Viscosities Of Pure And Aqueous Solutions Of .

ANNUAL TRANSACTIONS OF THE NORDIC RHEOLOGY SOCIETY, VOL. 21, 2013Viscosities of Pure and Aqueous Solutions of Monoethanolamine (MEA),Diethanolamine (DEA) and N-Methyldiethanolamine (MDEA)Udara S. P. R. Arachchige1,a, Neelakantha Aryal1, Dag A. Eimer1, and Morten C. Melaaen11 Telemark University College, Porsgrunn, 3901, anolamine and methyldiethanolaminesolutions were examined at a temperaturerange from (293.15 to 423.15) K for pureamines and (293.15 to 353.15) K foraqueous amines at different compositions.The experimental viscosities measured inthis work are in good agreement with thosereported in the literature.INTRODUCTIONAlkanolamines have been used for theacid gas absorption process for a longperiod. The physical properties of thosealkanolamines are important for processdesign. The main objective of this paper isto provide values for viscosities of differentaqueous amines at different temperatureswhich are needed for the acid gas absorptionprocess. Acid gas absorption process takesplace at 313 K temperature. However,different operating temperatures areinterested for high performance. Therefore,physical properties like viscosity of aminesare important to calculate for differenttemperature range to perform mathematicalcalculations. The physical properties such asdensity, viscosity and solubility data ofsolvents are important for the acid gasabsorption and regeneration process.Different types of amines are available, suchas primary amines (MEA, DGA), secondaryamines (DEA), tertiary amines (MDEA,299TEA), hindered amines (AMP) and cyclicamines(Piperazine).Importantalkanolamines for industrial application aremonoethanolamine (MEA), diethanolamine(DEA), di-2-propanolamine (DIPA) and Nmethyldiethanolamine(MDEA)[1].Aqueous MEA solutions are widely used forgas treating processes due to high reactivity,low operating cost and ease of reclamation[2]. However, the possibilities of using othersolvents like DEA and MDEA have to beanalyzed in order to lower the cost of CO2capturing. This work has been carried out todetermine the effect of temperature on theviscosity of different types of amines atdifferent concentration levels at atmosphericpressure. The experiments were performedtochecktheviscositiesofmonoethanolamine (MEA), diethanolamine(DEA) and methyldiethanolamine (MDEA).Thepurealkanolamineviscositymeasurements were carried out for thetemperature range (293.15 to 423.15) K andalkanolamine solution viscosity weremeasured in the range of (293.15 to 353.15)K. This represents an extension ofpreviously reported data.The measured data for the different kindof amines are compared with those availablefrom the literature. The pure viscosity datafor MEA, DEA and MDEA solutions arecompared with data from Li and Lie1,DiGuilio et al. [3] and Mandal et al. [4] Thedata given by Amundsen et al. [5], Rinker et

al. [6] and Li and Lie [1] are used tocompare the aqueous viscosity data forMEA, DEA and MDEA solutions.Agreement between the measurement dataand literature values were found to besatisfactory.The obtained results were used toproduce correlations for amine viscosity atdifferent temperatures. A number ofcorrelations for computation of viscosity ofliquids are presented in the literature. Vogel[7] has reported the simple three constantcorrelation for pure liquid viscosity andViswanath and Natarajan [8] utilized asimilar form for both dynamic andkinematic viscosities.The equation presented by Vogel wasmodified by Goletz and Tassios [9] toinclude the boiling point of the substance.Dutt [10] described a similar idea to Goletzand has derived a correlation using densityand boiling point of the component. Pureliquid viscosity can be represented bypolynomial type equation mentioned byGirifalco [11] which was extended byThorpe and Rodger [12].Digullio et al. [3] have reported a threeconstant equation which is closer to Vogel’sequation for pure amines’ viscosity. Amongthose, Digullio’s equation is selected forcalculation of pure amines’ viscosity due toless deviation when fitting experimentalvalues.The aqueous amine viscosities measuredin this work are used to regress thepolynomial for representation of amineviscosities. Teng et al. [13] and Chowdhuryet al. [14] have reported the correlations foraqueous amine viscosity variation withmolar concentration for specific temperaturevalues. The correlation from Teng et al. [13]is selected for this study because of lessdeviation when fitted to experimentalvalues.300EXPERIMENTAL SECTIONDynamic viscosity was measured usingMCR 101 Anton Paar double-gaprheometer. The viscometer was calibratedagainst the petroleum distillate and mineraloil calibration fluid from Paragon Scientificltd. The calibration factor was decidedaccording to the given temperature for thecalibration liquid and experimental viscosityachieved during the calibration. The lowtemperature measurements were achievedby applying cooling water supply to therheometer setup at (293.15, 298.15 and303.15) K. The MEA was purchased fromMerck KGaA, DEA and the MDEA fromMerck Schuchardt OHG. The purity of thechemicals in mass basis are 99.5%, 99% and98% respectively for MEA, DEA andMDEA. The information about chemicalsare given in Table 1. Without furtherpurification, all these amines were used forexperimental studies. De-gassed distilledwater was used for preparation of aqueousamine solutions. All the experiments areperformed at 1.01 bar operating pressure.Table 1. Purity of the amines used tOHGRESULTS AND DISCUSSIONThe results from the experimental workhave been sub-divided into two sections:viscosities of pure amines and viscosities ofaqueous amines.

