Adsorption_4

8/11/2019 Adsorption_4

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Physico-chemistry of surface

Bogdan KUCHTA

Bogdan Kuchta

Laboratoire MADIREL

Universit Aix-Marseille


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Introduction

All object are finite they have a surface !!!

Interface in molecular biology contacts between nerve ends

Interfaces between phases li!uid"gas# solid"gas# $$$$# %

&pecial situation' porous materials big surface'

( )ery * divided + ' &pecific surface between ,$- and ./,,m.g(- even -,,,, m.g(-%

( 0r porous ' in particular# pores with si1es below 2, nm

( And 3pulveri1ed4 ' grains of dimension below - m

These are nano-materials which are the most

interesting from the technological point of view

(dimensions "" nm#$

%chematic

representation of

different types of

nanomaterials'

a% 5aolinite

b% clay 6de 7aris8# cement

c% gel of silica# polymers

d% porous glasses

(a)

(c)

(b)

(d)


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&otion of interface

%eparation between two volume

phases

Although the word 6interface8 is used as

6surface8 and other way around# by surface

usually we understand the interface

between solid"gas or solid"li!uid$

If we tal5 about interface we need to

define what are the phases forming the

interface$

e'emple ' interface solidgas 9

interface solidli)uid

1

10

100

1000

10000

0.001 0.01 0.1 1 10

d/ m

a/ m2g

-1

nanomatriaux

tat collodal

tat divis

:volution of geometric surface

as a function of the diameter

of silica particles$

( Below -, ;m# we call it divided materials having

the specific surface up to m*g-+

( Below ,m# we call it 6colloids8 9

( Below " nm# we call it 3nano(materials4


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divis=s ou poreu>

Celles !ui r=sultent de leurs propri=t=s adsorbantes '

Purification des gaz atmosph?res confin=es% ou des liquides

alimentaires huiles# sucres# eau potable% ' charbons actifs

Rcupration de solvants tunnels de peinture% ou dessence

cannisters de r=servoirs d8automobiles% ' charbons actifs

Dessiccation des gaz ou des liquides ' gels de silice, zolithes

Affinage de leau potable ' charbons actifs

Stockage du ga1 naturel# de l8hydrog?ne ' nanotubes, zolithes,

charbons

limination de toxines ' alumines, magnsie, argiles, charbons

mmagasinement dnergie m=cani!ue ' silices poreuses hydrophobes


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divis=s ou poreu>

Celles !ui r=sultent de leur =tat finement divis : 7oudresp!"tosanitaires ' soufre

Pigments ou c!arges pour mati?res plasti!ues ou caoutchoucs ' soufre,

noirs de carbone, silices prcipites, oxydes de titane ou de zinc

Agents glifiants pour peintures# colles# alcool solidifi= ' silice

pyrogne

@ati?res premi?res pour l8industrie des cramiques# avant frittage 'kaolin, alumine, magnsie, oxyde duranium, nitrures

#iants !"drauliques : pltres et ciments

lectrodes poreuses pour piles# accumulateurs# super(condensateurs 'carbone

Agents pour le relargage progressifd8engrais ou de principes actifs

m=dicamenteu> ' zolithes, gels ou verres poreux


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7orous @aterials

0ne can say that thepores are cavities that

are deeper then wider$

7ore e>ist in grains of

matter$ Also# we useporosity inter(granular$

c

a

f

d

ba : corrugation

b : bottle neck

c : opening

d : interconnection

e : close-endedf: closed (isolated)


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.ondensation capillaire

@=canismes

Adsorption ( d=sorption

ns"ms

7"70

Adsorption

d=sorption

C

Au point C

Au point


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Cas d un pore cylindrique: adsorption

Augmentation de la pression

Diminution du rayon de courbure

instabilits P=/r

r r



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Cas d un pore cylindrique: dsorption

diminution de la pression

r

Pads diffrent de PdsP=2/r



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Cas d un pore cylindrique ferm une e!trmit

P"ads#=P"des#



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Autre origine de l$ystrsis

% Pores en fore de bouteille :

&idange pour le rayon de 'el&incorrespondant lou&erture

% !onnectivit : un pore peut se &ider

sil est la surface

ou sil est ad(acent

un autre pore d( &id "percolation#



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Methods versus diension of "ores

a

cb

d

e

f

micropores msopores macropores )*

ultra + super microcapillaires / capillaires / macrocapillaires

nanopores

#$%# #$$ #$# #$& #$' #$( #$) #$*

$+'n #$n&n,#n #$$n #- #)$n,

n

, normes .PAC

adsor"tion

remplissagemicropores

condensationcapillaire

thero"orotrie

"orotrie au ercure

icrocaloritrie d.adsor"tion

icrocaloritrie d.iersion

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