Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 1, Pages: 158-165  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal web link: http://www.jett.dormaj.com  
Removal of CO from Gas Mixture by Aqueous  
2
Blends of Monoethanolamine + Piperazine and  
Thermodynamic Analysis Using the Improved  
Kent Eisenberg Model  
1
*2  
1
Hamid Niknam , Alireza Jahangiri , Nasibeh Alishvandi  
1
- Department of Chemical Engineering, Jami Institute of Technology, Isfahan, Iran  
2
- Assistant Professor, Department of Chemical Engineering, Shahrekord University, Shahrekord, Iran  
Received: 02/08/2018  
Accepted: 10/02/2019  
Published: 30/03/2019  
Abstract  
In this study, a system was designed to determine CO  
liquid equilibrium data of CO  
concentrations (1+12wt%, 2+12wt%, and 3+12wt%), at different partial pressure of CO  
various temperatures (303, 313 and 323 K) at a total pressure of 0.83 atm were tested. Also, the variation of CO  
system temperature, and the effect of adding PZ to MEA solvent were studied. The experimental results showed that by  
increasing the concentration of PZ and CO partial pressure, CO loading increases and the temperature rise leads to a decrease  
in CO loading. The values obtained for CO loading in these experiments were in the range of 0.005-0.216 (molCO2/molAmine),  
2
solubility in alkanolamine solvents. In what follows, the vapor-  
2
solubility in the 12 wt% MEA aqueous solution and PZ + MEA mixture with various  
(8.44, 25.33, and 42.22 kPa) and  
partial pressure,  
2
2
2
2
2
2
and the maximum obtained value was for 3wt% of PZ + 12wt% of MEA at 303 K. Finally, the improved Kent-Eisenberg model  
parameters were fitted by using the MATLAB software and the experimental conditions of this study. Average absolute  
deviations percentage between the calculated and experimental loading was 24.4%, which indicates that the improved Kent-  
Eisenberg model is in good agreement with experimental data.  
Keywords: CO  
2
solubility, MEA aqueous solution, Piperazine additive, improved Kent-Eisenberg thermodynamic model  
1
increases the solubility of amine in water and reduces the  
1
Introduction  
vapor pressure of the solution, while the amine group  
increases the alkali property of solution (2). Based on the  
number of radical groups bonded to the nitrogen atom, the  
amines are divided into three categories:  
Nowadays, one of the biggest environmental issues in  
the world is the increase in greenhouse gas emissions, and  
carbon dioxide gas is the most important greenhouse gas  
due to its highest atmospheric lifetime and having the  
highest concentration in the atmosphere. This gas traps  
more energy and heat in the atmosphere which results in  
severe climate change. Power plants, refineries, and steel  
1
. Primary amines such as MEA (Monoethanolamine) and  
DGA (Diglycolamine).  
. Secondary amines such as DEA (Diethanolamine),  
DIPA (Diisopropanolamine).  
Tertiary amines MDEA  
2
2
and cement industries are the largest CO producers in the  
3.  
such  
as  
world (1). So far, several methods have been proposed for  
carbon dioxide removal by various researchers. These  
methods include physical absorption, absorption by  
chemical solvents, membrane separation and several other  
processes. The process of gas absorption by chemical  
reaction of liquid solvents has been widely used in the  
treatment of acidic gases and gas purification. Among the  
methods of chemical absorption, the capture of carbon  
dioxide by alkanolamine solutions can be mentioned  
