Ahmad, Faizan

Bustam, Mohammad Azmi

Lau, Kok Keon

Murshid, Ghulam

Shariff, Azmi Mohd

English

Teeside University's Research Repository

October 2011, Volume 2, No.5 International Journal of Chemical and Environmental Engineering   Thermophysical Analysis of Aqueous Solutions of Piperazine (PZ) and 2-Amino-2-hydroxymethyl-1, 3-propanediol + Piperazine (PZ + AHPD)  Ghulam Murshid a, Azmi Mohd Shariff, Lau Kok Keong, Muhammad Azmi Bustam & Faizan Ahmad Universiti Teknologi PETRONAS Bandar Seri Iskandar 31750, Tronoh, Perak, Malaysia a Corresponding author E-mail:  hmurshid@gmail.com   Abstract Physical properties such as density, viscosity, and surface tension of aqueous solutions of Piperazine (PZ) with mass fractions (100 w = 6.88, 13.76) were measured. All these properties were also measured for aqueous blends of 2-amino-2-hydroxymethyl-1,3- propanediol with Piperazine (AHPD + PZ) with mass fractions { 100 (w1/w2) = (1/6.88, 1/13.76, 7/6.88, 7/13.76, 13/6.88, 13/13.76 and 19/6.88, 19/13.76) }. These properties were investigated over the temperature range of 298.15 K to 333.15 K and were corr elated as a function of temperature. There was a decrease in all measured properties with increasing temperature  Keywords: CO2, AHPD, PZ, Acid Gas Contactor, Physical Properties  1. Introduction Alkanolamines are used for the removal of acid gases such  as  carbon  dioxide  (CO2)  and  hydrogen sulphide (H2S) from the process of different industrial gaseous streams through absorption process. The most industrially used alkanolamines include; mono-ethanolamine (MEA), di-ethanolamine (DEA) and N-methyldiethanolamine (MDEA).1 Recently sterically hindered amines are proposed as potential new solvents for acid gas removal due to their unique cyclic structure, high CO2 loading and efficient regeneration .2-10 One of the sterically hindered amines is 2-Amino-2-hydroxymethyl-1,3-prpoanediol (AHPD). Reaction kinetics and solubility data shows that AHPD   is   a   good   potential   solvent   for   acid   gas removal.11-13 Recently there has been a growing interest in use of aqueous solutions of alkanolamines containing an activator to enhance the rate of reaction. Piperazine (PZ)  has emerged as an  effective  activator.14-17 The addition of PZ to aqueous solution of AHPD has shown acceleration   in   the   rate   of   reaction   with   CO2.18 Therefore, PZ activated aqueous solution of AHPD could be a potential   solvent   for   acid   gas   removal. The knowledge of physical properties of solvents is essential to design the absorption system for acid gas removal. The properties like density and viscosity are also important for the determination of rate of reaction and mass transfer rate modeling of gas sweetening unit.7,11,19 Surface tension can also affect the important design parameters such as the column hydrodynamics and gas holdup in the acid gas contactor.20 Therefore, in this paper the physical properties (density, viscosity and surface tension) of aqueous solutions of PZ and (AHPD + PZ) are presented. All the experimentally measured physical properties were also correlated as a function of temperature.  2.  Materials and  Methods Piperazine with a purity of 99.9 % (GC, area %) an AHPD 99 % (GC area %) were purchased from Merck, Malaysia and were used without further purification. The bi-distilled water was used to prepare solutions. All the solutions were prepared gravimetrically using an analytical balance (Mettler Toledo AS120S) with a measuring accuracy of ±0.0001 g. The total amine concentrations were also experimentally determined by titration with 0.5 M HCl using methyl orange indicator and the concentrations were accurate with in ± 0.1 %.   