See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/229306177
Effect of anti-scale agents on the solubility of CO2 in seawater at
temperatures of 60 to 90ºC and pressures of 1–2 bar
Article in Desalination · July 2008
DOI: 10.1016/j.desal.2007.05.034
CITATIONS
READS
9
220
5 authors, including:
Khaled Mekhlif Alanezi
David Mee
Public Authority for Applied Education and Training
University of Nottingham
11 PUBLICATIONS 180 CITATIONS
5 PUBLICATIONS 122 CITATIONS
SEE PROFILE
SEE PROFILE
Nicholas P. Hankins
Nidal Hilal
University of Oxford
New York University Abu Dhabi
89 PUBLICATIONS 2,294 CITATIONS
502 PUBLICATIONS 28,313 CITATIONS
SEE PROFILE
Some of the authors of this publication are also working on these related projects:
Membrane Characterization View project
Oil water separation View project
All content following this page was uploaded by Khaled Mekhlif Alanezi on 01 January 2022.
The user has requested enhancement of the downloaded file.
SEE PROFILE
Desalination 227 (2008) 46–56
Effect of anti-scale agents on the solubility of CO2 in seawater at
temperatures of 60 to 90ºC and pressures of 1–2 bar
Khalid Al-Anezia, Chris Somerfielda, David Meea, Nick Hankinsb, Nidal Hilala*
a
Centre for Clean Water Technologies, School of Chemical, Environmental and Mining Engineering,
University of Nottingham, Nottingham, NG7 2RD, UK
Tel. +44 (115) 951-4168; Fax: +44 (115) 951-4115; email: nidal.hilal@nottingham.ac.uk
b
Centre for Sustainable Water Engineering, Department of Engineering Science, The University of Oxford,
Parks Road, Oxford OX1 3PJ, UK
Received 28 March 2007; Accepted 8 May 2007
Abstract
The objective of this work is to present experimental data that would show the effect of temperature, salinity,
pressure and the presence of anti-scale additives on CO2 solubility in seawater. The paper examines the solubility
of CO2 in real seawater and real seawater dosed with two different anti-scale additives. The study has been performed
at temperatures between 60ºC and 90ºC and at pressures of 1 and 2 bar. To assess the effect of each anti-scale
additive on CO2 gas solubility varying doses, 2–10 ppm of anti-scale additive have been used. For the purpose of the
experimentation an experimental rig has been designed to ensure adequate contact between the gas phase and the
aqueous phase. The continuous quantitative analysis of CO2 concentration flowing from the experimental rig was
measured using a CM-5011 Carbon Coulometer. A mass balance was carried out to calculate the amount of CO2
absorbed into solution; Henry’s law constant was then calculated.
Keywords: Desalination; Carbon dioxide solubility; Anti-scale additives; Henry’s law constant
1. Introduction
Multistage flash (MSF) and multi-effect
desalination (MED) are two of the main pro-
*Corresponding author.
processes currently practiced for the production
of pure water from seawater. The high temperature encountered in these processes causes scale
formation. These alkaline scales and non-alkaline
scales tend to be deposited onto the heat transfer
surfaces, which results in a serious loss of thermal
Presented at the First Oxford and Nottingham Water and Membranes Research Event, 2–4 July 2006, Oxford, UK.
0011-9164/08/$– See front matter © 2008 Elsevier B.V. All rights reserved
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
distillers efficiency and in turn this leads to
reduction in pure water production. Therefore
scale deposition is a major problem occurring
when using these techniques for water purification [1,2]. Mechanical and technical problems
affecting the performance of the plant may occur
without effective scale control. A number of
studies [3–8] have investigated the CO2 release
rates in thermal desalination plants and it’s affect
on alkaline scale formation. Al-Rawajfeh et al.
[3,5] developed a model to predict CO2 release
rates in MED plants. They estimated CO2 solubility in saline solution by considering the ionic
strength and the salting-out parameter. They
claim that their model is useful in understanding
the carbonate system in ME distillers, the model
gives a reasonable estimate of scale formation
and also allows scale prevention methods to be
designed more effectively.
