Faculty of Science – Chemistry

Ó William L. Primrose, 2019

Matrix and pH Effects on the Degradation Kinetics of Xanthates in
Mining Waters
William L. Primrose, Adrian M. Batista. Supervisor: Dr. Kingsley Donkor

ARTICLE INFO

ABSTRACT

Date of Submission:

Determination of optimal pH conditions for a xanthate solution
representative of a real matrix in an industrial setting (such as a
flotation tank or a tailings pond) was researched to help ensure
mill efficiency in mines. The primary method for analysis was the
use of headspace GC-MS. Aqueous samples of xanthates in basic
solutions without minerals were tested for degradation by testing
for the generation of carbon disulfide (CS2). Potassium isopropyl
xanthate (PIPX) and potassium amyl xanthate (PAX) were primarily
studied and rate constants were compared to determine optimal
pH conditions for the slowest degradation of individual xanthates.
The rate constant for 110.6 ppm PIPX was found to be 5.79 x 10-5 h-1
at pH 7.73; at the same pH, the rate constant was found to be 3.91 x
10-6 h-1 for 1075.2 ppm. The rate constant for PAX was found to be
5.43 x 10-5 h-1 at pH 9.08, 1.23 x 10-5 h-1 at pH 9.26, 8.12 x 10-6 h-1 at pH
9.34, and 4.36 x 10-5 h-1 at pH 9.48.

30 May 2019

Keywords:
Xanthate
Decomposition
Rate
Carbon disulfide
Gas Chromatography-Mass
Spectrometry

Introduction

mineral via xanthate with 100 % efficiency;

Xanthates are a class of chemical that are
consistently used in the mining industry

one of the leading problems with xanthates
in the mill processes of large mines is that

during their mill process as a way to collect

they are used in aqueous conditions

minerals from ore samples by way of
floatation. They are popular due to their low

wherein water is a key factor in the
degradation of the xanthates in solution.

cost and their efficient ability to bind to
metals of interest such as copper, nickel,

This degradation releases carbon
disulphide which in turn renders the ability

zinc, and iron (Shen et al., 2016). Xanthates

of that molecule to bind to a mineral inert

share similarities in their dithiocarbonate

without the presence of a negatively

groups and vary in their alkyl chains,
written as R-OCS2- (Shen et al., 2016). The

charged sulphur. Thus, a deeper
understanding of xanthate kinetics in

negatively charged sulphur is what binds to

aqueous conditions is necessary to

the metals in the floatation tanks and is

optimize mill processes.

frothed to float it to the top for collection
(Kemppinen et al., 2014). However, the

Carbon disulphide (CS2) is a liquid at room
temperature but is highly toxic and volatile

process is not a simple extraction of

with a vapour pressure of 48.210 kPa at 25

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Faculty of Science – Chemistry

Ó William L. Primrose, 2019

°C (World Health Organization, 2005). As
such, minimizing the generation of CS2 not

Aldrich Canada Ltd., Oakville, Ontario,
Canada. New Afton Gold Mine in Kamloops,

only has an economic impact through
lessened use of xanthates over time, it also

BC, Canada provided solid xanthate
samples. Nearly all samples were dissolved

has a health and environmental
implication if less CS2 is produced due to its

in 18 MW water; where 18 MW water was
unavailable, deionized water was used

tendency to accumulate thus posing a risk
to workers nearby as well as the

instead.

environment surrounding a given mine
(Shen et al., 2016).

Instrumentation

Due to the high volatility of CS2, testing for
its presence is easily done in a sealed

Agilent 7890B-GC coupled 5977A-MS using
an Agilent PAL3 auto sampler with a

headspace vial. As such, in this project
xanthate degradation was studied using

headspace injection tool. An HP-5MS 5%
phenyl methyl silox capillary column was

headspace Gas Chromatography-Mass
Spectrometry (GC-MS). The GC was used for

used. For the remainder of the instrument
parameters, see Table 1.

the quantification of CS2 generated and the
MS was used for confirming the presence

