Презентация Physics and chemistry of surface phenomena онлайн
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- Всего слайдов:10 слайдов
- Для класса:1,2,3,4,5,6,7,8,9,10,11
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Слайды и текст к этой презентации:
№1 слайд
Содержание слайда: Zaporizhzhya State Medical University
Analytical Chemistry Department
PHYSICS AND CHEMISTRY OF SURFACE PHENOMENA
Lecturer: Monaykina Yulia Vitalievna
2016
№2 слайд
Содержание слайда: Surface phenomena are the processes that occur at the interface in heterogeneous systems.
Surface phenomena are the processes that occur at the interface in heterogeneous systems.
The spontaneous process of solute accumulation at the interface is called adsorption.
№3 слайд
Содержание слайда: The substance which adsorbs the solute is called adsorbent.
The substance which adsorbs the solute is called adsorbent.
The adsorbed solute is called
adsorbate.
The interface may be: gas – liquid,
liquid – liquid,
solid – liquid,
solid – gas.
№4 слайд
Содержание слайда: Adsorption at the gas-liquid and liquid-liquid interface
№5 слайд
Содержание слайда: The ability of dissolved substances to change the surface tension of the solvent is called surface activity.
The ability of dissolved substances to change the surface tension of the solvent is called surface activity.
A measure of the surface activity is a derivative of the surface tension on the concentration, taken with an opposite sign :
For narrow concentration ranges the formula is:
№6 слайд
Содержание слайда: The Duclos-Traube rule:
The surface activity increases about 3 -3,5 times with each addition of a methylene group to the homolog.
№7 слайд
Содержание слайда: Molecules and atoms can attach themselves onto surfaces in two ways:
Molecules and atoms can attach themselves onto surfaces in two ways:
In physisorption (physical adsorption), there is a weak van der Waals attraction of the adsorbate to the surface. During this process the chemical identity of the adsorbate remains intact, i.e. no breakage of the covalent structure of the adsorbate takes place.
In chemisorption (chemical adsorption), the adsorbate sticks to the solid by the formation of a chemical bond with the surface.
№8 слайд
Содержание слайда: Adsorption at the solid-solution interface
Adsorption at the solid-solution interface
Solutes adsorption by solid adsorbents is more complex as the solvent molecules can compete with adsorbate molecules for the adsorptive sites on the adsorbent surface as well as can interact with the adsorbate and adsorbent surface.
Two kinds of adsorption on a solid adsorbent are distinguished:
molecular
and
ionic adsorption.
№9 слайд
Содержание слайда: OTHER FACTORS AFFECTING ADSORPTION
OTHER FACTORS AFFECTING ADSORPTION
Surface area of adsorbent. Larger sizes of surface area
imply a greater adsorption capacity.
Particle size of adsorbent. Smaller particle sizes reduce
internal diffusional and mass transfer limitation to the
penetration of the adsorbate inside the adsorbent (i.e.,
equilibrium is more easily achieved and nearly full
adsorption capability can be attained)
Contact time or residence time. The longer the time the
more complete the adsorption will be.
№10 слайд
Содержание слайда: Structure of biological membranes
Structure of biological membranes
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