cyanex 272 - CYTEC Industries

CYANEX ® 272
Extractant

2 CYANEX 272 Extractant
Solvent Extraction Reagent
• Selective for cobalt over nickel
from sulfate and chloride media.
• Selective for zinc in the presence
of calcium and cobalt.
• Extracts other metal cations.
INTRODUCTION
CONTENTS
Chemical Structure .............................................................................3
Typical Properties ...............................................................................3
Stability ...............................................................................................3
Solubility Losses .................................................................................4
Toxicity ...............................................................................................4
Suitability of Construction Materials ..................................................4
COBALT RECOVERY
Cobalt Nickel Selectivity .....................................................................5
Sulfate Solution (Table 1) ............................................................5
Chloride Solution (Table 2) ..........................................................5
Calcium Rejection ...............................................................................6
Cobalt Extraction Isotherm.................................................................6
Cobalt Loading ...................................................................................6
Scrubbing Isotherm ............................................................................7
Stripping Isotherms ............................................................................7
Using H 2 SO 4 (Table 7) .................................................................7
Using HCl (Table 8) ......................................................................7
Continuous Separation of Cobalt from Nickel in
Sulfate Solution ..................................................................................7
Effect of Process Variables on Cobalt-Nickel
Separation Factor ...............................................................................8
Effect of Temperature (Table 9) ...................................................9
Effect of Equilibrium pH (Table 10)..............................................9
Effect of Diluent Aromaticity (Table 11) ......................................9
Effect of Phase Modifier (Table 12) .............................................9
OTHER POTENTIAL APPLICATIONS
Diluent Oxidation and Prevention ....................................................10
Recovery from Ammoniacal Solutions (Table 13) ............................10
Extraction from Single Metal Sulfate
Solutions (Table 14) .........................................................................10
Extraction from Single Metal Chloride
Solutions (Table 15) .........................................................................11
ANALYTICAL METHODS
In Organic Solvents by Titration .......................................................13
In Organic Solvents by Gas Chromatography ..................................14
In Aqueous Solutions by Gas Chromatography ...............................15
HEALTH AND SAFETY ..............................................15

INTRODUCTION
CYANEX ® 272 extractant has proven to be the reagent of choice for
the separation of cobalt from nickel from both sulfate and chloride
media. It is now being used to produce a major portion of the
world’s cobalt.
Since the active component of CYANEX 272 extractant is a
phosphinic acid, metals are extracted through a cation exchange
mechanism. Although CYANEX 272 extractant is selective for
cobalt in the presence of nickel, a variety of other cations can also be
extracted depending upon the solution pH.
CYANEX 272 extractant is totally miscible with common aromatic
and aliphatic diluents, and is extremely stable to both heat and
hydrolysis.
Chemical Structure
The active component of CYANEX 272 extractant is
bis(2,4,4-trimethylpentyl)phosphinic acid.
CYANEX 272 Extractant
Typical Properties
Bis(2,4,4-trimethylpentyl)phosphinic acid 85%
3
Appearance Colourless to light
amber liquid
Molecular Weight 290 g/Mol
Specific Gravity at 24ºC 0.92
Viscosity, Brookfield at 25ºC 142cp
50ºC 37cp
Solubility in distilled H 2 O at pH 2.6 16 μg/ml
Stability
pH 3.7 38 μg/mL
Boiling Point >300°C
Pour Point -32°C
Flash Point, closed cup >108ºC
Specific Heat @ 52°C 0.48 cal/gm/°C
Thermal Conductivity 2.7 x 10-4
cal/cm/sec/°C
The hydrolytic stability of CYANEX 272 extractant was examined
in several tests which involved equilibrating the reagent with
aqueous cobalt-nickel sulfate solutions at pH 5 and 50°C.
The experimental procedure involved contacting the aqueous and
organic phases in a stirred vessel for one week and then stripping
the organic phase with sulfuric acid. The solvent was subsequently
returned to the vessel for a further one week contact with a fresh
aqueous solution. The procedure was repeated for a total contact
time of four weeks.
Analysis by titration and 31
P NMR failed to detect any degradation
of the reagent, nor were any statistically significant changes in
cobalt-nickel selectivity observed.
Furthermore, no degradation has been detected in plants which have
been operating continuously for as long as 25 years.