Table 1. Instrument and Method Parameters

of CS2 by looking for a peak at 76 m/z.
Following the previous study by Batista
(2018) which showed xanthate
decomposition follows first order kinetics,
this project’s goal was to study the effects
of pH on the decomposition behaviour of
xanthates in aqueous solution. In particular,
this research is focused on the comparison
of different xanthates using the same
method, something not currently found in
the literature. After developing the method
for detection of CS2 under varying pH, the
goal was to compare four different
xanthates; two were primarily studied and
the rest will be studied in future trials.
Reagents

Pure, analytical-grade CS2 was readily
available from the Thompson Rivers
University (TRU) Chemistry Department
and was originally purchased from Sigma-

All trials were isothermal and run on TRU’s

Sample Volume (mL):

0.075

Incubation Time (min):

15

Heat Agitator:

On

Incubation Temperature (°C):

30

Heat Syringe:

On

Syringe Temperature (°C):

46

Pre Injection
Flush Time (s):

10

Sample
Sample Vial Penetration Depth (mm):

15

Sample Vial Penetration Speed (mm/s): 50
Sample Aspirate Flow Rate (mL/min):

12

Sample Post Aspirate Delay (s):

1

Injection Signal Mode:

Plunger Up

Inlet Penetration Depth (mm):

45

Inlet Penetration Speed (mm/s):

50

Pre Inject Time Delay (s):

0.5

Injection Flow Rate (mL/min):

1

Post Inject Time Delay (s):

0.5

Flush Time (s):

60

Continuous Flush:

On

Advanced
Agitator Speed (rpm):

250

Agitator On Time (s):

15

Agitator Off Time (s):

5

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Faculty of Science – Chemistry

Ó William L. Primrose, 2019

Run time for the sample was set to 5 min
and the GC oven was set to 33 °C; the intent

Sample Preparation

was to set a temperature close to ambient
temperature to replicate mill conditions.

was added to a 500 mL volumetric flask and
diluted to the mark with 18 MW water to

However, cooling the oven to 25 °C proved
to be difficult, so 33 °C was a choice made

prepare stock solutions of approximately
100 ppm. Stock solutions we remade after a

from instrumental limitations. The GC was
run with a split ratio of 100:1 and a split flow

solution was a week old and were made
from 98% pure potassium isopropyl

of 100 mL/min.
The MS began its scan at 1.75 min following

xanthate (PIPX) and 97% pure potassium
amyl xanthate (PAX) Each sample vial was

the 1.75 min solvent delay and scanned
between BLANK and BLANK m/z.

a 20 mL headspace vial with 10 mL of stock
solution added to it. The pH level was

Calibration – Preparation of CS2

adjusted using 0.012 M sodium hydroxide;
Shen et al. used sodium hydroxide to set pH

Stock solution of CS2 was made by adding
79.4 µL of pure CS2 to 100 mL of 18 MW

in their method and as such their method
was applied here, though a buffer solution

water, forming 100 ppm solution. Then, 10
mL of the 100 ppm stock solution was

may also be a viable method of pH control
for future studies. The pH level was

diluted with 18 MW water in a 100 mL

adjusted to various levels as per Tables 3 –

volumetric flask to form 10 ppm stock

6.

Approximately 0.0500 g of solid xanthate

solution. The 10 ppm stock solution was
used to generate the standards for the

Results and Discussion

calibration curve as per Table 2.

Calibration

Table 2. Preparation of Calibration Curve

The calibration curve, shown in Figure 1,

Volume Stock Final Volume

Concentration

added (mL)

(mL)

(ppm)

0.5

100.0

0.05

shows the concentration of CS2 in ppm of
the standards and the respective peak area

1.0

100.0

0.10

5.0

100.0

0.50

10.0

100.0

1.00

15.0

100.0

1.50

was found to be 0.0023 ppm and the limit of
quantification (LOQ) was found to be 0.023

20.0

100.0

2.00

ppm.

observed; the calibration curve showed
good linearity. The limit of detection (LOD)

As per the recommendation of Li et al.

Minimizing Loss of CS2

(2015), the standards were agitated in their vials for 15 min prior to injection.

One goal of the method development was
to increase the reproducibility of the trials.