2.1 Density The densities of aqueous solutions of PZ and (AMP + PZ) were measured using a digital vibrating glass U-tube densitometer   (DMA   5000,   Anton   Paar)   with   the measuring accuracy of  ±  0.000005  g.m-3.  The  density meter was calibrated before and after each measurement with water of Millipore quality. All the densities were measured at a temperature range of (298.15 to 333.15) K with a temperature controlled accuracy of ±0.01 K (PT Thermophysical Analysis of Aqueous Solutions of Piperazine (PZ) and 2-Amino-2-hydroxymethyl-1, 3-propanediol + Piperazine (PZ + AHPD)  319  100).   The   reported   densities   were   measured   after achieving thermal equilibrium and the equipment was set to slow mode for better accuracy. Each reported data is the average of at least three data points. The experimental uncertainty of measured density was estimated ± 5. 10-6 g . cm-3  2.2 Viscosity The viscosities of aqueous solutions were measured using a calibrated Ubbelohde viscometer of sizes. The viscometer containing amine solutions was immersed in thermostatic bath (Tamson, TVB445) with built in stirring system with temperature controlled accuracy of ± 0.01 K. The   bath   temperature   was   regulated   with   Pt-100 temperature   probe.   The   kinematic   viscosities   were calculated  by  multiplying  the   efflux  time   with  the viscometer constant with the following 1    Ct   (1)  Where υ is the kinematic viscosity in centistokes (cSt), C is the viscometer constant (cSt . s-1) and t is the efflux time in seconds (s). The dynamic viscosities of the aqueous amine solutions were calculated by multiplying the corresponding densities with the measured kinematic viscosities with an uncertainty of ± 0.028 mPa. S.  2.3 Surface Tension  The surface tension was measured using IFT 700 (VINCI Technologies) with a precision of ± 0.03 mN/m with the temperature  accuracy  of  ±  0.2  K.  The  pendent  drop  method was used to measure the surface tension in which a drop is created inside a  thermostatic chamber and a camera is installed which focuses and records the shape and   contact   angle   properties.   All   the   values   were measured between the temperature range of (298.15 to 333.15) K and the reported data is the average of 5 data points. The measured experimental uncertainties at a corresponding temperature were found ± 0.38 mN . m-1 and ± 0.2 K  3 Results and Discussion The density of aqueous solutions of PZ (2) and (AHPD (1) + PZ (2)) was measured over the temperature range of 298.15 K to 333.15 K. The measured values are presented in Table 1 as a function of temperature and concentration. Where  w1  and  w2  representing the  mass  fractions  of AHPD and PZ respectively. The measured densities were correlated as a function of temperature by the following eq 2  Z  A0  A1T   (2) Where Z represents density or surface tension, A0, A1 are fitting parameters and T is the temperature in K. These parameters were calculated using the method of least square and presented in Table 2 along with the standard deviations. The eq 3 was used to calculate standard deviations   [  n  1/2 ] SD   (Zexp tl   Zcalcd )  / n [ i                 ]  (3)   