Physical chemistry of surface phenomena. Basics of adsorptive therapy презентация

Physical chemistry of surface phenomena. Basics of adsorptive therapy

SURFACE PHENOMENA  are phenomena associated with the existence of interphase boundaries. SURFACE PHENOMENA ARE STUDIED BY COLLOID CHEMISTRY

Surface phenomena Inside the fluid forces are balanced From the side of gas resultant is directed into the interface between the liquid and the liquid tends to decrease

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.

THE SURFACE ENERGY THE SURFACE TENSION Surface tension  is the work required for the creation of 1 m2 of surface []= J/m2 Surface tension is the excessive energy, referred to a unit surface area of the phase separation = Е/ S

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.

SORPTION

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

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

Adsorption Adsorption is spontaneous change of component concentration in the surface layer compared to the volume of a phase

Gibbs Equation

Surface activity The ability of the solute to change surface tension is called surface activity (γ) The measure of surface activity :

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.

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 <O.    SIS: inorganic acids, bases, salts, glycerol, α - amino acids. Surfactants-nonactive substance (SNS): do not alter the surface tension of the solvent. σ solution = σ solvent; g = O.     SNS: sucrose.

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.

The structure of SAS molecules: SAS molecule consists of: non-polar hydrophobic hydrocarbon group (“tail”) polar hydrophilic group (“head”): -ОН, -СООН, -С(О)-О,-NН2; -SО3H. “tail” “head”

ADSORPTION ON THE SOLUTION-GAS ADSORPTION ON THE SOLUTION-GAS BORDER

Calculation of the adsorption isotherm G= ƒ(с) For the calculation of the adsorption isotherm you are to plot the dependence σ from c.

Gibbs’ isotherm of adsorption 1. Low С

ADSORPTION ON THE SOLID-GAS ADSORPTION ON THE SOLID-GAS BORDER

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.

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.

Determination of the constants in the Freundlich equation lg A = lg k + 1/n lg c

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.

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

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.

Langmuir’s isotherm of adsorption

Theory of polymolecular adsorption BET (Brunauer, Emmett, Teller)

ADSORPTION ON THE BORDER OF 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

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.

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

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.

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+

Chromatography Chromatography is dynamic method of analysis based on multiply repeated processes of sorption and desorption.

From the history of chromatography

HPLC Agilent Technologies

HPLC Milichrom

HPLC HP

GLC “Agilent Technologies”

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.

Enterosorbents

Enterosorbents Smecta

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.

Hemodialysis Hemodialysis (from hemo-and διάλυσις - decomposition, office) is extrarenal method of blood purification during acute and chronic renal failure.

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.

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.

Hemosorbtion Hemosorbtion (from the Greek. Haema blood + lat. Sorbere absorb) is a method of treatment aimed at removing from the blood of various toxic products and the regulation of hemostasis by contact with the blood outside the body of the sorbent.