Headspace vials with a 20 mL capacity

A concern was raised that due to its
volatility, some CS2 may have been

were used for all standards and 10 mL of
the stock solutions were added to the vials.

escaping the headspace vials each time a
vial cap was pierced by the heated injection

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Faculty of Science – Chemistry

Ó William L. Primrose, 2019

syringe. Thus, trials a – f were done in the
following manner: for each pH level, 8

the R2 values become 0.9033, 0.8727, and
0.9518, respectively. This observation is left

separate vials were created under the same
conditions (10 mL aliquot of xanthate

as an aside to show the projected
correlation because the values go closer to

sample in same pH condition) and sealed
with brand new headspace caps with the

unity, however statistical determination of
which data points to remove was not

intention that each cap would only be
pierced once. Therefore, vial 1 would be

completed and so the data herein is
reported as recorded. Data for trials g – p

pierced at hour 1, vial 2 at hour 2, and so on
and so forth. Assuming that the rate of

are shown in Figure 3 and Table 8.

decomposition remains constant between
trials, then the data from each vial should

Final Results

still follow a linear, first-order curve.
Further, if it was true that the use of an

evolution increases as pH is decreased and
furthermore, the rate follows a linear trend.

individual vial was skewing the precision,
then the R2 value on the corresponding

Shen et al. (2016) also showed a similar
trend with sodium isobutyl xanthate (SIBX)

curve would be expected to increase
compared to a curve from a method using

wherein the xanthates decomposed to the
greatest extent at approximately pH 2 and

only one vial being pierced every hour.

decomposed less and less as pH increased.

However, increased reproducibility was not

Their research was primarily focused on

observed. Instead, trials a – f heralded

developing a method to act as a foundation

erratic results from data point to data point

for researching these compounds further,

and no discernable trend was found as seen
in Figure 2 (Table 7).

whereas the aim of this project was to
begin filling in specific gaps in the

Overall, the data shows that the rate of CS2

literature regarding rate constants.
Using a method which used a single vial
per trial which is pierced multiple times
over a set time interval drastically

The rate constant for 110.6 ppm PIPX was
found to be 5.79 x 10-5 h-1 at pH 7.73; at the

improved results and a trend was found.
Over time, CS2 evolved in a manner

same pH, the rate constant was found to be
3.91 x 10-6 h-1 for 1075.2 ppm. While the rate

consistent with first order kinetics and the
reproducibility was within reasonable

is noticeably smaller at the higher
concentration, and assuming a constant

limits (R2 = 0.8641 – R2 = 0.9811). In trials n

rate, is should follow that the rate constant

through p, however, an instrument error
resulted in the data being skewed for the

will decrease as per the equation Rate =
k[xanthate] i.e. as the xanthate

first data point in each series. For trials n, o,
and p, the R2 values observed were 0.7394,

concentration increases, a constant rate
will cause a decrease in rate constant. As

0.7383, and 0.8554, respectively. However, if
the first data point in each set is discarded,

such, no major difference in rate between

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Faculty of Science – Chemistry

Ó William L. Primrose, 2019

concentrations was observed at this level of
experimentation.

by by-products such as carbon disulphide
gas. This will help ensure that mines can

The rate constants for potassium amyl

create environmentally sustainable
procedures and processes to keep their

xanthate (PAX) are shown in Table 8 and 9,
but Table 9 shows the trend as pH level

workers in safe conditions and their mills
operating at peak efficiency.

rises. The slowest rate constant appears at
pH = 9.34. The rate constant begins to

Future Work

increase again slightly at pH 9.48 which
may be a result of the alkaline conditions

The next step for this project is to run more
trials with additional xanthates, namely

facilitating the appearance of dixanthogen
compounds or dithiocarbonates which

sodium isobutyl xanthate (SIBX) and
sodium ethyl xanthate (SEX) for further

have been detected in more basic solutions
(Shen et al., 2016). This suggests that there

comparison of common xanthates used in
the industry. As well, calculation of figures

exists a “sweet spot” for pH level such that
higher pH slows the rate of decomposition,

of merit and validation of the method will
be done in the next stages of the research.

but pH that is too high allows side reaction
rates to increase, thus using up xanthates

Additionally, trials should be done in a
buffer solution as well to determine the

anyway. Further trials will have to be

efficiency of adjusting the pH using solely

conducted over smaller pH intervals to

NaOH. Lastly, further trials will have to be

prove this.

conducted over smaller pH intervals to
prove where the minimum rate constant

Conclusion

exists for each xanthate.

