key concepts-wetting, adso, emulsions, collods
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7/23/2019 Key Concepts-wetting, Adso, Emulsions, Collods
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Course Name: CH412-INTERFACIAL SCIENCE
Key concepts in INTERFACIAL SCIENCE
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Key concepts in IS
• ettin!
• A"sorption
• Emu#sions
• Co##oi"s
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ettin!
• ettin! is t&e a%i#ity o' a #i(ui" to maintain contact
)it& a so#i" sur'ace* resu#tin! 'rom intermo#ecu#ar
interactions )&en t&e t)o are %rou!&t to!et&er+
• T&e "e!ree o' )ettin! ,)etta%i#ity is "etermine" %y
a 'orce %a#ance %et )een a"&esi.e an"
co&esi.e 'orces+
• ettin! "ea#s )it& t&e t&ree p&ases o' materia#s:
!as* #i(ui"* an" so#i"+
• It is no) a center o' attention in nanotec&no#o!y an"
nanoscience stu"ies "ue to t&e a".ent o' many
nanomateria#s in t&e past t)o "eca"es
,e+!+ !rap&ene* car%on nanotu%e+
https://en.wikipedia.org/wiki/Wetting
ettin!
•ettin! is important in t&e %on"in!
or a"&erence o' t)o materia#s+ ettin! an"
t&e sur'ace 'orces t&at contro# )ettin! are
a#so responsi%#e 'or ot&er re#ate" e''ects*
inc#u"in! so-ca##e" capi##ary e''ects+
• e!ar ess o t e amount o )ett n!* t e
s&ape o' a #i(ui" "rop on a ri!i" sur'ace is
rou!&#y a truncate" sp&ere+
• T&ere are t)o types o' )ettin!: non-reacti.e
)ettin! an" acti.e )ettin!
https://en.wikipedia.org/wiki/Wetting
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ater "rop#et immerse" in
oi# an" restin! on a %rass
sur'ace
ater %ea"s on a 'a%ric t&at &as %een
ma"e non)ettin! %y c&emica# treatment
https://en.wikipedia.org/wiki/Wetting
Inter'acia# interactions o' materia#s+ A
Interaction (uanti'ie" as contact an!#e
,see 'ormu#a+ / Interaction "escri%e"
in terms o' !oo" )ettin! ,sprea"in!*partia# ,poor )ettin!* or non)ettin!+
Contact an!#e 'or a #i(ui" "rop#et on
a so#i" sur'ace
ettin!Contact
an!#e
0e!ree o'
)ettin!
Stren!t& o':
So#i"#i(ui"
interactions
Li(ui"#i(ui"
interactions
θ = 0 Perfect
wetting strong weak
0 < θ < 90 highwettabi!ity
strong strongweak weak
90 " θ <
#$0
!ow
wettabi!ity weak strong
θ = #$0 perfect!y
non%wetting weak strong
https://en.wikipedia.org/wiki/Wetting
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A"sorption
•
A"sorption is the adhesion of atoms& ions& or mo!ecu!es from a gas&!i'uid& or disso!(ed so!id to a surface. )his process creates a fi!m of
the adsorbate on the surface of the adsorbent.
• )his process differs from absorption& in which a f!uid *the
absorbate+ permeates or is disso!(ed by a !i'uid or so!id
*the absorbent +.
• ,dsorption is a surface%based process whi!e absorption in(o!(es the
who!e (o!ume of the materia!.
• )he term sorption encompasses both processes& whi!e desorption is
the re(erse of it. ,dsorption is a surface phenomenon.
https://en.wikipedia.org/wiki/ ,dsorptionwww.chemgapedia.de
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www.physics.siu.edu
A"sorption
•
-imi!ar to surface tension& adsorption is a conse'uenceof surface energy.
• n a bu!k materia!& a!! the bonding re'uirements *be
they ionic&co(a!ent& or meta!!ic+ of the constituent atoms of
the materia! are fi!!ed by other atoms in the materia!.
owe(er& atoms on the surface of the adsorbent are not
who!!y surrounded by other adsorbent atoms and therefore
.
• )he eact nature of the bonding depends on the detai!s of the
species in(o!(ed& but the adsorption process is genera!!y
c!assified as p&ysisorption *characteristic of weak (an der
Waa!s forces+ or c&emisorption *characteristic of co(a!ent
bonding+. t may a!so occur due to e!ectrostatic attraction.
https://en.wikipedia.org/wiki/ ,dsorption
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Emu#sions
• )he word 1emu!sion1 comes from the Latin )or" for
1to mi!k1& as mi!k is an emu!sion of fat and water&
among other components.
• )wo !i'uids can form different types of emu!sions. ,s
an eamp!e& oi! and water can form& first& an oi!%in%water emu!sion& wherein the oi! is the dispersed
p ase& an wa er s e spers on me um.
• -econd& they can form a water%in%oi! emu!sion&
wherein water is the dispersed phase and oi! is the
eterna! phase.