which has been studied widely over past decades.  
(
Methyldiethanolamine) and TEA (Triethanolamine).  
In the last few decades, the MEA solvent has been  
2
extensively used to absorb CO from natural gases. The  
advantages of this solvent include low molecular weight,  
high CO absorption rate, and a very low tendency to  
2
absorb hydrocarbons. The major problem with MEA is its  
limited loading capacity due to the production of  
carbamate ion and its high energy-consuming recovery  
(
3). Today, organic diamines such as PZ (Piperazine),  
AEEA (Aminoethylethanolamine), and HMDA are used  
as additives to alkanolamine because of their high  
absorption capacity and rapid reaction with CO . PZ is the  
2
Alkanolamines consist of at least one hydroxyl group  
OH ) and one amine group (RNH  
−
(
2
). The hydroxyl group  
Corresponding author: Dr. Alireza Jahangiri, Assistant Professor, Department of Chemical Engineering, Shahrekord  
University, Shahrekord, Iran. E-mail: jahangiri@eng.sku.ac.ir, Tel: +98 9192672218, Fax: 03832324401  
1
58  
Journal of Environmental Treatment Techniques  
2019, Volume 6, Issue 1, Pages: 158-165  
most widely known diamine that is used in combination  
with other amines as an activator to increase the reaction  
speed. PZ is an organic compound composed of a six-  
membered ring containing two nitrogen atoms at opposite  
positions (4). Table 1 presents a summary of the studies  
conducted over a wide range of temperatures, pressures,  
and concentrations for blend of MEA and PZ aqueous  
solutions. To design gas purification systems, it is required  
to obtain vapor-liquid equilibrium data (VLE) of aqueous  
alkaline amine. Therefore, providing a thermodynamic  
model, which can predict the equilibrium behavior of these  
systems, is advantageous from the operational and  
economic point of view. So far, extensive studies have  
been carried out on the thermodynamic models for  
electrolyte solutions that can be used in gas sweetening  
industries. Kent and Eisenberg (5) by assuming that the  
liquid phase was ideal, calculated the solubility of acid  
gases in amines using a temperature-dependent function  
for the chemical equilibrium constants. Deshmukh and  
Mather (6) obtained the solubility of gases in amine  
systems by applying the Guggenheim equation and the  
method of Edwards et al. (7) by using activity coefficients.  
Austgen et al. (8) with the help of the Electrolyte-NRTL  
Model (9), achieved the energy parameters of interactions  
among the components of amine systems. Li and Mather  
loading and amine concentration. Hu and Chakma (14)  
presented a modified model based on the Kent-Eisenberg  
model for the equilibrium constant of main amine  
reactions as a function of temperature, partial pressure of  
the acid gas and amine concentration. In a similar manner,  
Li and Shen (15), for calculating the CO  
combined system (H O+MEA+MDEA), considered the  
chemical equilibrium constant as a function of the  
temperature, amine concentration, and CO loading. In this  
research, the improved Kent-Eisenberg model has been  
used to predict the CO solubility in PZ and MEA aqueous  
2
solubility in a  
2
2
2
solutions. In this model, the activity coefficient is not  
applied in equations to correct the non-ideality of the  
system and components. Instead, the non-ideality of the  
species will be considered in the optimization of  
equilibrium constants coefficients.  
2
Experimental  
1
.2 Materials  
Materials used in this work are MEA (>99.5% pure)  