This project has shown that xanthate
decomposition rate constants tend to
decrease at higher pH levels which is in
line with literature that suggested an
increased rate of degradation in more
acidic conditions. However, highly alkaline
conditions may also be increasing the rate
of xanthate decomposition.
The implications of this research include
increase in mineral yield such that mining
companies (like New Gold New Afton Mine)
can further develop their industrial
processes to make better use of xanthates.
As well, mining companies will be able to
minimize and potentially decrease
environmental and health hazards posed

Acknowledgements

I would like to thank Dr. Kingsley Donkor
and Dr. Dipesh Prema for their support as
well as Trent Hammer for his instrument
expertise and guidance. Thank you to
Dayton Shaw for helping keep the lab
spaces safe and organized and thank you to
TRU’s Chemistry Department for continued
support. A big thank you to New Afton Gold
Mine for support and providing samples,
and to NSERC for providing funds to make
this project possible. Finally, thank you to
the TRU Research Office (UREAP) for
funding my project. This has been an
invaluable experience and I am grateful to
all those involved for making this project a
success.

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References

1. Kemppinen J, Aaltonen A, Sihvonen T, Leppinen J, Sirén H. 2015. Xanthate
degradation occurring in flotation process waters of a gold concentrator plant.
Elsevier [Internet]. 25 September 2018; Minerals Engineering Volume 80: 1 – 7.
Available from https://link.springer.com/article/10.1007%2Fs11270-010-0598-3 DOI
http://dx.doi.org/10.1016/j.mineng.2015.05.014
2. Li N, Chen Y, Zhang C, Zhou W, Fu M, Chen W, Wang S. 2015. Highly Sensitive
Determination of Butyl Xanthate in Surface and Drinking Water by Headspace Gas
Chromatography with Electron Capture Detector. Chromatographia [Internet].
Volume 78: 1305 – 1310. Available from
https://link.springer.com/content/pdf/10.1007%2Fs10337-015-2940-9.pdf DOI
10.1007/s10337-015-2940-9
3. Michaud D. [Internet]. 2015. Flotation Collectors. 911 Metallurgist:
911metallurgist.com; [updated 10 August 2015; cited 25 September 2018]. Available
from https://www.911metallurgist.com/blog/flotation_collectors
4. Mustafa, S., Hamid, A., Naeem, A., Sultana, Q. (2004). Journal of the Chemical Society
of Pakistan. 26(4): 363-366
5. Rostad C E, Schmitt C J, Schumacher J G, Leiker T J. 2010. An Exploratory
Investigation of Polar Organic Compounds in Waters from a Lead–Zinc Mine and
Mill Complex. Water, Air, & Soil Pollution [Internet]. Volume 217 (1 – 4): 431 – 443.
Available from https://link.springer.com/article/10.1007%2Fs11270-010-0598-3 DOI
10.1007/s11270-010-0598-3
6. Shen Y, Nagaraj D R, Farinato R, Somasundaran P. 2016. Study of xanthate
decomposition in aqueous solutions. Elsevier [Internet]. 25 September 2018;
Minerals Engineering Volume 93: 10 – 15. Available from
https://www.sciencedirect.com/science/article/pii/S0892687516300863 DOI
https://doi.org/10.1016/j.mineng.2016.04.004
7. World Health Organization | Institutional Repository for Information Sharing
[Internet]. 12 April 2005. Geneva: World Health Organization. Available from
http://apps.who.int/iris/handle/10665/42554

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Faculty of Science – Chemistry

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Tables and Figures
Table 1. Instrument and Method Parameters
Sample Volume (mL):

0.075

Incubation Time (min):

15

Heat Agitator:

On

Incubation Temperature (°C):

30

Heat Syringe:

On

Syringe Temperature (°C):

