Zsigmondy


Explanations of hysteresis in capillary condensation probably begin in 1911 with Zsigmondy [198], who attributed the effect to contact angle hysteresis due to impurities this might account for behavior of the type shown in Fig. XVII-28a, but not in general for the many systems having retraceable closed hysteresis loops. Most of the early analyses and many current ones are in terms of a model representing the adsorbent as a bundle of various-sized capillaries. Cohan [199] suggested that the adsorption branch—curve abc in Fig. XVII-28Z)—represented increasingly thick film formation whose radius of curvature would be that of the capillary r, so that at each stage the radius of capillaries just filling would be given by the corresponding form of the Kelvin equation (Eq. III-19)  [c.665]

R. Zsigmondy, Z Anorg. Chem., 71, 356 (1911).  [c.683]

The model proposed by Zsigmondy—which in broad terms is still accepted to-day—assumed that along the initial part of the isotherm (ABC of Fig. 3.1), adsorption is restricted to a thin layer on the walls, until at D (the inception of the hysteresis loop) capillary condensation commences in the finest pores. As the pressure is progressively increased, wider and wider pores are filled until at the saturation pressure the entire system is full of condensate.  [c.113]

Following Zsigmondy, early workers in the field assumed the pores to be cylindrical and the angle of contact to be zero, so that the meniscus was hemispherical. The mean radius of curvature r thus became equal to the radius of the pore less the thickness of the adsorbed film on the walls. By application of the Kelvin equation it was therefore possible to calculate the minimum radius of pores in which capillary condensation can take place, from the relative pressure at D, the lower limit of the hysteresis loop. General experience from the time of Anderson (working in Zsigmondy s laboratory) onwards, shows that this minimum radius varies from system to system, but is rarely below 10 A. The upper limit of the applicability of the Kelvin equation, r 250 A, is a practical one, set by the experimental difficulty of measuring very small lowerings of vapour pressure (cf. Table 3.8). The justification for defining mesopores by reference to the limits 10 to 250 A therefore rests on the fact that the classical capillary equations, especially the Kelvin equation, are applicable in this range.  [c.113]

A. Zsigmondy, Z. Anorg. Chem. 71, 356 (1911).  [c.190]

R. Zsigmondy and W. Bachmann, Z. A.norg. Chem. 103, 119 (1918).  [c.89]

R. Zsigmondy, Z. Phys. Chem. (Eeipcfg) 56, 65 (1906).  [c.402]

The model proposed by Zsigmondy—which in broad terms is still accepted to-day—assumed that along the initial part of the isotherm (ABC of Fig. 3.1), adsorption is restricted to a thin layer on the walls, until at D (the inception of the hysteresis loop) capillary condensation commences in the finest pores. As the pressure is progressively increased, wider and wider pores are filled until at the saturation pressure the entire system is full of condensate.  [c.113]

R. Zsigmondy (Gottingen) demonstration of the heterogeneous nature of colloid solutions by methods which have since become fundamental in modem colloid chemistry.  [c.1297]

R. Zsigmondy, Z. Anal Chem., 40, 697 (1901) Colloids and the EItramicroscope, J. Alexander, TransL, John Wiley Sons, Inc., New York, 1909.  [c.402]

Following Zsigmondy, early workers in the field assumed the pores to be cylindrical and the angle of contact to be zero, so that the meniscus was hemispherical. The mean radius of curvature r thus became equal to the radius of the pore less the thickness of the adsorbed film on the walls. By application of the Kelvin equation it was therefore possible to calculate the minimum radius of pores in which capillary condensation can take place, from the relative pressure at D, the lower limit of the hysteresis loop. General experience from the time of Anderson (working in Zsigmondy s laboratory) onwards, shows that this minimum radius varies from system to system, but is rarely below 10 A. The up[>er limit of the applicability of the Kelvin equation, r 250 A, is a practical one, set by the exjjcrimental difficulty of measuring very small lowerings of vapour pressure (cf. Table 3.8). The justification for defining mesopores by reference to the limits 10 to 250 A therefore rests on the fact that the classical capillary equations, es[>ecially the Kelvin equation, are applicable in this range.  [c.113]


See pages that mention the term Zsigmondy : [c.112]    [c.122]    [c.112]    [c.122]    [c.190]   
Physical chemistry of surfaces (0) -- [ c.665 ]