Solubility-enhancement

THE EFFECT OF PROTON-DONATING MODEFIER ON THE SOLUBILITY ENHANCEMENT OF TRIS(p-DIKETONATO) CHROMIUM(HI) IN SUPERCRITICAL CARBON DIOXIDE... 

The above proposed process can be expected to easily put into practice as ammonia is abuandant as the main feedstock for fertilizer. Nevertheless, there is also a problem that Co(NH3)6 is apt to be oxidized to Co(NH3)6 which is unable to form the peroxo binuclear complex and ineffective to O2 solubility enhancement, thus reaction (4) is inhibited. But Co will be relatively stable, and Co may be reduced to Co " by H2O [12]. As a result, a regenration method has also been proposed by using the activated carbon as the catalyst[7], in which Co(NH3)6 dissociation into Co " and NH3 occurs on the activated carbon surface followed by reduction of Co with H2O into Co, O2 and H. ... 

Trends of solubility enhancement for each diamondoid follow regular behavior like other heavy hydrocarbon solutes in supercritical solvents with respect to variations in pressure and density [38, 39]. Supercritical solubilities of... 

In another smdy, the introduction of an adamantyl group to the poly(etherimide) structure caused polymer glass transition temperature, Tg, and solubility enhancements in some solvents like chloroform and other aprotic solvents [92]. 

Stroo HP et al. (2003) Remediating chlorinated solvent source zones Environ Sci Technol 37 225A-230A. Tick GR, P Lourenso, AL Wood, ML Brusseau (2003) Pilot-scale demonstration of cyclodextrin as a solubility-enhancement agent for remediation of a tetrachloroethene-contaminated aquifer Environ Sci Technol 37 5829-5834. 

Improvement of the properties of a drug may be achieved by the chemical modification of the parent drug. The preparation of an ester, salt, or other modification of the parent structure may be employed with parenteral drugs to increase stability, alter drug solubility, enhance depot action, avoid formulation... 

Schilling, M., F. Patett et al. (2007). Influence of solubility-enhancing fusion proteins and organic solvents on the in vitro biocatalytic performance of the carotenoid cleavage dioxygenase AtCCDl in a micellar reaction system. Appl. Microbiol. Biotechnol. 75(4) 829-836. 

Cho, H.-H., Park, J.-W., Liu, C.K. (2002) Effect of molecular structures on the solubility enhancement of hydrophobic organic compounds by environmental amphiphiles. Environ. Toxicol. Chem. 21, 999-1003. 

The ORAC assay proposed by Ou and others (2001) is limited to hydrophilic antioxidants because of the aqueous environment of the assay. However, lipophilic antioxidants play a critical role in biological defense systems. Huang and others (2002) expanded the assay to the lipidic fraction by introducing a randomly methylated 13-cyclodextrin (RMCD) as a water-solubility enhancer for lipophilic antioxidants. Various kinds of foods, including fruit juices and drinks, fruits, vegetables, nuts, and dried fruits, have been evaluated with this method (Zhou and Yu 2006 Wu and others 2004 Kevers and others 2007 Wang and Ballington 2007 Almeida and others 2008 Mullen and others 2007). 

Huang D, Ou B, Hampsch-Woodill M, Flanagan JA and Deemer EK. 2002. Development and validation of oxygen radical absorbance capacity assay for lipophilic antioxidants using randomly methylated (3-cyclodextrin as the solubility enhancer. J Agric Food Chem 50(7) 1815-1821. 

To evaluate compound solubility, a /.iPLC system equipped with a cartridge containing 24 parallel columns (80 x 0.5 mm (inner diameter equivalent)) was employed. Sets of calibration standards were prepared for 24 compounds at different concentrations (in a 50 50 CH3CN H20 solvent). A maximum standard concentration of 500 jt/M was selected to maintain the amount of DMSO co-solvent in all samples and standards below 5% v/v to minimize possible solubility enhancements due to the presence of DMSO when working with stock solutions provided at 10 mM in DMSO. Standards were added to the appropriate wells of a 384-well plate. The plate was covered with a heat seal foil and transferred to the /./PI.C system for analysis. Figure 6.26 depicts the process for preparation of standards 95 /./I. of a buffer of desired pH were added to the appropriate wells. An additional 5, uL of each compound at a concentration of lOmM (in DMSO) was added to the corresponding wells. The plate was shaken for 90 min and centrifuged at 4000 rpm for 3 min. 

