jurnal b.ing distribusi
TRANSCRIPT
-
8/13/2019 Jurnal b.ing Distribusi
1/120
Copyright 2004 by Taylor & Francis Group, LLC
4
Solvent Etraction E!uilibria
JAN RYDBERG* Chal"ers #niversity o$ Technology, Go% teborg,Se'en
GREGORY R. CHOPPIN* Flori'a State #niversity, Tallahassee, Flori'a,
#(S()(
CLAUDE MUSIKAS* Co""issariat a* l+Energie )to"i!ue, aris,
France
TATSUYA SEKINE
Science #niversity o$ To-yo, To-yo, .apan
4.1 INTRODUCTION
The ability o$ a solute /inorganic or organic to 'istribute itsel$ beteen an
a!ueous solution an' an i""iscible organic solvent has long been applie' to
separation an' puri$ication o$ solutes either by etraction into the organic phase,leaving un'esirable substances in the a!ueous phase1 or by etraction o$ the
un'esirable substances into the organic phase, leaving the 'esirable solute in the
a!ueous phase( The properties o$ the organic solvent, 'escribe' in Chapter 2,
re!uire that the 'issolve' species be electrically neutral( Species that pre$er the
organic phase /e(g(, "ost organic co"poun's are sai' to be lipophilic /li-ing
$at3 or hydrophobic /'isli-ing ater3, hile the species that pre$er ater
/e(g(, electrolytes are sai' to be hydrophilic /li-ing ater3, or lipophobic
/'isli-ing $at3( ecause o$ this, a hy'rophilic inorganic solute "ust be ren5
'ere' hy'rophobic an' lipophilic in or'er to enter the organic phase(6pti"i7ation o$ separation processes to pro'uce the purest possible pro'5
uct at the highest yiel' an' loest possible cost, an' un'er the "ost $avorable
environ"ental con'itions, re!uires 'etaile' -nole'ge about the solute reac5
tions in the a!ueous an' the organic phases( 8n Chapter 2 e 'escribe' physical
$actors that govern the solubility o$ a solute in a solvent phase1 an' in Chapter
9, e presente' the interactions in ater beteen "etal cations an' anions by
This chapter is a revise' an' epan'e' synthesis o$ Chapters 4 /by :y'berg an' Se-ine an' ; /by
)llar', Choppin,
-
8/13/2019 Jurnal b.ing Distribusi
2/120
Copyright 2004 by Taylor & Francis Group, LLC
y B)
hich neutral "etal co"plees are $or"e'( This chapter 'iscusses the e!uations
that eplain the etraction 'ata $or inorganic as ell as organic co"plees in a
!uantitative "anner1 i(e(, the "easure' solute 'istribution ratio, Dsolute, to the
concentration o$ the reactants in the to phases( 8t presents che"ical "o'eling
o$ solvent etraction processes, particularly $or "etal co"plees, as ell as a
'escription o$ ho such "o'els can be teste' an' use' to obtain e!uilibriu"
constants(
The subDect o$ this chapter is broa' an' it is possible to 'iscuss only the
si"plerthough $un'a"entalaspects, using ea"ples that are representative(
The goal is to provi'e the rea'er ith the necessary insight to engage in solvent
etraction research an' process 'evelop"ent ith goo' hope o$ success(
4.1.1 The Distribution Law
The distribution law, 'erive' in => by ( Hernst, relates to the 'istributiono$ a solute in the organic an' in the a!ueous phases( For the e!uilibriu" reaction
) /a! ) /org
the Hernst 'istribution la is ritten
Concentration o$ Species ) in organic phase B)org
/4(=a
KA, ) = = /4(=b
Concentration o$ Species ) in a!ueous phase B)a!
here brac-ets re$er to concentrations1 E!( /4(= is the sa"e as E!s( /=(2 an'
/2(29( KA,) is the distribution constant /so"eti"es 'esignate' by P, e(g(, in
Chapter 21 see also )ppen'i C o$ the solute ) /so"eti"es re$erre' to as the
distribuend ( Strictly, this e!uation is vali' only ith pure solvents( 8n practice,
the solvents are alays saturate' ith "olecules o$ the other phase1 e(g(, ater
in the organic phase( Further, the solute ) "ay be 'i$$erently solvate' in the
to solvents( Hevertheless, E!( /4(= "ay be consi'ere' vali', i$ the "utual
solubilities o$ the solvents /see Table 2(2 are s"all, say
-
8/13/2019 Jurnal b.ing Distribusi
3/120
li-e HaCl64( #n'er such con'itions the activity $actor ratio o$ E!( /4(2 is as5
su"e' to be constant, an'KA is use' as in E!( /4(= as con'itions are varie' at
a constant ionic strength value( 8n the $olloing 'erivations, e assu"e that the
activity $actors $or the solute in the a!ueous an' organic solvents are constant(
E$$ects 'ue to variations o$ activity $actors in the a!ueous phase are treate' in
Chapter ;, but no such si"ple treat"ent is available $or species in the organic
phase /see Chapter 2(
The assu"ption that the activity $actor ratio is constant has been $oun' to
be vali' over large solute concentration ranges $or so"e solutes even at high
total ionic strengths( For ea"ple, the 'istribution o$ ra'ioactively labele' GaCl9beteen 'iethyl ether an' ;< KCl as $oun' to be constant /KD,Ga = at all
Ga concentrations beteen =09
an' =0=2
< B=(
8n the $olloing relations, tables, an' $igures, the te"perature o$ the sys5
te"s is alays assu"e' to be 2JC, i$ not speci$ie' /te"perature e$$ects are'iscusse' in Chapters 9 an' ;, an' section 4(=9(;( e use org to 'e$ine speciesin the organic phase, an' no sy"bol $or species in the a!ueous phase /see )p5
pen'i C(
4.1.2 The Distribution Ratio
The 8#)C 'e$inition o$ the distribution ratio, D, is given in the intro'uction
to Chapter = an' in )ppen'i C( For a "etal species < it can be ritten
Concentration o$ all species containing
DM
=< in organicphase
Concentration o$ o$ all species containing
< in a!ueousphase
B
-
8/13/2019 Jurnal b.ing Distribusi
4/120Copyright 2004 by Taylor & Francis Group, LLC
J0
Fig. 4.1 Li!ui'5li!ui' 'istribution plots( /a The 'istribution ratiosD $or three 'i$$erentsubstances ), , an' C, plotte' against the variable Z o$ the a!ueous phase( Z "ay
represent pK, concentration o$ etractant in organic phase /BK)org, $ree ligan' ion con5
centration in the a!ueous phase /B), a!ueous salt concentration, etc( /b Sa"e syste"s
shoing percentage etraction IE as a $unction o$ Z( D an' Z are usually plotte' on
logarith"ic scale(
range o$ D is best "easure' $ro" about 0(==0, though ranges $ro" about
=0J=0
4can be "easure' ith special techni!ues /see section 4(=J(
8n "any practical situations, a plot li-e Fig( 4(=a is less in$or"ative than
one o$ percentage etraction, IE, hereM
IE ==00D N/=+D /4(4
Such a plot is shon in Fig( 4(=b $or the sa"e syste" as in Fig( 4(=a( ercentage
etraction curves are particularly use$ul $or 'esigning separation sche"es( )
series o$ such curves has alrea'y been presente' in Fig( =(9(
) convenient ay to characteri7e the S5shape' curves in Figs( =(9 or 4(=b,
here the etraction 'epen's on the variableZ, is to use the logZ value o$ J0Ietraction, e(g(, logBCl ( The pKJ05value in'icates logBK+ $or J0I etrac5
tion( This is shon in Fig( 4(= $or 'istribuen's ) an' (
-
8/13/2019 Jurnal b.ing Distribusi
5/120
2
Oery e$$icient separations are o$ten nee'e' in in'ustry, an' a single e5
traction stage "ay be insu$$icient( The 'esire' purity, yiel', etc( can be achieve'
by "ultiple etractions, as 'iscusse' in Chapter P /see also section =(2( 8n
the 'esign o$ separation processes using "ultistage etractions, other etraction
'iagra"s are pre$erre'( 6nly single stage etraction is 'iscusse' in this chapter,
hile "ultistage etraction is 'iscusse' in the secon' part /Chapters P=4 o$
this boo-(
4.2 THERMODYNAMICS OF EXTRACTION SYSTEMS
Etraction $ro" a!ueous solutions into organic solvents can be achieve' through
'i$$erent che"ical reactions( So"e "ay see" very co"plicate', but usually oc5
cur through a nu"ber o$ rather si"ple steps1 e assu"e this in "a-ing a "o'el
o$ the syste"( The sub'ivision o$ an etraction reaction into its si"pler steps is
use$ul $or un'erstan'ing ho the 'istribution ratio varies as a $unction o$ the
type an' concentration o$ the reagents( 6$ten these "o'els allo e!uilibriu"
constants to be "easure'(
)s solute, e consi'er both nonelectrolytes /abbreviate' as ) or , or5
ganic or inorganic, an' electrolytes /e(g(, as "etal5organic co"plees, "etal
ions ren'ere' soluble in organic solvents through reactions ith organic anions
)
an' ith a''uct $or"ers ( The syste" o$ e!uations shon later is only
vali' as long as no species are $or"e' other than those given by the e!uations,
all concentrations re$er to thefree concentrations /i(e(, unco"plee', an' activ5ity $actors an' te"peratures are constant( Further, e assu"e that e!uilibriu"
has been establishe'( 8t "ay be note' that the use o$ e!uilibriu" reactions "ean
that the reactions ta-e place in the a!ueous phase, the organic phase or at the
inter$ace, as is illustrate' in the net ea"ples, but 'o not sho any inter"e'i5
ates $or"e'1 this in$or"ation can be obtaine' by -inetic stu'ies, as 'escribe' in
Chapter J, or by $ingerprinting3 techni!ues such as "olecular spectroscopy(
e$ore a 'etaile' analysis o$ the che"ical reactions that govern the 'istri5
bution o$ 'i$$erent solutes in solvent etraction syste"s, so"e representative
practical ea"ples are presente' to illustrate i"portant subprocesses assu"e' tobe essential steps in the overall etraction processes(
4.2.1 Case I: Extraction of ran!" #itrateb! $%%uct &ormation
This is a puri$ication process use' in the pro'uction o$ uraniu"( The overall
reaction is given by
#62Q+2 KH6
9+2 T/org#6
2/H6
9
2/T
2
/org
/4(J
here T stan's $or tributylphosphate( The organic solvent is co""only -ero5
sene( 8n Table 4(= this etraction process is 'escribe' in $our steps( 8n Table
-
8/13/2019 Jurnal b.ing Distribusi
6/120
Copyright 2004 by Taylor & Francis Group, LLC
9
2 2 ;
i
e
e
Table 4.1 Sche"atic :epresentation o$ the Kypothetical Steps in #/O8
Etraction by T an' Their )ssociate Gi o$ :eaction
Secon'
First step step Thir' step Fourth step
6rganic phase T #62/T2/H692/T +'iluent
2+)!ueous solution 2 KH69 +#622+
#62/H692 +2T +/KH69 +#62
K26
+ #62/H692 +2K T #62/T2/H692#62/T2/H692
StartFinal G= >0 G2 >0 G9 0 G4 0Gex 9, is "ore basic than the reactive oygen o$ ater, T, hich
slightly 'issolves in ater /Step 2, replaces ater in the #62/K26;/H692 co"5ple to $or" the adduct complex #62/T2/H692( This reaction is assu"e' to
ta-e place in the a!ueous phase /Step 9( Adduct formation is one o$ the "ost
co""only use' reactions in solvent etraction o$ inorganic as ell as organic
co"poun's( /HoteM the ter" adduct is o$ten use' both $or the 'onor "olecule
an' $or its pro'uct ith the solute( The net process is the etraction o$ the
co"ple /Step 4( Even i$ the solubility o$ the a''uct $or"er T in the a!ueous
phase is !uite s"all /i(e(, DT very large, it is co""on to assu"e that the
replace"ent o$ hy'rate ater by the a''uct $or"er ta-es place in the a!ueous
phase, as shon in the thir' step o$ Table 4(=1 $urther, the solubility o$ the
a''uct #62/T2/H692 "ust be "uch larger in the organic than in the a!ueousphase /i(e(, D#6 /T /H6 =, to "a-e the process use$ul( 6ther inter"e'iate2 2 9 2reaction paths "ay be conte"plate', but this is o$ little signi$icance as G0
'epen's only on the starting an' $inal states o$ the syste"( The use o$ such a
ther"o'yna"ic representation 'epen's on the -nole'ge o$ the G0 values asthey are necessary $or vali' calculations o$ the process(
The relation beteen G0 an'Ke is given byo oGe
=Gi =RT lnK
e /4(;
-
8/13/2019 Jurnal b.ing Distribusi
7/120
Copyright 2004 by Taylor & Francis Group, LLC
K =K = K
#
e
4
6"itting ater o$ hy'ration, the e!uilibriu" constant $or the net etraction pro5
cess in E!( /4(J isKe, here
[#62 /H69 2 /T2 ]orgKe
=
[#6
2Q
][KH6
]
2
[T]2
/4(P2 9 org
The extraction constant,Ke, can be epresse' as the pro'uct o$ several e!uilib5
riu" constants $or other assu"e' e!uilibria in the net reactionM
2e i 2,H69 A: 2,TP AC
/4(
here 2,H69 is the complex formation constant o$ #62/H692, an' 2,T the
$or"ation constant o$ the etractable #62/H692/T2 co"ple $ro" $ro"
#62/H692 an' T( KA: an' KAC are the distribution constants of the un!