and anhydrous PZ (>99% pure). These chemicals were  
purchased from Merck Company. Carbon dioxide  
(
>99.9% pure) and nitrogen (>99.9% pure) were procured  
from ISFAHAN GAS company. Distilled water was used  
for preparation of all the solutions.  
(
10) by using Clegg-Pitzer model (11) and Kaewsichan et  
al. (12) by utilizing the Electrolyte-UNIQUAC model  
predicted the solubility of acid gases in alkanolamine  
solutions. In the Kent-Eisenberg model, the equilibrium  
constant for amine reactions (carbamate and protonation  
reaction) is only dependent on the temperature. However,  
in Jou et al. (13), the equilibrium constant of amine  
reaction, in addition to temperature was influenced by the  
2
.2 Experimental apparatus and methods  
Fig. 1 shows the laboratory system used in this work. This  
system was used by Jahangiri et al. (16) to determine the  
solubility of CO . The procedure is summarized in several  
2
steps:  
Table 1: Summary of experimental data for the MEA, PZ and blend of MEA–PZ–H  
2
O–CO  
2
system.  
Source (author)  
Dang and Rochelle (17)  
Aboudheir et al. (18)  
Puxty et al. (19)  
Conc. [MEA] (M) Temp. (K)  
Loading(mol CO2/mol Amine)  
2.5 and 5  
3-9  
5
2.5-10  
6.82-6.97  
7-13  
313 and 333  
293-333  
313-333  
313-393  
373-443  
313-373  
293-343  
0.91-0.614  
0.1-0.5  
0-0.5  
0.017 - 0.864  
0.303-0.52  
0.2-0.5  
Aronu et al. (20)  
Xu and Rochelle (21)  
Dugas and Rochelle (22)  
Luo et al. (23)  
1-5  
Conc. [PZ] (M)  
0.2-0.6  
0.75-3  
0-0.4  
Bishnoi and Rochelle (24)  
Ermatchkov et al. (25)  
Aroua and Salleh (26)  
Derks et al. (27)  
Kamps et al. (28)  
Xu and Rochelle (21)  
Dugas and Rochelle (22)  
298-343  
283-393  
293-323  
298-333  
313-393  
354-465  
313-373  
0-1.0  
0.05-0.95  
0-0.8  
0.3-1.25  
0-0.75  
0.224-0.451  
0.226-0.411  
0.1-1  
0.2-0.6  
1.7-3  
4.93-8  
2-12  
Conc. [MEA+PZ] (M)  
0.4+0.6 333  
.9+0.6  
.8+1.2  
7+2  
Dang and Rochelle (17)  
Dugas and Rochelle (22)  
0.06-0.14  
0.01 - 0.44  
0.41- 0.43  
0.242-0.477  
1
3
333  
313 and 333  
313-373  
1
59  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 1, Pages: 158-165  
1
bath  
2
- Setting the system to the desired temperature by water  
solvent reduces the pressure of system which will be  
compensated by elevating mercury container in order to  
perform the test under constant pressure. If the level of  
fluid in the manometer stays constant for a while, the test  
is completed, and the volume of dissolved gas is read from  
the burette. To determine the number of dissolved moles,  
we can use ideal gas law Eq.1 since the total pressure is  
almost 1 atm.  
- Fill the container with the solvent and place it on the  
spiral  
3
4
. Open the gas valve until the system is full of the gas.  
- Close the gas valve and elevate the mercury container  
by the jack and block the outlet of gas by the water syringe.  
- At the start of the absorption, the gas is pressurized in  
the burette. During this time, the dissolved gas in the  
5
Figure 1: Vapor-liquid equilibrium apparatus for atmospheric pressure (a: Spiral tube, b: Scaling burette, c: Manometer, d: Water bath, e:  
Mercury jack, f: Cell, g: Solvent Container, h: Circulating Pump, i: CO Capsule)  
2
Pυ  RT  
(1)  
3 Modeling of equilibrium data  
The equations describing the main reactions occurring  
To obtain the moles of solvent consumed, Eq. 2 could be  
applied.  
2 2  
in the MEA–PZ–H O–CO system are assumed as  
follows:  
2
Physical absorption of CO :  
Vd  
n   
(2)  
HCO  
2
  