4 CYANEX 272 Extractant
Solubility Losses
Losses of CYANEX 272 extractant by distribution to aqueous
cobalt-nickel sulfate solutions were determined in a number of
shake-out tests. The effect of two variables, pH and aqueous phase
salt concentration, was studied.
Aliquots of the organic and aqueous phases were contacted for
5 minutes at 50ºC and A/O = 1. After coalescence, the aqueous
phases were analyzed for CYANEX 272 extractant using a gas
chromatographic procedure. The solvent was composed of 12 v/o
CYANEX 272 extractant in Kermac* 470B diluent. Ammonium
hydroxide was used for pH adjustment. The results of the extractant
solubility (truly dissolved data) are given below.
Aqueous Composition (g/l) CYANEX 272
Ni Co Total Salt Equilibrium Extractant
Conc. pH Solubility
(μg/ml)
100 2 300 3-5 0.5-1.5
25 25 133 4.6 2
5.3 2
6.2 2
5 5 27 4.6 3
5.5 8
6.5 25
___________________________________________
The solubility losses follow the general pattern expected of an acidic
extractant. Distribution to the aqueous phase was found to be
proportional to pH and inversely proportional to salt concentration.
As can be seen, the losses are not excessive and this is corroborated by
operating plant experience where total annual losses from both solubility
and entrainment are approximately 10-15% of the solvent inventory.
Toxicity
The acute oral (rat) and acute dermal (rabbit) LD 50 values for
CYANEX 272 extractant are >3.5 g/kg and >2.0 g/kg, respectively.
The product produced only limited to mild eye and skin irritation
during primary irritation studies with rabbits. The acute LC 50 , (96
hr) for the bluegill sunfish and rainbow trout are 46 mg/L and 22
mg/L, respectively. When CYANEX 272 extractant was assayed for
mutagenic potential in the Ames Salmonella Test, it was determined
to be non-mutagenic.
CYANEX 272 extractant is considered as a non-toxic material.
* A product of Kerr McGee Refining Corp.
Suitability of Construction Materials
Metals: Samples of stainless steel (304 and 316), mild steel and
aluminum in the form of coupons (approximate dimensions 50mm
x 20mm x 3mm) were immersed in capped jars for 8 1 /2 months at
50°C (temperature was maintained only during working hours). No
corrosion was observed in the three steel samples but aluminum
exhibited minimal corrosion at a rate of 1 mil/year.
Plastics and Rubbers: Samples of various plastics and rubbers were
immersed in CYANEX 272 extractant and kept at 50°C for a total
of 424 hours. The following observations were made:
Material Remarks
Butyl Rubber Unsuitable. Increase in dimensions
and softening.
Teflon Fluorocarbon Film** Suitable. No measured effect.
Polypropylene Suitable. No measured effect.
Natural and Black Latex Unsuitable. Complete dissolution
in less than 192 hours.
PVC Laboratory Grade Short term suitability. Loss of
plasticity in less than 192 hours.
PVC Solvent Grade Suitable. Only small change in
dimensions observed.
Red Gum Rubber Unsuitable. 100% increase in
weight and dimensions and
softening.
Viton Fluoroelastomer** Suitable. No measured effect.
Silicon Unsuitable. Disintegrated after 56
hours.
EPDM Unsuitable.
** Dupont Dow Elastomers

CYANEX 272 Extractant
5
COBALT RECOVERY
Cobalt-Nickel Selectivity
The results of batch shake-out tests showing the effect of pH on
Co-Ni selectivity from both sulfate and chloride media are given in
Tables 1 and 2, respectively.
TABLE 1 – SULFATE SOLUTION
Solvent (v/o) 12% CYANEX 272 extractant, 5%
isodecanol in Kermac 470B diluent
Aqueous (g/l) 1.96 Co, 98.0 Ni as sulfates
Temperature 50°C
Contact Time 5 minutes
A/O 1
pH Control NH 4 OH
% Extraction Equilibrium Separation
Co Ni pH Factor
21.5 0.04 3.8 700
43.7 0.08 4.2 1000
88.0 0.37 5.3 2000
96.7 1.05 5.7 2700
100 1.81 6.1
TABLE 2 – CHLORIDE SOLUTION
Solvent (v/o) 10% CYANEX 272 extractant, 5%
isodecanol in Kermac 470B diluent
Aqueous (g/l) 0.88 Co, 1.76 Ni as chlorides
Temperature 50°C
Contact Time 5 minutes
A/O 1
pH Control NaOH
% Extraction Equilibrium Separation
Co Ni pH Factor
2.9 0.1 3.2 40
54.2 0.3 4.0 370
98.1 7.0 5.1 680
99.7 30.0 5.5 680
99.9 72.9 6.2 650

