Transcript Solvent extraction

Solvent extraction
Tech.
LLE
phase 1
raffinate
phase 2
Extractant\
Chromatography
stationary
mobile
Dialysis
retentate
diffusate
← extractant
← raffinate
(sample was dissolvent in)
q：fraction of solute extracted
1-q：fraction of solute
KD 
conc. A in phase 1
conc. A in phase 2
C A raff

C A ext
WA raff

WA ext
Vraff
Vext
or
WA 1
WA 2
WA 1
WA 2
V1
V2
is the ratio of total amount (weight) of A in one
phase to that in the 2nd phase
partition ratio ： k   1  q  Wraff
(capacity factor)
q
Wext
Vext V2

phase ratio：  
Vraff V1
KD  k  
(1) Partition coefficient
1  q V2 solute raff
KD  k   

q V1 solute ext
(2)
q
Cext V ext
1

Cext V ext  Craff V raff 1  K D
(3)

Vext
1  q  1  
 Vext  K DVext
(4)
  1  k  KD
1
1
q

1 k 1 KD
(

1
)
1  k

K DVraff
k
 

 Vext  K DVraff k   1
1 q 
KD
KD 1
操作模式
(1)Single contact
(2) Multiple contact (crosscurrent extraction)
(3) Multiple contact (countercurrent extraction)
Multiple extraction
extracted
left
1st extract
q
1-q
2nd
q(1-q)
1-q-q(1-q)=(1-q)2
q(1-q)n-1
(1-q)n
：
：
N
 Vext

K DVraff
k
 
1  q  1  

 Vext  K DVext  Vext  K DVraff k   1
(1  q ) n

K DVext

V
 ext  K DVraff




n
Effect of pH value on extraction
KD ─→ D ( distribution coeff. )
D
conc. of all form of solute in extractant
HAo
org.
aq.
HAaq + H2O
H3O+ + A-
conc. of all form of solute in raffinate
HA aq  A  aq

HA o

H A 


Ka
aq
HA o HA aq
aq

HA 
1
D

  HA 
1 A
1
Ka
H
   H  K H   K
KD


a
1 KD
Ka 

1



D
 
H 

 
 
 
 H  Ka 

D  K D 

 H

[H+] >>Ka
(a) very acid
D=KD
(b) at pH
H   K

a
 D  2K D
(c) [H+] <<Ka
D  KD
Ka
H
 
D >>KD
Effect of pH value on extraction
KD ─→ D ( distribution coeff. )
D
conc. of all form of solute in extractant
Bo
org.
Baq  BH  aq 1  BH  aq Baq


Bo Baq
Bo
aq.
BH+aq
conc. of all form of solute in raffinate
H+ +
B
H B 

BH 

H 
1

Ka


D
Ka
1
KD
 
Ka K D  H  K D

Ka
  
 Ka  H
D  K D 
Ka

(a) very acid [H+] >>Ka
D >> KD
(b) at pH
H   K

a
 D  KD / 2
(c) [H+] <<Ka
D  KD


Suppose that the partition coefficient for an amine, B,
is 0.33 and the acid dissociation constant of BH+ is
Ka=1.0x10-9. If 50 mL of 0.010M aqueous amine is
extracted with 100 mL of solvent. What will be the
formal concentration remaining in the aqueous phase
(a) at pH 10.0? (b) 8.0?
Application
Extraction of metal ions
aqueous phase
-
n+
nL + M
HL
HL
Ka
Kf
MLn
L- + H+
MLn
organic phase (ionic liquid)
加入chelator (HL)
HL (aq)
HL (o)
K d1

HL 

HL 
(o)
(1)
( aq )

H O L 


H3O+(aq) +L-(aq)
HL (aq)+ H2O
Mn+(aq)+
MLn(aq)
nL-
(aq)
MLn(o)
MLn(aq)
K d2
Ka
Kf
3
HLaq

ML 

M L 

HL 

HL 
( aq )
n

( aq )
( aq )

(2)
(3)
n(o)
n ( aq )
(4)
→ HL, MLn在有機相中溶解度大
 K d1 , K d 2 >>1
→ [L-] is pH dependent
D