Where SD represents standard deviations, Zexptl represents measured physical properties, Zcalcd  represents calculated values and n represents the total number of data points. The measured viscosities are presented in Table 3 as a function of temperature and concentrations. The measurements were made for a temperature range from 298.15 K to 333.15 K. It is indicated from Table 3 that there is  a  decrease in  viscosity values over  the  entire range  of  temperature. However an  increasing trend  in viscosity values of aqueous solutions of PZ (2) and (AHPD (1) + PZ (2)) systems was observed with the increase in concentration of PZ (2) and AHPD (1). The following eq 4 was used to correlate the measured viscosity values as a function of temperature  log  ()  Ao   A1 / T   (4)  Where η is viscosity, Ao, A1 are fitting parameters and T is temperature in K. The fitting parameters and standard deviations are presented in Table 4 and eq 3 was used to calculate the standard deviations. Surface tension of aqueous solution of PZ (2) and (AHPD (1) + PZ (2)) was measured for the temperature range of (1) + PZ (2)) was measured for the temperature range of 298.15 K to 333.15 K. According to Table 5 the measured surface tension values decreased with increasing temperature.   Surface   tension   also   decreased   as   the concentration  of  both  PZ  and  AHPD  increased.  The measured values were fitted to the eq 2 as a function of temperature and standard deviations were calculated by eq   3.   The   fitting   parameters   along   with   standard deviations are listed in Table 6 Thermophysical Analysis of Aqueous Solutions of Piperazine (PZ) and 2-Amino-2-hydroxymethyl-1, 3-propanediol + Piperazine (PZ + AHPD)  320   Table 1. Density ρ (g.m-3) of Aqueous PZ (2) and AHPD (1) + PZ (2)  T  aqueous PZ (w2)  AHPD (1) + PZ (2) + water: 100(w1/w2)   6.88  13.76  1 / 6.88  1 /13.76  7 / 6.88  7 /13.76  13 / 6.88  13 / 13.76  19 / 6.88  19 / 13.76  298.15  1.000184  1.004535  1.002762  1.007333  1.018254  1.02308  1.034335  1.039527  1.051294  1.055913  303.15  0.998686  1.002826  1.001247  1.005596  1.016594  1.021184  1.032525  1.037474  1.049334  1.053702  308.15  0.996974  1.000928  0.999526  1.003676  1.014745  1.019123  1.030549  1.03527  1.047222  1.051354  313.15  0.995073  0.998855  0.997614  1.001582  1.012716  1.016903  1.028393  1.032921  1.044959  1.048867  318.15  0.99299  0.996614  0.995523  0.999322  1.010535  1.014536  1.026106  1.030436  1.042546  1.046239  323.15  0.990738  0.994214  0.993263  0.996908  1.008202  1.012023  1.02364  1.027827  1.04002  1.043525  328.15  0.988328  0.991664  0.99085  0.994342  1.005717  1.00937  1.021112  1.025088  1.037379  1.040693  333.15  0.98577  0.98897  0.988284  0.992918  1.003087  1.006588  1.018424  1.022229  1.034604  1.03778   Table 2. Fitting Parameters of Equation 1 for Density ρ (g.m-3) of Aqueous PZ (2) and AHPD (1) + PZ (2)   aqueous PZ (w2)  AHPD (1) + PZ (2) + water: 100(w1/w2)   6.88  13.76  1 / 6.88  1 /13.76  7 / 6.88  7 /13.76  13 / 6.88  13 / 13.76  19 / 6.88  19 / 13.76  A0  1.1240  1.1271  1.1380  1.1353  1.1483  1.1643  1.1708  1.1875  1.1942  1.2112  A1  -0.0004  -0.0004  -0.0004  -0.0004  -0.0004  -0.0005  -0.0005  -0.0005  -0.0005  -0.0005  SD  0.004  0.004  0.016  0.009  0.011  0.009  0.014  0.002  0.007  0.006   Table 3. Viscosity η (mPa.S) of Aqueous PZ (2) and AHPD (1) + PZ (2) T  aqueous PZ (w2)  AHPD (1) + PZ (2) + water: 100(w1/w2) K  