6 CYANEX 272 Extractant
Calcium Rejection
Unlike other organophosphorus cobalt extractants, CYANEX 272
extractant will extract cobalt preferentially to calcium when both are
present in the same feed stream. This performance characteristic is
demonstrated in Table 3 and Figure 1.
TABLE 3 – CALCIUM REJECTION IN THE PRESENCE OF
COBALT AND NICKEL
Solvent (v/o) 15% CYANEX 272 extractant, 10%
p-nonylphenol in Kermac 470B diluent
Aqueous (g/1) 1.60 Co, 77 Ni, 0.31 Ca as sulfates
Temperature 50°C
Contact Time 5 minutes
A/0 1
pH Control NH 4 OH
% Extraction Equilibrium
Co Ni Ca pH
3.1 0 0.95 1.99
17.2 0.04 1.24 3.34
54.3 0.17 3.33 3.85
91.7 1.03 12.0 4.84
98.3 3.95 25.7 5.72
100 13.4 5.16 6.63
FIgURE 1
Cobalt Extraction Isotherm
Procedural details and results of our extraction studies are given in
Table 4.
TABLE 4
Solvent (v/o) 12% CYANEX 272 extractant,
5% isodecanol in Kermac 470B diluent.
Aqueous (g/1) 5 Co as sulfate
Temperature 50°C
Equilibrium pH 5.0±0.1
pH Control 1N NaOH
Equilibrium Cobalt Concentration (g/l)
A/O Solvent Aqueous
10 6.32 4.68
5 6.13 4.13
2 5.54 2.58
1 2.72 0.06
The actual loading capacity of this solvent was 6 g/l cobalt, whereas
the stoichiometric capacity is approximately 10 g/l cobalt.
Cobalt Loading
Loading studies were carried out at 50°C and pH 6.0 ± 0.1. The
pH was controlled by the addition of ammonia. Other details and
results are shown in Table 5.
TABLE 5
Solvent (v/o) 30% CYANEX 272 extractant in
Kermac 470B diluent
Aqueous (g/l) 10 Co as sulfate
Theoretical Maximum (g/l) Approximately 24
Contact Time 5 minutes
Co % of Theoretical
A/O in Solvent (g/l) Maximum
0.5 5 21
1.0 10 42
1.5 15 63
3.0 23* 96
5.0 23* 96
*At this loading the solvent was judged to be too viscous for practical use. The 15 g/l
solvent did not exhibit this viscosity problem. The maximum practical loading for the
conditions cited is probably about 65-75 % of theoretical. This would correspond to a
CYANEX 272 extractant:cobalt ratio of 6:2.

