Izlaganje sa skupa

Where Are We in Explanations of Ionic Solubility, Precipitation, Coagulation, and Flocculation Phenomena? (Processes of Aggregation as Spatial-temporal Indicators of Dynamical Structures in the Electrolytic Solution, the Emerging Solid Phase, and the Methoric Layer between the Solid-liquid Bulk Phases)

Božo Težak ; University of Zagreb, Croatia, Yugoslavia

Sažetak

A confusion concerning the explanations, concepts and theories
in the major sectors of the physics and chemistry of our
environment exemplified in the case of real systems of aqueous
solutions is pointed out. The much more general, coherent and
integrating approaches have failed as it is evidenced by the treatment
of phenomena of precipitation, ion-ion and ion-solvent
interactions, and colloid stability.
To support such standpoints some remarks of R. H. Stokes1,
V. K. La Mer2 and J. N. Mukherjee are mentioned. In this sense
the application of van der Waals cumulative attraction and electrical
double layer repulsion for colloid stability/instability (the so-
called DLVO-theory) is taken to be a serious hindrance to the
progress in this field. The same case is with the indiscriminate use
of the solubility product constants.
In summarizing statements about the earlier material published
in the proceedings of the International Schools, Conferences
and Symposia on Solid/Liquid Interfaces held in Yugoslavia in 1969,
1972 and 1975, the influence of substantial composition as well as
of concentrational conditions of the systems on the discontinuities
in the formation of precipitates, including the embryonation, nucleation,
crystal growth, and stability/instability states of primary
particles (sols in statu nascendi) are emphasized.
The explanation of the discontinuities in the kinetics of aggregation
is given by relationships between the concentration in bulk
solution, the structure of emerging solid, and the concentration in
the methoric layer between the solid-solution bulk phases, Higher
concentration of osmotically active species in methoric layer than
in the bulk solution is taken to be the cause . for stability, and the
lower one for instability of colloid particles.
For presentation of experimental results on precipitation the
rational scheme in three-dimensional diagrams showing the time-
dependent formation of solid phase in the basic plot of the logarithms
of concentrations of the two precipitating components, thus
representing the so-called 'precipita.tion bodies' (PBs) are given.
The relevance of the expression given in Schulze-Hardy-Tefak
formulation:

Ključne riječi

Hrčak ID:

194565

URI

https://hrcak.srce.hr/194565

Datum izdavanja:

5.11.1980.

Posjeta: 612 *