scholarly journals Dissolution Behavior of Al2O3 Inclusions in CaO-Al2O3 Based Slag Representing Aluminothermic Reduction Slag

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1061
Author(s):  
Guan-Yong Shi ◽  
Ting-An Zhang ◽  
Zhi-He Dou ◽  
Li-Ping Niu
Keyword(s):  
Dissolution Rate ◽  
Thermal Reduction ◽  
Dissolution Behavior ◽  
Rotating Speed ◽  
Slag Refining ◽  
Intermediate Phases ◽  
High Temperature Synthesis ◽  
Metallurgical Slags ◽  
Cylinder Method ◽  
Key Steps

In the preparation of CuCr alloy using the self-propagating high-temperature synthesis (SHS)-metallurgy method, the dissolution of alumina in molten slag has an important influence in two key steps: aluminum thermal reduction and slag refining. In the present work, the dissolution behavior of Al2O3 into molten SHS-metallurgical slags was investigated by employing the rotating cylinder method and static dissolution method. It is concluded that the increase of MgO, CaF2, CaO, and Na3AlF6 contents can increase the dissolution rate of alumina in SHS-metallurgical slag, and the order of influence is from strong to weak. Both temperature and rotating speed can increase the dissolution rate, and the rate-limiting step is the diffusion of alumina in the boundary layer, with the solid alumina first reacting with lime to form two intermediate phases, CaO·2Al2O3 and CaO·6Al2O3, and finally dissolving into the slag in the form of an aluminum polymer.

Development of the Synthetic Rock Technique for the Immobilization of Iodine: Kinetics of the Alumina Matrix Dissolution under High Alkaline Conditions

2012 ◽  
Vol 1518 ◽  
pp. 79-84 ◽  
Author(s):  
Hideaki Miyakawa ◽  
Tomofumi Sakuragi ◽  
Hitoshi Owada ◽  
Osamu Kato ◽  
Kaoru Masuda
Keyword(s):  
Dissolution Rate ◽  
Rate Constant ◽  
Base Material ◽  
Dissolution Behavior ◽  
Treatment Technique ◽  
Release Behavior ◽  
Alumina Matrix ◽  
Synthetic Rock ◽  
The Matrix ◽  
Iodine Release

ABSTRACTIodine filters expended after nuclear fuel reprocessing contain radioactive iodine (I-129), almost all of which exists as silver iodide (AgI). The synthetic rock technique is a solidification treatment technique using hot isostatic press (HIP), in which the alumina adsorbent base material is synthesized to form a dense solidified material (synthetic rock), and I-129 is physically confined in the form of AgI in the alumina matrix. Thus, it is necessary to understand the matrix dissolution behavior to evaluate the iodine release behavior.Experiments involving the dissolution of the matrix were carried out under various temperatures (35–70 °C) and pH values (10–12.5) that reflect the disposal conditions. The results of the experiments showed that the dissolution rate of Al visibly increases with temperature and pH. The dissolution rate constant was calculated from the initial data assuming the dissolution of the matrix as a primary reaction. The logarithmic rate constant showed a good linear correlation with the pH and the reciprocal of temperature. The 27Al-NMR analysis of the solutions of the dissolved matrix showed that the major chemical species present in the solutions was Al(OH)4-. This indicated that the dissolution of the matrix can be described by the following equation: Al2O3 + 2OH- + 3H2O → 2Al(OH)4-. Subsequently, the empirical equation of the rate of dissolution of the matrix as a function of the temperature and pH was derived. It will be used to evaluate the iodine release behavior from the synthetic rock.

Improving Biomaterials from a Cellular Point of View

2006 ◽  
Vol 925 ◽  
Author(s):  
Venu Gopal Varanasi ◽  
T. Vallortigara ◽  
P. M. Loomer ◽  
E. Saiz ◽  
A. P. Tomsia ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Cell Number ◽  
Point Of View ◽  
Dissolution Behavior ◽  
Ti Alloy ◽  
Bioactive Glasses ◽  
Culture Studies ◽  
Cell Numbers ◽  
Number Increase

ABSTRACTBioactive glasses (6P55) used for coating Ti/Ti-alloy were tested for their in vitro behavior in a comparative study with commercial Bioglass™ (45S5) and commercial Ti alloy (Ti6Al4V). In vitro testing included pH and dissolution rate determination in simulated body fluid (SBF) along with in vitro cyto compatibility testing. It was seen in this work that 6P55 and 45S5 had similar dissolution behavior, demonstrating t½ dependence and maximum pH of approximately 8.1 after 10 days of immersion. This pH was reduce by 0.2 0.4 pH units when the in vitro V:A ratio was increased from 1 to 3. The dissolution rate of these glasses approached 0 after additional immersion tests after 15 days and the pH stablilized at less than 7.5. Cell culture studies showed that both glasses behaved in similar fashion after 16 hours in culture. Both glasses had an increase in cell numbers of close to 200-250%, whereas Ti6Al4V had a less pronounced cell number increase (∼ 180%)