It should be noted that the loading capacity of CYANEX 272
extractant will vary depending upon several parameters, notably pH,
temperature, and extractant concentration, and may be more or
less than the figure cited. For example, with a 15% CYANEX 272
extractant solution at 50°C and pH 5-5 the solvent can be loaded
to 100% of the theoretical maximum while remaining sufficiently
mobile for practical use.
Scrubbing Isotherm
As can be seen from the results in Table 6, even if a high quantity of
nickel is co extracted with the cobalt, it can be successfully scrubbed
from the loaded solvent.
TABLE 6
Solvent (v/o) 12% CYANEX 272 extractant,
5% isodecanol in Kermac 470B diluent
Solvent Loading (g/1) 1.9 Co, 1.9 Ni
Scrub Feed (g/1) 30 Co (as sulfate), initial pH 3.7
Temperature 50°C
Equilibrium Concentration
in Scrubbed Solvent (μg/ml)
O/A Co Ni Co-Ni Ratio
10 3820 4.5 850
5 3790 2.2 1720
2 3740 1.3 2900
1 3730 1.1 3400
Stripping Isotherms
Stripping from a solvent modified with isodecanol tended to
produce hazing. Substituting p nonylphenol or TBP for the
isodecanol essentially eliminated this problem.
Tables 7 and 8 show stripping isotherms obtained with a
p-nonylphenol modified solvent.
CYANEX 272 Extractant
7
TABLE 7 – USINg H 2 SO 4
Solvent (v/o) 12% CYANEX 272 extractant,
10% p-nonylphenol in Kermac 470B
diluent
Solvent Loading (g/l) 3.26 Co (2 μg/ml Ni)
Temperature 40°C
Contact Time 5 minutes
Strip Feed (g/1) 20.5 Co (as sulfate), 24.5 H 2 SO 4
Equilibrium Cobalt Conc. (g/l)
O/A Solvent Aqueous
6.67 0.58 38.4
5 0.22 35.7
4 0.19 32.5
3.33 0.03 31.3
2.86 0 29.8
2 0 27.0
TABLE 8 – USINg HCl
Solvent (v/o) 12% CYANEX 272 extractant,
10% p-nonylphenol in Kermac 470B
diluent
Solvent Loading (g/1) 9.26 Co
Temperature 50°C
Contact Time 5 minutes
Strip Feed (g/1) 19.4 Co (as chloride) 100 HCl
Equilibrium Cobalt Conc. (g/l)
O/A Solvent Aqueous
2 0 37.9
3 0 47.1
5 0 65.7
7.5 0.01 88.8
10 0.35 108.5
Continuous Separation of Cobalt from Nickel in
Sulfate Solution
In continuous countercurrent tests (four extraction and two scrub
stages) carried out at Warren Spring Laboratory (Stevenage, U.K.),
more than 99.5% of the cobalt in the feed was recovered as a
product containing a Co-Ni ratio of greater than 1000 to 1.

8 CYANEX 272 Extractant
The experimental conditions are shown below. A circuit flowsheet
and the relevant assays are given in Figure 2.
Solvent (v/o) 20% CYANEX 272 extractant (NH4
salt)*, 10% p-nonylphenol in the diluent
MSB 210**
Aqueous Feed (g/l) 2 Co, 100 Ni as sulfates, 20
(NH 4 ) 2 O 4 , pH 5
Scrub Feed (g/l) 40 Co as sulfate, pH 3
Temperature 50°C
Phase Ratios Extraction A/O = 2
Scrubbing O/A = 32
Mixer Residence Time 3.5-4 minutes (Based upon total
liquid flow)
*The phosphinic acid contained in the solvent was converted 70% to the ammonium
salt by reaction with concentrated ammonium hydroxide solution (S.G. = 0.88). A
phase modifier was used since converting more than 50% of the free acid to a salt
+ +
(NH4 or Na ) usually requires a modifier to prevent third phase formation.
** A product of Shell Chemical Co.
Effect of Process Variables on Cobalt-Nickel
Separation Factor
The effect of pH, temperature and diluent aromaticity on the
cobalt-nickel separation factor in sulfate solutions was measured
in a series of statistically designed tests and the data fitted to the
following mathematical model:
log 10 S = 1.8827 + 0.0332T + 0.01249A + 0.0033PT -
0.002151PA - 0.0003405T 2
Where:
FIgURE 2 – CONTINUOUS TESTINg OF CyANEx 272 ExTRACTANT
S = Co Ni Separation Factor
T = Temperature (ºC)
A = % Aromatics in diluent
P = Equilibrium pH

