Showing papers on "Dissolution published in 2009"
TL;DR: In this paper, it was shown that both softwood (southern yellow pine) and hardwood (red oak) can be completely dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc) after mild grinding.
943 citations
TL;DR: In this article, the authors developed a method to estimate the cocrystal solubility in pure solvent and establish the influence of constituent drug and ligand properties on cocrystals.
Abstract: Pharmaceutical cocrystals can improve solubility, dissolution, and bioavailability of poorly water soluble drugs. However, true cocrystal solubility is not readily measured for highly soluble cocrystals because they can transform to the most stable drug form in solution. The objectives of this study are to develop a method to estimate the cocrystal solubility in pure solvent and establish the influence of constituent drug and ligand (i.e., coformer) properties. Cocrystal solubility and solubility product were derived from transition concentration measurements where a solution is in equilibrium with solid drug and cocrystal. Transition concentrations and solubilities are reported for carbamazepine cocrystals in water, ethanol, isopropanol, and ethyl acetate. The aqueous solubility for seven carbamazepine cocrystals was estimated to be 2−152 times greater than the solubility of the stable carbamazepine dihydrate form. Cocrystal solubility is shown to be directly proportional to the solubility of constituent...
705 citations
TL;DR: Two high-throughput systems are presented based on extinction or scattered light measurements and results indicate that among the ionic liquids tested EMIM Ac is the most efficient for dissolving cellulose, and it was observed that AMIM Cl is themost effective ionic liquid for Dissolving wood chips.
669 citations
TL;DR: In this article, a wide range of potentially suitable solvents for the dissolution and homogeneous processing of cellulose was screened and some remarkable results were obtained, for example, an odd-even effect was found for different alkyl side-chain lengths of the imidazolium chlorides which could not be observed for the bromides.
425 citations
TL;DR: In this article, a set of four reactive flow-through experiments at temperature T = 100 degrees C and total pressure P = 12 MPa was performed in limestone reservoir samples, with various ranging from 0.7 to 10 MPa, showing non-uniform dissolution features associated with transport-controlled mass transfer, while reaction-controlled uniform dissolution is observed for P-CO2 = 2.5 MPa.
392 citations
TL;DR: In this article, the authors review the mechanisms which control the kinetics of mineral dissolution and precipitation and show that accurate knowledge of aqueous chemistry and thermodynamics is essential for quantifying the available kinetic data of mineral water interaction.
Abstract: Recent years have seen the growing development and application of reactive transport models to describe, at different spatial and temporal scales, natural and industrial processes involving water-rock interactions such as continental weathering and its impact on ocean chemistry and climate, cycling of metals and the formation of ore deposits, porosity formation/reduction and oil migration in sedimentary basins, transport and geological sequestration of CO2, and geothermal power generation. The successful application of these models requires a comprehensive and robust kinetic data base of mineral-water interactions. To address this need significant efforts have been made over the past two decades to i) measure in the laboratory mineral dissolution/crystallization rates and ii) develop robust rate laws which could be incorporated in reactive transport algorithms. The aim of this chapter is to review the mechanisms which control the kinetics of mineral dissolution and precipitation and show that accurate knowledge of aqueous chemistry and thermodynamics is essential for quantifying the available kinetic data of mineral water interaction.
The main processes involved in reactive transport in a porous and/or fractured media: advection, molecular diffusion, mechanical dispersion and fluid-solid reactions (dissolution and crystallization) are illustrated in Figure 1⇓. Crystal dissolution and growth proceed via the transport of aqueous reactants and products to and from the surface coupled to chemical reactions occurring at the surface. The overall rate of dissolution or crystallization is controlled by the slowest of these coupled processes, either surface reaction or transport of aqueous species. When surface reactions are fast relative to molecular diffusion, dissolved species are depleted at the solid surface; the reaction is “transport” controlled1. If transport is fast relative to surface reactions, no depletion is observed; the overall reaction rate is “surface reaction” controlled. The rotating disk reactor method (Gregory and Riddiford 1956) allows discrimination …
343 citations
TL;DR: These novel SNEDDS carriers appear to be useful for controlling the release rate of poorly water soluble drugs.
342 citations
TL;DR: In this paper, dissolution rates of calcite, dolomite and magnesite were measured at 25, 60, 100 and 150°C at far from equilibrium conditions in 0.1 M NaCl solutions of pH from 3 to 6.
330 citations
TL;DR: In this article, the authors determined the solubility, surface properties (electrophoretic mobilities and surface charge) and dissolution kinetics of phytoliths extracted from fresh biomass of representative plant species (larch tree and elm, horsetail, fern, and four grasses) containing significant amount of biogenic silica.