charged species, the reagent an' the etractable co"ple, respectively(
Ke 'eter"ines the e$$iciency o$ an etraction process( 8t 'epen's on the
internal che"ical para"eters3 o$ the syste", i(e(, the che"ical reactions an'
the concentration o$ reactants o$ both phases( The latter 'eter"ine the nu"erical
value o$ the distribution factor for the solute, hich $or our ea"ple is
D =B#
tot,org
=#62 (H69 )2 (T)2org
/4(>a
B# 2Q 2n tot,a!#62 +#62 (H69 )n
2n8n the a!ueous phase e have inclu'e' the #62/H69n co"plees but eclu'e'
the #62/H692/T2 co"ple, because the concentration o$ the last co"ple
in the a!ueous phase is negligible co"pare' to the other to( 8n 'ilute solutions,2+the nitrate co"ple can be neglete' co"pare' to the $ree #62
8n the latter case the # 'istribution e!uals
= [KH6 ]2
[T]2
concentration(
/4(>bD# Ke 9 org
6$ the reaction steps, only the $irst three have values o$ G0
>01 hoever,the large negative value o$ the $ourth step "a-es the overall reaction G0 nega5tive, thus $avoring the etraction o$ the co"ple( The $irst step can be "easure'
by the 'eter"ination o$ the 'initrato co"ple in the a!ueous phase( The secon'
is relate' to the 'istribution constant KD,T in the solvent syste"( )lso, the
$or"ation constant o$ the a!ueous #62/H692/T2 can be "easure' /$or e5
a"ple by H
-
8/13/2019 Jurnal b.ing Distribusi
8/120
Copyright 2004 by Taylor & Francis Group, LLC
chelate is a ea- organic aci'( For ea"ple, the uranyl ion can be neutrali7e'
-
8/13/2019 Jurnal b.ing Distribusi
9/120
by to TT)
/)ppen'i AMJe anions to $or" the neutral #6 /TT) /K 62 2 2 2co"ple( This co"ple is etractable into organic solvents, but only at high
concentrations o$ the TT) anion(
) large a''uct $or"ation constant increases the hy'rophobicity o$ the
"etal co"ple an' thus the 'istribution ratio o$ the "etal( This is co""only
re$erre' to as a synergistic effect( Figure 4(2 illustrates the etraction o$ the
#62/TT)2 co"ple $ro" 0(0= < KH69 into cycloheane( ecause the linear
6R#R6 group is believe' to have $ive to seven coor'ination sites, here only
Fig. 4.2 Synergistic etractionM Aistribution o$ #/O8 beteen 0(0= < KH69 an' "i5
tures o$ thenoyltri$luoroacetone /TT) an' tributylphosphate /T, or tributylphos5
phineoi'e /T6, at constant total "olarity /BTT)org plus BTorg or BT6org =0(02
-
8/13/2019 Jurnal b.ing Distribusi
10/120
9
9
n
$our are occupie' in this co"ple, the uranyl group is coor'inativaly unsatu5
rate'( )t the le$t vertical aes o$ Fig( 4(2, the $ree coor'ination sites are occu5
pie' by ater an'Nor H6, only1 an' the #/O8 co"ple is poorly etracte', log
D# about =( hen T or T6 /tributylphosphine oi'e? Bboth in'icate'by are a''e' hile BKTT) +B is -ept constant, theD# value increases toabout ;0 $or T an' to about =000 $or T6( )t the pea- value, the co"ple
is assu"e' to be #62/TT)2= or 2( The 'ecrease o$D# at even higher B is 'ue
to the correspon'ing 'ecrease in BTT), so that at the right vertical aes o$
Fig( 4(2 no #/O8TT) co"ple is $or"e'( For this particular case, at "uch
higher nitrate concentrations, the #/O8 is co"plee' by H6
an' is etracte'
as an a''uct co"ple o$ the co"position #62/H692 =2, as 'iscusse' earlier
$or Case 8(
The pri"ary cause $or synergis" in solvent etraction is an increase in
hy'rophobic character o$ the etracte' "etal co"ple upon a''ition o$ the a'5'uct $or"er( Three "echanis"s have been propose' to eplain the synergis"
$or "etal +chelan'@ + a''uct $or"er( 8n the $irst suggeste' "echanis", thechelate rings 'o not coor'inately saturate the "etal ion, hich retains resi'ual
aters in the re"aining coor'ination sites an' these aters are replace' by other
a''uct5$or"ing "olecules( The secon' involves an opening o$ one or "ore o$
the chelate rings an' occupation by the a''uct $or"ers o$ the vacate' "etal
coor'ination sites( The thir' "echanis" involves an epansion o$ the coor'ina5
tion sphere o$ the "etal ion upon a''ition o$ a''uct $or"ers so no replace"ent
o$ aters is necessary to acco""o'ate the a''uct $or"er( )s pointe' out be$ore,it is not possible $ro" the etraction constants to choose beteen these alterna5
tive "echanis"s, but enthalpy an' entropy 'ata o$ the reactions can be use' to
provi'e "ore 'e$initive argu"ents(
The KTT) +T syste" can serve to illustrate the "ain points o$ ther5"o'yna"ics o$ synergis"( The o"erall extraction reaction is ritten asM
96, see )ppen'i A, ea"ple =;, at the en' o$ this boo-(@$heland or chelator is the chelating ligan'(
-
8/13/2019 Jurnal b.ing Distribusi
12/120
9 =9
9 2 9 9 2 =2
The a''uct $or"ation reaction in the organic phase /the synergistic reaction3
is obtaine' by subtracting E!s( /4(=0b an' /4(=0c $ro" E!( /4(=0aM
-
8/13/2019 Jurnal b.ing Distribusi
13/120
an' )n "ay go $ro" > to an', $inally, bac- to >( The last step re$lects the
operation o$ the thir' "echanis" propose' $or synergis"(
Th/TT)4 can be 'issolve' in 'ry ben7ene ithout hy'rate ater( The
values o$ the reaction o$ E!( /4(=2 in the syste" areM logK =J(4;, %o =9>(2
-
8/13/2019 Jurnal b.ing Distribusi
14/120
-. "ol=
, T&o =(0 -. "ol
=
=( The negative entropy is un'erstan'able
as the net 'egrees o$ $ree'o" are 'ecrease' /to reactant "olecules co"bine
to $or" one pro'uct "olecule( Koever, the %o
value is "uch "ore negative(
These e!uations 'o not provi'e co"plete 'e$inition o$ the reactions that
"ay be o$ signi$icance in particular solvent etraction syste"s( For ea"ple,KTT) can eist as a -eto, an enol, an' a -eto5hy'rate species( The "etal co"5
bines ith the enol $or", hich usually is the 'o"inant one in organic solvents
/e(g(,K =BKTT)enolNBKTT)-eto = ; in et ben7ene( The -inetics o$ the -eto enol reaction are not $ast although it see"s to be cataly7e' by the
presence
o$ a reagent such as T or T66( Such reagents react ith the enol $or" in
'rier solvents but cannot co"pete ith ater in etter ones( KTT) T
an' T K26 species also are present in these synergistic syste"s(
Koever, i$ etraction into only one solvent /e(g(, ben7ene is consi'ere', thesee$$ects are constant an' nee' not be consi'ere' in a si"ple analysis(
8n section 4(=9(9 e return brie$ly to the ther"o'yna"ics o$ solvent e5
traction(
4.3 OVERVIEW OF EXTRACTION PROCESSES
J0
-
8/13/2019 Jurnal b.ing Distribusi
15/120
Copyright 2004 by Taylor & Francis Group, LLC
Table 4.2 Sy"bolic Survey o$ Fun'a"ental Li!ui'5Li!ui' Aistribution rocessesa
Type (5A )onelectrolyte extractionb
Solute ) etracte' into organic phase /solvent)
/E!uilibriu" governe' by the Hernst 'istribution la
Solute is the nonelectrolyte ) in ater)
Type (5 )onelectrolyte adduct formation and extractionc
)''uct ) in organic phase /plus eventually
Solute ) an' a''uct $or"er /or etractant
Type ((5A Extraction of nonadduct organic acids
)ci' an' 'i"er /an' possible poly"ers in organic phase
)ci' 'issociation in a!ueous phase
)
/ ) +
)
K)K=U2K2)2+((
(
K)
K +)+
Type ((5 Extraction of acid as adduct
)ci' a''uct /an' aci' an' a''uct $or"er in organic phase K) / /+ K)
/ /)ci' 'issociation in a!ueous phase
K)
+ K)K++
)
Type(((5'
Extraction of saturated metal complex
Heutral, coor'inatively saturate' "etal co"ple in organic phase
-
8/13/2019 Jurnal b.ing Distribusi
16/120
Copyright 2004 by Taylor & Francis Group, LLC
+7)
0 9J J; 9P =22
en7ene /5bon's 2(JP 2P JJ P 9J0Hitroben7ene 94( =4 2= 4= =P
&ourceM :e$( 4(
ligan' concentrations are "ore co"ple( So"e o$ these si"pli$ications are not
use' in later chapters(
4.4 EXTRACTION OF INERT MOECUES !TYPE I"A#
Kere, an' in later sections, e begin ith sa"e -in' o$ rectangular $igure to
in'icate the type o$ etractionM to the right e in'icate the 'istribution o$ the
solutes in a to5phase syste" /the organic phase is sha'e'1 the syste" is also
brie$ly 'escribe' by the tet to the le$t, an'o$ coursein 'etail in the "ain
tet(
SoluteA etracte' into organic phase /solvent A
/Hernst 'istribution la $or regular "itures an' solventsM The non5electrolyte soluteA in ater A
8$ the solute ) 'oes not un'ergo any reaction in the to solvents, ecept $or the
solubility cause' by the solvation3 'ue to the nonspeci$ic cohesive $orces in
the li!ui's, the 'istribution o$ the solute $ollos the Hernst 'istribution la, an'
the e!uilibriu" reaction can be 'escribe' either by a 'istribution constant KD,A,
or an /e!uilibriu" etraction constantKeM
)/a!)/org1
KA,)
=Ke
=B)org
NB)a! /4(=4
Ke alays re$ers to a to5phase syste"( The measured distribution ratio $orthe solute ),D), e!ualsKD,), an' is a constant in'epen'ent o$ the concentration
o$ ) in the syste"( 6nly eternal3 con'itions in$luence the KD,) value( 8n