The effect of these process variables on the separation factor is
shown in Tables 9 through 11.
TABLE 9 – EFFECT OF TEMPERATURE
Solvent (v/o) 22% CYANEX 272 extractant in the
diluent (95% MSB 210* diluent, 5%
Aromatic 150** diluent).
Aqueous (g/l) 2 Co, 100 Ni as sulfates
pH 5.5
A/O 1
Co-Ni Separation Factor Temperature °C
* A product of Shell Chemical Co.
**A product of Exxon Co., USA.
1320 30
1850 35
2480 40
3220 45
4000 50
4790 55
5510 60
TABLE 10 – EFFECT OF EQUILIBRIUM pH
Temperature 50°C
Diluent (v/o) 95% MSB 210, 5% Aromatic 150
Other Conditions See Table 9
Co-Ni Separation Factor pH
2810 4.5
3010 4.7
3230 4.9
3470 5.1
3730 5.3
4000 5.5
CYANEX 272 Extractant
TABLE 11 – EFFECT OF DILUENT AROMATICITy
Temperature 50°C
Diluent (v/o) 100% MSB 210 (aliphatic) to
pH 5.5
100% Aromatic 150
Other Conditions See Table 9
Co-Ni Separation Aromaticity
Factor v/o
3970 0
4030 10
4090 20
4160 30
4220 40
4280 50
4350 60
4420 70
4480 80
4550 90
4620 100
9
The effect of the phase modifiers TBP, p-nonylphenol, isodecanol
and TOPO (tri-n-octylphosphine oxide) on the separation factor is
shown in Table 12.
TABLE 12 – EFFECT OF PHASE MODIFIER
Extractant (v/o) 22%
Modifier 10 v/o (TBP, isodecanol,
p-nonylphenol) 10 w/o TOPO
(solid)
Aqueous (g/l) 10 Co, 100 Ni as sulfates
A/O 1
Temperature 55°C
Equilibrium pH 5.5
Contact Time 5 minutes
Diluent MSB 210
Co-Ni Separation
Modifier Factor
None 6700
TBP 3400
p-Nonylphenol 1800
Isodecanol 1000
TOPO 1000

10 CYANEX 272 Extractant
OTHER POTENTIAL APPLICATIONS
Diluent Oxidation and Prevention
Hydrocarbon diluents oxidize readily to carboxylic acids in the
presence of a cobalt (Co 2+ ) catalyst. The formation of carboxylic
acids, which are active nickel extractants, can seriously reduce the
cobalt-nickel selectivity obtained with CYANEX 272 extractant.
However, inhibitors such as BHT can be used to prevent this
oxidation. Plants following this practice have run for many years
without loss of selectivity.
Recovery from Ammoniacal Solutions
CYANEX 272 extractant can be used to recover cobalt from
ammoniacal as well as acidic solutions. The data in Table 13 show
that it outperforms other organophosphorus extractants.
TABLE 13 – ExTRACTION FROM AMMONIACAL
SOLUTIONS
Solvent (v/o) 20% extractant, 5% isodecanol in
Kermac 470B diluent
Aqueous (g/L) 0.97 Co 3+ , 0.95 Ni 2+ , (NH4 ) 2SO4 for
2-
a total SO4 concentration of 16
Temperature 50°C
pH Control 11.6 with NH 4 OH
Contact Time 5 minutes
A/0 1
% Extracted Co/Ni
Extractant Co Ni Separation Factor
CYANEX 272 91.5 15.6 58
PC-88A 91.4 22.0 18
D2EHPA 90.4 46.9 7
Although CYANEX 272 extractant is designed primarily for cobaltnickel
separations, the data in Tables 14 and 15, and Figures 3 and
4 show that it will extract a variety of metal cations and indicate its
potential for other selective separations.
TABLE 14 – ExTRACTION FROM SINgLE METAL SULFATE
SOLUTIONS
Solvent 0.6 M CYANEX 272 extractant, 10 v/o
p-nonylphenol in Kermac 470B
diluent
Aqueous 0.015 M metal as sulfate
Temperature 50ºC
pH Control NH 4 OH or H 2 SO 4 as appropriate
Contact Time 5 minutes
A/O 1
Metal % Ext. Final pH Metal % Ext. Final pH
8.8 0.25 27.6 6.33
23.6 0.85 36.0 6.59
Fe 3+ 61.2 1.33 Ni 2+ 52.3 6.72
88.1 1.75 84.0 7.22
98.7 2.31 92.8 7.47
14.6 0.90 14.5 3.00
24.2 1.42 29.7 4.20
Zn 2+ 53.3 1.88 Mg 2+ 67.1 4.76
87.7 2.40 82.0 4.99
99.4 3.08 97.4 5.81
6.4 1.73 23.9 1.11
17.7 2.64 41.9 2.50
Cu 2+
21.7 2.90 Al 3+
87.5 2.92
73.9 3.56 97.2 3.14
85.7 3.84
94.8 4.08
9.2 1.78 42.3 3.40
Co 2+ 19.0 3.34 Mn 2+ 86.1 3.96
70.8 4.11 99.8 5.66
99.8 5.98
Ca 2+ 3.4 4.15 7.9 1.11
20.4 4.53 V 4+ 21.1 1.34
81.7 5.38 46.5 1.44
99.6 6.52 85.1 1.81
4.2 2.00
19.7 3.00
Cd 2+ 63.1 3.51
91.0 4.00
99.5 5.00