Table 3. Comparison of the Viscosities η of Pure DEA Measuredin This Work with Literature Values from Temperature T (293.15 to 423.15) KPure Amine ViscositiesViscosities of pure MEA, DEA andMDEA from temperature range (293.15 to423.15) K are tabulated in Tables 2, 3 and 4,respectively. The experimental viscosityresults for pure amines, tabulated in Tables3 to 5, are plotted in Fig. 1 as viscosity vs.temperature. As shown in the Fig. 1,viscosities of pure amines are decreasingwith the increase of temperature. Theviscosities of pure MEA, DEA and MDEAmeasured in this work agree well with theliterature values taken from Li and Lie1,DiGuilio et al. [3] and Mandal et al. [4],respectively.Theaverageabsolutedeviations between the literature values andour data are (0.019, 1.21, 0.39) mPa·s forpure MEA, DEA and MDEA respectively.The deviations are in the range ofexperimental uncertainties which is givenunder the each table.Standard uncertainties u are u(T) 0.3 K and the combinedexpanded uncertainties Uc are Uc(η) 0.843 mPa·sTable 2. Comparison of the Viscosities η of Pure MEA Measuredin This Work with Literature Values from Temperature T (293.15 to 423.15) KTable 4. Comparison of the Viscosities η of Pure MDEA Measuredin This Work with Literature Values from Temperature T (293.15 to 423.15) KT/KThisworkLi andLie1DiGuilio etT/KDiGuilioMandal etet his work566.3119.535.0923.410.535.67ThisLi andworket al.422.43Lie [1]DiGuilio et al. [3]al. 62393.152.65618.98323.152.912Mandal andard uncertainties u are u(T) 0.3 K and the combinedexpanded uncertainties Uc are Uc(η) 0.015 6714.314.385969.9877.1513.9872.5047.088

mPa sStandard uncertainties u are u(T) 0.3 K and the combinedexpanded uncertainties Uc are Uc(η) 0.122 mPa·s10001510η /mPa 5413.15T/KFigure 1. Pure amines’ viscosity variationwith temperature at (293.15 to 423.15) K: ,MEA; , MDEA; , DEA.Aqueous Amine ViscositiesThe viscosity data for aqueous MEA,DEA and MDEA solutions are presented inTables 5, 6 and 7, respectively. Theexperiments were performed to measureviscosities of amines with concentrations inthe range from mass fraction (0.1 to 0.9) forthe temperature range (293.15 to 353.15) K.The aqueous MEA, DEA and MDEAviscosity data of Amundsen et al. [5],Rinker et al. [6] and Li and Lie [1] arecompared with our experimental data(Figures 2, 3 and 4). The average absolutedeviations are (0.08, 0.02, 0.02) mPa·s foraqueous MEA, DEA and MDEA,respectively and the maximum deviation is0.25 mPa·s when compared against theliterature sources. Hence, aqueous amineviscosities measured in this work are ingood agreement with those reported byAmundsen et al. [6], Edward et al.5, Li andLie [1].The dynamic viscosities of aqueousMEA, DEA and MDEA are plotted versustemperature in Figures 2, 3 and 4.302Figure 2. Comparison of aqueous MEAviscosity as a function of temperature. Linesare experimental data: , 20%; ---, 30%;, 40%;, 50%;, 70%;,90%. Symbols refer to literature data [5]: ,20%; , 30%; x, 40%; , 50%; Δ, 70%; ,90%.43η/mPa s0293.15210293.15313.15333.15353.15T/KFigure 3. Comparison of aqueous DEAviscosity variation with temperature. Lines, 20%;are experimental data: , 10%;, 30%. Symbols refer to literaturedata6: , 10%; , 20%; , 30%.

Figure 4. Comparison of aqueous MDEAviscosity variation with temperature: Linesare experimental data: , 20%; ---, 30%;, 40%;, 50%. Symbols refer toliterature data1: , 20%; , 30%; , 40%;o, 50%.1210η/mPa KTable 5. Viscosities of Aqueous MEA Solutions Measured in This Work from Temperature T (293.15 to 353.15) K as a function of massfraction.Temp10 %20 %30 %40 %50 %60 %70 %80 %90 150.4490.5890.7790.9771.2911.774Standard uncertainties u are u(T) 0.3 K and the combined expanded uncertainties Uc are Uc(η) 0.015 mPa·sTable 6. Viscosities of aqueous DEA solutions measured in this work from T (293.15 to 353.15) K as a function of mass fraction.Temp10 %20 %30 %40 %50 %T/K60 %70 %80 %90 00.8331.0991.6852.6594.21607.1113.03580 %90 %Standard uncertainties u are u(T) 0.3 K and the combined expanded uncertainties Uc are Uc(η) 0.843 mPa·sTable 7. Viscosities of aqueous MDEA solutions measured in this work from T (293.15 to 353.15) K as a function of mass fraction.TempT/K10 %20 %30 %40 %50 %60 %70 029.03058.28781.670303