eternal3 con'itions e inclu'e the organic solvent, in a''ition to physical
con'itions li-e te"perature an' pressure(
The noble gases an' the halogens belong to the sa"e type o$ stable "olec5
ular co"poun'sM :u64, 6s64, GeCl4, )sCl9, SbCl9, an' KgCl2( The si"plest
ea"ple is the 'istribution o$ the inert gases, as given in Table 4(9( The larger
Table 4.3 Aistribution :atios o$ So"e Gases eteen 6rganic Solvents
an' 0(0= < HaCl64 at 2JC
Solute
-
8/13/2019 Jurnal b.ing Distribusi
22/120
:n is etracte' "ore easily than the s"aller Ve, because the or- to pro'uce a
cavity in the ater structure is larger $or the larger "olecule( The energy to
pro'uce a cavity in nonpolar solvents is "uch less, because o$ the ea-er inter5
actions beteen neighboring solvent "olecules( Energy is release' hen the
solute leaves the a!ueous phase, alloing the cavity to be $ille' by the hy'ro5
gen5bon'e' ater structure( Thus the 'istribution constant increases ith in5
creasing inertness o$ the solvent, hich is "easure' by the 'ielectric constant
/or relative per"ittivity( The halogens r2 an' 82 sho an opposite or'er 'ue
to so"e lo reactivity o$ halogens ith organic solvents( Oery inert solvents
ith lo per"ittivity, such as the pure hy'rocarbons, etract inert co"poun's
better than solvents o$ higher per"ittivity1 conversely, li!ui's o$ higher per"it5
tivity are better solvents $or less inert co"poun's(
-
8/13/2019 Jurnal b.ing Distribusi
23/120
Copyright 2004 by Taylor & Francis Group, LLC
:eagent pKa logKA,K)
6ine >(P 2(P
25 9(9
J5)cetyloine P( 2(
4,P5Aichlorooine P(4 9(>
P,P5Aiio'ooine (0 4(2
J5Chloro5P5io'ooine P(> 9(>
a)!ueous phase 0(= < Ha
2JC(l641 organic phase chloro$or" at
&ourceM :e$s( a, b(
Fig. 4.4 Aistribution constantsKA,K) o$ $atty aci's as a $unction o$ the nu"ber n o$
carbon ato"s in the al-yl chain /$= is acetic aci' in the syste" 0(= < HaCl64Nben7ene(
/Fro" :e$( P(
Table 4.$ Aissociation,Ka, an' Aistribution,KD,%A,
Constants $or Substitute' 6inesa
C
-
8/13/2019 Jurnal b.ing Distribusi
24/120
Copyright 2004 by Taylor & Francis Group, LLC
: is C CK C : W is thenoyl, K C SCXX XX
4
Table 4.% AissociationKa an' Aistribution ConstantsKA,K) $or 5Ai-etones1)!ueous hase 0(= < HaCl6
a
logKA:
:eagent /solute pKa C;K; CKCl9 CCl4
)cetylacetone, ))1 CK9 : CK9 (P; 0(P; =(9; 0(J=en7oylacetone, Y)1 CK9 : C;KJ (P4 9(=J 9(;0 2(=
Aiben7oyl"ethane, A(9J J(94 J(40 4(J=
Thenoyltri$luoroacetone, TT)1 ::CF9 ;(9 =(;= =(4 =(J4
6 6
a
6rganic phases 0(= < in solute1 2JC(&ourceM :e$( 4(
lea'ing to a re'uction in the 'istribution constant( Thus, either the si7e e$$ect
relate' to the ater structure or the presence o$ hy'rophilic groups in the solute
'eter"ines the general level o$ its 'istribution constant(
4.$ EXTRACTION OF ADDUCT"FORMIN&NONEECTROYTES !TYPE I"'#
)''uctA in organic phase /plus evt( A
/ Solute ) an' a''uct $or"er /etractant A +A
The etraction o$ a solute ) "ay be i"prove' by its reaction ith another
solute /etraction reagent3, or extractant, , $or"ing an adduct compound,)( This occurs through che"ical interaction beteen ) an' (
/org
) Q
)
KD,
=Borg
NB /4(=Ja
Kad
=B)NB) B /4(=Jb
hereKa' is the adduct formation constant /in the a!ueous phase
)
)/org KD,) =B)org NB) /4(=Jc
an'KD,) the a''uct 'istribution constant( The etraction constant $or the overall
-
8/13/2019 Jurnal b.ing Distribusi
25/120
Copyright 2004 by Taylor & Francis Group, LLC
reaction is
-
8/13/2019 Jurnal b.ing Distribusi
26/120
Copyright 2004 by Taylor & Francis Group, LLC
a'= org org org
0
o
)/a! Q /org
)/org
an' also
D)
=Ke
Borg
Ke
=B)org
NB)a!
Borg
=KD,)
Ka'K
D
,
/4(=J'
/4(=Je
For the etraction reaction it "ay su$$ice to rite the reaction o$ E!(
/4(=J', though it consists o$ a nu"ber o$ "ore or less hypothetical steps( )s
"entione', e!uilibriu" stu'ies o$ this syste" cannot 'e$ine the in'ivi'ual steps,
but supple"entary stu'ies by other techni!ues "ay reveal the vali' ones( E!ua5
tion /4(=J in'icates that the reaction ta-es place at the boun'ary /interface
beteen the a!ueous an' organic phases( Koever, it is co""on to assu"e that
a s"all a"ount o$ 'issolves in the a!ueous phase, an' the reaction ta-es place
in the steps
)/a! +/a!)/a!)/org
These e!uations allo 'e$inition o$ a 'istribution constant $or the species ),
KD,) Bsee E!( /4(=Jc( Aistribution constants can also be 'e$ine' $or each o$
the species ), an' ) /KD,), etc( but this is o$ little interest as the concentra5
tion o$ these species is relate' through Ke( ) largeKe $or the syste" in'icates
that large 'istribution ratios D) can be obtaine' in practice( )s shon in E!(
/4(=J, the concentration o$ in$luences the 'istribution ratioD)(Consi'er $irst the etraction o$ hea$luoroacetylacetone /KF) by T66
by Ea"ple =, an', secon', the etraction o$ nitric aci' by T /Ea"ple P(
The principles o$ volu"e an' ater5structure e$$ects, 'iscusse' $or the solute )
in section 4(4, are also i"portant in the 'istribution o$ the a''ucts(
Ea"ple =M Etraction o$ hea$luoroacetylacetone /KF) by trioctylphospine
oi'e /T66(
)bbreviating KF) /co"p( structure Je, )ppen'i A by K), an' T66
by , e can rite the relevant reactions
K)/a!K)/org K =BK) NBK) =D /4(=;a A org 0
K)/org +/orgK)/org
K Z BK) NBK) B /4(=;b
K)/org +2/orgK) /orgK
Z BK) NBK) B2
/4(=;c 2 a'2 2 org org org
assu"ing that 2 a''ucts are $or"e', K) an' K)2, the latter containing 2
T66 "olecules( E!uation /4(=;a 'enotes the 'istribution o$ unco"plee'
K)3 byDo( Co"bining these e!uations yiel's
D D= == +Ka'=B +Ka'2B
2/4(=;'
Figure 4(J shos the relative 'istribution, logD D=
, o$ hea$luoroace5
-
8/13/2019 Jurnal b.ing Distribusi
27/120
Copyright 2004 by Taylor & Francis Group, LLC
tylacetone as a $unction o$ the concentration o$ the a''uct $or"er T66( KF)
-
8/13/2019 Jurnal b.ing Distribusi
28/120
o
org org
Fig. 4.$ :elative increase, DNDo in etraction o$ hea$luoroacetylacetone /KF) into
heane $ro" 0(=< HaCl64 at pK =2, at 'i$$erent concentrations o$ the a''uct trioctyl5phosphine oi'e /T66 in the organic phase( The $itte' curve is DND == +=04(22
BT66 +=0P(J=BT662 ( /Fro" :e$( >(
is a "o'erately ea- aci', hile T66 associates strongly ith hy'rogen5
bon' 'onors in nonpolar solvents li-e heane( The constants ere 'eter"ine'
to log Ka'= = 4(22 an' log Ka'2 = P(J=( Thus even at "o'erately lo T66concentrations, the 'i"er a''uct3 'o"inates(
4.% EXTRACTION OF NONADDUCT OR&ANIC ACIDS!TYPE II"A#
)ci' an' 'i"er /an' possibly %A=U2 %2A2
+( ( ( poly"ers in organic phase )ci' 'issociation in a!ueous phase /%+A%
%A%++
A
/an' protonation
Tables 4(J4(P an' Fig( 4(; list organic aci's co""only use' as "etal
etractants( hen the aci's are not protonate', 'issociate', poly"eri7e', hy5
'rate', nor $or" a''ucts, the 'istribution ratio o$ the aci' K) is constant in a
given solvent etraction syste"M
K)/a!K)/org D,K) =BK)org NBK) =DK)
/4(=P
This is shon by the hori7ontal tren's in Fig( 4(;, $or hich E!( /4(=P is vali'1
-
8/13/2019 Jurnal b.ing Distribusi
29/120
i(e(, the 'istribution constantKD,K) e!uals the "easure' 'istribution ratio( hen
-
8/13/2019 Jurnal b.ing Distribusi
30/120
)ci' 'iluentb
S / 2(=
en7oyltri$luoroacetone /TF) CCl4 E ;(09 2(9>
Thenoyltri$luoroacetone /TT) en7ene J(2P ;(9 =(;
AMo Chloro$or" E =(4=5Hitroso525naphthol Chloro$or" =(9J P(; 2(>P
Ai/25ethylheylphosphoric aci'$
0I o$ the organic phase is acetylacetone /
-
8/13/2019 Jurnal b.ing Distribusi
31/120
Copyright 2004 by Taylor & Francis Group, LLC
Fig. 4.% Aistribution ratios calculate' by E!( /4(22 $or acetylacetone /K))1 ben7oyl5
acetone /K)1 be7oyltri$luoroacetone /KTF)1 an' oine /5hy'roy!uinoline,
K6[, in the syste" 0(= < HaCl64 NCCl4, using the $olloing constants( /Fro" :e$s(
a, b(
K)) K) KTF) K6[
logKA 0(J= 2(= 2(9> 2(=
logKa (;P (9> ;(09 >(;;
logKaK E E J(00
in'icates 'i$$erent interactions beteen the acetylacetone an' the to solvents(
8t is assu"e' that the polar CKCl9 interacts ith K), "a-ing it "ore soluble in
the organic phase1 it is also un'erstan'able hy the 'istribution o$ K) 'ecreasesith 'ecreasing concentration /"ole $raction o$ CKCl9( C;K; an' aro"atic sol5
vents 'o not behave as 'o "ost aliphatic solventsM in so"e cases the aro"atics
see" to be inert or even antagonistic to the etracte' organic species, hile in
other cases their pi5electrons interact in a $avorable ay ith the solute( For
acetylacetone, the interaction see"s to be very ea-( The salting5in e$$ect is
shon both in Figs( 4(Pa( an' 4(Pb(
4.).1 Dissociation
)ci's 'issociate in the a!ueous phase ith a 'issociation constantKa
-
8/13/2019 Jurnal b.ing Distribusi
32/120
Copyright 2004 by Taylor & Francis Group, LLC
-
