of SDR. With the acquired 92–97% fit quality, which is the degree of similarity between calculated and real torrefaction curves, the traditional method approached using the Arrhenius equation showed a poor ability on kinetics prediction, whereas the TPR kinetic model optimized by the particle swarm optimization (PSO) algorithm showed that all the fit qualities are as high as 99%. The results suggest that PSO can simulate the actual torrefaction kinetics more accurately than the traditional kinetics approach. Moreover, the PSO method can be further employed for simulating the weight changes of reaction intermediates throughout the process. This computational method could be used as a powerful tool for industrial design and optimization in the biochar manufacturing process.

Characterization of Type B Carbonate Apatite Sintered Bodies

2011 ◽  
Vol 1301 ◽  
Author(s):  
N. Watanobe ◽  
T. Yoshioka ◽  
T. Ikoma ◽  
T. Kuwayama ◽  
T. Higaki ◽  
...  
Keyword(s):  
Dissolution Kinetics ◽  
Carbonate Apatite ◽  
Artificial Bone ◽  
Type B ◽  
Desorption Process ◽  
Different Temperatures ◽  
Acidic Conditions ◽  
Kinetics Of ◽  
Potential Use

ABSTRACTThe dissolution kinetics of type B carbonate apatite (CAp) disks sintered at different temperatures were investigated under acidic conditions similar to an osteoclastic desorption process in bone remodeling. The type B CAp disks, which were uniaxially pressed at 98MPa and sintered at temperatures of 600 to 700 ºC, showed single crystalline phase and a high relative density of 60-62 % compared to the stoichiometric density of 3.16g/cm3 of hydroxyapatite (HAp). The dissolution rate of type B CAp disks sintered at 650 ºC was 3.5 times faster than that of HAp disks at 650 ºC. These results indicate that the Type B CAp sintered disks show potential use as a biodegradable material for artificial bone.

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%.

Preliminary Investigation of Bone Cement Using Calcium Phosphate Glass

2005 ◽  
Vol 284-286 ◽  
pp. 109-112 ◽  
Author(s):  
Byung Hyun Lee ◽  
Min Chul Kim ◽  
Kyoung Nam Kim ◽  
Kwang Mahn Kim ◽  
Seong Ho Choi ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Calcium Phosphate ◽  
Phosphate Glass ◽  
Setting Time ◽  
Preliminary Investigation ◽  
Distilled Water ◽  
Liquid Ratio ◽  
Ft Ir ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

The mixed pastes of binary calcium phosphate glass with Ca/P ratio of 0.6 and distilled water were set after about 4 hr, while never set when calcium phosphate glass with Ca/P lower than 0.5. Their compressive strength was ranged from 16.0 to 23.3 MPa. When Na2HPO4 solution was used instead of distilled water as liquid phase, the setting time became drastically much shorter. As the mole concentration of Na2HPO4 solution increased from 0.25 M to 2 M, setting time was shortened to 35 min from almost 3 hr, but compressive strength decreased from 28.8 MPa to 13.2 MPa. At constant mole concentration, as the mass ratio of a powder to liquid ratio increased, setting time was shortened and maximum compressive strength was measured when a powder/liquid ratio was 2.5. However, no crystallized phases were detected either during setting or after complete setting. The XRD , FT-IR and SEM examinations indicated that calcium phosphate glass dissolved and then glass phase precipitated again. We concluded, therefore, that Na2HPO4 just affected the kinetics of dissolution and precipitation of CPG. The mechanism of hardening has yet to be studied.

The Dissolution Kinetics of Tincal in Phosphoric Acid Solutions

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Yuksel Abali ◽  
Salih U Bayca ◽  
Ayse E Guler
Keyword(s):  
Particle Size ◽  
Phosphoric Acid ◽  
Dissolution Rate ◽  
Acid Concentration ◽  
Reaction Temperature ◽  
Dissolution Kinetics ◽  
Reaction Model ◽  
Acid Solutions ◽  
Liquid Ratio ◽  
Kinetics Of

In this study, the dissolution kinetics of tincal in phosphoric acid solutions was investigated. The effects of reaction temperature, acid concentration, solid to liquid ratio, particle size and stirring speed were determined in the experiments. The results showed that the dissolution rate increased with increasing acid concentration, reaction temperature, stirring speed and increased with decreasing particle size and solid to liquid ratio. The dissolution rate was found to be based on the first order pseudo homogenous reaction model. The activation energy of the tincal in phosphoric acid solution was determined as 42.28 kJ.mol-1.

Kinetics of SiO2 Nanofibres Dissolution in the Simulated Lung Environment

2008 ◽  
Vol 39-40 ◽  
pp. 347-350 ◽  
Author(s):  
Lukáš Brázda ◽  
Jarmila Studničková ◽  
Petr Exnar ◽  
Aleš Helebrant
Keyword(s):  
Dissolution Rate ◽  
Weight Changes ◽  
Factors Affecting ◽  
Lung Fluid ◽  
Corrosive Solution ◽  
Concentration Changes ◽  
Tissue Geometry ◽  
Rate Limit ◽  
Risk Of Cancer ◽  
Kinetics Of

To avoid the risk of cancer or respiratory diseases, nanofibres have to biodegrade in lung fluid when inhaled. There are two main factors affecting behaviour of the nanofibres in living tissue – geometry of fibres and biopersistence. A dissolution rate of SiO2 nanofibres in a simulated lung environment was tested in this work. Distilled water buffered with TRIS and HCl to pH 7.6 was used as a simple simulated extracellular lung fluid (SLF). Fibres were tested both under the static and dynamic conditions of the corrosive solution. Dissolution rates were calculated from both SiO2 concentration changes in solutions and weight changes of fibres during the exposition. The dissolution rate of tested SiO2 nanofibres was at the rate limit, where fibres could be considered as harmless for health.

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 Treatment of black copper with the use of iron scrap - part I

2020 ◽  
Vol 74 (4) ◽  
pp. 237-245
Author(s):  
Norman Toro ◽  
Kevin Pérez ◽  
Manuel Saldaña ◽  
Eleazar Salinas-Rodríguez ◽  
Pía Hernández
Keyword(s):  
Particle Size ◽  
Dissolution Rate ◽  
Acidic Medium ◽  
Mineral Resources ◽  
Reducing Agent ◽  
Iron Scrap ◽  
Effect Of Particle Size ◽  
High Concentrations ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

Currently, there is a large amount of mineral resources not being exploited in large copper minings, a clear example are black copper minerals. These resources are generally not incorpo-rated into the extraction circuits or are not treated, either in stocks, leach pads, or debris. These exotic minerals have considerable amounts of Cu and Mn, which are commercially very attractive. They are refractory to conventional leaching processes, therefore, the use of reducing agents is necessary for treatment of these minerals in order to dissolve the present MnO2, which in turn allows Cu extraction. In this research, iron scrap Fe0 was used as a reducing agent for the dissolution of Mn from a black copper mineral in an acidic medium and compared to previous studies of the use of Fe2+ under the same conditions. In addition, the effects of a pretreatment process (agglomeration and curing) by adding NaCl are investigated in order to favor the reduction of MnO2. Finally, it was discovered that there is a higher kinetics of dissolution of Mn when working with Fe0 in short periods of time, although similar extraction efficiencies are obtained after prolonged times. The pretreatment process by adding NaCl resulted in increased Mn extraction in short periods of time (30 min). At applying high concentrations of the reducing agent, the effect of particle size on the dissolution rate of MnO2 was shown to be insignificant.

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