cyanex ® 272 extractant

CYANEX® 272 Extractant

2 CYANEX 272 Extractant

CYANEX® 272 ExtractantCYANEX® 272 Extractant

CONTENTSINTRODUCTIONChemical Structure .............................................................................3Typical Properties ...............................................................................3Stability ...............................................................................................3Solubility Losses .................................................................................4Toxicity ...............................................................................................4Suitability of Construction Materials ..................................................4

COBALT RECOVERYCobalt Nickel Selectivity .....................................................................5 Sulfate Solution (Table 1) ............................................................5 Chloride Solution (Table 2) ..........................................................5Calcium Rejection ...............................................................................6Cobalt Extraction Isotherm.................................................................6Cobalt Loading ...................................................................................6Scrubbing Isotherm ............................................................................7Stripping Isotherms ............................................................................7 Using H2SO4 (Table 7) .................................................................7 Using HCl (Table 8) ......................................................................7Continuous Separation of Cobalt from Nickel in Sulfate Solution ..................................................................................7Effect 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 APPLICATIONSDiluent Oxidation and Prevention ....................................................10Recovery from Ammoniacal Solutions (Table 13) ............................10Extraction from Single Metal SulfateSolutions (Table 14) .........................................................................10Extraction from Single Metal ChlorideSolutions (Table 15) .........................................................................11

ANALYTICAL METHODSIn Organic Solvents by Titration .......................................................13In Organic Solvents by Gas Chromatography ..................................14In Aqueous Solutions by Gas Chromatography ...............................15

HEALTH AND SAFETY ..............................................15

Solvent Extraction Reagent

•Selectiveforcobaltovernickelfromsulfateandchloridemedia.

•Selectiveforzincinthepresenceofcalciumandcobalt.

•Extractsothermetalcations.


3CYANEX 272 Extractant


INTRODUCTIONCYANEX® 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 StructureThe active component of CYANEX 272 extractant is bis(2,4,4-trimethylpentyl)phosphinic acid.

Typical Properties Bis(2,4,4-trimethylpentyl)phosphinic acid 85%

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 H2O at pH 2.6 16 μg/ml

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

StabilityThe 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 31P 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.



Solubility LossesLosses 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.

ToxicityThe acute oral (rat) and acute dermal (rabbit) LD50 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 LC50, (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 MaterialsMetals: 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 81/2 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 RemarksButyl 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




COBALT RECOVERYCobalt-Nickel SelectivityThe 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.

TABLE1–SULFATESOLUTION

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 NH4OH

% 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

TABLE2–CHLORIDESOLUTION

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



Calcium RejectionUnlike 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.

TABLE3–CALCIUMREJECTIONINTHEPRESENCEOFCOBALTANDNICKEL

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 NH4OH

% 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

FIgURE1

Cobalt Extraction IsothermProcedural details and results of our extraction studies are given in Table 4.

TABLE4

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 LoadingLoading 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.

TABLE5

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 IsothermAs 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.

TABLE6

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 Concentrationin 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 IsothermsStripping 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.

TABLE7–USINgH2SO4 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 H2SO4

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

TABLE8–USINgHCl

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 SolutionIn 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.



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 (NH4)2O4, 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 FactorThe 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:

log10S = 1.8827 + 0.0332T + 0.01249A + 0.0033PT - 0.002151PA - 0.0003405T2

Where:

S = Co Ni Separation Factor

T = Temperature (ºC)

A = % Aromatics in diluent

P = Equilibrium pH

FIgURE2–CONTINUOUSTESTINgOFCyANEx272ExTRACTANT




The effect of these process variables on the separation factor is shown in Tables 9 through 11.

TABLE9–EFFECTOFTEMPERATURE

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

1320 30 1850 35 2480 40 3220 45 4000 50 4790 55 5510 60

* A product of Shell Chemical Co.

**A product of Exxon Co., USA.

TABLE10–EFFECTOFEQUILIBRIUMpH

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

TABLE11–EFFECTOFDILUENTAROMATICITy

Temperature 50°C

Diluent (v/o) 100% MSB 210 (aliphatic) to

100% Aromatic 150

pH 5.5

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

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.

TABLE12–EFFECTOFPHASEMODIFIER

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


Diluent MSB 210

Co-Ni Separation Modifier Factor

None 6700 TBP 3400 p-Nonylphenol 1800 Isodecanol 1000 TOPO 1000



OTHER POTENTIAL APPLICATIONSDiluent Oxidation and PreventionHydrocarbon diluents oxidize readily to carboxylic acids in the presence of a cobalt (Co2+) 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 SolutionsCYANEX 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.

TABLE13–ExTRACTIONFROMAMMONIACALSOLUTIONS

Solvent (v/o) 20% extractant, 5% isodecanol in Kermac 470B diluent

Aqueous (g/L) 0.97 Co3+, 0.95 Ni2+, (NH4)2SO4 for a total SO4

2- concentration of 16

Temperature 50°C

pH Control 11.6 with NH4OH


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 cobalt-nickel 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.