46

Pre Injection
Flush Time (s):

10

Sample
Sample Vial Penetration Depth (mm):

15

Sample Vial Penetration Speed (mm/s): 50
Sample Aspirate Flow Rate (mL/min):

12

Sample Post Aspirate Delay (s):

1

Injection Signal Mode:

Plunger Up

Inlet Penetration Depth (mm):

45

Inlet Penetration Speed (mm/s):

50

Pre Inject Time Delay (s):

0.5

Injection Flow Rate (mL/min):

1

Post Inject Time Delay (s):

0.5

Flush Time (s):

60

Continuous Flush:

On

Advanced
Agitator Speed (rpm):

250

Agitator On Time (s):

15

Agitator Off Time (s):

5

Table 2. Preparation of Calibration Curve
Volume Stock Final Volume

Concentration

added (mL)

(mL)

(ppm)

0.5

100.0

0.05

1.0

100.0

0.10

5.0

100.0

0.50

10.0

100.0

1.00

15.0

100.0

1.50

20.0

100.0

2.00

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Faculty of Science – Chemistry

Ó William L. Primrose, 2019

Table 3. Development of PIPX standards (a - f)

Xanthate

PIPX

PIPX

[Xanthate] Sample
ppm

100.8

100.2

label

Volume 0.012
pH

pOH

M NaOH
added (L)

Volume
0.012 M
NaOH
(mL)

Total
Volume
(L)

a
b

10.95
10.24

3.05
3.76

0.000800
0.000150

0.8000
0.1500

0.01080
0.01030

c

9.77

4.23

0.000050

0.0500

0.01010

d

9.31

4.69

0.000017

0.0170

0.01002

e

9.01

4.99

0.0000085

0.0085

0.01009

f

8.49

5.51

0.0000025

0.0025

0.01003

Table 4. Development of PIPX standards (g - h)

Xanthate

[Xanthate] Sample
ppm

label

Volume 0.012
pH

pOH

M NaOH
added (L)

Volume
0.012 M
NaOH
(mL)

Total
Volume
(L)

PIPX

110.6

g

7.72

6.28

0.000022

0.0220

0.50002

PIPX

1075.2

h

7.72

6.28

0.000022

0.0220

0.50002

Table 5. Development of PIPX standards (i - j)

Xanthate

[Xanthate] Sample
ppm

label

Volume 0.012
pH

pOH

M NaOH
added (L)

Volume
0.012 M
NaOH
(mL)

Total
Volume
(L)

PAX

103.2

i

9.48

4.52

0.000025

0.0250

0.01003

PAX

103.2

j

9.08

4.92

0.000010

0.0100

0.01001

Table 6. Development of PIPX standards (k - p) for triplicate trials

Xanthate

PAX

PAX

[Xanthate] Sample
ppm

102.6

102.6

label

Volume 0.012
pH

pOH

M NaOH
added (L)

Volume
0.012 M
NaOH
(mL)

Total
Volume
(L)

k

9.26

4.74

0.000015

0.0150

0.01002

l

9.26

4.74

0.000015

0.0150

0.01002

m

9.26

4.74

0.000015

0.0150

0.01002

n

9.34

4.66

0.000018

0.0180

0.01002

o
p

9.34
9.34

4.66
4.66

0.000018
0.000018

0.0180
0.0180

0.01002
0.01002

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Faculty of Science – Chemistry
Table 7. Raw data for trials a – f
Series a

Injection Time (h)

Ó William L. Primrose, 2019

Series b

Concentration
(ppm)

Peak
Area

Series c

Injection Time (h)

Concentration
(ppm)

Peak
Area

Injection Time (h)

Concentration
(ppm)