8/13/2019 Jurnal b.ing Distribusi
33/120
Copyright 2004 by Taylor & Francis Group, LLC
) org
a
a
+
K)KQ +
)
K =BKQ B) NBK) /4(=
The 'istribution ratio incorporates theKa $or etraction o$ aci's, K), asM
D =BK) /BK)+B)
=
=KD,K)/=+
Ka
BKQ
=
/4(=>
8n'e ) in'icates that the 'istribution ratio re$ers to the concentration o$ all
species o$ ) in the organic an' in the a!ueous phase( 8n Fig( 4(; the 'istribution
o$ the 5'i-etones is constant in the higher hy'rogen ion concentration range/loer pK here they are un'issociate'( 8n the higher pK region, D)beco"es
inversely proportional to the hy'rogen ion concentration 'ue to increase in the
concentration o$ the 'issociate' $or" o$ the aci' ), in agree"ent ith E!(
/4(=>(The free ligand concentration, B)
, is an i"portant para"eter in the $or5
"ation o$ "etal co"plees /see Chapter 9 an' section 4(( 8n a solvent etrac5
tion syste" ith the volu"es , an' ,org o$ the a!ueous an' organic phases,
respectively, B) is calculate' $ro" the "aterial balanceM
here
log B) =logK logBK
Q
+log /mK),t
N ,org
log/
/4(20a
= Q =/ =KD
,K)
+, ,org
+Ka
BK ,
,org
/4(20b
mK),t is the total a"ount /in "oles o$ K) /reagent a''e' to the syste"( 6$ten= omK),t ,org is abbreviate' BK)org, in'icating the original concentration o$ K) in
the organic phase at the beginning o$ the eperi"ent /hen BK)a! =0( hen,org =, an' pK pKa, / == +KD,K)( Fro" E!( /4(20 it can be 'e'uce' thatB)
increases ith increasing pK, but ten's to beco"e constant as the pK value
approaches that o$ the pKa value( 8n the e!uations relating to the etraction o$
"etal co"plees, K) is o$ten i'entical ith reagent :1 the in'ees "ay be
change' accor'ingly, thus e(g(, KD,K) KA:( /HoteM Oarious authors use slightly'i$$erent no"enclature1 here e $ollo re$erence )ppen'i C(
4.).2 *rotonation
)t lo pK, so"e organic aci's accept an etra proton to $or" the K 2) co"5
ple( This lea's to a 'ecrease in theD) value at pK
-
8/13/2019 Jurnal b.ing Distribusi
34/120
Copyright 2004 by Taylor & Francis Group, LLC
beteen CKCl9 /upper curves or C;K; /loer curves an' a!ueous phase 0(= an' =(0
B)
0Cu 2 org AC 2
)t the highest )
concentrations a hori7ontal asy"ptote is approache'M
li" D =BCu) NBCu) =K /4(40B)
Cu 2 org 2 AC
The hori7ontal asy"ptote e!uals the 'istribution constant o$ Cu)2, i(e(, KAC(
Fro" the curvature beteen the to asy"ptotes, the stability constants = an'2 can be calculate'(
This ea"ple in'icates that in solvent etraction o$ "etal co"plees ith
aci'ic ligan's, it can be "ore a'vantageous to plot log D vs( logB), rather
than against pK, hich is the "ore co""on /an' easy techni!ue(
8n or'er to calculateD< $ro" E!( /4(9;, several e!uilibriu" constants as
ell as the concentration o$ $ree )
are nee'e'( Though "any re$erence or-s
report stability constants B=>, 20 an' 'istribution constants B4, 2=, $or practical
purposes it is si"pler to use the etraction constantKe $or the reactiona',b 2 b org 2 org org
8n the absence o$ any a''uct $or"er, DYn is given as a $unction o$ the $ree
ligan' concentration by E!( /4(9;, i(e(,0 the parentheses in E!( /4(4b e!uals
=1 'enoting thisDYn5value asDo, an' intro'ucing it into E!( /4(4 gives
/= B B2
L /4(J0D =D +Kad ,= org +Ka',2 org +
DYn /instea' o$ DYn in'icates that this epression is vali' only at constant
B), or, better, constant BK
+ an' BK)
=org Bsee E!s( /4(9; an' /4(4=c( 8n Fig(
4(=2, log DYnDo is plotte' as a $unction o$ log Borg( The 'istribution ratio
procee's $ro" al"ost 7ero, hen al"ost no a''uct is $or"e', toar's a li"it5
ing slope o$ 2, in'icating that the etracte' co"ple has a''e' to "oleculeso$ to $or" Yn)22( Fro" the curvature an' slope the Ka',b5values ere 'eter5
"ine' /see section 4(=0( The calculation o$ the e!uilibriu" constants is $urther
'iscusse' un'er Ea"ple =9(
Tables 4(==4(=9 presents a''uct $or"ation constants accor'ing to E!(
/4(4P( For the al-aline earths TT) co"plees in carbon tetrachlori'e in Table
4(==, the T "olecules bon' perpen'icular to the s!uare plane o$ the to TT)
rings, pro'ucing an octahe'ral co"ple( The higher the charge 'ensity o$ the
Table 4.11 )''uct For"ation Constants$or the :eaction
-
8/13/2019 Jurnal b.ing Distribusi
56/120
)''uct $or"ing
ligan' / logKa'= logKa'2 logKa'= logKa'2
TT)/sel$5a''uct 0(J; E >0(J Keone =(=; =(J2 =(P= 2(94
[uinoline 9(2> E 9(4 J(=;
T 9(;9 J(40 J(9; (>;T66 J(40 P(;0 P(4> =2(2;
&ourceM :e$( 4(
Table 4.12 )''uct For"ation Constants $or the :eaction Eu)9/org +bT/org V Eu)9/Tb/org, E!( /4(2;a, here org =CKCl9,an'%A Substitute' )cetylacetone Ligan's
Ligan' /A LogKa LogKa'= LogKa'2
)cetylacetone, )) (P; =(>0
en7oylacetone, Y) (P4 =(;0
Tri$luoroacetone, TF) E 9(92 4(;4
en7oyltri$luoroacetone, T) E 9(;4 J(2
25Furoyltri$luoroacetone, FT) E 9(J0 J(00
Thenoyltri$luoroacetone, TT) ;(9 9(94 J(2
&ourceM :e$( 4(
central ato", the stronger is the a''uct co"ple ith T( HoteM $hargedensity re$ers to the electrostatic interaction beteen ions o$ opposite charge
accor'ing to the orn e!uation Bsee /2(=9, an' /9(=9 /base' on the Coulo"b
interac5 tion( 8t is "ostly given as the ratio beteen the ionic charge, #+ /or
#+# an' the ionic ra'ius r+ /or r+r( Table 4(=2 co"pares the a''uct $or"ation
o$ the europiu" 5'i-etone co"plees ith T in chloro$or"( 8nEu/TT)9 the TT)s only occupy si o$ the eight coor'ination positions
available1 the to e"pty positions have been shon to be occupie' by ater(
Though the ten'ency is not strong, the stronger the aci' /i(e(, the larger its
electronegativity, the larger is the a''uct $or"ation constant( Table 4(=9
co"pares the a''uct $or"a5 tion ten'ency o$ the Eu/TT)9 co"ple ith
various a''uctants( The basicity o$ the 'onor oygen ato" increases in the
or'er as shon in Table 4(=9, as 'oes the a''uct $or"ation constant1 this is in
agree"ent ith the or'er o$ basicity in Table 4( an' the 'onor nu"bers o$
Table 9(91 see also section 4(2(
Table 4.13 Constants $or For"ation o$ Eu/TT)9b )''ucts)ccor'ing to E!( /4(2;a
Chloro$or" Carbon tetrachlori'e
-
8/13/2019 Jurnal b.ing Distribusi
57/120
Copyright 2004 by Taylor & Francis Group, LLC
4
9
4
The 'i$$erence beteen the to solvent syste"s is li-ely a result o$ CKCl9solvating the Eu co"ple to so"e etent, hile CCl4 is inert( This has to
e$$ectsM theKAC value increases 'ue to the solvation by CKCl9 /not shon in the
table, hile the a''uct $or"ation constantKa' 'ecreases as the solvation hin'ers
the a''uct $or"ation1 the "ore inert solvent CCl4 causes an opposite e$$ect, a
loerKAC an' a largerKa'(
4..2 (eta" Inorganic Com6"exes with rganic
$%%uct &ormers T!6e (8+7b
The etraction o$ "ineral salts is generally less co"plicate' than the etraction
o$ "ineral aci's(
-
8/13/2019 Jurnal b.ing Distribusi
58/120
Copyright 2004 by Taylor & Francis Group, LLC
4
D
Dn
Yn
Fig. 4.13 Aistribution ratio o$ Yn/88 hen etracte' $ro" = < Ha/SCH,Cl6
into
0(00= < T66 in heane, as a $unction o$ a!ueous SCH
concentration( The $olloingPe!uilibriu" constants ere obtaine' ith E!( /4(J9M = 9(P, 2 2=, 9 =J,Ke 2(J =0
b =2( /Fro" :e$( 2;($or
YnL +b /orgYnL /org
/4(J=
2 2 b
$or hich e "ay 'e$ine an e!uilibriu" constantKe,b(
ecause "ore than one solvate' species "ay be etracte', the 'istribution ratio
beco"es
BYnL +BYnL + L=2 org 2 2 org
BYn+BYnL+BYnL2+BYnL
9+
L
/4 J2
8nserting the partial e!uilibriu" constants Bsee E!( /4(4;,
BL K Bb
=2 2 e ,b org
Yn
=+BLn/4(J9
here both su""ations are ta-en $ro" =( The solvation nu"ber b can be 'eter5
"ine' $ro" the 'epen'ence o$ D on Borg hile BL is -ept constant( Fro" the
slope o$ the line in Fig( 4(=9 at lo SCH concentrations, it $ollos that b =21 thus only one a''uct co"ple is i'enti$ie'M Yn/SCH2/T662( The authors
ere able to calculate the $or"ation constants n $ro" the 'eviation o$ thecurve $ro" the straight the line at constant Borg, assu"ing b constant( ith
-
8/13/2019 Jurnal b.ing Distribusi
59/120
4
4
org
D"
these e!uilibriu" constants, the line through the points as calculate' ith E!(
/4(J9(
4..3 'e"f5$%%ucts T!6e ($+0,$b
Ky'ration only occurs in neutral co"plees that are coor'inatively unsaturate'by the organic ligan'( The hy'rate ater re'uces the etractability o$ the co"5
ple( 8n the absence o$ strong 'onor "olecules, hich can replace this hy'rate
ater, there is still a chance $or the un'issociate' aci' to replace the ater,
lea'ing to aself5adduct accor'ing to the reaction
-
8/13/2019 Jurnal b.ing Distribusi
60/120
hich is abbreviate', using the earlier relations, to
-
8/13/2019 Jurnal b.ing Distribusi
61/120
Copyright 2004 by Taylor & Francis Group, LLC
D3
Fig. 4.14 Etraction o$ "/888 by acetylacetone /K)a $ro" = < HaCl64 into ben5