MW  
CO2 (g)  CO (aq)  
(4)  
2
where V is the volume, d is density, and M  
molecular mass. Given the moles of CO  
we are able to obtain the loading values required to  
W
is the  
and the solvent,  
Ionization of water:  
2
+
-
K
[H ][OH ]  
1
+
-
  
H O  
H +OH  
K   
(5)  
2
  
1
determine the solubility of CO  
by using Eq.3.  
2
in PZ and MEA solutions  
(3)  
[H O]  
2
nCO2  
Formation of carbon dioxide:  
α
K
CO2  
2
-
+
  
nMEA +nPZ  
CO +H O  
HCO +H  
2
2
  
3
- +  
HCO ][H ]  
3
[
K   
(6)  
2
[
CO ][H O]  
2 2  
Formation of bicarbonate:  
1
60  
Journal of Environmental Treatment Techniques  
2019, Volume 6, Issue 1, Pages: 158-165  
+
2-  
PZ balance:  
K
[H ][CO ]  
-
3
2-  
+
3
  
+
-
+
-
HCO3  
CO +H  
3
K   
(7)  
(8)  
  
3
-
[PZ]  [PZ]+[PZH ]+[PZCOO ]+[H PZCOO ]  
t
[HCO ]  
3
-
+[PZ(COO ) ]  
17  
   
2
Reversion of the protonation of MEA:  
+
K
[MEA][H ]  
And according to Henry's law, the vapor phase equilibrium  
can be expressed as:  
+
4
+
MEA+H  
  
MEAH  
K   
  
4
+
[MEAH ]  
PCO  HCO .[CO2 ]  
(18)  
Formation of MEA carbamate:  
2
2
K
-
5
-
  
MEA+HCO3  
MEACOO +H O  
  
MEA][HCO ]  
2
where PCO2 is the partial pressure of CO  
2
and HCO2 is the  
-
3
[
Henry’s law constant for CO in solution.  
2
K   
(9)  
5
-
The chemical equilibrium constant is a function of  
temperature and is obtained by Eq. 19 where A, B, C, and  
D parameters for each of the reactions are specified in  
Table 2.  
[
MEACOO ][H O]  
2
Reversion of the protonation of PZ:  
+
K
[PZ][H ]  
A
+
6
  
+
PZ+H  
PZH  
K   
(10)  
Ki or HCO = exp( )+BlnT+CT+D  
(19)  
  
6
+
2
[
PZH ]  
T
Table 2 Coefficients of the reaction equilibrium constants used  
in this work  
Formation of first order PZ carbamate:  
K
7
-
+
  
PZ+CO2  
PZCOO +H  
퐾
푖
A
B
-22.4  
-36.7  
-35.4  
0
0
0
0
0
C
0
0
0
0.0576  
0
D
Ref.  
  
K
1
K
2
K
3
K
4
K
5
K
6
K
7
K
8
K
9
-13446  
-12092  
-12431  
-17.3  
-1545.3  
3814.4  
3616  
140.93 (29)  
235.48 (29)  
220.06 (29)  
-38.84 (29)  
-
+
[
PZCOO ][H ]  
K   
(11)  
7
[
PZ][CO2 ]  
2.151  
(29)  
Formation of second order PZ carbamate:  
-1.5016 14.119 (30)  
K
-
8
-
+
0
0
-8.635 (30)  
-3.654 (30)  
6.822  
192.8  
  
PZCOO +CO2  
PZ(COO ) +H  
  
2
1322.1  
-6066.9 -2.29  
-
+
0.0036  
(30)  
(30)  
[
PZ(COO ) ][H ]  
2
K   
(12)  
HCꢀ2 -9624.4 -28.7 0.01441  
8
-
[
PZCOO ][CO ]  
2
Li and Shen (15) showed the final form of equilibrium  
constants as follows:  
Reversion of protonation of the first order PZ carbamate:  
K
+
-
9
-
+
  
3
H PZCOO  
PZCOO +H  
  
F = exp (a +a /T(K)+a /T (K)+b α +b /α  
1
2
3
1 co  
2
co2  
(20)  
2
- +  
+
b3/α2 +b ln  
m )  
   