Carbon dioxide solubility data in seawater and
seawater dosed with different anti-scale additives
typical of multistage flash (MSF) and multi-effect
desalination (MED) plants are essential in the
modeling of CO2 release rates in thermal desalination distillers. Al-Anezi and Hilal [10] discussed in more detail the effect of CO2 gas
solubility in seawater on scale formation in MSF
desalination plants. The addition of anti-scale
additives to seawater brines in thermal desalination plants is the main method utilized in trying to
combat the formation of alkaline scales on the
process equipment. The presence of the anti-scale
additives prevents hard water salts from forming
scale by dispersing any crystallites and other
suspended solids. Anti-scale additives must show
sufficient thermal stability especially when they
are incorporated in thermal desalination plants, as
discussed in the studies [10–14]. A comparative
study on the use of two different anti-scale additives in MSF distillation plants was done [15] and
their research shows the use of two different antiscale additives are effective in controlling alkaline scale deposition. Their results also show
improvement in the performance of the heater,
47
but in these studies there was no mention of the
effect of the addition of anti-scale additive on
CO2 gas solubility in the seawater brine.
The objective of this work was to generate
experimental data on the CO2 solubility in seawater with and without anti-scale additives. Comparison of the effect of each anti-scale additive
used in desalination plants on the solubility of
CO2 in seawater was also undertaken. In this
study the CO2 solubility in seawater has been
measured at 60–90EC and 1 and 2 bar.
2. Materials and methods
2.1. Samples and materials
The experimental rig shown in Fig. 1 consists
of an equilibrium cell, a controlled constanttemperature water bath, two stainless steel calibrated gas flow-meters (N032-41) supplied by the
Cole-Parmer Instrument Company, a ChromPack
gas-clean moisture filter and a U.I.C. CM-5011
Carbon Coulometer. The equilibrium cell (main
cell) used in this study was 3400 mL in capacity
and was immersed fully in the constant-temperature water bath. 100% N2 gas and 2% CO2/
98% N2 gas were used in the experiments these
were obtained from BOC Limited. The ChromPack gas-clean moisture filter was installed at the
main outlet vapor line to ensure that the outlet gas
was dried and this avoids problems with gas
flow-meter measurements. The main outlet vapor
was analyzed continuously at 6-s intervals to
quantitatively measure CO2 concentration using
the CM-5011 Carbon Coulometer®. Full details of
the experimental apparatus and procedure are
described elsewhere [16].
The saline solutions used in this study were
real seawater obtained 5 miles from the coast of
Kuwait Bay in the Arabian Gulf. Two anti-scale
additives — Genesys SW® supplied by Genesys
International LTD and Sokalan MSF® — were
tested in this study. Table 1 show the analyses of
48
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
Fig. 1. Schematic representation of experimental rig (water bath section and Carbon Coulometer section).
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
Table 1
Analyses of the real seawater using an ICP-AEP Optima3300DV by Perkin-Elmer and titration; seawater pH=8.21
and seawater 1027.4 kg/m3 at 20EC
Raw seawater composition
ppm (mg/l)
Calcium as Ca2+
Sodium as Na+
Magnesium as Mg2+
Potassium as K+
Sulphates as SO42!
Manganese as Mn
Bicarbonates as HCO3
Chloride as Cl!
Bromide as
Total
530
10,800
1,616
454
2,520
<1
159
22,931
65
39,074
K CO2 = PCO2 / X CO2
49
(1)
The units we have used for KCO2 are bar/mole
fraction. When working at high temperature a
correction for water vapor (PH2O) is made using
the following expression:
Pgas = Xgas (PT!PH2O)
(2)
where Xgas is the mole fraction of CO2 gas and PT
is the total pressure of the system in bar. Full
details of the measurements, calculations and
assumptions used to evaluate the solubility of
CO2 in the solutions are described elsewhere [16].
3.1. CO2 solubility in real seawater dosed with 2,
5 and 10 ppm of Genesys SW anti-scale additives
the real seawater. The CO2 gas solubility tests
were carried out at 1 and 2 bar, and 60, 80 and
90EC with 2, 5 and 10 ppm doses of each antiscale additive. The precision for the various conditions was determined by repeating a number of
the experiments. The total dissolved CO2 in the
aqueous solutions was calculated by carrying out
a mass balance on the system. The data of CO2
Henry’s constants in the different solutions were
also calculated for the system.
