Density of aqueous solutions of PZ-MPDL at various concentrations and temperatures

“Density of blended PZ-MPDL aqueous solution was measured over ranges of temperatures (313, 323, and 333 K) and PZ/MPDL concentration ratios (5/25, 10/20, and 15/15 %wt.). The experimental results are shown in Table 2 and plotted in Fig. 1. It was found that density of blended PZ-MPDL decreased as temperature increased. This trend corresponds well with that of water, 30 %wt. MEA, and 30 %wt. AMP [10][11]. It was also observed that density of blended PZ-MPDL increased as concentration of PZ in the blended solvent increased. This dues to the fact that density of PZ is higher than that of pure MPDL [8]. Additionally, Fig. 1 clearly shows that the density of blended PZ-MPDL is close to that of benchmarking industrially used 30 %wt. MEA and water and is slightly higher than 30 %wt. AMP. As a result, it can be said that the novel blended PZ-MPDL over a concentration range of 5/25 %wt. to 15/15 %wt. can be used for carbon capture in terms of density. It is also worthwhile to mention that there was no precipitation of the blended solvent over studied ranges of concentration and temperature.

As presented in Fig. 1, the density of blended PZ-MPDL can be calculated by a predictive correlation and presented as solid lines. The predictive correlation was developed based on a polynomial model as a function of MPDL concentration and temperature as shown in Eq. (1).(1)ρ=α0+α1C+α2C2where ρ is density of blended PZ-MPDL solvent (g/cm3), C is MPDL concentration in the blended PZ-MPDL solvent (%wt.) and α0α1, and α2 are temperature dependent coefficients, which are depending on temperature (T) in Kelvin as shown in Eqs. (2)(4)(2)α0=a1+a2T+a3T2(3)α1=a1′+a2′T+a3′T2(4)α2=a1″+a2″T+a3″T2

Table 2. Experimental density of PZ-MPDL solvent.

Temperature (K) Density (g/cm3)
Empty Cell 5/25 %wt. 10/20 %wt. 15/15 %wt.
313 0.9990 1.0019 1.0086
323 0.9942 0.9966 1.0041
333 0.9898 0.9926 1.0011


Fig. 1. Density of aqueous solutions of PZ-MPDL at various concentrations and temperatures; dots are the experimental data, solid lines are predicted data from the correlation developed in this work, and dash lines are literature data of MEA, AMP, and water [10][11].”

“To determine these temperature dependent coefficients α0α1, and α2, a non-linear regression analysis was applied. The constant parameters for each temperature dependent coefficient are presented in Table 3. From Eqs. (1)(4) and constant parameters in Table 3, the density of blended PZ-MPDL can be predicted and presented as solid lines in Fig. 1. It can be seen that the predicted results very well corresponded with the experimental results with an AAD of 0.06%.”

Table 3. Constant parameters for the temperature dependent coefficient for density prediction.”


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