TABLE14–ExTRACTIONFROMSINgLEMETALSULFATESOLUTIONS

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 NH4OH or H2SO4 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 6.59Fe3+ 61.2 1.33 Ni2+ 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 4.20Zn2+ 53.3 1.88 Mg2+ 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 2.50Cu2+ 21.7 2.90 Al3+ 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 3.40Co2+ 19.0 3.34 Mn2+ 86.1 3.96 70.8 4.11 99.8 5.66 99.8 5.98

Ca2+ 3.4 4.15 7.9 1.11 20.4 4.53 V4+ 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 Cd2+ 63.1 3.51 91.0 4.00 99.5 5.00




TABLE15–ExTRACTIONFROMSINgLEMETALCHLORIDESOLUTIONS

Solvent 0.6 M CYANEX 272 extractant in Exxsol D-80

Aqueous 0.015 M metal as chloride

Temperature 50°C

pH Control NH4OH or HCl as appropriate


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 0.3Ca2+ 48.9 5.00 Fe3+ 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 2.6Co2+ 86.7 4.1 Cu2+ 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 1.2Ni2+ 44.7 5.2 Zn2+ 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 Mg2+ 66.2 5.0 89.1 5.4 99.0 6.4 99.9 6.6



Figure3–ExtractionofMetalsbyCyANEx272ExtractantfromSulfateSolutions

Figure4–ExtractionofMetalsbyCyANEx272ExtractantfromChlorideSolutions




ANALYTICAL METHODSAnalysis for Active Component in CYANEX 272 Extractant in Organic Solvents by TitrationThe active component of CYANEX 272 extractant is bis(2,4,4-trimethylpentyl)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.

ApparatuspH meterMagnetic stirrerStandard laboratory glassware

Reagents75 v/o 2-propanol in distilled water0.1N Standard NaOH solution in 75 v/o 2-propanol100 g/l H2SO4

All reagents are AR grade.

Procedure1. Contact approximately 50 ml of the solvent to be analyzed

with 50 ml of 100 g/l H2SO4 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.

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.

CalculationA 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 50 9.9 8.00 +40 90 10.0 8.90 +90 180 10.1 10.70 -130 50 10.2 11.20 -40 10 10.3 11.30

Then, T2 = (10.0 + 0.1) x ____90___ = 10.04 ml 90 + 130



T1 and T3 may be calculated in an analogous manner.

When all three titers are known, the concentration of bis(2,4,4-trimethylpentyl)phosphinic acid may be determined.

bis(2,4,4-trimethylpentyl) phosphinic acid (g/1) =

[T2 – (T3 – T2) – 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) =

T3 – T2 x N(NaOH) x 194 x 1000

1000 x 25 x 25 200

H2SO4 (g/l) = T1 x 49 x N(NaOH) x 1000

1000 x 25 x 25 200

Notes1. A minimum net titer, i.e. [T2 – (T3 – T2) – T1], 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 T1, T2 and T3 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 T1 and T3 should be assigned a value of zero in the calculations. Typically, T1 and T3 - T2) will be < 0.2 and < 0.1 ml of 0.1N NaOH, respectively, corresponding to <0.3 g/l H2SO4 and < 0.6 g/l phosphonic acid

Analysis for Active Component in CYANEX 272 Extractant in Organic Solvents by Gas ChromatographyThe concentration of the active component, bis(2,4,4-trimethylpentyl)phosphinic acid in the organic solvent is determined by gas chromatography of its methylate derivative.

Procedure1. Pipette a 400 μL aliquot of the organic phase and transfer

it into a HP autosampler vial. Add 400 μL of Methyl-8® Concentrate* (dimethylformamide dimethyl acetal) and 400 μL of toluene.

2. Prepare standard solutions of CYANEX 272 extractant in toluene.

3. Pipette a 400 μL aliquot of the standard solutions and transfer it into a HP autosampler vial. Add 400 μL of Methyl-8® Concentrate and 400 μL of toluene.

4. Analyze the methylated sample and standard solutions by gas chromatography as described under chromatographic conditions.

* A product of Pierce Co., USA

Chromatographic ConditionsInstrument: Hewlett-Packard 6890

Oven Parameters Initial Temperature: 50°CFinal Temperature: 300°CMaximum Temperature: 310°CRate: 10°C per minuteInitial Time: 0 min.Final Time: 10 min.Run Time: 35 min.

Inlet ParametersMode: SplitInitial Temperature: 300°CPressure: 4.7 psiSplit Ratio: 10:1Split Flow: 68.9 mL/minTotal Flow: 78.3 mL/minGas Saver: OnSaver Flow: 15.0 mL/minSaver Time: 2 minGas Type: Helium

Column Parameters Type: J&W capillary column type DB-5 (5% phenyl-methylpolysiloxane)Model Number: J&W J125-5032 DB-5Maximum Temperature: 300°CNominal Length: 30 mNominal Diameter: 540 μmNominal Thickness: 1.50 μmMode: Constant flowInitial Flow: 6.9 mL/minNominal Initial Pressure: 4.7 psiAverage Velocity: 47 cm/sec




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 ChromatographyThe concentration of the active component, bis(2,4,4-trimethylpentyl)phosphinic acid in water is determined by gas chromatography of its methylated derivative.

Procedure1. 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.

Health and SafetyThe 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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cyanex ® 272 extractant

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