3. Results and discussion
Gas solubility in aqueous solutions can be
expressed in many ways and Henry’s law constant is one of these methods. Experiments have
been carried out on CO2 gas solubility in seawater
and Henry’s law constant for CO2 gas (KCO2) in
this system have been evaluated.
It is known that Henry’s law gives the exact
total solubility of gases that are not involved in
further reactions in solution, but it underestimates
the total solubilities of the reactive gases such as
CO2 and SO2 [17]. For the purpose of our calculation the following form of Henry’s law constant
for CO2 solubility in aqueous solutions was used:
The experiments were carried out in 1L aqueous solutions; when CO2 equilibrium was reached
the experiment was stopped. The data collected
using the CM-5011 Carbon Coulometer were
downloaded and the CO2 solubility in solution
and Henry‘s law constant were calculated.
The effect of dosage rate of Genesys SW antiscale additives on CO2 gas solubility in seawater
at 1 and 2 bar and temperature of 60, 80 and
90EC was studied and can be seen in Figs. 2–9.
Figs. 2–4 show that adding the anti-scale additives to the seawater solution leads to an increase
in CO2 solubility. Fig. 2 shows the measured CO2
concentration in seawater was 43.5 ppm at 1 bar
and 60EC, but when 2 ppm of Genesys SW antiscale additive was added to the seawater, the CO2
concentration in seawater increased to 72 ppm.
This trend of increasing CO2 solubility continued
as the concentration of the Genesys SW anti-scale
additive in the seawater was increased. In other
words, CO2 solubility in seawater dosed with
anti-scale additive tends to be more than with
seawater alone. This is in good agreement with
the previous work done by Glade and Genthner
[18] whose model included the affect of the
presence of the anti-scale additives in seawater on
50
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
Fig. 2. CO2 solubility (ppm) in 1 L seawater dosed with
0, 2, 5 and 10 ppm Genesys SW anti-scale additive at
1 (•) and 2 (—) bar, temperatures of 60EC and constant
gas flow-rates.
Fig. 4. CO2 solubility (ppm) in 1 L seawater dosed with
0, 2, 5 and 10 ppm Genesys SW anti-scale additive at
1 (•) and 2 (—) bar, temperatures of 90EC and constant
gas flow-rates.
of the dissolution of CO2 in aqueous solution.
This is very much in line with the experimental
CO2 release in MSF desalination plants. Also,
Mubarak [15] studied the effect of anti-scale
presence on the seawater. He found that the
bicarbonate ions [HCO3!] and carbonate ions
[CO32!] in seawater increased as a result of the
addition of the anti-scale additive to the seawater.
It is known that carbonate ions occur as a result
Fig. 3. CO2 solubility (ppm) in 1 L seawater dosed with
0, 2, 5 and 10 ppm Genesys SW anti-scale additive at
1 (•) and 2 (—) bar, temperatures of 80EC and constant
gas flow-rates.
Fig. 5. CO2 solubility (ppm) in 1 L seawater dosed with
0 (•), 2 (—), 5 () and 10 (×) ppm Genesys SW antiscale additive at 1 bar, temperatures of 60, 80 and 90EC
and constant gas flow-rates.
results that we have obtained (Figs. 2–4). The
effect of temperature on CO2 solubility in
seawater is also shown in Figs. 5 and 6. The trend
in these figures show that as the system temperature increases the CO2 solubility decreases, which
is expected, and agrees really well with trends
shown in the literature [19,20]. The anti-scale
additive has to show thermal stability as
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
51
Fig. 6. CO2 solubility (ppm) in 1 L seawater dosed with
0 (•), 2 (—), 5 () and 10 (×) ppm Genesys SW antiscale additive at 2 bar; temperatures of 60, 80 and 90EC
and constant gas flow-rates.
Fig. 7. CO2 solubility (ppm) in 1 L real seawater dosed
with 0 (•), 2 (—), 5 () and 10 (×) ppm Genesys SW
anti-scale agent at 60EC, 1 and 2 bar and constant gas
flow-rates.