6.88  13.76  1 / 6.88  1 /13.76  7 / 6.88  7 /13.76  13 / 6.88  13 / 13.76  19 / 6.88  19 / 13.76  298.15  1.08  1.39  1.11  1.33  1.6  1.69  1.85  2.1  2.61  3.26  303.15  0.96  1.27  0.99  1.21  1.42  1.51  1.68  1.88  2.33  2.8  308.15  0.86  1.16  0.87  1.08  1.26  1.35  1.48  1.68  2.06  2.45  313.15  0.78  1.01  0.8  0.94  1.12  1.19  1.32  1.51  1.83  2.12  318.15  0.71  0.90  0.71  0.85  0.99  1.06  1.19  1.37  1.57  1.84  323.15  0.65  0.79  0.64  0.74  0.89  0.97  1.08  1.22  1.41  1.58  333.15  0.54  0.65  0.52  0.61  0.74  0.8  0.91  1.04  1.16  1.24   Table 4. Fitting Parameters of Equation 4 for Viscosity η (mPa.S) of Aqueous PZ (2) and AHPD (1) + PZ (2)   aqueous PZ (w2)  AHPD (1) + PZ (2) + water: 100(w1/w2)   6.88  13.76  1 / 6.88  1 /13.76  7 / 6.88  7 /13.76  13 / 6.88  13 / 13.76  19 / 6.88  19 / 13.76  A0  -2.80  -3.08  -3.07  -3.17  -3.03  -2.90  -2.73  -2.62  -3.02  -3.51  A1  843.76  965.45  929.61  985.91  964.10  932.34  892.37  877.66  1024.84  1199.22  SD  0.002  0.008  0.003  0.006  0.003  0.003  0.004  0.003  0.006  0.003  Thermophysical Analysis of Aqueous Solutions of Piperazine (PZ) and 2-Amino-2-hydroxymethyl-1, 3-propanediol + Piperazine (PZ + AHPD)  319                      Conclusion Physical properties like density, viscosity and surface tension of aqueous solutions of PZ and (AHPD + PZ) were experimentally measured. The measurements were made over the temperature range of 298.15 K to 333.15 K. An overall decrease in all properties was observed with increasing temperature. Surface tension values also decreased with the  increase of PZ and AHPD concentrations. The empirical correlations were used to correlate all the measured properties as a function of temperature   ACKNOWLEDGEMENT The authors would like to thank CO2 absorption research group & Universiti Teknologi PETRONAS for providing funding and research facilities to conduct the research work  REFERENCES [1]    Paul,  S.  and  Mandal,  B.  Density  and  Viscosity  of  Aqueous Solutions of (N-   Methyldiethanolamine + Piperazine) and (2- Amino-2-methyl-1-propanol + Piperazine) from (288 to 333) K. J. Chem. Eng. Data, 2006. 51(5): p. 1808-1810. [2]    Bougie, F. and Iliuta, M.C. CO2 Absorption into Mixed Aqueous Solutions of 2-Amino-2-hydroxymethyl-1,3-propanediol and Piperazine. Industrial & Engineering Chemistry Research, 2009. [3]    Park, J.-Y.; Yoon, S. J.; and Lee, H. Effect of Steric Hindrance on Carbon Dioxide Absorption into New Amine Solutions: Thermodynamic and Spectroscopic Verification through Solubility and NMR Analysis. Environ. Sci. & Technol, 2003. 37(8): p. 1670- 1675. [4]   Vazquez, G.; Estrella  A.; Jose M,  N.; Raquel R.; and Eva, R. Surface Tension of Binary Mixtures of Water +  Monoethanolamine and Water +  2-Amino-2-methyl-1-propanol and Tertiary Mixtures of These Amines with Water from 25 oC to 50 oC. . J. Chem. Eng. Data, Data, 1997. 42(1): p. 57-59.                      [5]  Samanta, A. and Bandyopadhyay, S.S. Density and Viscosity of Aqueous Solutions of Piperazine and (2-Amino-2-methyl-1 propanol + Piperazine) from 298 to 333 K. J. Chem. Eng. Data ,2006. 51(2): p. 467-470. [6]  Mandal, B.P.; Biswas A.K.; and Bandyopadhyay, S.S. Absorption of carbon dioxide into aqueous blends of 2-amino-2-methyl-1- propanol and diethanolamine. Chem. Eng. Sci, 2003. 58(18): p. 4137-4144. [7]  Yang, Z.