Physical chemistry of surface phenomena. Basics of adsorptive therapy

Содержание

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Colloidal Chemistry A colloid is a substance microscopically dispersed evenly throughout

Colloidal Chemistry

A colloid is a substance microscopically dispersed evenly throughout another

substance.
The designation ‘‘colloid’’ is used for particles that are of some small dimension and cannot pass through a membrane with a pore size10-6 m (micrometer).
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Colloidal Science an interdisciplinary intersection dealing with colloids, heterogeneous systems consisting

Colloidal Science

an interdisciplinary intersection dealing with colloids, heterogeneous systems consisting

of a mechanical mixture of particles between 1 nm and 1000 nm dispersed in a continuous medium.
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Surface tension

Surface tension

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Dispersed liquids in nature

Dispersed liquids in nature

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Minimal surfaces Costa’s minimal surface (1982) Catenoid Helicoid

Minimal surfaces

Costa’s minimal surface (1982)

Catenoid

Helicoid

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There is an extra energy associated with a surface Molecules on

There is an extra energy associated with a surface

Molecules on the

surface are less bounded than molecules in the bulk.
There is therefore an energy associated with a free surface.
More rigorously: there is a free energy associated with an interface.
This energy is the surface tension γ
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Surface phenomena The increased surface area of the phase separation is

Surface phenomena

The increased surface area of the phase separation is associated

with the transition of molecules from the depth of the phase on the surface.
This work of dW is proportional to the square of the formed surface dS:
-dW=σ·dS
σ- the coefficient of proportionality, called surface tension.
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Surface tension σ is the work required for the creation of

Surface tension σ
is the work required for the creation of

1 m2 of surface
[σ]= J/m2
Surface tension is the excessive energy, referred to a unit surface area of the phase separation σ= Е/ S

THE SURFACE ENERGY THE SURFACE TENSION

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Surface tension Surface tension depends on: the nature of fluid σ(Н2О)=72,8

Surface tension

Surface tension depends on:
the nature of fluid
σ(Н2О)=72,8 J/m2; σ(serum)=45,4 J/m2).
temperature

(↑t ↓σ , when tboil. σ =0).
pressure (↑p ↓σ ).
the concentration of the dissolved substance.
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The surface tension can be thought of as a force F

The surface tension can be thought of as a force

F

A

 

The energy

per unit area is γ
It can often be thought of as a force
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A didactic setup (Cf. Wilhelmy plate)

A didactic setup (Cf. Wilhelmy plate)

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WETTABILITY Why does one fabric absorb water well while another seems

WETTABILITY

Why does one fabric absorb water well while another seems to

refuse it?
Why does water collect into large drops on a greasy surface and instead form an adherent film on a clean surface?
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WETTABILITY

WETTABILITY

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Cohesion (n. lat. cohaerere "stick or stay together") or cohesive attraction

Cohesion (n. lat. cohaerere "stick or stay together") or cohesive attraction or cohesive force is the action or property of

molecules sticking together, being mutually attractive.
Adhesion is the tendency of dissimilar particles or surfaces to cling to one another
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CAPILLARITY

CAPILLARITY

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Capillary forces What is the force between two spheres?

Capillary forces

What is the force between two spheres?

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SORPTION

SORPTION

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Medical & biological importance: Assimilation of nutrients and drugs Transfer of

Medical & biological importance:

Assimilation of nutrients and drugs
Transfer of

O2 and CO2 from the lungs to the tissues
The action of enzymes
Detoxification: a) Hemosorption - blood purification b) lymphosorption – lymph purification.
Absorption of toxic substances in the gastrointestinal tract (enterosorption).
Chromatography: - Separation of mixtures of aminoacids; - Cleaning of drugs; - Quantitative determination of vitamins, hormones; - Diagnosis of diseases
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Sorption -change in the concentration of one or more components in

Sorption -change in the concentration of one or more components in

heterogeneous systems

Sorption - the process of absorption of one substance by another
Sorbent - absorber
Sorbtiv (sorbate) - absorbed substance
Adsorption - absorption by sorbent surface
Absorption - absorption by the entire volume of the sorbent

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Adsorption Adsorption is spontaneous change of component concentration in the surface

Adsorption

Adsorption is spontaneous change of component concentration in the surface layer

compared to the volume of a phase
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Gibbs Equation G - the amount of adsorbed substance [mole/m2] а

Gibbs Equation

G - the amount of adsorbed substance [mole/m2]
а – equilibrium

activity of the substances in solution [mole/l] R - universal gas constant = 8,31 J/моль∙(°К) - surface activity of the dissolved substance.