Fig. 8. CO2 solubility (ppm) in 1 L real seawater dosed
with 0, 2, 5 and 10 ppm Genesys SW anti-scale agent at
80EC, 1 and 2 bar, and constant gas flow-rates. 1 L real
seawater (•); solution dosed with 2 ppm Sokalan MSF
(—), solution dosed with 5 ppm Sokalan MSF (), and
solution dosed with 10 ppm Sokalan MSF (×).
Fig. 9. CO2 solubility (ppm) in 1 L real seawater dosed
with 0 (•), 2 (—), 5 () and 10 (×) ppm Genesys SW
anti-scale agent at 90EC, 1 and 2 bar, and constant gas
flow-rates.
discussed by the author of this article [13]. With
regard to CO2 solubility our experimental results
show that at high temperature (> 80oC) the
performance of the Genesys SW anti-scale
additive is effected. A 50% increase in CO2 solubility using different anti-scale additive dosages
obtained at 60EC and 80EC were observed com-
pared to the CO2 solubility in seawater only.
However, the results using anti-scale additive
obtained at 90EC show only a 20–34% increase in
CO2 solubility; hence the conclusion that the antiscale additive increases CO2 solubility more when
used at temperatures at or below 80 C (Figs. 5
and 6).
Figs. 7–9 show that CO2 solubility increases
as the system pressure increases; this is expected
52
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
Fig. 10. Henry’s law constant KCO2 (bar/mole fraction) in
1 L real seawater (•) with 2 (—), 5 () and 10 (×) ppm
Genesys SW anti-scale additive at 1 bar and constant gas
flow-rates.
Fig. 11. Henry’s law constant KCO2 (bar/mole fraction) in
1 L real seawater (•) with 2 (—), 5 () and 10 (×) ppm
Genesys SW anti-scale additive at 2 bar and constant gas
flow-rates.
Fig. 12. CO2 gas solubility (ppm) in 1 L real seawater
dosed with 2, 5 and 10 ppm Sokalan MSF type anti-scale
additive at 60EC and 1 (•) and 2 (—) bar and constant
gas flow-rates.
Fig. 13. CO2 gas solubility (ppm) in 1 L real seawater
dosed with 2, 5 and 10 ppm Sokalan MSF type anti-scale
additive at 80EC and 1 (•) and 2 (—) bar and constant
gas flow-rates.
as the system pressure has a direct effect on CO2
solubility in seawater.
Figs. 10 and 11 show the calculated Henry’s
law constant for CO2 in solutions decreases as the
system temperature increases and this is expected
since system temperature affects KCO2 in aqueous
solutions.
3.2. CO2 solubility in real seawater dosed with 2,
5 and 10 ppm of Sokalan MSF type anti-scale
additives
The CO2 solubility in seawater experiments
with different dosages of Sokalan MSF type antiscale additives were undertaken at 60, 80 and
90EC and 1 and 2 bar. Figs. 12–14 show that CO2
solubility in the seawater increased as the Sokalan
MSF type anti-scale additive concentration in
seawater increased. This phenomenon was seen
earlier in Figs. 2–4 when using Genesys SW antiscale additive. With regard to CO2 solubility our
experimental results show that at high temperature (>80EC) the performance of the Sokalan
MSF anti-scale additive is affected. A 70% increase in CO2 solubility using different anti-scale
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
53
Fig. 14. CO2 gas solubility (ppm) in 1 L real seawater
dosed with 2, 5 and 10 ppm Sokalan MSF type anti-scale
additive at 90EC and 1 (•) and 2 (—) bar and constant
gas flow-rates.
Fig. 15. CO2 solubility (ppm) in seawater dosed with
0 (•), 2 (—), 5 () and 10 (×) ppm Sokalan MSF antiscale additive at 1 bar; temperatures of 60, 80 and 90EC
and constant gas flow-rates.
Fig. 16. CO2 solubility (ppm) in seawater dosed with 0
(•), 2 (—), 5 () and 10 (×) ppm Sokalan MSF anti-scale
additive at 2 bar; temperatures of 60, 80 and 90EC and
constant gas flow-rates.