co  
4
2
[
PZCOO ][H ]  
K   
(13)  
9
+ -  
H PZCOO ]  
[
i i  
Where a and b are the adjustable parameters which are  
obtained by using experimental data.  
In this study, we assume the equilibrium constants as the  
Mass balances and charge balance equations can be  
written as follows:  
Charge balance:  
2
function of temperature, the partial pressure of CO , and  
the amine concentration. Adjustable equilibrium constants  
are related to the K values calculated from Eq.19, the  
+ + + - 2-  
MEAH ]+[PZH ]+[H ]  [HCO ]+2[CO ]+  
3 3  
[
[
i
parameters of Table 2, and F parameter. These constants  
are as follows:  
-
-
-
-
PZCOO ]+[MEACOO ]+[OH ]+2[PZ(COO ) ] (14)  
2
CO  
2
balance:  
K = K F  
(21)  
(22)  
7
7
-
2-  
-
α[MEA+PZ]total  [CO ]+[HCO ]+[CO ]+[PZ(COO ) ]  
2
3
3
2
K = K F  
9
9
-
+
-
-
3
+
[PZCOO ]+[H PZCOO ]+[MEACOO ]  
(15)  
F = exp (a +a /T(K)+a /T (K)+b ln P (kPa))  
1
2
3
1
co2  
+
b (P  
(kPa))+c1  
MEA  
+c2  
PZ  
)
(23)  
MEA balance:  
2
co2  
+
-
[
MEA] [MEA]+[MEAH ]+[MEACOO ]  
(16)  
t
1
61  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 1, Pages: 158-165  
In Eq. 23, a  
derived from experimental data for a four-component  
system (MEA-PZ-H O-CO ). However, in this method,  
i
, b  
i
, and c  
i
are the adjustable parameters  
reversion of protonation the first order PZ carbamate) were  
optimized by the experimental data of CO  
2
solubility for  
2
′
2
′
PZ MEA aqueous solutions, and the obtained  
+
only the values of K and K parameters are modified by  
coefficients are given in Table 4.  
7
9
using optimization of the proposed parameters, and for  
other reactions, the initial equilibrium constants are used.  
The absolute deviations obtained from the difference  
between the calculated molar load and the molar load  
obtained from the experimental results by using Eq.24, and  
the molar load is calculated using Eq. 25.  
start  
′
7
′
9
The guess values for K and K parameters  
α
-α  
calc exp  
AD% =  
×100  
(24)  
The guess values for unknown concentrations  
Concentration evaluation using 13 equations  
α
exp  
The algorithm used for modeling is shown in Fig. 2.  
4
Results  
NO  
In this study, the solubility of CO  
2
in different  
F[C ]…..[C ]<TOL  
1
12  
concentrations of various solutions (%12MEA,  
%
%
1PZ+%12MEA, and  
3PZ+%12MEA) wt%, at different partial pressure (8.44,  
%2PZ+%12MEA,  
2
5.33, and 42.22) kPa and at various temperatures (303,  
Calculate the loading by using Eq. (25)  
313, and 323) K were determined and calculated  
experimentally. The experimental data and the predicted  
results from Kent-Eisenberg model are presented in the  
Table 3. In the improved Kent-Eisenberg model, the non-  
ideality effect was only considered in the coefficients of F  
function, and the amine protonation reaction and  
formation of MEA carbamate were regarded as non-ideal  
′
′
9
Print K , and K  
YES  
NO  
7
F < ɛ  
Fig. 2: Calculation algorithm by using the improved Kent-  
Eisenberg model based on solving simultaneous nonlinear  
equations  
′
reactions. K7 (the equilibrium constant formation of the  
′
9
first order PZ carbamate) and K (the equilibrium constant  
-
3
2-  
3
-
-
+
-
-
[
CO ]+[HCO ]+[CO ]+[MEACOO ]+[PZCOO ]+[H PZCOO ]+[PZ(COO ) ]  
2
2
α   
(25)  
[MEA+PZ]t  
Table 3 Comparison between the experimental and calculated loading of CO  
temperatures.  
2
in the aqueous solution of MEA+ PZ at different  
PCO  
T/K  
2
MEA (12%wt)  