Peak
Area

1
2
3
4
5
6
7

2.65
3.70
4.75
5.80
6.85
7.90
8.95

0.0330
0.0301
0.0336
0.0355
0.0323
0.0327
0.0341

510077
421051
526675
583833
486876
499509
540455

1
2
3
4
5
6
7

2.03
3.08
4.13
5.18
6.23
7.28
8.33

0.0348
0.0352
0.0336
0.0365
0.0363
0.0362
0.0358

563759
576239
526561
613296
606902
605391
594096

1
2
3
4
5
6
7

1.00
2.05
3.10
4.15
5.20
6.25
7.30

0.0358
0.0327
0.0361
0.0380
0.0339
0.0394
0.0364

593947
499156
601537
659226
534699
700135
612135

8
Series d

10.0

0.0333

519315

8
Series e

9.38

0.0347

560915

8
Series f

8.35

0.0392

696003

Concentration
(ppm)

Peak
Area

Concentration
(ppm)

Peak
Area

Concentration
(ppm)

Peak
Area

0.0537
0.0213
0.0224
0.0266
0.0294
0.0296
0.0316
0.0292

1E+06
159278
190057
318131
400850
405423
465506
395405

0.0265
0.0265
0.0246
0.0227
0.0267
0.0285
0.0294
0.0284

313608
313124
255370
199555
320194
375162
400962
370079

0.0340
0.0261
0.0228
0.0298
0.0255
0.0300
0.0408
0.0746

540093
301743
203706
413101
285044
418546
741993
2E+06

Injection Time (h)
1
2
3
4
5
6
7
8

1.53
2.58
3.63
4.68
5.72
6.77
7.82
8.87

Injection Time (h)
1
2
3
4
5
6
7
8

1.53
2.58
3.63
4.68
5.72
6.77
7.82
8.85

Injection Time (h)
1
2
3
4
5
6
7
8

1.53
2.58
3.63
4.68
5.72
6.77
7.82
8.85

Table 8. Summary of Results
Series pH level

[Xanthate]

Xanthate

Rate Constant

(ppm)

Used

k (h )

-1

-1

Average k (h )

a
b
c
d
e
f
g
h
i

10.95
10.24
9.77
9.31
9.00
8.48
7.73
7.73
9.48

100.8
100.8
100.8
100.8
100.8
100.2
110.6
1075.2
103.2

PIPX
PIPX
PIPX
PIPX
PIPX
PIPX
PIPX
PIPX
PAX

5.79E-05
3.91E-06
4.36E-05

-

j

9.08

103.2

PAX

5.43E-05

-

k
l
m

9.26
9.26
9.26

102.6
102.6
102.6

PAX
PAX
PAX

1.27E-05
8.77E-06
1.56E-05

1.23E-05

n
o
p

9.34
9.34
9.34

102.6
102.6
102.6

PAX
PAX
PAX

1.27E-05
1.27E-05
1.27E-05

1.27E-05

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Faculty of Science – Chemistry

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Table 9. Summary of Results Sorted by Ascending pH Level

Series

pH level

[Xanthate] (ppm)

Xanthate Used

-1

-1

g

7.73

110.6

PIPX

Rate Constant k (h )
5.79E-05

Average k (h )
-

h

7.73

1075.2

PIPX

3.91E-06

-

f

8.48

100.2

PIPX

-

-

e

9.00

100.8

PIPX

-

-

j

9.08

103.2

PAX

5.43E-05

-

k

9.26

102.6

PAX

1.27E-05

l

9.26

102.6

PAX

8.77E-06

m

9.26

102.6

PAX

1.56E-05

d

9.31

100.8

PIPX

-

n

9.34

102.6

PAX

7.80E-06

o

9.34

102.6

PAX

7.80E-06

p

9.34

102.6

PAX

8.77E-06

1.23E-05
8.12E-06

i

9.48

103.2

PAX

4.36E-05

-

c

9.77

100.8

PIPX

-

-

b

10.24

100.8

PIPX

-

-

a

10.95

100.8

PIPX

-

-

Figure 1. Calibration curve for carbon disulphide observed via gas chromatography
6.00E+07

5.00E+07

y = 3E+07x - 986108
R² = 0.9681

Peak Area

4.00E+07

3.00E+07

2.00E+07

1.00E+07

0.00E+00
0.00

-1.00E+07

0.50

1.00

1.50

2.00

2.50

[Carbon disulfide] in solution (ppm)

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Faculty of Science – Chemistry