G - the amount of adsorbed substance [mole/m2]
с – the concentration of the substance in solution [mole/l]
R - universal gas constant = 8,31 J/моль∙(°К)

G - the amount adsorbed substance [mole/m2]
р – the equilibrium gas pressure, Pa R - universal gas constant = 8,31 J/моль∙(°К))

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Surface activity The ability of the solute to change surface tension

Surface activity

The ability of the solute to change surface tension is

called surface activity (γ)
The measure of surface activity :
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Traube-Duclos rule: When extending the chain-CH2 - in homological series of

Traube-Duclos rule:

When extending the chain-CH2 - in homological series of surface

activity increases in 3-3,5 times, respectively, increases the ability to adsorption.

НСООН СН3СООН СН3СН2СООН СН3СН2СН2СООН

σ

с

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SAS, SIS, SNS Surface-active substances (SAS): reduce σ solvent. σ solution

SAS, SIS, SNS

Surface-active substances (SAS): reduce σ solvent. σ solution <

σ solvent; g> O. SAS: alcohols, organic acids, esters, proteins, cholesterol, fats, lipids, soaps.
Surface-inactive substance (SIS): increase σ of solvent. σ solution > σ solvent; g Surfactants-nonactive substance (SNS): do not alter the surface tension of the solvent. σ solution = σ solvent; g = O. SNS: sucrose.
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The isotherm of surface tension The dependence of σ on the

The isotherm of surface tension

The dependence of σ on the concentration
the

dissolved substance at a constant
temperature is called isotherm of surface
tension.

SIS
SNS
SAS

σ

с

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Surfactants Surfactant classification according to the composition of their head: nonionic, anionic, cationic, amphoteric.

Surfactants

Surfactant classification according to the composition of their head: nonionic, anionic,

cationic, amphoteric.
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Surfactants in nature Pulmonary surfactants

Surfactants in nature

Pulmonary surfactants

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Effect of surfactants on surface tension Critical micellar concentration

Effect of surfactants on surface tension

Critical micellar concentration

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What is the pressure in a soap bubble ? « Amusons

What is the pressure in a soap bubble ?

« Amusons nous sur

la terre comme sur l'onde,
Malheureux celui qui se fait un nom
Richesses, Honneurs, Faux éclat de ce monde 
Tout n’est que boules de savon. »

Taken from the Nobel lecture of P.-G. de Gennes
Rev. Modern Phys. 64 (1992) 645

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What can you tell about the pressure in a liquid from

What can you tell about the pressure in a liquid from

the shape of a rising bubble?
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ADSORPTION ON THE LIQUID-GAS BORDER

ADSORPTION ON THE LIQUID-GAS
BORDER

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Calculation of the adsorption isotherm G= ƒ(с) For the calculation of

Calculation of the adsorption isotherm G= ƒ(с)

For the calculation of the

adsorption isotherm you are to plot the dependence σ from c.

1-the isotherm of surface tension,
2-adsorption isotherm

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Gibbs’ isotherm of adsorption 1. Low С 1 2 G c

Gibbs’ isotherm of adsorption

1. Low С

1

2

G

c

gas

water

2. High С

gas

water

«Langmuir’s palisade»

G

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ADSORPTION ON THE SOLID-GAS BORDER

ADSORPTION ON THE SOLID-GAS
BORDER

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Adsorption by solids The adsorption value depends on: 1. The size

Adsorption by solids

The adsorption value depends on:
1. The size of the

adsorbent surface
if S↑ surface then adsorption ↑.
2. Temperature (↑t ↓G ).
3. Type of sorbent affinity thereof to the solvent. - Hydrophilic. - Hydrophobic.
4. Charge of the adsorbent and the adsorptive.
5. Adsorptive concentration.
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Freundlich equation А = x/m = k · p1/n G =

Freundlich equation

А = x/m = k · p1/n G = x/m

= КF · Cn
х – the amount of substance of the adsorptive (mole) m – mass of adsorbent p – equilibrium gas pressure, С – equilibrium concentration in the system
V adsorption = V desorption
к – Freundlich constant, к = А at р = 1
n – empirical constant.
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Determination of the constants in the Freundlich equation lg A =

Determination of the constants in the Freundlich equation

lg A = lg

k + 1/n lg c

lgx/m
lgA

lgK

tgα=1/n

Freundlich isotherm in conventional coordinates

Freundlich isotherm in logarithmic coordinates

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The theory of Langmuir 1) On each absorption place on the

