f i~ntf i~ar1c ~ of Carbon cliox,de

Non t<)xic
No11 fl·u11111ablc
1nbic11t cri tica l tcn1pcralurc

S uporcrltlcn l

L iq uid C I
old

.. Gas
s, Vapour
t
1

-78.5 -56 7 31 Tf'>C

Pr ,1.1se cliagra1n of carbon dioxide

I
\\'\\''\\' b qub c ulc/s• il1muldoon1co:?- I JPf. .-icccsscd on I~ ·os. 09
 Phys ical p rope rties of CO2 near the critic al poin t (7 .4 MPa

1000 - - - - -- - - - - - . - - - - - - - - - - - - - - - - --
•
900 L----- 3 I .0 °C
800
700
g 600 ,_ _ c x t O (k.J/ (kg · K ))
«s p
3
....cu 500 - - p (kg/m )
-a,
5 400 - - ix t03 (W/ (tn · K))
- - µ x 106 (Pa ·s)
~ 3 00
Q... - - Z x J03 -
200
00
I
0 'I
oo L_ J--.. £-- -0- ~L•-~4~0---- ---;5~0 -..-&..-~a~oD-L...-~100ioO
L
0 2
1 c n 1pera tu~e (°C) 11 T noorua:E • I
 Importance of Solubility

,. So lubility

,. It in<l1calcs rcluL1vc ex tractability of a compound as a function

of ll.!n1pcraturc and pressure.

,. Pr~c1pitat1on of components - separation process.

,, i\ lixlurcs solubilities extraction and purifi ca tion processes

 Sofubiti·i·y o·r organics

lubility of Botanical Ingredients in Lic1uid and SC CO2

Very Soluble SparinglySoluble Ahnost Insoluble

Nonpolar aud slirJ1tlypolarlow Higuer~1\V. organics,(<400), Organics

. ,vilh ~if.\V.above 400.
11 \\1. ( 2~0) O1~m1ics, e.g .. e.g.. subslituled 1e1venesand e.g., sugars, proteins, tannins.
mono and sesqni1e1pcnes.e.g .. sesgui1e1venes. waler, oleic ,vnxes, inorganic
.. salts.
lluols pyrn1.111es, nnd 1uiazoles. ncid, glycerol. decauol. chlorophyll, carotenoids.~ ""---.
ncellc nc1d, be1v lldehyde snlurntedlipidsup to C11 nrnlic ncids, au1i110 acids.
hxanol, 2lycerol. acetates nilrntes. peslicides.
-
insecticides. el; .
I .
.
...
~
~
- . .•
r w <

'
 - ---------

Addi·rion of Co-solvent

• A cosolvent or entrainer - organic substance -

vo latility bin SCF and solute - Concentration
( 1- 5 ruol%) - Change the characteristics of
t
solvent tie lines

gas
• Polarity, and Specilic interactions - ,vithout T = const
ch:.111ging density and con1prcssibility of SCf 0 Mola Fraction X , - - 1 .0

• Solvent ; SCf - • mixture critical point for

tl1c fixed concentration - not dificrcnt fro111 gas
critical point of pure solvent

• T,vo plJasc region exists beyond the critical

temperature fo r a particular pressure
P: const CP

• A mixture is not necessorily supercritical - at O Mole Fraction X, - - 1.0

a te111pernture nbove the c-r of mixture

 Addition of Co-solvent

• SCF + Co-solvent - beyond tJ1e CP of

111ixt urc lo solubilizc liquid solute - 3
Temury systetu
P =const
• A ll three con1ponents are usually T =const
distributed both in liqu id and SCF
c)
phuscs

• Tltc ex tent of solubilisulion of

l:oruponcnt in 1,vo phases -
Distribut ion coeOicient

• Distribution cocfficicut - Ratio of

concentrntion of lhe component in
fl uid phnsc and Jjquid phase - end tie lines
points of Lie lines
2 1
 Solubility behavior in SCF

• Bi_nary systen1 - Solid solute + SCF - Solubility isotherm - pressure dependent

• Solubility of solute - dec re ases initially reaches minimum - exponential

increase ,vith pressure in U1c vic inity of CP and in SCF slate.

I · Different isolben11s - converge - Cross over pressure

• Lo,ver and Upper C ross over pressure - Retrograde solubility

• Solid- fluid systc n1 - 1\n isobaric increase in tcn1pernturc - decrease the

so lubility

• Usually observed in high co1nprcssibility region of SCF Solvent

IITR00RKtt a r,~
 Solubility behavior in SCF

:z
0
--
-~ -
- --- - - - -
- - - - - - - T 1

- - - ..
I
t-- I
u .,, .,,
I
'
~ , ,,
I
/ I
I
LL- , I
,
/ ''I
___.
UJ
, '
0 , I
I
I
~
I
• I

'I
I
I
•I
I
I
,
' . .._ . --
I
, I
• . ,, ,, I
I
' ,, I
'' ,, ,, I
I

---
' .,, I
'" I
I
I
I
'
0

PRESSURE
 Solubility behavior in SCF

• Solid Naphthalene - melting point

SO.? °C; Ethylene CP: Tc- 9.3 °C;
Pc= 50.5 bar w
z
~
• At J? °C isothenu, lhe solubility
of solid naphthalene increases as
~
::c:
00100 12•c
the pressure is increased to 50 bar, ~
z
i.e. near critical point of ethylene u.
0
z
• At pressure > 90 bar, solubility of -I-
0

~w
naphthalene in SC- Ethylene 00010

asyn1pt0Lically reaches n va lue of

1.5 mo l%. ...J
0
:E
• The density isothenn and
0 ~ 100 I~ 200 2!-0 300 3..~
solubil ity isothcn11s looks sin1ilar
indicating that Solubility of solute PRESSURE (bar)
is density dependent
 Solubility behavior in SCF

• Higher dens1t1cs n1ore n1oleculru- 1nterJcllons bin solute ond solvcnl - enhances
-
the soluhilit,. of solid solute

• Density alone docs not gi,c co1nph:tc cxpla11at1011 or solubility c11hancc1nc11l

• \'ol3tility of so In.I solute contributes lo soltu solubility 111 SCl·

• Rctn1gmdc soluhili1y - n.•l:1th c in1pacl or\'olalility and density cOccl

• ,\n isob;1ric j tc1npcr:11urc density .J, solubility .J,

• •\n r h.!lllpcr.llun: - i volalllil)- or the solute - solubility r

• ,\t P < Pu, the density c11cct do1ninating volntility cficct - increase in
solubility by .J, tcn1pcm1urc or increase in f

• ,\t P > P11• ll1c volatility ellcct do1nin:inl j 1cn1pcmt11rl.!