Viscosity of blended PZ-MPDL solvent – influence of solvent concentration and temperature

“Viscosity of blended PZ-MPDL aqueous solution was experimentally determined over temperatures and PZ/MPDL concentration ratios of 313–333 K and 5/25–15/15 %wt., respectively. The viscosity data are presented in Table 4 and plotted in Fig. 2. The results showed that viscosity of the blended PZ-MPDL solvent decreased as temperature increased and increased as concentration of PZ increased. For the effect of temperature, it is well understood that the viscosity of liquid amine solution decreases as temperature increases (as illustrated in Fig. 2) for 30 %wt. MEA, 30 %wt. MDEA, 30 %wt. AMP, 12/18 %wt. PZ/AMP, and 12/18 %wt. PZ/MDEA [10][12]. Since PZ is originally in a solid form, an addition of PZ in MPDL solvent resulted in an increasing of solvent viscosity as presented in Table 4 and Fig. 2. Even though the viscosity of blended PZ-MPDL was found to be higher than that of conventional single amine solvents, but its viscosity was in the same range with that of conventional blends such as PZ-AMP and PZ-MDEA [12]. This observation confirmed that the novel blended PZ-MPDL had a reasonable range of viscosity for carbon capture application.

In this study, the predictive correlation was developed for calculating the viscosity of blend PZ-MPDL solvent over ranges of temperature and blended ratio. By applying a polynomial model, the correlation can be presented in Eq. (5) with temperature dependent coefficients β0β1, and β2.(5)μ=β0+β1C+β2C2where μ is dynamic viscosity of blended PZ-MPDL solvent (mPa s), C is concentration of MPDL in the blended solvent (%wt.) and β0β1, and β2 are temperature dependent coefficients, which are function of temperature (T) in Kelvin as shown in Eqs. (6)(8)(6)β0=b1+b2T+b3T2(7)β1=b1′+b2′T+b3′T2(8)β2=b1″+b2″T+b3″T2

Table 4. Experimental viscosity of PZ-MPDL solvent.

Temperature (K) Viscosity (mPa s)
Empty Cell 5/25 %wt. 10/20 %wt. 15/15 %wt.
313 2.6625 2.6934 2.7364
323 1.9674 1.9881 2.0242
333 1.5171 1.5328 1.5675


Fig. 2. Viscosity 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 conventional amines [10][12].”

“The constant parameters for temperature dependents parameters were determined using non-linear regression analysis, the results are shown in Table 5. Based on the polynomial model of Eq. (5) and the constant parameters given in Table 5, the viscosity of blended PZ-MPDL can then be calculated. As shown in Fig. 2 (solid lines), it can be said that the developed correlation can be successfully predicted the viscosity of blended PZ-MPDL with an AAD of 0.07%.”

Table 5. Constant parameters for the temperature dependent coefficient for viscosity prediction.”


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