7ene at three 'i$$erent original concentrations o$ K)a in the organic phase( p) =
logB)a
is calculate' accor'ing to E!( /4(20( The analysis o$ the syste" yiel'e' theconstants log = J(9J, log 2 >(20, log 9 =9(22, log 4 =4(0;, Ka'= P, Ka'2 9, an' KAC0(00, shon $orPm in Fig( 4(=J( /Fro" :e$s( 2Pa,b(
K B)9 /=+K BK) +K BK)2 +L
=AC 9 a '= o rg a '2 org
" B)n/4(JJb
here KAC re$ers to the 'istribution o$ uncharge' ")9 beteen the ben7ene
an' the a!ueous phase
KAC
=B")9
orgNB")
9 /4(J;
Ka',b is the e!uilibriu" constant $or the sel$5a''uct $or"ation in the organic
phase, i(e(,
") /org +b K)/org") /K)
/org/4(JPa
9 9 b
K =B") /K) B") = BK)b /4(JPba',b 9 b org 9 org org
For pe'agogic reasons e rerite E!( /4(JJb
-
8/13/2019 Jurnal b.ing Distribusi
62/120
Copyright 2004 by Taylor & Francis Group, LLC
D
4
n
K /=+K BK) +K BK)2 +L
=AC a ',= org a ',2 org
"
/B)9 = B)n
/4(J3 n
Hote that the 'eno"inator only re$ers to species in the a!ueous phase(
Thus at constant BK)org, the curvature o$ the etraction curve an' its position
along the B) aes is only cause' by varying B)
, i(e(, the a!ueous phase
co"pleation( The nu"erator re$ers to the organic phase species only, an' is
responsible $or the position o$ the etraction curve along the D5ais1 thus at
three 'i$$erent constants BK)org, three curves are epecte' to be obtaine', ith
eactly the sa"e curvatures, but higher up along the D5scale ith higher
BK)org concentration1 see Fig( 4(=4(
The asy"ptote ith the slope o$ 9 at high p) /i(e(, lo B), $its E!(
/4(J, hen "9+
'o"inates the 'eno"inator /i(e(, the a!ueous phase, hile
the asy"ptote ith slope o$ += $its the sa"e e!uation hen the a!ueous phase
is 'o"inate' by ")
( eteen these to li"iting slopes, the other three")n co"plees are $or"e' in varying concentrations( ) 'etaile' analysis o$
the curves yiel'e' all e!uilibriu" constants Ke,Kn, Ka',b an' KAC /see section
4(=4(9, hich are plotte' in Fig( 4(=J( The curves in Fig( 4(=4 have been
calculate' ith these constants(Kn is 'e$ine' by
n
=Kn
accor'ing to E!( /9(J(
/4(J>
The "ai"u" 'istribution ratio $or the "5K) syste" /D" about 0(=
is reache' in the pK range ;P( 8t is ell -non that the lanthani'es hy'roly7ein this pK region, but it can be shon that the concentration o$ hy'roly7e'
species is
-
8/13/2019 Jurnal b.ing Distribusi
63/120
Copyright 2004 by Taylor & Francis Group, LLC
-
8/13/2019 Jurnal b.ing Distribusi
64/120
Copyright 2004 by Taylor & Francis Group, LLC
Table 4.14 Constants $or the For"ation o$ So"e
La/888 )cetylacetone, )) C;K; 2(;
Eu/888 Thenoyltri$luoroacetone, TT) CKCl9 0(J;
Eu/888 Thenoyltri$luoroacetone, TT) CCl4 0(J
Eu/888 8sopropyltropolone, 8T CKCl9 2(=
Eu/888 8sopropyltropolone, 8T CCl4 2(0
#/O8 )cetylacetone, )) CKCl9 =(=;
#/O8 Thenoyltri$luoroacetone, TT) C;K; 0(J0
&ourceM :e$( 4(
reaction probably occurs in the organic phase( Table 4(=4 contains both very
inert /e(g(, CCl4, polar /CKCl9, an' pi5bon'ing solvents /C;K;(
4.1+ META EXTRACTION 'Y I,UID ANIONEXCHAN&ERS !TYPE III"D#
6rganic phase ith anion :HK+*
/:HK
+M*
pp n
echanger an' "etal co"ple )!ueous phaseM "etal ith M
#++nL
+p:HK
+*
/:HK
+
-
8/13/2019 Jurnal b.ing Distribusi
65/120
4
4 9
Copyright 2004 by Taylor & Francis Group, LLC
'iagra"1 hoever, here it su$$ices to use concentrations( )n interesting $eature
in Fig( =(9 is the 'i$$erences beteen "etals in various oi'ation state, notably
Fe/88 an' Fe/888, the latter being "uch "ore easily etracte' than the $or"er
because Fe/888 $or"s "uch stronger co"plees ith Cl
ions( The re!uire"ent
$or etraction o$ "etals by an a"ineli-e T6), or by its a"ine salt, T6)K+Cl
,
is the $or"ation o$ negatively charge' "etal chlori'e co"plees in the a!ueous
phase( The co"ple $or"ation $ro" 2 an' in the parapos5
ition, 9(>(
These general rules hol' rather ell $or the aci'ic organic etractants an'
can be use' to etrapolate $ro" relate' co"poun's to ne ones as ell as to
'evelop ne etractants( The e$$ect o$ various substituen's on pKa is etensively
'iscusse' in tetboo-s on organic che"istry Be(g(, =4, 94(
4.13.1.) The C'+,e- '/(i'! #'/ S(0i,i(%
C'!&(!( !Ke also increases ith increasing $or"ation constant o$ the uncharge' "etal
co"ple, 7( Ther"o'yna"ic $actors an' geo"etrical aspects that in$luence thesi7e o$ n are 'iscusse' in Chapter 9( So"e $urther observations $ollo(
To achieve the highest possibleD value, the concentration o$ the etracte'
uncharge' co"ple /
-
8/13/2019 Jurnal b.ing Distribusi
83/120
ever, at high pK the "etal "ay be hy'roly7e'( ) care$ul balance "ust be struc-
beteen 7,Ka, an' pK to achieve an opti"u" "ai"u" concentration o$ theuncharge' co"ple(
4.13.2 Effects of (o"ecu"ar ;o"ume an% ater'tructure 6on
-
8/13/2019 Jurnal b.ing Distribusi
84/120
=A ,
,
KAC values $or the lanthani'e acetylacetonates are the reverse $ro" that epecte'
$or the si7e e$$ect( The eplanation is li-ely that the neutral co"ple ith the
$or"ula Ln)9 is coor'inatively unsaturate', hich "eans that a hy'rate' co"5
ple eists in the a!ueous phase /possibly also in the organic phase( The "ore
coor'inatively unsaturate' lanthani'e co"plees /o$ the larger ions can acco"5
"o'ate "ore ater an' thus are "ore hy'rophilic( The result is a KAC several
or'ers o$ "agnitu'e loer $or the lightest, La, than $or the heaviest, Lu(
The tetravalent "etal acetylacetonates B9; have all coor'ination nu"bers
/CH or > in the neutral co"plees( For Th /ra'ius =0> p" at CH > there is
o$ten one "olecule o$ ater in Th)4, hereas $or the correspon'ing co"plees
o$ #/8O an' Hp/8O /ra'ius =00 an' > p", respectively, CH =, there see"sto be none( The "easure' 'istribution constants /log KAC are $or Th 2(JJ an'
$or # an' Hp 9(J2 an' 9(4J, respectively, in = < HaCl64Nben7ene( This agrees
ith the greater hy'rophilic nature o$ the Th)4 K26 co"ple(4.13.).) C'//e,(i'!& Be(2ee! KDR !" KDC[ualitatively, the 'istribution constants o$ the co"pleing reagent an' the corre5
spon'ing neutral "etal co"ple are relate' 'ue to their si"ilar outer sur$ace
toar' the solvents( Thus it is reasonable that there shoul' be goo' correlation
beteen KA: an' KAC $or ho"ologous series o$ reagents or co"plees( This is
in'ee' the case, as is seen hen KA,: is plotte' vs( KA,C, in Fig( 4(20 $or a
co"ple ith a variation o$ the solvent, an' in Fig( 4(2= $or co"plees o$
relate' reagents ith the sa"e solvent( This correlation can be relate' to thesolubility para"eter concept 'iscusse' later(
4.13.3 The 'o"ubi"it! *arameter
8n Chapter 2 e learne' that the cohesive $orces that -eep "olecules together
in a solution can be 'escribe' by
2 =/% RTN,
/2(=1 4(PJa
here 2 is the cohesi"e energy density, an' , the solubility parameter, ,, the
"olar volu"e an' %,, the "olar heat o$ vapori7ation( This hol's $or regularsolutions B9P that sho i'eal entropy e$$ects in "iing solute an' solvent, an'
no interactions occur besi'es the cohesive $orces beteen the solute an' solvent
"olecules( BHoteM :egular solutions ehibit heat changes hen "ie', hile $or
i'eal solutions, the heat o$ "iing is 7ero /see section 2(4(=( There is no
change o$ state in association or in orientation( Thus the or- re!uire' to pro5
'uce a cavity, Gcav, by the solute in the solvent is given by
Gcav 2cav
/2(=01 4(PJb
hereAcav is a proportionality $actor an' , is the "olar volu"e o$ the solute (
-
8/13/2019 Jurnal b.ing Distribusi
85/120
= + +
Fig. 4.2+ Aistribution constantsKAC $or uncharge' "etal co"plees ;0s B9a40c( Several revies on
the use o$ this theory $or to5phase 'istribution processes are also available
B4=,42( :ecently this theory has been re$ine' by the use o$ %ansen solubility
parameters B;,49,44, accor'ing to hich
2 2 2 2
total 'ispersion polar hy'rogen /4(PJchere interactions beteen the solute an' the solvent are 'escribe' by contribu5
tions $ro" the various types o$ cohesive $orces( 8n general, the 'ispersion /or
Lon'on $orces 'o"inate( 8n Fig( 4(22 the "easure' 'istribution ratios o$ an
a"ericiu" co"ple beteen an a!ueous nitrate solution an' various organic
solvent co"binations are co"pare' ith 'istribution ratios calculate' $ro" tabu5
late' Kansen para"eter values B4J(
Fe solubility para"eters are available $or the "etal5organic co"plees
'iscusse' in this chapter( )nother approach is then necessary( The 'istribution
constant $or the reagent /etractant, R, can be epresse' asM
-
8/13/2019 Jurnal b.ing Distribusi
86/120
Copyright 2004 by Taylor & Francis Group, LLC
Fig. 4.21 Aistribution constants,KAC, $or uncharge' "etal co"plees
-
8/13/2019 Jurnal b.ing Distribusi
87/120
Copyright 2004 by Taylor & Francis Group, LLC
org : : org a!