MEA(12%wt)+PZ(1%wt) MEA(12%wt)+PZ(2%wt) MEA(12%wt)+PZ(3%wt)  
kPa  
L.Exp.  
L.Calc.  
AD% L.Exp.  
L.Calc.  
0.014  
0.012  
0.01  
AD%  
27.2  
33.3  
66.6  
L.Exp.  
0.012  
0.01  
L.Calc.  
0.014  
0.011  
0.01  
AD%  
16.6  
10  
L.Exp.  
L.Calc.  
AD%  
7.7  
3
3
3
03 8.44  
13 8.44  
23 8.44  
0.009 0.015 66.6  
0.008 0.013 62.5  
0.005 0.011 120  
0.011  
0.009  
0.006  
0.013  
0.012  
0.0115 0.0111 3.4  
0.007  
42.8  
0.008  
0.009  
12.5  
3
3
3
3
03 25.33  
13 25.33  
23 25.33  
03 42.22  
0.091 0.139 52.7  
0.082 0.111 35.3  
0.098  
0.092  
0.08  
0.128  
0.103  
0.085  
0.214  
30.6  
11.9  
6.2  
0.101  
0.094  
0.082  
0.201  
0.119  
0.095  
0.078  
0.199  
17.8  
1
0.104  
0.097  
0.088  
0.216  
0.111  
0.089  
0.073  
0.185  
6.7  
8.2  
17  
0.07  
0.091 30  
4.8  
1
0.169 0.232 37.2  
0.185  
15.6  
14.3  
3
3
13 42.22  
23 42.22  
0.153 0.185 20.9  
0.128 0.152 18.7  
0.163  
0.138  
0.171  
0.141  
4.9  
2.1  
0.179  
0.153  
0.159  
0.131  
11.1  
14.3  
0.194  
0.162  
0.148  
0.122  
23.7  
24.6  
Table 4: Optimized coefficients of Kꞌ  
7
9
and Kꞌ equilibrium constants  
퐾
푖
a
1
a
2
a
3
b
1
b
2
c
1
c
2
′
K
K
-2.03  
3.97  
-1.08  
-0.017  
0.0654  
-3.51  
1.93  
-4.42  
2.78  
-0.82  
1.2  
0.287  
7
′
9
-0.072  
-0.325  
1
62  
Journal of Environmental Treatment Techniques  
2019, Volume 6, Issue 1, Pages: 158-165  
4
-1 Effect of CO  
2
partial pressure, temperature and PZ  
O-CO  
concentration for the systems of (MEA-PZ-H  
2
2
)
C=%12MEA+%1PZ  
Figs. 3 to 6 show the effects of partial pressure,  
temperature, and concentration parameters.  
0
.2  
.18  
0.16  
0
4
-1-1 Effect of partial pressure  
As it is shown in the charts, an increase of CO  
pressure enhances CO solubility in the solution. The  
2
partial  
2
0
0
.14  
.12  
0.1  
.08  
.06  
.04  
.02  
0
higher the partial pressure of the CO gas, the greater the  
2
solubility.  
In similar works, Murshid et al. (31) and Yang et al. (32)  
observed that CO solubility in AMP + PZ mixture  
enhances with the increase of CO pressure.  
2
2
0
0
0
0
C=12%MEA  
0
0
0
0
.18  
.16  
.14  
.12  
T = 303 K  
T = 313 K  
T = 323 K  
0
20  
40  
60  
CO Partial Pressure (kPa)  
2
0
.1  
0
0
0
0
.08  
.06  
.04  
.02  
0
2
Figure 4 effect of CO partial pressure on the loading value for  
MEA-PZ-CO -H O) system at concentration (12%MEA+1%PZ)  
and different temperature  
(
2
2
T = 303 K  
T = 313 K  
T = 323 K  
4
-1-3 Effect of PZ concentration  
The increase of loading (numbers on the y axis) is  
apparent from the increase of PZ concentration at all  
temperatures and partial pressures. In addition, Chung et  
al. (33) showed that adding PZ to TEA would increase CO  
2
0
20  
40  
60  
loading. Also, Dash et al. (34, 35), Murshid et al. (31),  
Yang et al. (32), and Ali and Aroua (36) showed that  
increasing the concentration of PZ in the solution results  
CO Partial Pressure (kPa)  
2
Figure 3: effect of CO  
MEA-CO -H O) system at concentration (12%MEA) and  
different temperature  
2
partial pressure on the loading value for  
2
in the enhancement of the CO solubility.  
(
2
2
C=12%MEA+2%PZ  
4
-1-2 Effect of temperature  
One of the affecting factors on the solubility is  
0
.25  
temperature. As can be seen, CO  
solvents decreases with temperature rise. This can be  
justified by the fact that CO molecule is a nonpolar  
2
solubility in different  
0
.2  
2
molecule and at low temperatures, it is almost stable.  