TABLE 15 – ExTRACTION FROM SINgLE METAL
CHLORIDE SOLUTIONS
Solvent 0.6 M CYANEX 272 extractant in
Exxsol D-80
Aqueous 0.015 M metal as chloride
Temperature 50°C
pH Control NH 4 OH or HCl as appropriate
Contact Time 5 minutes
A/O 1
Metal % Ext. Final pH Metal % Ext. Final pH
0.0 3.33 32.6 0.2
25.7 4.36 35.2 0.3
Ca 2+ 48.9 5.00 Fe 3+ 66.4 0.7
91.9 5.90 95.2 1.1
99.4 6.45 99.0 1.4
1.9 2.8 0.0 2.0
48.0 3.5 8.5 2.6
Co 2+ 86.7 4.1 Cu 2+ 51.9 3.1
95.9 4.4 86.2 3.5
100.0 5.5 97.6 3.9
0.0 3.6 12.6 0.9
19.3 4.9 22.6 1.2
Ni 2+ 44.7 5.2 Zn 2+ 54.2 1.6
84.8 5.9 67.9 1.7
95.1 6.3 76.2 1.8
99.7 7.0 92.9 2.1
1.2 3.4
41.2 4.4
Mg 2+ 66.2 5.0
89.1 5.4
99.0 6.4
99.9 6.6
CYANEX 272 Extractant
11

12 CYANEX 272 Extractant
Figure 3 – Extraction of Metals by CyANEx 272 Extractant from Sulfate Solutions
Figure 4 – Extraction of Metals by CyANEx 272 Extractant from Chloride Solutions

ANALYTICAL METHODS
Analysis for Active Component in CYANEX 272
Extractant in Organic Solvents by Titration
The active component of CYANEX 272 extractant is bis(2,4,4trimethylpentyl)phosphinic
acid. Its concentration in an organic
solvent is determined by titration with standard caustic solution.
The extractant contains small quantities of a dibasic impurity (2,4,4-
trimethylpentyl phosphonic acid) which also titrates with caustic.
The endpoints are detected potentiometrically.
Apparatus
pH meter
Magnetic stirrer
Standard laboratory glassware
Reagents
75 v/o 2-propanol in distilled water
0.1N Standard NaOH solution in 75 v/o 2-propanol
100 g/l H 2 SO 4
All reagents are AR grade.
Procedure
1. Contact approximately 50 ml of the solvent to be analyzed
with 50 ml of 100 g/l H 2 SO 4 for 5 minutes at 50°C. Separate
the phases and allow to stand for 15-30 minutes. Centrifuge the
solvent or filter through PS paper* to remove entrained aqueous.
2. To prepare the analyte solution, pipette a 25 ml aliquot of the
solvent and dilute to 200 ml in a volumetric flask with the
appropriate diluent (Escaid**, Kermac*** etc.). Alternatively, the
75 v/o solution of 2-propanol may be used for volume make-up.
3. Pipette 25 ml of the analyte solution into a 150 ad tall-form
beaker. Dilute to approximately 50 ml with the 2-propanol
solution. Insert the pH electrodes and begin stirring.
* Phase separation paper available from Whatman Inc.,Clifton, NJ.
** A product of Exxon Chemical Co., USA
*** A product of Kerr McGee Refining Corp.
CYANEX 272 Extractant
13
4. Note the initial pH and begin to titrate with 0.1N NaOH.
Record the pH as a function of the volume of NaOH added.
Three endpoints should be observed. As each endpoint is
approached, the incremental addition of NaOH should be
reduced to 0.1 ml to facilitate calculation of the titer by the
method of second differences.
Calculation
A typical potentiometric curve is as follows:
The titer T1 corresponds to the neutralization of sulfuric acid
dissolved in the solvent. T2 represents the neutralization of the
phosphinic acid plus the reaction of the first of two replaceable
hydrogen ions associated with the phosphonic acid. The phosphonic
acid is totally neutralized at T3.
0.1N NaOH First Second
(ml) pH Differential Differential
9.8 7.50
9.9 8.00
50
90
+40
10.0 8.90
180
+90
10.1 10.70
50
-130
10.2 11.20
10
-40
10.3 11.30
Then, T2 = (10.0 + 0.1) x ____90___ = 10.04 ml
90 + 130