• 2u!tip!e emu!sions are a!so possib!e& inc!uding a1water%in%oi!%in%water1 emu!sion and an 1oi!%in%
water%in%oi!1 emu!sion.https://en.wikipedia.org/wiki/3mu!sion
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Emu#sions
• ,n emu#sion is a miture of two or more !i'uids that are
norma!!y immiscib!e *unmiab!e or unb!endab!e+.
• Emu#sions are part of a more genera! c!ass of two%phase
systems of matter ca!!ed co!!oids.
https://en.wikipedia.org/wiki/Wetting
Emu#sions
•
,!though the terms colloid an" emulsion aresometimes used interchangeab!y& emulsion shou!d be
used when both the "isperse" an" t&e continuous
p&ase are #i(ui"s+
• n an emu!sion& one !i'uid *the dispersed phase+
is dispersed in the other *the continuous phase+.
•
Eamp#es o' emu#sions inc!ude (inaigrettes& mi!k&mayonnaise *3gg yo!ks& oi! and (inegar+& and
some cutting f!uids for meta! working.
3gg yo!ks: t&e ye##o) sp&erica# part o' an e!! t&at is
surroun"e" %y t&e a#%umen
https://en.wikipedia.org/wiki/3mu!sion
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Co##oi"s• , co##oi" is a substance in which microscopica!!y dispersed
inso!ub!e partic!es are suspended throughout another
substance. -ometimes the dispersed substance a!one is ca!!ed
the co!!oid
• the term co##oi"a# suspension refers unambiguous!y to the
o(era!! miture *a!though a narrower sense of the word
suspension is contradistinguished from co!!oids by !arger
4 .
• 5n!ike a so!ution& whose so!ute and so!(ent constitute on!y
one phase& a co!!oid has a dispersed phase *the suspended
partic!es+ and a continuous phase *the medium of
suspension+.
• )o 'ua!ify as a co!!oid& the miture must be one that doesnot sett!e or wou!d take a (ery !ong time to sett!e appreciab!y.
https://en.wikipedia.org/wiki/6o!!oid
$i#3 is an emu#si'ie" co##oi" o' #i(ui" %utter'at !#o%u#es "isperse" )it&in a )ater-%ase"
so#ution+
www.chm.bris.ac.uk
maryha!!y.wordpress.com
https://en.wikipedia.org/wiki/6o!!oid
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science.howstuffworks.com$ars&ma##o): Spon!y con'ection ma"e o' !e#atin an"
su!ar an" corn syrup an" "uste" )it& po)"ere" su!ar
$em%ranes• , mem%rane is a se!ecti(e barrier b/w two phases.
• ,t times& it is a!so an outer co(ering of ce!! or ce!!
organe!!e that a!!ows the passage of certain
constituents and retains other constituents found in
.
• )he inf!uent of a membrane is known as the feed%stream& the !i'uid that passes through the
membrane is known as the permeate and the !i'uid
containing the retained constituents is the retentate
or concentrate.
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$em%ranes
• )he concept of a membrane has been known since the
eighteenth century& but was used !itt!e outside of the
!aboratory unti! the end of Wor!d War .
• 7rinking water supp!ies in 3urope had been compromised by
the war and membrane fi!ters were used to test for water
safety.
• owe(er& due to the !ack of re!iabi!ity& s!ow operation&
reduced se!ecti(ity and e!e(ated costs& membranes were not
wide!y ep!oited.
• )he first use of membranes on a !arge sca!e was with micro%
fi!tration and u!tra%fi!tration techno!ogies.
• -ince the #9$0s& these separation processes& a!ong with
e!ectrodia!ysis& are emp!oyed in !arge p!ants and& today& a
number of eperienced companies ser(e the market.
$em%ranes• )he degree of se!ecti(ity of a membrane depends on the
membrane pore si4e.
• 7epending on the pore si4e& they can be c!assified as
microfi!tration *28+& u!trafi!tration *58+& nanofi!tration *8+
and re(erse osmosis *;+ membranes.
• em ranes can a so e o (ar ous t c ness&
with homogeneous or heterogeneous structure.
• 2embranes can be neutra! or charged& and partic!e transport
can be acti(e or passi(e.
• )he !atter can be faci!itated by pressure& concentration&
chemica! or e!ectrica! gradients of the membrane process.
• 2embranes can be genera!!y c!assified into synthetic
membranes and bio!ogica! membranes
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$em%rane processes an" "ri.in! 'orce
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www.intechopen.com
$em%rane C#assi'ications
www.smartmembraneso!utions.co.n4
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Types o' $em%rane Separation
an" Scope o' App#ication
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$em%rane /ioreactor System,Se)a!e treatment
systems
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$em%rane $ateria#s-c#assi'ication
• ,!most a!! industria! membrane processes are made from natura! or
synthetic po!ymers.
• )hese membranes are sometimes known as organic membranes.
atura! po!ymers inc!ude woo!& rubber *po!yisoprene+ and ce!!u!ose.