Fig. 17. CO2 Solubility (ppm) in 1 L of real seawater
dosed with 2, 5 and 10 ppm Genesys Sw anti-scale
additive (•) and Sokalan MSF anti-scale additive (—) at
90EC, 1 bar and constant gas flow-rates.
additive dosages obtained at 60EC and 80EC were
observed compared to the CO2 solubility in
seawater only. However, the results using antiscale additive obtained at 90EC show around the
60–70% increase in CO2 solubility; hence the
conclusion that the Sokalan MSF anti-scale
additive shows nearly the same increase in CO2
solubility when used at temperatures at or below
90EC (Figs. 15 and 16).
Figs. 17 and 18 clearly show that at 90EC, the
level of CO2 solubility in the seawater using
Sokalan MSF type anti-scale additives is greater
than when using Genesys SW anti-scale additive.
Because the use of Sokalan MSF type anti-scale
54
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
Fig. 18. CO2 solubility (ppm) in 1 L of real seawater
dosed with 2, 5 and 10 ppm Genesys SW anti-scale
additive (•) and Sokalan MSF additive (—) at 90EC,
2 bar and constant gas flow-rates.
Fig. 19. Henry’s law constant KCO2 (bar/mole fraction) in
1 L real seawater dosed with 0 (•), 2 (—), 5 () and
10 (×) ppm MSF anti-scale additive at 60, 80 and 90EC
and 1 bar and constant gas flow-rates.
additive leads to more CO2 dissolved in the
seawater, this would in principle retard scaling.
But the nature and effect of scale precipitation in
the flash chamber after pressure release also
require considerations due to the sudden loss of
CO2 from bulk brine during flashing, which may
cause corrosion as discussed by [14–21].
3.3. Repeatability and reproducibility of the
experimental results
The system designed to obtain CO2 solubility
in aqueous solution showed very good repeatability. As can be seen from Table 2, the
reproducibility of CO2 solubility experimental
results was more than 95% so this shows very
good consistency and reliability.
Fig. 20. Henry’s law constant KCO2 (bar/mole fraction) in
1 L real seawater dosed with 0 (•), 2 (—), 5 () and
10 (×) ppm MSF anti-scale additive at 60, 80 and 90EC,
2 bar and constant gas flow-rates.
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
55
Table 2
Reproducibility of a random number of solubility experiments at different temperatures and pressures
System T and P
Seawater dosed with xpm of anti-scale
additive
CO2 conc.,
ppm
Repeated CO2
conc., ppm
Results
reproducibility, %
60°C and 1 bar
60°C and 2 bar
60°C and 2 bar
80°C and 1 bar
90°C and 1 bar
90°C and 2 bar
Seawater with 5 ppm Genesys SW
Seawater with 5 ppm Genesys SW
Seawater with 10 ppm Genesys SW
Seawater with 10 ppm Genesys SW
Seawater with 2 ppm Sokalan MSF type
Seawater with 2 ppm Sokalan MSF type
84
287
300
62.4
57.7
188
83
282
312
63.2
60.2
193.4
98.81
98.25
96
98.73
95.6
97.13
4. Conclusions
Acknowledgment
As the temperature of the system increases,
CO2 solubility in aqueous solutions usually
decreases. The laboratory investigations showed
that adding an anti-scale agent increased the CO2
solubility in the seawater. The CO2 solubility also
increases as the concentration of the anti-scale
agent in the system increases. A higher CO2
concentration in the seawater at high temperature
would in principle retard scaling and is therefore
advantageous.
The anti-scale additives vary in performance
depending on the type of mechanisms by which
they function in controlling or retarding scale
formation. The absorbance of CO2 in seawater is
a function on the anti-scale additive used. When
Genesys SW anti-scale additive was added to the
seawater, CO2 concentration in the seawater
increased and the increase was more evident at
60EC and 80EC than at 90EC. The Sokalan MSF
type anti-scale additive absorbs more CO2 in the
seawater at 90EC than when the Genesys SW
anti-scale additive was used. The relative drop in
CO2 solubility at 90EC for each anti-scale additive investigated demonstrates that the thermal
stability issues of anti-scale additives need consideration. The nature and effect of scale precipitation after pressure release in the flash chamber
is very important, and a sudden loss of CO2 from
bulk brine and then corrosion especially in the
presence of other non-condensable gases will
occur.
The authors would like to thank Ted Darton,
Technical Director, Genesys International Ltd.
UK for donating the anti-scale agent Genesys
SW.