284 citations
TL;DR: In this article, four cellulose dissolution agents, NaOH/Urea solution, N-methylmorpholine-Noxide (NMMO), ionic liquid (1-butyl-3methylimidazolium chloride; [BMIM]Cl) and 85% phosphoric acid were employed to dissolve cotton cellulose.
269 citations
TL;DR: In this paper, a geochemical code incorporating a modified reactive surface model successfully accounted for the passivation effect of secondary calcite layers, which played a major role both as coatings of reactive surfaces and by maintaining large undersaturation with respect to wollastonite dissolution.
TL;DR: The results suggested that both the high pH and bioglass debris on the surface of bacteria may be the possible mechanisms of the antibacterial effect of 45S5 BAG particulates.
Abstract: Previous studies have shown that bioactive glasses possessed antibacterial effect on common bacteria due to the high aqueous pH value caused by the bioactive glass dissolution In the present study, the efficiency of the antibacterial effect of 45S5 Bioglass (45S5 BAG) against S aureus, S epidermidis and E coli and its mechanism were investigated The results showed that 45S5 BAG exhibited a strong antibacterial effect against the bacteria, and the sensitivity of gram-negative and gram-positive bacteria to Bioglass was different Furthermore, a dose-dependent bacterial adhesion on 45S5 BAG particles and the formation of needle-like Bioglass debris were observed, which resulted in the damage of cell walls and inactivation of bacteria The results suggested that both the high pH and bioglass debris on the surface of bacteria may be the possible mechanisms of the antibacterial effect of 45S5 BAG particulates
TL;DR: The improving dissolution behavior of the rutin nanocrystal-loaded tablet should lead to a better bioavailability of the poorly soluble rutIn in the body.
TL;DR: In this article, a conceptual model was developed to illustrate corrosion processes of steel in oilfield formation water system, where the anodic reactions of the steel contain a direct dissolution of Fe, Fe → Fe2+++ + 2e, and the formation of corrosion scale, FeCO3, by Fe + HCO 3 - → FeCO 3 + H+ ++ 2e.
TL;DR: In this article, the dissolution of CuO in HCl, H 2 SO 4, HNO 3 and citric acid solutions was investigated in a batch reactor employing parameters expected to affect the dissolution rate of copper such as stirring speed, temperature and acid concentration.
TL;DR: In this article, a model for the temperature field of a strip under EPT was established based on the contributions of the coupling of the thermal and athermal effects with the free energy and the direct electron-atom interactions, the thermodynamics and kinetics of the electropulsing induced dissolution of β -Mg 17 Al 12 are discussed.
TL;DR: In this paper, a combined textural and kinetic study of the replacement of pentlandite, (Fe,Ni)9S8, by violarite (NiFe)3S4, and describe the mechanisms and kinetic behavior of this reaction by considering the role of the fluid phase, the causes of coupling between dissolution and precipitation, and the rate-limiting steps controlling the kinetic behavior.
TL;DR: In this article, the dissolving ability of 1-butyl-3-methylimidazolium chloride (BMIMCl) and 11 other commercial ionic liquids (not reported as cellulose solvents) was studied.
Abstract: Cellulose (7% water) was thoroughly dispersed in various ionic liquids (IL) and the turbidity of the mixture was investigated to distinguish real dissolution from fine dispersion. The dissolving ability of 1-butyl-3-methylimidazolium chloride (BMIMCl know cellulose solvent) and 11 other commercial IL (not reported as cellulose solvents) was studied. From the latter, only 1,3-dimethylimidazolium dimethylphosphate (DMIMDMP) could dissolve cellulose. The influence of water content on the real dissolution of cellulose in these two IL was investigated. The maximum theoretical amount of dissolved anhydrous cellulose in the IL was determined by extrapolation methodology at different temperatures. For cellulose in BMIMCl, it was 8.75 g/100 g of IL at 95 °C. DMIMDMP could achieve real cellulose dissolution only in a practically anhydrous system (2.3 g/100 g of IL at 30 °C) but dissolution was physically limited by high viscosity.
TL;DR: The present study proposes the ZVAl/O2 process as a viable method of oxidative water treatment because of the stability of aquo-complexed Al3+ ions over a wider pH range.