The theory of Langmuir

1) On each absorption place on the surface

of the adsorbent can be only one molecule or adsorption is localized on the adsorption centers.
2) Adsorption is monomolecular, i.e. is carried out only in one layer.
3) Adsorption surface is homogenious.
4) Between the adsorbed molecules there is no interaction.
5) Adsorption is a reversible process.
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The theory of Langmuir According to this theory localization adsorption can

The theory of Langmuir

According to this theory localization adsorption can be

represented of the quasichemical equation similar to the chemical reaction:
Where A is adsorption center, B is molecule of substance AB is adsorption complex.
For example to the atoms of carbon, having free valences oxygen atoms can join
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Langmuir equation А = А КС for gases : G =

Langmuir equation

А = А КС for gases : G = G

_Кр_
1+(КС) 1+Кр
С – concentration
Р - gas pressure
К - adsorption equilibrium constant = Кdesorption
Кadsorption
at С << К А = А С, linear dependence of G on С
К
at С > К G= G , further increasing the concentration does not affect the adsorption.
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To find the constants A ∞ and K linear formula of

To find the constants A ∞ and K linear formula of

Langmuir equation is used.
Substituting the experimental data graphically it’s easy to find the necessary constants.
- Langmuir theory is valid if monomolecular layer is formed.
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Langmuir’s isotherm of adsorption с G

Langmuir’s isotherm of adsorption

с

G

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Theory of polymolecular adsorption BET (Brunauer, Emmett, Teller) Many experimental evidence

Theory of polymolecular adsorption BET (Brunauer, Emmett, Teller)
Many experimental evidence suggests

that, after the monomolecular layer formation (point B) Adsorption continues to rise, due to the excess surface activity.
S-shaped polymolecular adsorption isotherm
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ADSORPTION ON THE BORDER OF SOLID – SOLUTION In the study

ADSORPTION ON THE BORDER OF
SOLID – SOLUTION
In the study of

adsorption from solutions on solid adsorbents distinguish molecular adsorption (adsorption of nonelectrolytes or weak electrolytes) and the adsorption of electrolytes
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Molecular adsorption Experimentally determined value of the adsorption of knowing the

Molecular adsorption

Experimentally determined value of the adsorption of knowing the initial

concentration of the solution c0, the volume of solution V and the adsorbent mass m.

If you know the surface area of ​​the adsorbent, the adsorption isotherm belongs to a given value:
Isotherms of adsorption on carbon from aqueous solutions of 1-phenol, 2-succinic acid, 3-benzoic acid

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Molecular adsorption So, in the adsorption of aliphatic carboxylic acids from

Molecular adsorption

So, in the adsorption of aliphatic carboxylic acids from aqueous

solutions on a non-polar adsorbent - activated carbon - molecules are aligned by hydrocarbon radicals to an adsorbent, with adsorption of benzene (a nonpolar solvent) in the polar adsorbent - silica gel - orientation acid molecules will be reversed
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Conclusion From the above that is confirmed, that: For adsorption SAS

Conclusion

From the above that is confirmed, that:
For adsorption SAS from

the nonpolar or low-polar solvents hydrophilic substances (silica, clays); must be used
On the surfaces of hydrophobic (coal, graphite, talc) from aqueous solutions of SAS should be better adsorbed.
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The ion exchange adsorption The ion exchange adsorption - a process

The ion exchange adsorption

The ion exchange adsorption - a process in

which the adsorbent is added and the solution is exchanged between the equivalent amounts of similarly charged ions. RM1 + М2+ → RM2 + M1+ cation exchange
cationite
RА1 + А2- → RА2 + А1- anion exchange
anionite
To neutralize the excess acid in the gastric juice :
R–Kt+OH– + Cl– ⇄ R – Kt+Cl– + OH–
Potassium ions: R–An–H+ + Na+ ⇄ R–An–Na++ H+
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Chromatography Chromatography is dynamic method of analysis based on multiply repeated processes of sorption and desorption.

Chromatography

Chromatography is dynamic method of analysis based on multiply repeated processes

of sorption and desorption.
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Chromatography is physical chemical method used to separate substances analytical objectives

Chromatography is physical chemical method
used to separate substances

analytical objectives formulations

objectives

Used for identification and quantitative determination of organic and inorganic substances

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From the history of chromatography Mikhail Semenovich Tsvet (1872—1919) Birthday of

From the history of chromatography

Mikhail Semenovich Tsvet (1872—1919)

Birthday of chromatography

– 21.03.1903

The report of M.S. Tsvet "A new category of adsorption phenomena and their application to biochemical analysis" His method of M.S. Tsvet called - "chromatography" (written by color)