MLn( 0 )
ML0 
Co
 n

n
Caq M (aq)  MLn(aq)
M (aq)
 
 


(5)
CL：orignal molar conc. of HL in organic phase mass balance
CL  HL(o)   HL(aq)   L(aq)   nMLn(aq)   nMLn(o) 
→ excess chelator CL≈[HL(o)]
(6)
(3) (4)
K f  K d2
n(o)
n

( aq )
n
( aq )
 MLn ( o )
代入(5)

HL 

M L 
  K K M L 
f
n
( aq )
d2
n

( aq )
n
Co

D
 K f K d 2 L( aq ) 
Caq
(6)
( 2)
K a HL( o ) 
K a CL

 L( aq )  


(1)
K d1 H 3O( aq )  K d1 H 3O(aq ) 
 (6)代入(7) 
Co
D

Caq
K f K d1 K a
K d1
n
n
n
n
CL
K exCL
n 
n


H 3O( aq )  H 3O( aq ) 
(7)
Extraction of Metal Ions with RTIL
利用RTIL在重金屬離子之萃取,實驗時使用金屬螯
合物, RTIL(在此選用不溶於水的1-butyl-3methylimidazolium hexafluorophosphate ,
[BMIM][PF6]) 當有機層進行金屬離子的萃取，以便
探討RTIL取代揮發性溶劑於金屬離子之萃取的可行
性.
1.Guor-Tzo Wei*, Zusing Yang, Chao-Jung Chen, Anal.
Chimica, Acta 2003, 488(2), 183.
2.Guor-Tzo Wei*, Jin-Chu Chen, Zusing Yang, J. Chin. Chem.
Soc. 2003, 50, 1123.
傳統液-液相萃取:
需使用大量有毒、易燃、高揮發性的有機溶劑.
近代液-液相萃取:
a.使用supercritical fluid CO2萃取
b.使用不具揮發性、不可燃、毒性較低的ionic
liquid(IL) ，且可回收使用。
Presidential Green Chemistry Challenge Awards
http://www.epa.gov/greenchemistry/
Mission: To promote innovative chemical technologies that reduce or
eliminate the use or generation of hazardous substances in the design,
manufacture, and use of chemical products.
1996:
Alternative Synthetic Pathways Award: Monsanto Company,
The Catalytic Dehydrogenation of Diethanolamine
Alternative Solvents/Reaction Conditions Award: Dow Chemical
The Development and Commercial Implementation of 100 Percent
Carbon Dioxide as an Environmentally Friendly Blowing Agent f or the
Polystyrene Foam Sheet Packaging Market
Designing Safer Chemicals Award: Rohm and Haas
Designing an Environmentally Safe Marine Antifoulant
Small Business Award: Donlar Corporation
Production and Use of Thermal Polyaspartic Acid
Academic Award : Prof. Mark Holtzapple, Texas A&M Univ.
Conversion of Waste Biomass to Animal Feed, Chemicals, and Fuels
The Twelve Principles of Green Chemistry*
1. Prevention
It is better to prevent waste than to treat or clean up waste after it has been created.
2. Atom Economy
Synthetic methods should be designed to maximize the incorporation of all materials used in
the process into the final product.
3. Less Hazardous Chemical Syntheses
Wherever practicable, synthetic methods should be designed to use and generate
substances that possess little or no toxicity to human health and the environment.
4. Designing Safer Chemicals
Chemical products should be designed to effect their desired function while minimizing their
toxicity.
5. Safer Solvents and Auxiliaries
The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made
unnecessary wherever possible and innocuous when used.
6. Design for Energy Efficiency
Energy requirements of chemical processes should be recognized for their environmental
and economic impacts and should be minimized. If possible, synthetic methods should be
conducted at ambient temperature and pressure.
7. Use of Renewable Feedstocks
A raw material or feedstock should be renewable rather than depleting whenever technically
and economically practicable.
8. Reduce Derivatives
Unnecessary derivatization (use of blocking groups, protection/ deprotection,
temporary modification of physical/chemical processes) should be minimized or