14 CYANEX 272 Extractant
T 1 and T 3 may be calculated in an analogous manner.
When all three titers are known, the concentration of bis(2,4,4trimethylpentyl)phosphinic
acid may be determined.
bis(2,4,4-trimethylpentyl) phosphinic acid (g/1) =
[T 2 – (T 3 – T 2 ) – T1] x N(NaOH) x 290 x 1000
1000 x 25 x 25
200
Similarly the concentration of the phosphonic acid and dissolved
sulfuric acid may also be calculated.
2,4,4-trimethylpentyl phosphonic acid (g/1) =
Notes
T 3 – T 2 x N(NaOH) x 194 x 1000
1000 x 25 x 25
200
H 2 SO 4 (g/l) = T 1 x 49 x N(NaOH) x 1000
1000 x 25 x 25
200
1. A minimum net titer, i.e. [T 2 – (T 3 – T 2 ) – T 1 ], of 10 ml is
recommended to obtain reproducible results. In this procedure,
10 ml of 0.1N NaOH is equivalent to approximately 100 g/l
concentration of phosphinic acid. Where necessary, the size of the
aliquots and dilutions may be varied to ensure a sufficient volume of
titrant is consumed.
2. Approximate pH’s corresponding to the T 1 , T 2 and T 3 endpoints are
4, 9 and 11, respectively. However these values may vary depending
upon the composition of the solvent. After gaining experience with
a system, the NaOH may be added rapidly until the particular
endpoint pH is approached and then added in 0.1 ml increments to
define the point of inflexion in the curve.
3. The concentrations of sulfuric and phosphonic acids in the solvent
are usually small and these endpoints may not be observed. In this
case T 1 and T 3 should be assigned a value of zero in the calculations.
Typically, T 1 and T 3 - T 2 ) will be < 0.2 and < 0.1 ml of 0.1N
NaOH, respectively, corresponding to

Detector Parameters
Type Flame Ionization Detector (FID)
Temperature 300°C
Helium Flow 8 mL/min
Hydrogen Flow 35 mL/min
Air Flow 400 mL/min
Makeup Flow 35 mL/min
Makeup Gas Type Helium
Sample Injection
Volume 0.1 μL
Peak Areas Electronic integration. The compound has a
retention time of about 17.8 minutes.
Analysis for Active Component in CYANEX
272 Extractant in Aqueous Solutions by Gas
Chromatography
The concentration of the active component, bis(2,4,4trimethylpentyl)phosphinic
acid in water is determined by gas
chromatography of its methylated derivative.
Procedure
1. Transfer approximately 1 L of the aqueous solution into a
plastic container and place it in a water bath set for 45°C for
a few hours.
2. Remove the solution from the water bath and allow to cool to
room temperature.
3. From the bottom of the plastic container, dispense 600 g of
the solution into a 1 L separatory funnel.
4. Add to the solution 5 mL of concentrated sulphuric acid, 50
mL of toluene and approximately 100 g of sodium chloride.
5. Separate both aqueous and organic phases.
6. Pipette a 1000 μL aliquot of the organic phase and transfer
it into a HP autosampler vial. Add 200 μL of Methyl-8 ®
Concentrate.
7. Prepare standard solutions of CYANEX 272 extractant in
toluene.
8. Pipette a 1000 μL aliquot of the standard solutions and
transfer it into a HP autosampler vial. Add 200 μL of
Methyl-8 ® Concentrate.
9. Analyze the methylated sample and standard solutions by
gas chromatography. The chromatographic conditions
are identical to those previously described in the section
“Analysis for Active Component in CYANEX 272 Extractant
in Organic Solvents by Gas Chromatography,” except the
volume injected by the GC autosampler is 1.0 μL.
CYANEX 272 Extractant
Health and Safety
15
The oral and dermal toxicity of CYANEX 272 extractant is low.
CYANEX 272 extractant produces moderate eye and skin irritation
upon contact. CYANEX 272 extractant did not produce an allergic
dermal reaction in guinea pigs after repeated dermal exposure.
This product did not produce mutations in bacteria. CYANEX
272 extractant is toxic to fish and invertebrates and care should be
exercised to avoid environmental exposure.
Technical reference list available upon request.

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