Therefore, its dissolution is physical, and the bond  
between molecules of solute and solvent is physical. As  
the temperature of the solution increases, the kinetic  
energy of its molecules increases, and this results in  
breaking of the weak bond, and the molecules of dissolved  
gas which have more energy than the molecules of solvent  
are removed from the solution which reduces the  
solubility. It can be said that PZ acts like amine solvents,  
so for this solvent, the temperature rise reduces the  
loading. In another similar work, Murshid et al. (31)  
0.15  
0
.1  
T = 303 K  
T = 313 K  
T = 323 K  
0
.05  
0
2
showed that the solubility of CO in a solution of AMP +  
PZ decreases with temperature.  
0
20  
40  
60  
CO Partial Pressure (kPa)  
2
2
Figure 5 effect of CO partial pressure on the loading value for  
MEA-PZ-CO -H O) system at concentration (12%MEA+2%PZ)  
and different temperature  
(
2
2
1
63  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 1, Pages: 158-165  
hexamethylenediamine. Fluid Phase Equilibria.  
2
015;402:102-12.  
Mudhasakul S, Ku H-m, Douglas PL. A simulation  
model of CO absorption process with  
C=%12MEA+%3PZ  
2
3
.
.
0
0
0
.25  
a
2
methyldiethanolamine solvent and piperazine as an  
activator. International Journal of Greenhouse Gas  
Control. 2013;15:134-41.  
Nwaoha C, Saiwan C, Tontiwachwuthikul P, Supap T,  
Rongwong W, Idem R, et al. Carbon dioxide (CO 2)  
capture: absorption-desorption capabilities of 2-  
amino-2-methyl-1-propanol (AMP), piperazine (PZ)  
and monoethanolamine (MEA) tri-solvent blends.  
Journal of Natural Gas Science and Engineering.  
0
.2  
.15  
0
.1  
2
016;33:742-50.  
4.  
Freeman SA, Dugas R, Van Wagener DH, Nguyen T,  
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T = 303 K  
T = 313 K  
T = 323 K  
.05  
0
24.  
5. Kent RL. Beter data for amin treating. Hydrocarbon  
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0
20  
40  
60  
6
.
Deshmukh R, Mather A. A mathematical model for  
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Edwards TJ, Newman J, Prausnitz JM.  
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CO Partial Pressure (kPa)  
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2
Figure 6 effect of CO partial pressure on the loading value for  
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and different temperature  
(
2
2
7.  
5
Conclusions  
The results of this research are as follows:  
The increase of pressure or decrease of temperature  
causes the increase of CO solubility in each of the  
2
studied amines.  
8. Austgen DM, Rochelle GT, Peng X, Chen CC. Model  
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By increasing the concentration of PZ in the mixture  
of MEA + PZ, the solubility of CO increases.  
The experimental results on PZ showed that this  
amine has a very high potential for CO absorption,  
and as an activator, it can have a significant effect on  
the performance of the amine MEA.  
The average absolute deviations (AAD%) which was  
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value of the model and the experimental results was  
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&
Engineering Chemistry  
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electrolyte  
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The authors acknowledge the immense technical  
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