•
3amp!es of synthetic po!ymers inc!ude po!yamide& po!ystyrene andpo!ytetraf!uoroethy!ene *)ef!on+.
• 2embranes can a!so be made from other non%po!ymeric materia!s.
-uch membranes inc!ude inorganic membranes *for eamp!e meta!&
ceramic& carbon and 4eo!ites+ and !i'uid membranes.
• n addition& recent de(e!opments had !ed to the introduction of the so%
ca!!ed ybrid 2embranes *or 2ied 2atri 2embranes& where both
organic and inorganic components are used+.
• ,nother (ariation in membranes app!ication is the ipo!ar2embranes *P2+. where membranes of different ionic charge are
1sandwiched1 together.
$em%rane mo"u#es1+ #ate-an"-'rame
2+ Tu%u#ar
5+ Spira#-)oun"
4+ Ho##o) 'i%er
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•
#ate-an"-Frame $o"u#es• )he p!ate%and%frame modu!es were one of the
ear!iest types of membrane system&
• but because of their re!ati(e!y high cost they
ha(e been !arge!y rep!aced in most
%
ho!!ow%fiber modu!es.
• P!ate%and%frame modu!es are now used on!y
in e!ectrodia!ysis and per(aporation systems
and in a !imited number of re(erse osmosis
and u!trafi!tration app!ications with high!y
fou!ing conditions.
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synderfi!tration.com
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#ate-an"-'rame units use t&e
mem%rane itse#'* ai"e" %y #oc3 rin!s or
strips* to sea# o'' t&e 'ee" retentate
'rom miin! into t&e permeate
c&anne#s+
•
Tu%u#ar $o"u#es• )hese modu!es are now genera!!y !imited to
u!trafi!tration app!ications& for which the benefit of
resistance to membrane fou!ing outweighs the high
cost.
• )ubu!ar membranes contains as many as to > sma!!er
tu es& eac . to . cm n ameter& neste ns e a
sing!e !arger tube.
• n a typica! tubu!ar membrane system& a !arge number
of tubes are manifo!ded in series.
• )he permeate is remo(ed from each tube and sent to a
permeate co!!ection header.
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Tu%u#ar mem%rane mo"u#e
www.forwardosmosistech.com
Tu%u#ar mem%rane mo"u#e
www.kochmembrane.com
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cross '#o) mo"u#e
www.pa!!.com
$em%rane mo"u#e )it& mu#tip#e tu%u#ar
mem%ranes ,or mu#ti-tu%e mo"u#e
on!inembr.info
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• Spira#-)oun" mo"u#es• ndustria!%sca!e modu!es contain se(era! membrane en(e!opes& each
with an area of # to ? m?& wrapped around the centra! co!!ection pipe.
• 2u!ti%en(e!ope designs minimise the pressure drop encountered by
the permeate tra(e!!ing toward the centra! pipe.
• )he standard industria! spira!%wound modu!e is $%inch in diameter and@0%inch !ong.
• .
• )he feed so!ution passes across the membrane surface& and a portion
of the feed permeates into the membrane en(e!ope& where it spira!s
towards the centre and eits through the co!!ection tube as shown in
the 8igure.
• @ to A spira!%wound membrane modu!es are norma!!y connected in
series inside a sing!e pressure (esse!.
• , typica! $%inch diameter tube containing A modu!es has #00 to ?00
m? of membrane area.
Spira# )oun" mem%rane mo"u#e
en.wikipedia.org
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Ho##o)-'i%re mo"u#es
• o!!ow%fibre modu!es are characteristica!!y @%$inch *#0%?0 cm+ in diameter and B% *#.0%#.A m+
feet !ong.• o!!ow%fibre units are a!most a!ways run with the
feed stream on the outside of the fibre.
• Water passes through the membrane into theinside or 1!umen1 of the fibre.
• , number of ho!!ow%fibres are co!!ected together
and 1potted1 in an epoy resin at both ends andinsta!!ed into an outer she!!.
• n the she!!%side feed design& a !oop or c!osed bund!e of fibres iscontained in a pressure (esse!.
• )he system is pressurised from the she!! side& and the permeatepasses through the fibre wa!! and eits through the open fibreends. )his design is easy to fabricate and a!!ows (ery !argemembrane areas to be contained in an economica! system.
• ecause the fibre wa!! must support considerab!e hydrostaticpressure& the fibres usua!!y ha(e sma!! diameters and thick wa!!s&
% %
Ho##o)-'i%re mo"u#es-t)o "esins
diameter.• n the bore%side feed design& the fibres are open at both ends and
the feed is circu!ated through the bore *annu!us area+ of thefibres.
• )o minimise pressure drop inside the fibres& the diameter areusua!!y !arger than those of the fine fibres used in the she!!%sidefeed design.
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Ho##o) 'i%er mem%rane mo"u#e
www.kochmembrane.com
Ho##o) 'i%er mem%rane