Fig. 4.22 Co"parison o$ "easure' an' calculate' 'istribution ratios D)" o$ a"erici5
u"/8885terpyri'ine5'ecanoic aci' co"plees beteen 0(0J < KH69 an' various organic
solvent co"binations( The calculate' values are obtaine' ith the Kansen partial solubil5
ity para"eters( /Fro" :e$( 4J(
RT lnKA:
=,:
B/a!
:2 /
2 Q RT , /=N , =N , /4(P;
hereKA: is given in ter"s o$ "ole $ractions( The solubility para"eter o$ ater
has to be e"pirically esti"ate'( The ther"o'yna"ic value is 4, but, since the
syste" "ay be sensitive to the choice o$ a!, it is better to select a re$erence a!3
in each set o$ eperi"ents, assu"ing constant values $or the a!ueous syste"s in
the to 'i$$erent to5phase syste"s(
-
8/13/2019 Jurnal b.ing Distribusi
88/120
Thus $ro" solubility para"eters, hich are speci$ic $or the various solutes
an' solvents, an' "olar volu"es, values $orKA: can be esti"ate', or 'eviations
$ro" regularity can be assesse'( These 'eviations can be esti"ate' !uantita5
tively an', in in'ivi'ual syste"s, can be ascribe' to speci$ic reactions in either
o$ the phases, e(g(, hy'ration, solvation, a''uct $or"ation, etc(
Fro" E!( /4(P; the relation
logKAC
=/,C
N ,:
logKA:
+const(
/4(P
can be 'erive'1 the subscript $ re$ers to the neutral "etal co"ple( The "olar
volu"e ratio is close to or s"aller than #, here # is the nu"ber o$ singly
charge' anionic species attache' to the central "etal ion org a! org org a!
shoul' yiel' a straight line ith slope ,: N RT ln=0( ) plot o$ this relation in
Fig( 4(29 'e"onstrates a satis$actory correlation beteen 'istribution constants
an' solvent para"eters, in'icating the use$ulness o$ the solubility para"eter
concept in pre'ictingKA: as ell asKAC values(
Fig. 4.23 )pplication o$ the regular solution theory $or correlation o$ 'istribution con5stants $or Yn)2 an' Cu)2 ith solvent properties /solubility para"eters1 the nu"bers
re$er to the solvents liste' in Table 4(=0( /Fro" :e$( 22(
-
8/13/2019 Jurnal b.ing Distribusi
89/120
4.13.4 Effects of the 'o"=ent 0Di"uent Com6osition
The co"position o$ the organic phase solvent /'iluent in$luences the 'istribu5
tion o$ both the neutral "etal organic co"ple
-
8/13/2019 Jurnal b.ing Distribusi
90/120
heane 0(>J, cycloheane =(09, ethylben7ene 9(9=, an' ben7ene J(>9 /a!ueous
phase = < HaCl64, the 'ecrease observe' in Fig( 4(24 "ay si"ply be an e$$ect
o$ the increasing aliphatic character o$ the solvents(
4.13.> Effects of the $ueous (e%ium
The e$$ect o$ the ater activity o$ the a!ueous phase, 'iscusse' in Chapters 2,
9, an' ;, is 'eter"ine' by the total concentration an' nature o$ the salts( Gener5
ally, the 'istribution constant $or a neutral "etal co"ple oul' increase ith
increasing ionic strength, as illustrate' in Fig( 4(2J( This salting5out effect is
o$ten ascribe' to a re'uction in $ree ater available $or hy'ration( 6n the other
han', the salt also brea-s 'on the ater structure, hich coul' re'uce the
energy to $or" a hole in the phase(
4.13.) Effects of the Tem6erature
The intro'uction o$ a neutral co"ple into a solution phase involves a nu"ber
o$ processes that can be associate' ith large changes in enthalpy /solvation
processes an' in entropy /solvent orientation an' restructuring, lea'ing to con5
si'erable te"perature e$$ects1 see Chapter 2( 8n general, the 'istribution o$ a
neutral "etal co"ple increases ith increasing te"perature $or co"plees ith
signi$icant hy'rophobic character( The "etal acetylacetonate syste"s in Fig(
4(2; illustrate this e$$ect( 8n these particular syste"s, the $ree energy o$ 'istribu5
tion beteen the organic an' a!ueous phases is 'o"inate' by the enthalpy ter"(
Fig. 4.2$ The 'istribution constantKAC $or 7inc 'iacetylacetonate, Yn)2, beteen ben57ene an' various concentrations o$ HaCl64 in the a!ueous phase1 2JC( /Fro" :e$( 9;(
-
8/13/2019 Jurnal b.ing Distribusi
91/120
Fig. 4.2% Aistribution constant KAC $or "etal 'iacetylacetonates,
-
8/13/2019 Jurnal b.ing Distribusi
92/120
T6) 0(00J J BJ0
T(9 P BJ0,J=
A 2 2 2 4 > 2 2 2 2A
-
8/13/2019 Jurnal b.ing Distribusi
93/120
a 7 a
in the sa"e or'er B2Pa2, see Fig( 4(=J1 i(e(, the stronger the co"ple, the
ea-er the a''uct(
The increase, by a''uct $or"ation, in the coor'ination nu"ber o$ the cen5
tral ato" is possible not only $or ea- but also $or strong chelates, provi'e'
their ligan' bites are relatively short( To "a-e roo" in the inner sphere o$ the
"etal ion $or another a''uct5$or"ing ligan', three chelating ligan's o$ s"all
bite angle can easily be shi$te' aay ithout signi$icant energy5consu"ing 'is5
tortion o$ the chelate rings BJ9a,b( The electronic structure o$ the central ato"
is also o$ -ey i"portance $or synergis", as illustrate' by the easy a''uct $or"a5
tion o$ "etal ions ith un$ille' or partially $ille' ' or $ orbitals, contrary to,
e(g(, p5bloc- ele"ents( 8nner5 an' outer5sphere co"pleation is $urther 'iscusse'
in the net to paragraphs an' in Chapter =;(
4.13..) D'!'/ Lig!" E66e$(&
Table 4(=P shos etraction constants $or so"e "etal ions ith three al-ylphosphates substitute' by 0, =, an' 2 sul$ur ato"s, but ith al"ost i'entical
aliphatic branchings( Section 9(9 'iscusses har' an' so$t aci's an' bases /KS)
theory( )ccor'ing to this theory, har' aci's $or" strong co"plees ith har'
bases, hile ea- aci's $or" strong co"plees ith ea- bases( 8n Table 4(=P,
the "etals are or'ere' in increasing har'ness, the sub 88(b group being rather
so$t /Table 9(2( resu"ably the Ke values re$lect this pattern, as they are pro5
portional to K7
an' ( 8n Table 4(=P, the aci'ity o$ the aci's increases /i(e(, Kincreases in or'er ' SSK (;
logKe $or'66K 2(20 =(0 =(20 2(J2 0(44 2(>logKe $or /C4K>62 6SK J(40 9(P0 0(P0 4(P 4(29 0(94logKe $or /C4K>62 SSK 4(40 9(4> 2(40 (2
aOalues esti"ate' $ro" :e$s( J, 20, J4, JJ, an' J;( : is /C K CK/C K CK 6 (4 > 2 J 2 2
-
8/13/2019 Jurnal b.ing Distribusi
94/120
Copyright 2004 by Taylor & Francis Group, LLC
2 2 ;
2 2 ; 9
4.13..3 I!!e/ !" O7(e/ S+he/e C''/"i!(i'!
The etractabilities o$ "etal5organic co"plees 'epen' on hether inner or
outer sphere co"plees are $or"e'( Case 8, section 4(2(=, the etraction o$ ura5
nyl nitrate by T, is a goo' ea"ple( The $ree uranyl ion is surroun'e' by
ater o$ hy'ration, $or"ing #6 /K 6
2+
, hich $ro" nitric aci' solutions can2+ 2be crystalli7e' out as the salt #62/K26; /H692 , though it co""only is ritten2+#62/H692/K26;( Thus, in solution as ell as in the soli' salt, the #62 is
surroun'e' by ; K26 in an inner coordination sphere( 8n the soli' nitrate salt,
the 'istance d#56/nitratebeteen the closest oygen ato"s o$ the nitrate anions,
/O2HO, an' the #5ato" is longer than the correspon'ing 'istance, d#56/ater,
to the ater "olecules, OK2, i(e(, d#56/nitrate >d#56/ater1 thus the nitrateanions are in an outer coordination sphere(
hen the a''uct $or"er T is a''e', the O/6C4K>9 groups are closer
to the #5ato"s than the OK2+s, d#56/T
-
8/13/2019 Jurnal b.ing Distribusi
95/120
Copyright 2004 by Taylor & Francis Group, LLC
Fig. 4.2( Structure o$ the #62/H692 2/C2KJ696( The uranyl oygens are situate'
perpen'icular to the plane shon aroun' the central ato"( /Fro" :e$( =2(
-
8/13/2019 Jurnal b.ing Distribusi
96/120
Copyright 2004 by Taylor & Francis Group, LLC
e 2
2
9 4
9 4
9 4
9 4
e
stu'ie' by "a-ing substitutions in the organic ligan', hich structurally inter5
$eres ith the $or"ation o$ the co"ple( For ea"ple, Ayrssen B substitute'
oines /5hy'roy!uinolinols, )ppen'i A(; in various positions, Table 4(J,
an' "easure' their 'istribution constants, KAC( )lthough the pKa an' KA,K) in
Table 4(J 'i' not vary "uch ith the substitution, theKAC $or the Th)4 co"ple
ith unsubstitute' oine as 42J, an' $or the J5"ethyl substitute' co"ple
aroun' =000, hile the 25"ethyl substitute' co"ple as not etractable( This
can be attribute' to the 25"ethyl group bloc-ing the co"ple $or"ation(
Table 4(= listsK values $or #62+
an' u4+
ith $our organophosphorous
etractants, T an' A6), an' Ti an' A6i), the iso5$or"s being "ore
branche'( The 'ata in the upper hal$ o$ the table shos little change inKe hen
T is replace' by Ti( Thus the branching has little e$$ect 'ue to the $ree
rotation o$ the substituents aroun' the phosphorous ato"( 8n the loer group,
the a"i'e A6), an' its branche' iso"er A6i), the nature o$ :, : an' :in ::HC6:is i"portant 'ue to the "olecular rigi'ity o$ the a"i'e group( The
branche' substituent strongly 'epresses the etraction constant, hich li-ely is
'ue to a "uch loer stability constant $or the branche' co"ple( This e$$ect is
"ore pronounce' $or u/8O than $or #62+
( 8n a search $or selective syste"s