Ó William L. Primrose, 2019

Figure 2. Concentration of CS2 evolved (ppm) over time (h) for series a – f and their
reproducibility values
Series a

Series b

0.036

0.0370
R² = 0.0909

0.035

R² = 0.0866

0.0365
0.0360

0.034

0.0355

0.033

0.0350
0.032

0.0345

0.031

0.0340

0.03

0.0335

0.029
0

2

4

6

8

10

12

0.0330
0.000

2.000

Series c

4.000

6.000

8.000

10.000

Series d

0.0400

0.0600

0.0390

0.0500

R² = 0.346

0.0380

R² = 0.0782
0.0400

0.0370
0.0360

0.0300

0.0350

0.0200

0.0340
0.0100

0.0330
0.0320
0.00

2.00

4.00

6.00

8.00

10.00

0.0000
0.00

2.00

Series e

4.00

6.00

8.00

10.00

8.00

10.00

Series f

0.03000

0.0800

0.02900

0.0700

0.02800

0.0600

0.02700

0.0500

0.02600

R² = 0.4226

0.0400
R² = 0.3323

0.02500

0.0300

0.02400

0.0200

0.02300

0.0100

0.02200
0.00

2.00

4.00

6.00

8.00

10.00

0.0000
0.00

2.00

4.00

6.00

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Faculty of Science – Chemistry

Ó William L. Primrose, 2019

Figure 3. Concentration of CS2 evolved (ppm) over time (h) for series g – p and their
reproducibility values
Series g

Series h

0.095

0.070
R² = 0.9811

0.065

R² = 0.9392

[CS2] evolved (ppm)

[CS2] evolved (ppm)

0.085
0.075
0.065
0.055
0.045
0.035

0.060
0.055
0.050
0.045
0.040
0.035

0.025

0.030
0.00

2.00

4.00

6.00

8.00

10.00

0.00

2.00

4.00

Time (h)

6.00

8.00

10.00

8.00

10.00

Time (h)

Series i

Series j

0.08000

0.09500

R² = 0.8942

0.07500

R² = 0.8641
0.08500

0.07000
0.06500

0.07500

0.06000

0.06500

0.05500
0.05000

0.05500

0.04500

0.04500

0.04000
0.03500

0.03500
0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

0.00

2.00

4.00

Series k

6.00

Series l

0.04300

0.03700
R² = 0.9425

R² = 0.943

0.04100

0.03500

0.03900
0.03700

0.03300

0.03500

0.03100

0.03300
0.03100

0.02900

0.02900

0.02700

0.02700
0.02500

0.02500
0.00

2.00

4.00

6.00

8.00

10.00

12.00

0.00

2.00

4.00

Series m

6.00

8.00

10.00

12.00

14.00

Series n

0.05500

0.04200
R² = 0.7394

0.04100

R² = 0.8984

0.05000

0.04000
0.03900

0.04500

0.03800
0.04000

0.03700
0.03600

0.03500

0.03500
0.03000

0.03400
0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

0.00

1.00

2.00

Series o

3.00

4.00

5.00

6.00

7.00

Series p

0.04200

0.04200
R² = 0.7383

0.04100

0.04100

0.04000

0.04000

0.03900

0.03900

R² = 0.8554

0.03800

0.03800

0.03700

0.03700

0.03600

0.03600

0.03500

0.03500

0.03400

0.03400

0.03300

0.03300

0.03200
0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

12

Faculty of Science – Chemistry

Ó William L. Primrose, 2019

Figure 4. Chromatogram for Series g sample at 5 hours (pH 7.73, 110.6 ppm PIPX)

Figure 5. Chromatogram for Series n sample at 6 hours (pH 9.34, 102.6 ppm PAX)

Figure 6. Chromatogram for CS2 standard 6 (1.50 ppm)

Figure 7. Mass spectrum for Series g sample at 5 hours (pH 7.73, 110.6 ppm PIPX)

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Faculty of Science – Chemistry

Ó William L. Primrose, 2019

Figure 8. Mass spectrum for Series n sample at 6 hours (pH 9.34, 102.6 ppm PAX)

Figure 9. Mass spectrum for CS2 standard 6 (1.50 ppm)

14