-Y.; Soriano Allan N.; Caparanga Alvin R.; and Meng- Hui Li. Equilibrium solubility of carbon dioxide in (2-amino-2- methyl-1-propanol + piperazine + water). J. Chem. Thermodyn. 2010. 42(5): p. 659-665. [8] Lin, S.-H.; Chiang, P.-C.; Hsieh, C.-F.; Li, M.-H.;Tung, K.-L. Absorption of carbon dioxide by the absorbent composed of piperazine and 2-amino-2-methyl-1 propanol in PVDF membrane contactor. J. Chin. Chem. Engr. 2008. 39(1): p. 13-21. [9]   Sun, W.-C.; Yong, C.-B.; Li, M.-H. Kinetics of the Absorption of Carbon dioxide into mixed Aqueous solutions of 2-amino-2- methyl-l-propanol and piperazine. Chem. Eng. Sci 2005. 60(2): p. [10]  Seo, D. J.; Hong, W. H. Effect of Piperazine on the Kinetics of Carbon Dioxide with   Aqueous Solutions of 2-Amino-2-methyl-1- propanol.  Industrial  &  Engineering  Chemistry  Research,  2000. 39(6): p. 2062-2067. [11]  Derks, P.W.; Hogendoorn K.J.; and Versteeg, G.F. Solubility of N2O  in  and  Density, Viscosity,  and  Surface  Tension  of Aqueous Piperazine Solutions. J. Chem. Eng. Data. 2005. 50(6): p. 1947-1950. [12]  Aguila-Hernández, J.; Trejo, A. and Gracia-Fadrique, J. Surface tension  of  aqueous  solutions  of  alkanolamines:  single  amines, blended  amines  and  systems  with  nonionic  surfactants.  Fluid Phase Equilib. 2001. 185(1-2): p. 165-175. [13]  Muhammad, A.; Mutalib, M. I. A.; Muregesan, T; Shafeeq, A. Thermophysical Properties of Aqueous Piperazine and Aqueous (N-Methyldiethanolamine + Piperazine) Solutions at Temperatures (298.15 to 338.15) K. J. Chem. Eng. Data. 2009. 54(8): p. 2317- 2321.  [14]  Paul, S.; Mandal; B. Density and Viscosity of Aqueous Solutions of (2-Piperidineethanol + Piperazine) from (288 to 333) K and Surface Tension of Aqueous Solutions of (N Methyldiethanolamine + Piperazine) (2-Amino-2-methyl-1- propanol + Piperazine), and (2-Piperidineethanol  +  Piperazine) from (293 to 323) K. J. Chem. Eng. Data. 2006. 51(6): p. 2242-2245.  Table 5. Surface tension σ(mN.m-1) of Aqueous PZ (2) and AHPD (1) + PZ (2) T  aqueous PZ (w2)  AHPD (1) + PZ (2) + water: 100(w1/w2) K  6.88  13.76  1 / 6.88  1 /13.76  7 / 6.88  7 /13.76  13 / 6.88  13 / 13.76  19 / 6.88  19 / 13.76  303.15  69.71  65.16  60.91  59.42  57.52  54.45  53.21  51.8  49.21  47.11  308.15  68.99  64.19  60.08  58.49  56.61  53.48  52.11  50.69  48.42  46.15  313.15  68.39  63.14  59.17  57.52  55.75  52.63  51.19  49.99  47.41  45.29  318.15  67.68  62.2  58.5  56.52  54.98  51.55  50.29  49.02  46.39  44.5  323.15  67.06  60.87  57.68  55.61  54.19  50.58  49.04  48.25  45.51  43.47  333.15  65.88  58.98  56.11  53.55  52.65  48.67  47.35  46.41  43.67  41.71   Table 6. Fitting Parameters of Equation 2 for Surface tension σ(mN.m-1) of Aqueous PZ (2) and AHPD (1) + PZ (2)   aqueous PZ (w2)  AHPD (1) + PZ (2) + water: 100(w1/w2)   6.88  13.76  1 / 6.88  1 /13.76  7 / 6.88  7 /13.76  13 / 6.88  13 / 13.76  19 / 6.88  19 / 13.76  A0  108.36  128.46  109.11  118.69  106.35  113.10  112.62  105.16  105.97  101.43  A1  -0.1277  -0.2087  -0.1591  -0.1954  -0.1613  -0.1934  -0.1962  -0.1763  -0.1871  -0.1792  SD  0.046  0.089  0.050  0.036  0.057  0.042  0.097  0.077  0.054  0.048  

Thermophysical Analysis of Aqueous Solutions of Piperazine (PZ) and 2-Amino-2-hydroxymethyl-1, 3-propanediol + Piperazine (PZ + AHPD)

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Thermophysical Analysis of Aqueous Solutions of Piperazine (PZ) and 2-Amino-2-hydroxymethyl-1, 3-propanediol + Piperazine (PZ + AHPD)

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