$or separating trivalent actini'es $or" $ission lanthani'es, SpDuth et al( BJ> in5
vestigate' the etraction o$ trivalent ions $ro" a!ueous KH69 solutions contain5
ing 25bro"o'ecanoic aci' /KA) by "eans o$ terphenyl an' tria7ine 'eriva5
tives 'issolve' in the organic 'iluent tert5butylben7ene /T( Figure 4(2
shos the 'istribution ratio o$ the syste" as a $unction KA) in T ith an'ithout the terpyri'ine /$or"ula in Fig( 4(2>( This is an illustration o$ the
Table 4.1) Constants $or Etraction o$ )ctini'e Hitrate )''ucts ith
hosphoric )ci' Trial-ylesters /Free :otation o$ the P Substituents an'
ith),)5Aial-yla"i'es /:estricte' :otation )roun' the )"i'e
-
8/13/2019 Jurnal b.ing Distribusi
97/120
Copyright 2004 by Taylor & Francis Group, LLC
Fig. 4.2) Etraction o$ Eu/888 an' )"/888 $ro" ,KH69 ith 0(02 < oligopyri'ine
or tria7ine an' = < 25bro"o'ecanoic aci' in tert5butylben7ene( /Fro" :e$( J>(
necessity to achieve synergistic e$$ects by using a''uct $or"ers $or etraction
o$ "etal ions that otherise are too strongly hy'rate' to be etractable( The
structures o$ the terphenyls /a''uct $or"ers teste' are liste' in Fig( 4(2> ith
the 'istribution ratios achieve' $or )"/888, D)"( For ea"ple, in the syste"
ith A6A6V_,D)" is 4(2, hile ith T)ATY it is 9J>( The tria7ine T)A5
TY is "ore branche' /the terphenyl A6A6V_ "ore linear an' has a slightly
larger "olar volu"e, but the 'i$$erence "ay also be attribute' to the greater
basicity /i(e(, s"allerKa co"pare' to terphenyl( Koever, the =00 ti"es larger
-
8/13/2019 Jurnal b.ing Distribusi
98/120
Copyright 2004 by Taylor & Francis Group, LLC
Fig. 4.2* Structure o$ various oligopyri'ine an' tria7ine a''ucts, an' 'istribution ra5
tios /inserts $or )"/888 co"plees ith these oligopyri'ines /0(02
-
8/13/2019 Jurnal b.ing Distribusi
99/120
Copyright 2004 by Taylor & Francis Group, LLC
etraction by the tria7ine cannot be eplaine' by the KS) theory1 various
eplanations are suggeste' BJ>( Steric hin'rance can be pre'icte' by "o'eling
the "olecular structures an' che"ical reactions( )'vance' progra"s re!uire
"ain$ra"e co"puters, but use$ul progra"s are available $or 'es-top co"puters
B4>(
4.14 CACUATION OF E,UII'RIUM CONSTANTS
Earlier sections presente' che"ical "o'els $or the etraction o$ aci's an' "etals
into organic solvents, an' sho that these "o'els, epresse' "athe"atically,
agree ith eperi"ental 'ata at trace "etal concentrations an' at constant activ5
ity coe$$icients( These "o'els provi'e a rationale $or un'erstan'ing the che"i5
cal principles o$ solvent etraction(
Fro" plots o$ the 'istribution ratio against the variables o$ the syste"
B
-
8/13/2019 Jurnal b.ing Distribusi
100/120
Copyright 2004 by Taylor & Francis Group, LLC
2
This "etho' is use$ul hen only one species is etracte', but it has little
value $or the stu'y o$ solvent etraction syste"s that contain several co"ple
species(
4.14.1.) Lig!" N70e/ Me(h'"
This "etho' B;J;P is use$ul $or i'enti$ying the average co"position o$ the"etal species in the syste"( Consi'er E!( /4(9;a $or the etraction o$
-
8/13/2019 Jurnal b.ing Distribusi
101/120
Copyright 2004 by Taylor & Francis Group, LLC
n =n 0(J, logKn
log B)n /4(9
This "etho' o$ obtaining an esti"ate o$ the $or"ation constants as 'one as a
$irst step in the Th/8O5acetylacetone syste" in Fig 4(90, here in the loer
-
8/13/2019 Jurnal b.ing Distribusi
102/120
Copyright 2004 by Taylor & Francis Group, LLC
Fig. 4.3+ #pper curveM the 'istribution o$ Th/8O beteen ben7ene an' 0(= < HaCl64
as a $unction o$ a!ueous acetylacetonate ion concentration1 p) =logB)1 the asy"p5
totes have slopes 0 an' 4( Loer curveM The average nu"ber o$ ligan's per centralato", n7 , in sa"e syste", as obtaine' $ro" a 'erivation o$ the log D/p) curve(
#sing the ligan' nu"ber "etho', the $olloing e!uilibriu" constants ere esti"ate'/ith values $ro" graphical slope analysis ithin parenthesisM logK= (0 /P(J,
logK2 P(; /P(P, logK9 ;(4 /;(9, an' logK4 J(= /J(0( Log KA4 2(J0 is obtaine' $ro" the
hori7ontal asy"ptote( /Fro" :e$s( ;;a,b(
$igure, n7 is plotte' against log B), yiel'ing the preli"inary log
K
values
given in Fig( 4(9( 8n a si"ilar "anner, the a''uct $or"ation constants can be
'eter"ine'MEa"ple =9M The etraction o$ Yn/88 by 5'i-etones an' phosphoryl a''uct$or"ers /cont( o$ Ea"ple J(
Consi'er the $or"ation o$ a''ucts o$ the type
-
8/13/2019 Jurnal b.ing Distribusi
103/120
Copyright 2004 by Taylor & Francis Group, LLC
esti"ate' accor'ing to E!( /4(9(
-
8/13/2019 Jurnal b.ing Distribusi
104/120
Copyright 2004 by Taylor & Francis Group, LLC
2
4.14.2 ?ra6hic '"o6e $na"!sis
For a rational application o$ slope analysis it is i"portant to "easure the varia5
tion o$ the 'istribution ratioD ith one co"ponentx at a ti"e hile the others,
$, are -ept constant( The solvent etraction e!uation can then be epresse' in
the $or" o$ a si"ple polyno"ial o$ type
y =a0
+a=x +a
2
x
+L /4(J
here y is a $unction o$ the 'istribution ratio Dconst(C an' x a $unction o$ the
variable /e(g(, pK, the $ree ligan' ion concentration B), the concentration o$
$ree etractant K) or a''uct $or"er in the organic phase, etc((
4.14.).1 Li!e/ P,'(&
hen the 'istribution e!uation can be epresse' in the $or" y =a0 +a=x, $ro"a plot o$y vs(x the intercept on they ais yiel's the a0para"eter an' the slopethe a=para"eter( This treat"ent is re$erre' to as the limiting "alue method(
Ea"ple =4M The etraction o$ Cu/88 by KTT) /cont( $ro" Ea"ple 4(
Ea"ple 4 /Fig( 4(==a, is represente' by E!( /4(44, hich in logarith5
"ic $or" is ritten
logD =logK +2 log BK) +2 pK /4(;Cu e org
For constant BK)org /Fig( 4(==a, a plot o$ logDCu vs( pK yiel's a line o$ slope
2, hich intercepts pK =0 at logDCu =logKe +2log BK)org( )nother plot o$logDCu against log BK)org at constant pK yiel's a line that intercepts BK)org=0 at log DCu =log Ke +2pK /Fig( 4(==b( 8n either case, the KTT) syste"yiel's logKe ==(2J $or the CKCl9, an' =(0 $or the CCl4 syste"( The corre5spon'ing values $or the 8T syste" are =(;0 an' 0(>J, respectively(
Ea"ple =JM Etraction o$ Th/8O by acetylacetone /cont( $ro" Ea"ple =2(
8n Ea"ple =2, it as conclu'e' $ro" Fig( 4(90 that the a!ueous phase
containe' all Th)n5co"plees ith 0
-
8/13/2019 Jurnal b.ing Distribusi
105/120
Copyright 2004 by Taylor & Francis Group, LLC
= AC = 2 9
-
8/13/2019 Jurnal b.ing Distribusi
106/120
Copyright 2004 by Taylor & Francis Group, LLC
2 = = 2 9 4
H
is obtaine' $or hich there is no si"ple solution(
Ea"ple =;M Etraction o$ #/O8 by acetylacetone(
Fig( 4(9= shos the etraction o$ #/O8 by acetylacetone /%A $ro"
nitric aci' solutions, D#, as a $unction o$ p) =log B) at si 'i$$erent totalconcentrations o$ K)( ) co"parison ith Fig( 4(9 in'icates that e can epect
co"plees o$ the type
-
8/13/2019 Jurnal b.ing Distribusi
107/120
Copyright 2004 by Taylor & Francis Group, LLC
-
8/13/2019 Jurnal b.ing Distribusi
108/120
Copyright 2004 by Taylor & Francis Group, LLC
Fig. 4.31 Etraction o$ #/O8 by acetylacetone /K) $ro" 0(= < HaCl64 into chloro5
$or" as a $unction o$ pK at 'i$$erent total concentrations o$ K)( /Fro" :e$( ;>(
-
8/13/2019 Jurnal b.ing Distribusi
109/120
Copyright 2004 by Taylor & Francis Group, LLC
x
i 2
4.14.3 #umerica" (etho%s
The "ost co"plicate' e!uations presente' in this chapter are o$ the types shon
by E!( /4(>, here a series o$ co"plees are $or"e' in the organic phase an',
at the sa"e ti"e, one or a series o$ co"plees in the a!ueous phase( hen bothx an'y >0(8n practice, there$ore, one variable "ust be -ept constant /or 7ero, hile the
value o$ the other changes( This as 'escribe' $or Ea"ple =;( Thus, i$ x is
-ept constant, the 'ouble polyno"ial is re'uce' to a si"ple one
y =$x
iy
/$= =a
0+a
=x +a
2
x
+L /4(>0
here $ is a constant at constant x( The proble" is there$ore re'uce' to the
'eter"ination o$ the para"eters o$ a si"ple polyno"ial, to hich "any nu"eri5
cal "etho's have been applie' ith varying 'egrees o$ success( The "ain re5
!uire"ent is that all co"pute' para"eters shoul' be positive nu"bers /or 7ero(
8n or'er to solve an algebraic syste" o$ n para"eters, only n e!uations
are nee'e' /a "ini"u" ith no error esti"ates( hen the solvent etraction
reaction can be 'escribe' by E!( /4(>0, there are as "any e!uations as there
are eperi"ental points( Co""only, in solvent etraction =0J0 points are
nee'e' to cover the hole concentration range o$ interest, hile the nu"ber o$
un-non para"eters in si"ple cases is
-
8/13/2019 Jurnal b.ing Distribusi
110/120
i n i i i
2
ratioD( The least s!uare "etho' re!uires that & /the weighted s+uared residu!
