Hydrated properties

Grant, J. A., R. L. Williams, and H. A. Scheraga. 1990. Ab Initio Self-Consistent Field and Potential-Dependent Partial Equalization of Orbital Electronegativity Calculations of Hydration Properties of N-Acetyl-N -Methyl-Alanineamide. Biopolymers 30, 929-949. 

Micard V and Thibault JF. 1999. Oxidative gelation of sugar-beet pectins use of laccases and hydration properties of the cross-linked pectins. Carbohyd Polym 39 265-273. 

Goni I, Martin-Carron N. In vitro fermentation and hydration properties of commercial dietary fiber-rich supplements. Nutr Res 1998 18 1077-1089. 

A number of polymers exhibit this hydration property. Natural products such as cellulose and starch are or can be made water soluble. Synthetics such as polyvinyl alcohol and polyacrylic acid are also soluble in water. This discussion will be limited to synthetic materials such as polyacrylic acid and its salts, polyvinyl alcohol, polyacrylamide, and polyurethane... 

Table B5.1.1 Selected Tests of Protein Hydration Properties...

Hydration properties of proteins, 295 (table) Hydrogen, simultaneous moisture and oil determination, 23... 

Solid-phase microextraction (SPME), volatile lipid analysis, 534-535 Solubility, protein hydration properties, 295 (table)... 

Lewin Associates and Consultants Handbook of Gas Hydrate Properties and Occurrence... 

With the determination of hydrate structure, more rigorous predictive methods were formulated for hydrate thermodynamic property predictions. Barrer and Stuart (1957) initially suggested a statistical thermodynamic approach to determining gas hydrate properties. In a similar yet more successful approach,... 

Several companies (D.B.R. Oilphase/Schlumberger, Infochem Computer Services, Ltd., Calsep) have commercially available computer programs (DBR hydrate, Multiflash, PVTSim) for the prediction of hydrate properties, and such methods are incorporated into process flowsheeting programs such as ASPEN , HYPERCHEM , and SIMCI . Researchers in the CSM laboratory (Sloan and Parrish, 1983 Sloan et al., 1987 Mehta and Sloan, 1996) generated new parameters for the prediction of si, sll, and sH hydrates, which were incorporated into the program, CSMHyd. 

Measurement and modeling of time-dependent hydrate properties is clearly far more challenging than time-independent (thermodynamic) hydrate properties. Although significant advances have been achieved in measurement and modeling... 

The determination of in situ hydrates spawned a wave of research to measure hydrate properties needed for geological research and gas recovery. Several measurements were made of sonic velocity and thermal conductivity of hydrates in sediments (e.g., Stoll and Bryan, 1979 Pearson et al., 1984 Asher, 1987 Waite et al., 2005), while others measured the calorimetric properties (e.g., Rueff, 1985 Handa, 1986a,b,c,d Rueff et al 1988) needed to estimate dissociation energy. Davidson (1983) summarized hydrate properties as being similar to ice, with a few notable exceptions. Chapter 2 presents comparisons of physical property measurements of ice and hydrate. 

Along with the measurements of hydrate properties came several studies to determine the recoverability of gas from hydrates beneath the permafrost. Kamath and coworkers, in a research effort spanning over more than a decade, studied hydrate drilling and recovery in Alaska (Kamath, 1984 Kamath et al., 1984 Kamath and Godbole, 1987 Kamath and Holder, 1987 Roadifer et al., 1987a,b Godbole et al., 1988 Nadem et al., 1988 Sira et al., 1990 Kamath et al., 1991 Sharma et al., 1991, 1992). 

Lewin and Associates, Inc. and Consultants, Handbook of Gas Hydrate Properties and Occurrence, U.S. Department of Energy, DOE/MC/19239-1546 (1983). 

Sum, A., Measurements of Clathrate Hydrate Properties Via Raman Spectroscopy, M.S. Thesis, Colorado School of Mines, Golden, CO (1996). 

Vysniauskas, A., Bishnoi, P.R., Natural Gas Hydrates Properties, Occurrence and Recovery (Cox, J.L., ed.), Butterworths, Boston, MA (1983a). 

Hydrogen bonds cause unusual water, ice, and hydrate properties... 

Via NMR and Raman spectroscopy, we can measure the solid hydrate phase. Although an overview of such spectroscopy measurements is provided in Section 6.2, some of the important results for hydrate properties in comparison to ice are provided here. 

Substantially different from ice, the phase equilibria of natural gas hydrates represents the most important set of hydrate properties. In contrast to kinetic phenomena, hydrate phase equilibria are well defined and determine a boundary to the kinetic problem. This chapter addresses hydrate phase equilibria with approximate methods that provide an understanding of the phenomena involved. 

Finally, Section 4.6 concerns the relationship of phase equilibrium to other hydrate properties. The hydrate application of the Clapeyron equation is discussed... 

In this section two prediction techniques are discussed, namely, the gas gravity method and the Kvsi method. While both techniques enable the user to determine the pressure and temperature of hydrate formation from a gas, only the KVSI method allows the hydrate composition calculation. Calculations via the statistical thermodynamics method combined with Gibbs energy minimization (Chapter 5) provide access to the hydrate composition and other hydrate properties, such as the fraction of each cavity filled by various molecule types and the phase amounts. 

Section 5.1 presents the fundamental method as the heart of the chapter— the statistical thermodynamics approach to hydrate phase equilibria. The basic statistical thermodynamic equations are developed, and relationships to measurable, macroscopic hydrate properties are given. The parameters for the method are determined from both macroscopic (e.g., temperature and pressure) and microscopic (spectroscopic, diffraction) measurements. A Gibbs free energy calculation algorithm is given for multicomponent, multiphase systems for comparison with the methods described in Chapter 4. Finally, Section 5.1 concludes with ab initio modifications to the method, along with an assessment of method accuracy. 

With such corrections, Equation 5.22a finds many uses in the calculation of hydrate properties. The equation relies on the fitting of the Langmuir constant Cjj to experimental hydrate conditions. The method of relating the Langmuir constant to experimental conditions is given in Section 5.1.4. 

In sum, ab initio methods are beginning to fulfill their substantial promise for hydrates. For many hydrate guest components, ab initio methods have been shown to extend some of the most fundamental calculations from quantum mechanics to macroscopic properties, and to predict spectroscopic hydrate properties acceptably. 

This chapter deals with macro-, meso-, and molecular-level thermodynamic and transport hydrate properties of natural gas and condensate components, with and without solute. The feasibility of using these tools to measure the kinetics of hydrate formation and decomposition are also briefly discussed, while the results of these measurements have been discussed in Chapter 3. The results for insoluble substances such as porous media are discussed in Chapter 7. 

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