avoided if possible, because such steps require additional reagents and can
generate waste.
9. Catalysis
Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
10. Design for Degradation
Chemical products should be designed so that at the end of their function they
break down into innocuous degradation products and do not persist in the
environment.
11. Real-time analysis for Pollution Prevention
Analytical methodologies need to be further developed to allow for real-time, inprocess monitoring and control prior to the formation of hazardous substances.
12. Inherently Safer Chemistry for Accident Prevention
Substances and the form of a substance used in a chemical process should be
chosen to minimize the potential for chemical accidents, including releases,
explosions, and fires.
*Anastas, P. T.; Warner, J. C. Green Chemistry: Theory and Practice, Oxford University Press: New
York, 1998, p.30.
What is a Room Temperature Ionic Liquid (RTIL)?
(Room Temperature Molten Salt)
• Liquid salt consisting of at least one organic component
(cation or anion) with melting point below room
temperature
• Properties:
–Negligible vapor pressure
–High thermal stability (~250-400°C)
–High viscosity
–Hydrophobic or hydrophilic
–Dissolve many organic, organometallic, and
inorganic compounds
RTILs are regarding as “Green solvents”
Ethyl ammonium nitrate (EtNH+3)(NO-3), which has a
melting point of 12°C, was first described in 1914.
P. Walden, Bull. Acad. Imper. Sci. (St. Petersburg) 1800
(1914).
Osteryoung & Wilks, late1970, chloroaluminate salts in
electrochemistry
Sneddon & Hussey, 1980, groups chloroaluminate
salts in electrochemistry and organometallic researches.
After 1990, used as solvents for synthesis
Late 2000, the application in separation
Pure Appl. Chem., 2000, 72, 2275–2287
RTIL Structures
N+ N
• Cations
R
R`
R: methyl; R’: n-butyl
1-butyl-3-methylimidazolium, BMIM, C4MIM
• Anions
– PF6– BF4– Cl-
SbF6CF3SO3- (TfO)
N(CF3SO2)2- (NTf2)
1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6]
1-octyl-3-methylimidazotetrafluoroborate [OMIM][BF4]
General syntheses of ionic liquid: Green Chemistry, 2003. 5. 181-186.
Effect of the nature of anion on physical properties of BMIM salt
----------------------------------------------------------------------------------Anion
m.p.
d
Viscosity
Conductivity
oC
g/cm3
cP (20oC)
S/m
---------------------------------------------------------------------------------BF4-82(g) 1.17
233
0.17
PF6-8
1.36
312
0.14
Cl65
1.10
solid
solid
CF3COO~-40(g) 1.21
73
0.32
CF3SO316
1.29
90
0.37
(CF3SO2)N- -4
1.43
52
0.39
C3F7COO~-40(g) 1.33
182
0.10
C4F9SO320
1.47
373
0.045
---------------------------------------------------------------------------------(g) Glass transition
P.S. viscosity of water 1 cP.
Dissolution of Cellulose with Ionic Liquids
R.P. Swatloski, R.D. Rogers, et al. J.A.C.S. 124 (2002) 4974.
Room-temperature ionic liquids: a novel versatile lubricant
Chengfeng Ye , Weimin Liu , Yunxia Chen and Laigui Yu,
Chem. Commun., 2001, (21), 2244 - 2245
<>
Alkylimidazolium tetrafluoroborates are promising versatile lubricants for the contact
of steel/steel, steel/aluminium, steel/copper, steel/SiO2, Si3N4/SiO2, steel/Si(100),
steel/sialon ceramics and Si3N4/sialon ceramics; they show excellent friction
reduction, antiwear performance and high load-carrying capacity