als in epression E!( /4(>= is "ini"i7e'
* ) n & =wi /anxi yi
/4(>=
i== n=0 here ) += is the nu"ber o$ para"eters, an' * the nu"ber o$ eperi"entals
points1 ) +* = is re$erre' to as the nu"ber o$ 'egrees o$ $ree'o" o$ thesyste"1 each point has a valuexi N yi( ecause eperi"ents are carrie' out over
a large range o$ D, B) an'Nor B values, the points carry 'i$$erent algebraic
eight /e(g(, the value =000 obscures a value o$ 0(00=( There$ore, in or'er to
use the LS[ techni!ue properly, each point must be correctly weighted, wi( This
can be 'one in several ays, the "ost co""on being to eight it by yi, or by
2, or by a percentage value o$y 1 is the stan'ar' 'eviation in the "easure5i i in"ent o$yi( The 'i$$erence anxi yi /the residual is not 7ero, because the 'i$$er5
ence is to be ta-en beteen a "easure' value,yi /"eas(, an' the correspon'ing
calculate' value,y /calc(, by the a xn
$unction Bi(e(,y /calc( y /"eas(, usingthe actual an values at the ti"e o$ the operation(
The principle o$ the LS[ techni!ue is to co"pute the set o$ positive anvalues that give the s"allest su" o$ the resi'uals1 E!( /4(>= reaches the &"invalue( 8$ the resi'uals e!ual 7ero /hich rarely occurs in practice, &"in oul'
be 7ero, an' there oul' be a per$ect $it beteen the eperi"ental points an'
the calculate' curve(There are several "athe"atically 'i$$erent ays to con'uct the "ini"i7a5
tion o$ & Bsee :e$s( P0PJ( 1 reriting E!(
/4(JJb
3 =D B)n
N B)9
=K /=+
K
BK) +L /4(>2" n 9
hich can be sub'ivi'e' into
AC a'= org
3 =$ K /=+K
BK) +L /4(>9a
-
8/13/2019 Jurnal b.ing Distribusi
111/120
B) = AC a'= org
-
8/13/2019 Jurnal b.ing Distribusi
112/120
an'
3 =$ D B)n
N B)9
/4(>9bBK)org 2 " n 9
3BK)org contains the "easure'D", the B) values, an' the n values( 8t can thusin principle be treate' as an Ea"ple =; to yiel' the n values an' the $2 values/one $or each BK)org, re"e"bering that a0 ==( ecause 3B) N$= =3BK)orgN$2=3, a secon' plot o$ 3 against BK)org yiel's the KA9 an' Ka'b values( Theanalysis o$ the syste" yiel'e'KAC =0(00,Ka',= =P an'Ka',2 =9( 8n these cal5culations, a S8.1 'tirre% Ce"" 'emicontinuous Techniues
Each point5by5point eperi"ent re!uires a co"plete set o$ "iing, separation,
sa"pling, an' analysis( This usually lea's to scattere' results, though it "ay
not be critical, i$ theD values cover a li"ite' range $ro" 0(==0( Koever, the
"ore theD values 'eviate $ro" =, the "ore accurate "ust be the "easure"ents1
also the nu"ber o$ points re!uire' $or a reliable etraction curve usually in5
creases( To re'uce the uncertainty an' labor involve' ith the batch techni!ue,
the stirre' cell techni!ue has beco"e popular(
Figure 4(92 shos a typical ther"ostate' stirre' cell( The li!ui' volu"es
are co""only J0 + J0 "L( The stirrer "ay consist o$ a single pa''le at theinter$ace, or a 'ouble pa''le, one in the center o$ each phase( The cell "ay
contain ba$$les, etc(, to i"prove the "iing( Stirring "ay be violent, co"pletely'estroying the inter$ace an' pro'ucing very s"all / = "" 'roplets, or slo
-
8/13/2019 Jurnal b.ing Distribusi
113/120Copyright 2004 by Taylor & Francis Group, LLC
Fig. 4.32 ) ther"ostate' 'ouble Dac-et /= cell $or solvent etraction stu'ies /heavier
phase , lighter phase > un'er nonoi'i7ing con'itions, using a hy'rogen gas inlet /;
to a '5blac- catalyst /==, pK glass electro'e /9, "agnetic stirrer /=0, connections $or
a''itions /J( )lternative constructions contain rotating pa''les an' $ie' pipings con5
necte' to the to phases $or $re!uent sa"ple ith'raals(
in or'er not to 'estroy the inter$ace( The stirring rate is opti"i7e' to the ti"e
$or reaching e!uilibriu" an' co"plete phase separation( The eperi"ents are
either carrie' out ith inter"ittent violent stirring, in hich case sa"ples are
ith'ran a$ter each co"plete phase separation, or ith "il' stirring 'uring
hich it is possible to continously ithra sa"ples( E!ual volu"es are sa"ple'
each ti"e, co""only ( This
is particulary a'vantageous $or -inetic eperi"ents an' is $urther 'escribe' in
Chapter J( The sa"pling o$ the stirre' cell can be auto"ate', so that at regular
intervals pK an' te"perature are recor'e', an' sa"ples ith'ran $or auto"atic
analysis o$ concentration o$ interesting species in "ore or less stan'ar' $ashion(
8t is also possible to use ion5sensitive probes in one o$ the phases instea' o$
sa"pling(
4.1>.2 Centrifuga" Extraction5'e6aration '!stems
) 'i$$erent approach to solvent etraction eperi"entation, re$erre' to as the
)#FOE principle, as 'evelope' in the =>;0s B0a'( The )#FOE is
-
8/13/2019 Jurnal b.ing Distribusi
114/120Copyright 2004 by Taylor & Francis Group, LLC
illustrate' in Fig( 4(99( E$$icient "iing o$ the to phases an' their a''itions is
achieve' in the "iing vessel an' at the in$lo into the phase separator, hich
consists o$ a continuous flow centrifuge, hich in a special separation cha"ber
an' at very high rotational velocity /J,000J0,000 rotations per "inute sepa5
rates the "iture into to very pure phases, containing
-
8/13/2019 Jurnal b.ing Distribusi
115/120
Copyright 2004 by Taylor & Francis Group, LLC
Ti, or EE /polyether ether -etone to allo "easure"ents un'er very corro5
sive con'itions( The separate' phases pass )
-
8/13/2019 Jurnal b.ing Distribusi
116/120
Copyright 2004 by Taylor & Francis Group, LLC
site in an accelerator or a research reactor to the S8S) e!uip"ent via a gas5
Det transport syste"( The nucli'es are 'issolve' in an a!ueous phase that is $e'
into a centri$uge battery co"prising =4 solvent etraction steps( The pro'uct
solution leaving the last step is pu"pe', e(g(, to a nuclear ra'iation 'etection
syste"( The transport ti"e $ro" the target site to the 'etection syste" 'epen's
on the centri$uge si7e, nu"ber o$ centri$uge steps, an' $lo rate( For a one5step
che"istry, i(e(, 'issolution step an' a single centri$uge etraction, an' "ai"u"
$lo rates, the overall transport ti"e is aroun' 2(J s( This $ast transport has
alloe' 'etaile' 5spectroscopicstu'ies o$ ra'ionucli'es ith hal$5lives aroun'= s( :ecently the S8S) e!uip"ent as succes$ully applie' to stu'ies o$ the
heaviest ele"ents, an' solvent etraction 'ata ere obtaine' $or ele"ent =04 :$
BJ( Fast che"ical separation syste"s have been 'evelope' $or !uite a large
nu"ber o$ ele"ents B;(
Centri$ugal etractors have been 'esigne' $or a nu"ber o$ in'ustrial uses
/see succee'ing chapters( 8n so"e cases they have been scale' 'on to labora5
tory si7e but "ainly been use' $or 'eveloping in'ustrial "ultistage processes(
4.1>.3 Liui% *artition Chromatogra6h!
8n li!ui' partition chro"atography a solute 'istributes itsel$ beteen a "obile
li!ui' phase an' an i""obile solvent attache' to a soli' "atri /in the earliest
eperi"ents a clayli-e 0ieselguhr( 8t is outsi'e the scope o$ this chapter to
'iscuss this techni!ue, hich, hoever, is brie$ly 'escribe' in Chapter =J(
4.1% CONCUSION AND FINA COMMENTS
The solvent etraction process is usually 'escribe' by a single net reaction,
'e$ine' by the etraction constantKe( Oariations inKe cause' by "o'i$ications
o$ the solvent syste", such as changes in the te"perature or a!ueous ionic
strength, or by replacing one solvent by another, or "a-ing substitutions in the
etractant "olecule, "ay be eplaine' by care$ul consi'eration o$ the para"e5
ters o$ the syste"( Koever, such stu'ies are 'i$$icult an' not alays su$$icient
$or pre'icting ne syste"s( ) better $oun'ation $or un'erstan'ing the etractionprocess is to consi'er the steps in the process contributing to the net etraction
reaction, particularily hen these steps are governe' by regularities( nole'ge
o$ these regularities helps in interpreting syste"s as ell as in pre'icting ne
ones( Etension o$ these 'istribution 'ata to ther"o'yna"ic constants is li-ely
to give bene$its in increase' che"ical -nole'ge o$ the behavior o$ solutes in
'i$$erent solvent syste"s( )'vance' !uantu" che"istry calculations an' co"5
puter "o'eling o$ etraction processes can help us in 'esigning ne, selective
solvent etraction syste"s, as ell as in interpreting etraction pheno"ena /see
Chapter =;(
-
8/13/2019 Jurnal b.ing Distribusi
117/120
Copyright 2004 by Taylor & Francis Group, LLC
REFERENCES
=( Graha"e, A( C(1 Seaborg, G( T( 5(Am( $hem( &oc( 1938, 89M2J24(
2( 8rving, K( p( >=, (&E$688, &ol"ent Extraction $hemistry Ayrssen, A(1 LilDen7in,
.( 6(1 :y'berg, .( E's(1 Horth Kollan', )"ster'a" /=>;P(
9a( :y'berg, .(Ar0i" Kemi =>J4, :M=0=(9b( :y'berg, .('ec( Tra"( $him( 1956, ;;>(
;( arton, )( F( ( Se-ine, T( et al(ull( $hem( &oc(5ap( 1983, P9(
=9( .assi", T( ;(=4( P0(
=Pa( Harbutt, .(5((norg()ucl( $hem( 1981, @>M9949(
=Pb( Harbutt, .(5(Phys( $hem( 1991, C
-
8/13/2019 Jurnal b.ing Distribusi
118/120
Copyright 2004 by Taylor & Francis Group, LLC
29b( )llar', (1 .ohnsson, S(1 Harbutt, .1 Lun'!uist, :((&E$ ;;, $(M &pecial ,olume
?, =>PP(
24( Se-ine, T(1 8hara, H(ull( $hem( &oc(5ap( 1971, @@M2>42(
2J( Cecconie, T(1 Freiser, K(Anal( $hem( 1990, 8?M;22(
2;( ;P(
90a( Se-ine( T(1 Ayrssen, A(Anal( $him(Acta 1969, @P2(
99a( :y'berg, .('e"((norg( $hem( 1999, CM24J(
99b( :y'berg, .(Min(Pro(Ext(Met('e"( 2000, ?M=;P(
94( Carey, F( )(1 Sun'berg, :( .(Ad"anced =rganic $hemistry, Thir' E'ition, lenu"
ress, He _or-, =>>0(
9J( Fu-s, L(1
-
8/13/2019 Jurnal b.ing Distribusi
119/120
-
8/13/2019 Jurnal b.ing Distribusi
120/120
P;( M20JP(
P( E-berg, Ch( Bncertainties in Actinide &olubility $alculations (llustrated Bsing the
ThR=%RP=@ &ystem, Aiss( Chal"ers te-nis-a ho%gs-ola, Go%teborg,
=>>>(
P>( atari, K(1 Cunningha", L(1 Freiser, K(Anal( $hem( 1982, 0(0a( :einhar't, K(1 :y'berg,5( &ol"ent Extraction $hem( /(&E$ =>;;, Horth5Kollan'
ubl( Co( )"ster'a", ;=2 pp(
0b( :einhar't, K(1 :y'berg,5( $hem((nd( 1970, 4 pp(
0c( :y'berg, .(, et al(Acta $hem( &cand( 1969, ?>M;4P(
0'( :y'berg, .(, et al(,Acta $hem(, 1969, 2PP9, 2P=, 2P>P pp(
=(