Dissolution behavior of chemically amplified resist for advanced mask- and NIL mold-making as studied by dissolution rate monitor

2006 ◽  
Author(s):  
Kazumasa Takeshi ◽  
Kazuto Oono ◽  
Yoshiyuki Negishi ◽  
Daisuke Inokuchi ◽  
Keishi Tanaka ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Dissolution Behavior ◽  
Chemically Amplified ◽  
Chemically Amplified Resist ◽  
Mold Making

scholarly journals The Effect of PVP Molecular Weight on Dissolution Behavior and Physicochemical Characterization of Glycyrrhetinic Acid Solid Dispersions

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Xiaoyu Sui ◽  
Yan Chu ◽  
Jie Zhang ◽  
Honglian Zhang ◽  
Huiyu Wang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Dissolution Rate ◽  
Solid Dispersions ◽  
Physicochemical Characterization ◽  
Dissolution Behavior ◽  
Enhancement Effect ◽  
Glycyrrhetic Acid ◽  
Equilibrium Solubility ◽  
Drug Molecules ◽  
Pvp K30

The effect of polyvinylpyrrolidone (PVP) as glycyrrhetic acid (GA) solid dispersions carrier at different molecular weights on the dissolution behavior and physicochemical properties was investigated. PVP-GA-SDs prepared with all four molecular weight PVPs displayed good enhancement of dissolution rate and equilibrium solubility compared with pure drug and corresponding physical mixtures. The results showed that the enhancement effect of molecular weight on dissolution rate and equilibrium solubility follows PVP   K 30 > PVP   K 60 > PVP   K 17 > PVP   K 15 . In addition, the dissolution rate and solubility of the SDs with a carrier-drug ratio of 8 : 1 were better than the samples of 4 : 1. The DSC and XRD patterns showed that the crystallization of GA in SDs prepared by PVP K30 and PVP K60 was significantly inhibited, and both were transformed to amorphous. Based on FTIR and Raman detection, a hydrogen-bond between PVP and drug molecules is formed. SEM results showed that there were no significant differences in the appearance of SDs prepared with four PVPs, and no crystalline morphology of GA was seen. In conclusion, the findings of this study demonstrated that the dissolution performance of the PVP-GA-SDs prepared by the solvent method is related to the molecular weight of PVP, and the change in the molecular weight of PVP does not cause a monotonic change in dissolution of GA. The samples with PVP K30 as the carrier have the best dissolution performance.

scholarly journals Effect of Carrier Lipophilicity and Preparation Method on the Properties of Andrographolide–Solid Dispersion

Pharmaceutics ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 74 ◽  
Author(s):  
Guowei Zhao ◽  
Qingyun Zeng ◽  
Shoude Zhang ◽  
Youquan Zhong ◽  
Changhao Wang ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Dissolution Rate ◽  
Solid Dispersion ◽  
Preparation Method ◽  
Water Soluble ◽  
Vacuum Drying ◽  
Dissolution Behavior ◽  
Drying Method ◽  
Carrier Material ◽  
Poorly Water Soluble

Solid dispersion (SD) is a useful approach to improve the dissolution rate and bioavailability of poorly water-soluble drugs. This work investigated the effects of carrier material lipophilicity and preparation method on the properties of andrographolide (AG)–SD. The SDs of AG and the carrier materials, polyethylene glycol (PEG) and PEG grafted with carbon chains of different length (grafted PEG), have been prepared by spray-drying and vacuum-drying methods. In AG–SDs prepared by the different preparation methods with the same polymer as carrier material, the intermolecular interaction, 5% weight-loss temperature, the melting temperature (Tm), surface morphology, crystallinity, and dissolution behavior have significant differences. In the AG–SDs prepared by the same spray-drying method with different grafted PEG as carrier material, Tm, surface morphology, crystallinity, and dissolution behavior had little difference. In the AG–SDs prepared by the same vacuum-drying method with different grafted PEG as carrier material, the crystallinity and Tm decreased, and the dissolution rate of AG increased with the increase of grafted PEG lipophilicity. The preparation method has an important effect on the properties of SD. The increase of carrier material lipophilicity is beneficial to the thermal stability of SD, the decrease of crystallinity and the increase of dissolution rate of a poorly water-soluble drug in the SD.