Stoddart and co-workers have made use of Frechet-type dendrons as dendritic stoppers for self-assembled [n]rotaxanes [65]. The solubility enhancement that results from incorporating dendritic wedges at the termini facilitated the purification of these materials by column chromatography despite the polycationic nature of their bipyridinium backbone. Again, the dendritic wedges did not alter the electrochemical characteristics of the viologen subunits. Flowever, the enhanced solubility resulting from the presence of the dendritic components en-... 

The importance of the colloidal phase in the distribution of water pollutants is a relatively recent issue in the environmental literature [4,105,106]. The phenomenon of colloidal solubility enhancement was detected by workers in several fields and was largely unexplained. The concept was apparently developed and forwarded by working with partitioning behavior of water pollutants in water/ sediment systems. 

Microbes are ubiquitous in the subsurface environment and as such may play an important role in groundwater solute behavior. Microbes in the subsurface can influence pollutants by solubility enhancement, precipitation, or transformation (biodegradation) of the pollutant species. Microbes in the groundwater can act as colloids or participate in the processes of colloid formation. Bacterial attachment to granular media can be reversible or irreversible and it has been suggested that extracellular enzymes are present in the system. Extracellular exudates (slimes) can be sloughed-off and act to transport sorbed materials [122]. The stimulation of bacterial growth in the subsurface maybe considered as in situ formation of colloids. 

More recent work with cosolvency in dilute systems seems to indicate that the magnitude of the solubility enhancement is linear up to some 10-20% cosolvent fraction [55,172,184,250-262]. At very low concentrations of cosolvent, the assumption of non-interaction between the cosolvent and water cannot hold. In dilute solutions the individual cosolvent molecules will be fully hydrated and, as a result, will disrupt the water network structure. If the total volume disrupted is regarded as the extended hydration shell, and if Sc is the average solubility within this shell, then the overall solubility Sm in the water-cosolvent mixture will be approximated by... 

In dilute solutions, the solute will, on average, contact only one hydrated cosolvent molecule at a time, and the degree of solubilization should be a linear rather than a logarithmic function of cosolvent content. Thus, it is expected that the log-linear relationship between Sm andf. that applies at high cosolvent concentrations will become linear at low cosolvent levels due to a change in the mechanism of solubilization. If S is defined as solubility enhancement... 

Sm-Sw), then the relative solubility enhancement at low cosolvent concentration will be given by... 

The log-linear solubility enhancement by cosolutes may be important in characterizing concentrated leachate plumes or chemical spills, but will be of little importance in characterizations of the dilute aqueous systems that predominate in nature [19,55,143,145,158,184,226,241-247,249-263]. 

The impact of salt concentration on the formation of micelles has been reported and is in apparent accord with the interfacial tension model discussed in Sect. 4.1, where the CMC is lowered by the addition of simple electrolytes [ 19,65, 280,282]. The existence of a micellar phase in solution is important not only insofar as it describes the behavior of amphipathic organic chemicals in solution, but the existence of a nonpolar pseudophase can enhance the solubility of other hydrophobic chemicals in solution as they partition into the hydrophobic interior of the micelle. A general expression for the solubility enhancement of a solute by surfactants has been given by Kile and Chiou [253] in terms of the concentrations of monomers and micelles and the corresponding solute partition coefficients, giving... 

It has been reported that molecularly non-homogeneous surfactants are able to enhance the solubility of very hydrophobic chemicals, e. g., DDT, at surfactant concentrations well below the CMC. This is attributed to the successive micellization of the heterogeneous monomer species [271, 273, 274,276,278]. Examination of the solubility enhancement with different types of commercial surfactants reveals that molecularly homogeneous surfactants show relatively insignificant (but linear) solubility enhancement below CMC. Molecularly non-homogeneous surfactants, on the other hand, show a much greater solubility enhancement at concentrations below the CMC. 

Chiou et al. [189] were the first to consider the mechanism for water solubility enhancement of nonionic organic solutes by DOM of soil and bottom sediments. Such enhancement effects were effectively explained in terms of a par-... 

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