The authors also would like to thank the Public Authority for Applied Education and Training–Kuwait for the funding of Mr. Khalid AlAnezi.
References
[1] S. Patel and M.A. Finan, New antifoulants for
deposit control in MSF and MED plants. Desalination,124 (1999) 63–74.
[2] J.A.R. Bharadwaj and V.R. Raghavan, Influence of
noncondensables on modern thermal desalination.
Desalination, 49 (1984) 357–365.
[3] A.E. Al-Rawajfeh, H. Glade, H.M. Qiblawey and J.
Ulrich, Simulation of CO2 release in multiple-effect
distillers Desalination, 166 (2004) 41–52.
[4] A.E. Al-Rawajfeh, H. Glade and J. Ulrich, CO2
release in multiple-effect distillers controlled by mass
transfer with chemical reaction. Desalination, 156
(2003) 109–123.
[5] A.E. Al-Rawajfeh, H. Glade and J. Ulrich, Scaling in
multiple-effect distillers: the role of CO2 release.
Desalination, 182 (2005) 203–213.
[6] H. Glade and K. Genthner, The problem of noncondensable gas releases in evaporators, in:
Encyclopedia of Desalination and Water Resources,
D.M.K. Al-Gobaisi, ed., EOLSS Publishers, Oxford,
2000.
56
K. Al-Anezi et al. / Desalination 227 (2008) 46–56
[7] H. Glade, J.-H. Meyer and S. Will, The release of
CO2 in MSF and ME distillers and its use for the
recarbonation of the distillate: a comparison.
Desalination, 182 (2005) 95–106.
[8] H. Glade and J. Ulrich, Influence of solution
composition on the formation of crystalline scales.
Chem. Eng. Technol., 26(3) (2003) 277–281.
[9] K. Al-Anezi and N. Hilal, Scale formation in desalination plants: effect of carbon dioxide solubility.
Desalination, 204 (2007) 385–402.
[10] A.M. Shams El Din, M.E. El-Dahshan and R.A.
Mohammed, Scale formation in flash chambers of
high-temperature MSF distillers, Desalination, 177
(2005) 241–258.
[11] A.M. Shams El Din and R.A. Mohammed, Brine and
scale chemistry in MSF distillers. Desalination, 99
(1994) 73–111.
[12] N.S. Al-Deffeeri, Heat transfer measurement as a
criterion for performance evaluation of scale inhibition in MSF plants in Kuwait. Desalination, 204
(2007) 423–436.
[13] M.E. El-Dahshan, Corrosion and scaling problems
present in some desalination plants in Abu Dhabi.
Desalination, 138 (2001) 371–377.
[14] A. Mubarak, A kinetic model for scale formation in
MSF desalination plants. Effect of antiscalants.
Desalination, 120 (1998) 33–39.
View publication stats
[15] S.A. Al-Saleh and A.R. Khan, Comparative study of
two anti-scale agents Belgard EVN and Belgard EV
2000 in multi-stage flash distillation plants in
Kuwait. Desalination, 97 (1994) 97–107.
[16] K. Al-Anezi, C. Somerfield, D. Mee and N. Hilal,
Parameters affecting the solubility of carbon dioxide
in seawater at the conditions encountered in MSF
desalination plants. Conference on Desalination and
the Environment, EDS and Center for Research and
Technology Hellas (CERTH), Halkidiki, Greece,
2007.
[17] S.E. Manahan, Environmental Chemistry, 7th ed.,
CRC Press, Boca Raton, FL, 2000.
[18] H. Glade and K. Genthner, The problem of CO2
release in MSF distillers. IDA World Congress on
Desalination and Water Sciences, Abu Dhabi, UAE,
1995.
[19] J.J. Carroll, J.D. Slupsky and A.E. Mather, The
solubility of carbon dioxide in water at low pressure.
J. Phys. Chem. Ref. Data, 20(6) (1991) 1201–1209.
[20] R. Crovetto, Evaluation of solubility data of the
system CO2-H2O from 273K to the critical point of
water. J. Phys. Chem. Ref. Data, 20 (1991) 575.
[21] R.D. Ellis, J. Glater and J.W. McCutchan, Alkaline
scale abatement by carbon dioxide injection.
Environ. Sci. Technol., 5(4) (1971) 350–356.