Uses of RTILs in Anal. Chem.
• Novel solvents in liquid-liquid or micro extractions
• Run buffer additives in CE
• Matrixes in Matrix-Assisted Laser Desorption
Ionization (MALDI) mass spectrometry
• Stationary phases in gas-liquid chromatography
Extraction of Metal Ions with RTIL
aqueous phase
nL
-
HL
HL
n+
+ M
Ka
Kf
MLn
L- + H+
MLn
organic phase (ionic liquid)
Illustration of various equilibra involved in metal ion
extraction with ionic liquid .
鉛與dithizone 結合示意圖
C6H5
C6H5
N
N
N
N
2C6H5
N
N
C
SH
+ Pb2+
C6H5
N
N
S
N N
Pb
N
N
S
C6H5
H
H
dithizone
(green)
colorless
metal complex
(red)
C6H5
H
+
2H+
N
N
N
H
2
S
N
H
N
Cu2+
+
N
N N
S
H
Cu
N N
H
S
N
N
+
2H+
Dithizone
Blue
Green
Violet
N
2
+
N
Cu2+
OH
Oxine
O
Cu O
2H+
+
N
Blue
Yellow
2
N
+
N
N
Cu2+
N
N
N
N
N
HO
+
O Cu
O
N
PAN
Orange
Blue
Red
2H+
Percentage extracted (%)
100
80
60
40
20
0
0
1
2
3
4
5
6
7
8
9
10
11
pH value
The pH value effect on the extraction of lead ion with dithizone
in ( ) ionic liquid, ( ) chloroform.
12
Percentage extracted(%)
100
IL
80
60
CH2Cl2
40
20
0
0
1
2
3
4
5
6
7
8
pH value
Comparing the extraction of copper ions with ionic liquid and
dichloromethane with PAN
9
10
Percentage extracted (%)
100
Ag
+
80
Cu
60
Cd
2+
2+
Zn
2+
9
10
40
20
0
-1
0
1
2
3
4
5
6
7
8
11
12
pH value
The effect of pH value on the extraction efficiencies of metal ions with
dithizone by IL.
13
Percentage extracted(% )
100
Cu
80
2+
Zn
60
Ag
2+
Cd
2+
+
40
20
0
0
1
2
3
4
5
6
7
8
9
10 11 12
13 14
pH value
The effect of pH value on the extraction efficiencies of metal ions with PAN by IL.
IL
Dichloromethane
100
90
80
70
60
50
40
30
20
10
0
Hg2+ Zn2+ Pb2+ Ca2+ Cr3+ Mn2+ Cd2+ As5+Co2+ Ag+
The effect of 100 ppm cation on the extraction of 5 ppm Cu2+
with dithizone
IL
100
90
80
70
60
50
40
30
20
10
0
SCN-
Dichloromethane
citrate
Cl-
CO32-
PO43- CH3COO-
The effect of 100 ppm anion on the extraction of 5 ppm Cu2+
with dithizone
100
90
80
70
60
50
40
30
20
10
0
IL
SCN-
Dichloromethane
citrate
Cl-
CO32-
PO43- CH3COO-
The effect of 100 ppm anion on the extraction of 5 ppm Cu2+ with PAN
Preconcentration of Pb2+
Times Theoretical
Value (ppm)
Experimental
Value (ppm)
Recovery
(％)
5
10.00
10.00
100
10
20.00
20.00
100
20
40.00
38.20
95.5
25
50.00
45.75
95.8
50
100.00
99.00
99.0
(a) Separation of different metal ions; (b) Reproducibility of
Cadmium ions with reusal [C4MIM][PF6]
Metal
ions
Cu(II)
Cd(II)
pH
E%
2.74
56
0
Ag(I)
Cd(II)
1.43
Cd(II)
Ca(II)
7.08
pH
3.98
E (%)
43.16
3.89
38.42
3.93
44.74
89.48
0
4.01
43.68
3.99
42.63
87.2
0
4.02
44.21
3.99
46.32
Average = 43.31% RSD = 5.69%
(a)
(b)
Solute A has a partition coeff. of 1/3 between toluene and water.
Suppose that 100 mL of a 0.010 M aqueous solution A is extract
with toluene. What fraction of A remains in the aqueous phase (a)
if one extraction with 500 mL if performed and (b) if five
extractions with 100 mL are performed?
Solute A has a partition coeff. of 1/3 between toluene and water.
Suppose that 100 mL of a 0.010 M aqueous solution A is extract with
toluene. What fraction of A remains in the aqueous phase (a) if one
extraction with 500 mL if performed and (b) if five extractions with
100 mL are performed?

Vext
1  q  1  
 Vext  K DVext
(1  q)
n

K DVraff
k
 

 Vext  K DVraff k   1

K DVext
 
 Vext  K DVraff



n