Richard Kuhn ( Institute of Basic Medicine , Heidelberg ) ( 1938, Nobel Prize in Chemistry for the suggested color adsorption chromatography carotenoids and vitamins )
Alfred Vintershtayn ( 1915, Nobel Prize in Chemistry for his research of chlorophyll )
Archer Martin Porter , Richard Laurence Millington Singe ( 1938, first countercurrent extractor using water and chloroform to separate oligopeptides ; 1940. Using liquid-liquid chromatography for separation of amino acids ; November 19 , 1941. The article " A new form of use of the two liquid phases for chromatography " in «Biochemical journal»;1952 . Nobel Prize for the discovery of partition chromatography
Archer Porter Martin , Anthony James Trafford ( 50s first gas chromatograph )
Izmailov, Schreiber ( 1938g. first work on thin-layer chromatography )
Stahl (1956 Using thin-layer chromatography as an analytical method )

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«No other discovery had such a huge long lasting effect in

«No other discovery had such a huge long lasting effect in

organic chemistry as the analysis using Tsvet’s adsorption chromatography»
Carrere, 1947.

Chromatographic methods are used for:
quantitative assessment of the basic substance in the bulk drug;
determination of impurities in bulk drug and medicinal forms;
the preliminary and confirming stages in the pharmaceutical, chemical and toxicological analysis;
determining the purity of water and food;
studying the kinetics of chemical reactions;
analyzing oil, etc.

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The principle of chromatographic separation of substances The stationary phase The

The principle of chromatographic separation of substances

The stationary phase

The mobile phase

Molecules

of substances to be separated

Separation effect is based on the fact that the compounds tested the distance at which separation occurs, with some inherent for this compound delay

Chromatographic process consists of a number of sorption and desorption, as well as the elution solution and that every time lead to a new equilibrium

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Column chromatography the stationary phase is in the column; the technique

Column chromatography

the stationary phase is in the column;
the technique used in

gas and liquid chromatography

Schematic diagram of the chromatograph for column chromatography

Container with eluent

The pumping system

sample inlet

Separating column

detector

The mobile phase GC - gas-carrier The mobile phase in LC - eluent

recorder

chromatogram

Signals of substances or peaks

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Identification by GLC For Identification of compounds in the mixture, its

Identification by GLC

For Identification of compounds in the mixture, its retention

time compared with a retention time of standard sample
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HPLC Agilent Technologies

HPLC Agilent Technologies

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HPLC Milichrom

HPLC Milichrom

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HPLC HP

HPLC HP

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GLC “Agilent Technologies”

GLC “Agilent Technologies”

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Enterosorption It is method of treatment of various diseases, based on

Enterosorption

It is method of treatment of various diseases, based on the

ability of enterosorbents bind and excrete various exogenous substances, microorganisms and their toxins, endogenous intermediate and final products of metabolism that are able to accumulate, or to penetrate into a cavity of the digestive tract in the course of the illness.
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Enterosorbents Polyphepan (lignin) Activated carbon (sorbex, carbolong, carbolen)

Enterosorbents

Polyphepan (lignin)

Activated carbon (sorbex, carbolong, carbolen)

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Enterosorbents Smecta Silicon organic sorbent Enterosgel

Enterosorbents

Smecta

Silicon organic sorbent Enterosgel

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Enterosorption Enterosorption is part of efferent therapy (from the Latin word

Enterosorption

Enterosorption is part of efferent therapy (from the Latin word efferens

means output). Also enterosorption, this group includes hemodialysis, peritoneal dialysis, plasmapheresis, hemosorption and others.
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Hemodialysis Hemodialysis (from hemo-and διάλυσις - decomposition, office) is extrarenal method

Hemodialysis

Hemodialysis (from hemo-and διάλυσις - decomposition, office) is extrarenal method of

blood purification during acute and chronic renal failure.
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Peritoneal dialysis Peritoneal dialysis (dialysis Greek expansion, separation) is method of

Peritoneal dialysis

Peritoneal dialysis (dialysis Greek expansion, separation) is method of cleansing

the blood of endogenous and exogenous toxins with simultaneous correction of water-salt balance by diffusion and filtration solutions of substances through the peritoneum as a natural semipermeable membrane.
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Plasmapheresis Membrane plasma filter contains a chamber for the flow of

Plasmapheresis

Membrane plasma filter contains a chamber for the flow of blood

separated from the cameras for plasma collection by porous membrane. The membrane thickness of 10 micron has pores, diameter of which is about 0.5 microns, which allows you to freely pass through all the latest liquid blood components and detain all formed elements. Together with the liquid component of blood passes through the membrane pores and much of the toxines. Dirty plasma is filtered in a separate bag and removed, and clean blood cell mass is returned to the circulatory system.