Design, Fabrication and Characterization of Esomeprazole Nanocrystals for Enhancing the Dissolution Rate and Stability

2020 ◽  
Vol 14 ◽  
Author(s):  
Vijay Agarwal ◽  
Meenakshi Bajpai
Keyword(s):  
Particle Size ◽  
Dissolution Rate ◽  
Crystalline State ◽  
Physical Mixture ◽  
Water Soluble ◽  
Dissolution Behavior ◽  
Physical Treatment ◽  
Pxrd Pattern ◽  
Freeze Dried ◽  
Bulk Drug

Background: Poor solubility and low dissolution rate limit the work at poorly water-soluble drugs like Esomeprazole. To overcome this problem, different technologies had to be used but could not resolve the problem, significantly. The main aim of this study was to prepare the nanocrystals using evaporative precipitation ultrasonication method in order to improve the dissolution rate and stability of Esomeprazole (ESM). Methods: For getting the nanocrystals, different nanoformulations were prepared using the pluronic F-68 in different concentration, and then screened formulation was lyophilized in presence of two distinct cryoprotectants; mannitol and sucrose. The obtained nanocrystals were characterized for their re-dispersibility, crystalline state, dissolution behavior, particle size, polydispersibility index and morphology. Dissolution study of ESM nanocrystals was performed in buffer solution of pH-7.4, and compare to that of bulk ESM sample and ESM/pluronic F-68 physical mixture. Results: Cryoprotectant containing nanocrystals exhibit the re-dispersion in water after the manual shaking. 5% mannitol containing nanocrystals showed the least polydispersity index (0.42 ± 0.11) and narrowest particle size (186 ± 12.9 nm). The powder x-ray diffraction (PXRD) pattern and differential scanning calorimeter (DSC) thermograms revealed that crystalline state of drug was not changed after the different physical treatment. Freeze-dried nanocrystals showed a faster dissolution rate and almost 99.45% of drug was released within 60 min. However, the bulk drug and a physical mixture of bulk drug/pluronic F-68 showed only 22.65% and 21.3% of drug release, respectively, after 60 min. Conclusion: The different findings revealed that nanocrystals could be a potential alternate for solving the dissolution rate and stability issue of ESM like poorly soluble drugs.

Evaluation of Dissolution Rate and Behavior of MgO Carriers for Primary and Secondary Metallurgical Slags

2021 ◽  
Author(s):  
Elizaveta Cheremisina ◽  
Johannes Schenk ◽  
Andreas Viertauer ◽  
Roland Nilica ◽  
Roman Roessler
Keyword(s):  
Dissolution Rate ◽  
Metallurgical Slags ◽  
And Behavior

Nagelschmidtite as a candidate host phase for actinides, rare earth and different waste elements

MRS Advances ◽  
2017 ◽  
Vol 3 (20) ◽  
pp. 1073-1083
Author(s):  
Sergey V. Stefanovsky ◽  
Olga I. Stefanovsky ◽  
Ivan L. Prusakov
Keyword(s):  
Continuous Solid Solution ◽  
Induction Melting ◽  
Average Chemical Composition ◽  
Temperature Synthesis ◽  
Waste Forms ◽  
Phase Average ◽  
High Temperature Synthesis ◽  
Metallurgical Slags ◽  
Geological Formations ◽  
Nuclear Waste Forms

AbstractNagelschmidtite, Ca7P2Si2O16, is an end-member of continuous solid solution Ca2SiO4 – Ca3(PO4)2⋅2Ca2SiO4 within the pseudo-binary system Ca3(PO4)2 – Ca2SiO4 (whitlockite – larnite). This phase is capable to wide isomorphic exchanges in Ca, P and Si sites: Ca2+ = Sr2+; Ca2+ = Eu2+; Ca2+ + P5+ = (RE,An)3+ + Si4+, 2Ca2+ = Na+ + (RE,An)3+; 2Ca2+ = An4+ + ☐; Ca2+ + Si4+ = (RE,An)3+ + (Al,Fe)3+; Ca2+ + Si4+ = Na+ + P5+; 2Ca2+ = Na+ + (Al,Fe)3+; Ca2+ + P5+ = Na+ + S6+. It was found in metallurgical slags and geological formations. We revealed nagelschmidtite-type phase in vitrified phosphorus-bearing radioactive incinerator slags. The materials were glass-crystalline and contained nano-sized nagelschmidtite crystals distributed in vitreous matrix phase. Average chemical composition of the largest (few microns) crystals was recalculated to formula Na1.21K1.05Ca2.22Al2.02Fe0.46Si2.69P1.26U0.08O15.76. Significant oxygen misbalance suggests higher than U(IV) oxidation state for uranium – U(V) or U(VI). Capability of nagelschmidtite to be crystallized from melt makes it promising phase for actinides, rare earths and some other fission and corrosion products at using a melting route to nuclear waste forms including cold crucible induction melting and self-propagating high-temperature synthesis.

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