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Ostwald assessment

That said, we will focus in this chapter on the principal theoretical claims of the new physical chemistry and the extent to which these were responses to the professed needs of the majority of chemists, namely, the needs of the organic chemists. We also will assess the extent to which the concerns of physicists and chemists overlapped or dovetailed at the close of the nineteenth century. We will keep in mind the claim often made that physical chemistry is a bridge between physics and chemistry (which seems to make it peripheral to both) 16, or that it is a "unifying" and "general" discipline (Ostwald s... [Pg.126]

The kinetics (10) and the complex formation equilibria in the presence of nonionic micelles have been also investigated, at constant acidity. The stoichiometry was assessed by using Job s method and the apparent stability constants were evaluated according to Frank and Ostwald procedure (11), as previously reported for the systems iron/ sulfosalicylate and iron/salicylate in homogeneous aqueous acidic solution (12, 13). [Pg.157]

The liquidized product was visually observed to assess its fluidity, and an Ostwald viscometer was applied as a trial to determine its viscosity. Some part of the product was put into a syringe to see whether the product could be smoothly purged form the syringe tip. [Pg.241]

Two main procedures can be applied for the characterisation of suspensions and assessment of their stability (such as flocculation). The first method depends on the measurement of particle size distribution and the rate of flocculation and/or Ostwald ripening after dilution of the suspension with the dispersion medium, while the second procedure depends on measurement of the state of suspension without dilution, using rheological techniques. As both methods are described in detail in Chapters 19 and 20, only a summary will be provided here. [Pg.149]

Ostwald ripening can be quantitatively assessed from plots of the cube of the radius versus time t [31, 32],... [Pg.197]

In this chapter, a summary of the methods that can be applied to assess the structure of the solid/Uquid interface will first be provided, followed by details of assessing sedimentation, flocculation, and Ostwald ripening. In the latter cases (flocculation and Oswald ripening), information is needed on the particle size distribution, and several techniques are available to obtain this from diluted systems. It is essential to dilute the concentrated suspension with its own dispersion medium in order not to affect the state of the dispersion during examination. The dispersion medium can be obtained by centrifuging the suspension, when the supernatant liquid will be produced at the top of the centrifuge tube in the case... [Pg.397]

Assessment of Flocculation and Ostwald Ripening (Crystal Growth)... [Pg.405]

The assessment of flocculation and Ostwald ripening of a suspension requires measurement of the particle size and shape distribution as a function of time. Several techniques may be apphed for this purpose, and these are summarised below [6]. [Pg.405]

The above measurements should be supplemented by particle size distribution measurements of the diluted dispersion (ensuring that no floes are present after dilution) to assess the extent of Ostwald ripening. Another compHcation may arise from the nature of the flocculation which, if it occurs in an irregular fashion (producing strong and tight floes), may cause i (0) to be increased while cr may show some decrease, and this wiU complicate the analysis of the results. Yet, in spite of these complications, constant stress measurements may provide valuable information on the state of the dispersion on storage. [Pg.439]

The rheological data are given in Table 1. The second column of the table is the evaporation state of the oil in mass pereentage lost. The third column is the assessment of the stability of the emulsion based on both visual appearance and rheological properties. The power law constants, k and n, are given next. These are parameters from the Ostwald— de Waele equation which describes the Newtonian (or non-Newtonian) characteristics of the material. The viscosity of the emulsion is next and in column 7, the complex modulus which is the vector sum of the viscosity and elasticity. Column 8 lists the elasticity modulus and column 9, the viscosity modulus. In column 10, the isolated, low-shear viscosity is given. This is the viscosity of emulsion at very low shear rate. In column 9, the tan 5, the ratio of the viscosity to the elasticity component, is given. Finally, the water content of the emulsion is presented. [Pg.418]

As mentioned above, the best procedure to follow Ostwald ripening is to plot versus time, following Eq. (6.68). This gives a straight line, from which the rate of Ostwald ripening can be calculated. In this way one can assess the effect of the various additives that may reduce Ostwald ripening, e.g. addition of highly insoluble oil and/or an oil-soluble polymeric surfactant. [Pg.184]

The above trend depends on the extent of flocculation relative to Ostwald ripening. Therefore, following ap and with storage time requires knowledge of Ostwald ripening and/or coalescence. Only in the absence of this latter breakdown process can one use rheological measurements as a guide of assessment of flocculation. [Pg.241]

The above measurements should be supplemented by particle size distribution measurements of the diluted suspension (making sure that no floes are present after dilution) to assess the extent of Ostwald ripening. [Pg.243]

Equation (3.52) shows that the larger the difference between r and tj, the higher the rate of Ostwald ripening. The latter can be quantitatively assessed from plots of the cube of the radius versus time t [99,101,102],... [Pg.222]

Axelsson, L., Franzen, M., Ostwald, M., Bemdes, G., Lakshtni, G., Ravindranath, N.H., 2012. Perspective Jatropha cultivation in southern India assessing farmers experiences. Biofuels, Bioproducts and Biorefining 6 (3), 246—256. http //dx.doi.org/10.1002/bbb. [Pg.666]


See other pages where Ostwald assessment is mentioned: [Pg.269]    [Pg.618]    [Pg.192]    [Pg.601]    [Pg.303]    [Pg.439]    [Pg.453]    [Pg.502]    [Pg.214]    [Pg.219]    [Pg.138]    [Pg.184]    [Pg.247]    [Pg.302]    [Pg.537]    [Pg.226]    [Pg.227]    [Pg.253]    [Pg.255]    [Pg.410]   
See also in sourсe #XX -- [ Pg.405 , Pg.406 , Pg.407 , Pg.408 , Pg.409 ]




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