Abstract: Oxidative degradation of aquatic organic contaminants using zero-valent aluminum (ZVAl) in the presence of dissolved oxygen (O2) was investigated. The metal corrosion process in acidic conditions (pH <4) was accompanied by electron transfer from ZVAl to O2, which led to the simultaneous generation of Al3+ and hydrogen peroxide (H2O2). The oxidation of 4-chlorophenol (4-CP), a model substrate, was initiated by the generation of hydroxyl radicals (HO•) via electron transfer from Al0 to H2O2. Degradation was initiated after an induction period of about 2 h, during which the native oxide layer was dissoluted. The HO•-mediated oxidation reaction was completely quenched by adding methanol as a radical scavenger. Systematic studies on the effects of ZVAl loading, pH, and surface oxide content revealed that the oxide layer dissolution controlled the Al0-mediated oxidation of 4-CP. The proposed process is similarly compared with the zero-valent iron (ZVI) system, but the ZVAl/O2 system showed a higher oxidation ca...
TL;DR: Biogenic dissolution of carbonates by euendoliths in coral reefs may be a dominant mechanism of carbonate dissolution in a more acidic ocean.
Abstract: [1] Eight-month-old blocks of the coral Porites lobata colonized by natural Hawaiian euendolithic and epilithic communities were experimentally exposed to two different aqueous pCO2 treatments, 400 ppmv and 750 ppmv, for 3 months. The chlorophyte Ostreobium quekettii dominated communities at the start and at the end of the experiment (65–90%). There were no significant differences in the relative abundance of euendolithic species, nor were there any differences in bioeroded area at the surface of blocks (27%) between pCO2 treatments. The depth of penetration of filaments of O. quekettii was, however, significantly higher under 750 ppmv (1.4 mm) than under 400 ppmv (1 mm). Consequently, rates of carbonate dissolution measured under elevated pCO2 were 48% higher than under ambient pCO2 (0.46 kg CaCO3 dissolved m−2 a−1 versus 0.31 kg m−2 a−1). Thus, biogenic dissolution of carbonates by euendoliths in coral reefs may be a dominant mechanism of carbonate dissolution in a more acidic ocean.
TL;DR: In this article, a study was carried out of nanotubular anodic films formed on titanium at 20 V in fluoride/glycerol electrolyte, containing up to 50 vol% water.
TL;DR: In this article, a mathematical model was developed for leaching of zinc ores containing silicates such as hemimorphite which produce a gel during leaching with sulfuric acid.
TL;DR: In this paper, a pulsed power supply was used to generate discharges in aqueous solutions, and polycrystalline gold nanoparticles were formed in discharge during 1 min. The reduction and dissolution rates increased proportionately with the applied voltage.
TL;DR: In this article, the aging of glass and basalt fibers with different chemical constitutions in NaOH and cement solutions was investigated and the strength distributions have been evaluated using a Weibull distribution function.
Abstract: In alkaline solutions, the reaction of hydroxyl ions with Si–O–Si-groups of the glass network leads to the formation of hydrated surfaces and dissolved silicate. The rate of this corrosion depends on the chemical constitution of the fiber and the alkaline solution as well as on time and temperature. The investigation of the aging of glass and basalt fibers with different chemical constitutions in NaOH and cement solutions shows that the corrosion mechanism changes due to the inhibiting effect of calcium ions. The strength distributions have been evaluated using a Weibull distribution function. The mechanical behavior strongly depends on the chemistry of the solution and determines the parameters of the Weibull distribution function in terms of either single or mixed distributions. The corrosion in NaOH solution leads to a strong dissolution of the outer layer of the glass and basalt fibers, whereas during aging in cement solution at the same pH-value a limited, local attack was revealed.
TL;DR: In this paper, the detailed microstructure and tensile properties of as-cast and heat-treated new experimental alloy belonging to cast Al-Si near-eutectic alloys have been investigated as a function of Fe, Mn, Cu, and Mg content.
TL;DR: The superior physicochemical properties of rutin nanocrystals should overcome the absorption problem in the gastrointestinal tract and increase the bioavailability.
TL;DR: In this paper, the bulk material of six dioctahedral and two trio-clique swellable clay minerals was leached in H2SO4 and HCl at concentrations of 1.0, 5.0 and 10.0 M at 80 °C for several hours.
TL;DR: In this article, a static light scattering (SLS) was applied to monitor the rehydration process of milk protein concentrate (MPC) powder, and the size distribution and volume concentration of the suspended powder particles were measured to quantify the dissolution kinetics of MPC powder.
TL;DR: In this paper, the degradation of poly(ethylene terephthalate) (PET) was successfully achieved using ionic liquids, and the degradation process is a first-order kinetic reaction and the activation energy is 232.79 kJ mol−1.
TL;DR: In this paper, the electrochemical behavior of an AZ91 magnesium alloy was investigated in a low aggressive medium by means of local and global electrochemical impedance measurements, and the results were compared to those obtained on a pure magnesium sample.