Journal of Molecular Liquids 190 (2014) 208–214

Contents lists available at ScienceDirect

Journal of Molecular Liquids

j ourna l homepage: www.e lsev ie r .com/ locate /mol l iq

Density and viscosity for the solutions of 1-butanol with nitromethaneand acetonitrile at 303.15 to 323.15 K

Mohammad Shafiqur Rahman 1, Muhammad A. Saleh 2, Faisal Islam Chowdhury, M. Shamsuddin Ahmed,M. Mehedi Hasan Rocky, Shamim Akhtar ⁎Department of Chemistry, University of Chittagong, Chittagong4331, Bangladesh

⁎ Corresponding author.E-mail addresses: shafiqrly@gmail.com (M.S. Rahman)

(S. Akhtar).1 Present address: DTO, Bangladesh Railway, Pakshey, P2 Deceased.

0167-7322/$ – see front matter © 2013 Elsevier B.V. All rihttp://dx.doi.org/10.1016/j.molliq.2013.11.011

a b s t r a c t

a r t i c l e i n f o

Article history:Received 20 June 2013Received in revised form 6 November 2013Accepted 9 November 2013Available online 22 November 2013

Keywords:DensityExcess molar volumeViscosity1-ButanolNitromethaneAcetonitrileUNIFAC–VISCO model

Densities, ρ, and viscosities, η, for the solutions 1-butanol (1-BuOH) + nitromethane (NM) and 1-BuOH + acetonitrile (ACN) have been measured in the whole range of composition between 303.15 and323.15 K at 5 K interval. Excess molar volumes, Vm

E , were calculated from ρ at different temperatures and theirconcentration dependence was fitted to the Redlich–Kister equation. For both systems Vm

E were positive in theentire range, being more positive at higher temperatures. The maxima for Vm

E vs. x2 curves occurred nearly at0.425 and 0.625 mole fraction of NM and ACN, respectively, and their heights varied as, 1-BuOH + NM N 1-BuOH + ACN.Measured η for the mixtures of 1-BuOH + NM and 1-BuOH + ACN were analyzed by correlating with theGrunberg–Nissan equation. Also, predictions were made about their kinematic viscosities (ν) by using theUNIFAC–VISCO model, which were fairly in good agreement with the experimental ν at different temperatures.

© 2013 Elsevier B.V. All rights reserved.

1. Introduction

In continuation to our study on molecular interactions in liquid–liq-uid binary mixtures, we have already reported on some systems ofamines, amides, alcohols, alkyl carbonates, carboxylic acids, furans etc.both in aqueous and non-aqueousmedia [1–9]. Herein, we are to reporton the densities, excess molar volumes and viscosities for a pair of bina-ry systems: 1-butanol (1-BuOH) + nitromethane (NM) and 1-BuOH + acetonitrile (ACN), where both the components chosen aremore or less associated in type. In regard to H-bonding, neither NMnor ACN can act as proton donors except 1-BuOH. Therefore, while themolecules of 1-BuOH are self-associated through H-bonding and formsome highly ordered species, viz. oligomers/multimers; those of NMand ACN presumably exist in weaker orders as their stabilization isonly through dipole–dipole interactions.

Earlier, physico-chemical properties for different systems ofACN + alkanols were reported by Kinart et al. [10], Sandhu et al. [11],Aznarez and Postigo [12], Nikam et al. [13] and Saha et al. [14]. Similarreports were also made by Paez and Contreras [15], Ku and Tu [16],Pina and Francesconi [17] as well as Iloukhani and Almasi [18]. Somephysicochemical properties of 2-ethoxyethanol + ACN have been

, shamim3332000@yahoo.com

abna, Bangladesh.

ghts reserved.

investigated by Aralaguppi and others [19]. Furthermore, along withreporting the density data on CH3(CH2)n − 1OH + CH3CN at n = 1, 2,3 or 4, Tôrres et al. [20] correlated the Vm

E values to the ERAS-Model.Likewise, volumetric, viscometric and optical properties for the solu-

tions of NM with different alkanols were studied by Tu et al. [21] andCerdeirina et al. [22]. In another study Cerdeirina et al. [23] reportedon the thermodynamics of NM + 1-BuOH, while Piekarski and Somsen[24] have measured heat capacities and volumes of MeOH + NM. Re-cently, Ćwiklińska and Kinart [25] reported on thermodynamic andphysicochemical properties for the mixtures of NM with (2-methoxyethanol + 2-butoxyethanol). Again, Lee and Tu [26] dealtwith densities and viscosities of alkyl esters + NM, while Troncosoand co-workers [27] reported on densities and speeds of sound ofNM + butanol isomers.

In general, experimental results of densities, viscosities and excessproperties are used as tools to understand interactions that usuallyoccur among molecules with diversified structural moieties and/orfunctional groups. The present study thus aims to reveal underlying in-teractions that may occur within these liquid components having re-markable differences in chain lengths, sizes as well as nature offunctional groups present. Again, literature survey has further revealedthat, though a significant number of studies on volumetric and visco-metric properties of themixtures of ACN andNMwith alkanols (includ-ing 1-BuOH)weremade so far [10–27], only a few have been correlatedwith theoretical models. Therefore, our present aim further extends totreat some of the experimental data theoretically. Moreover, any com-parative study on physico-chemical properties for the systems of 1-

209M.S. Rahman et al. / Journal of Molecular Liquids 190 (2014) 208–214

butanol with NM and ACN may also be informative in understandingthe extent of relevant interactions as well.

2. Experimental

The liquids used to prepare binary mixtures with quoted purities: 1-butanol (99.8%) and acetonitrile (99.5%+) were procured from AldrichChemical Co. Ltd., while nitromethane (N98%) was from Merck-Schuchardt. All liquids were used without further purification, but priorto use kept over 4Amolecular sieves for at least 2–3 weeks. As ameasureof purity check, densities as well as viscosities of pure liquids were com-pared with the literature data [11,14,15,18,19,25–37]. Table 1 presentsthe comparison, which is found to be in satisfactory agreement.

The binary solutions were prepared by mass using an electronicbalance (Mettler Toledo B–S) of accuracy ±0.0001 g. Also, precautionwas taken to avoid any loss due to evaporation of the volatile compo-nents and the uncertainty inmole fraction was less than±110−4. Den-sities, ρwere measured by using a 5 ml bi-capillary pycnometer (MBL)and viscosities, ηwith an A-type Ostwald Viscometer (Technico, BS/U);previously calibrating both of them with twice-distilled water. A stop-watch reading up to ±0.1 s was used to record the time of flow. In allmeasurements, a thermostatically controlled water bath (ThermoHaake DC 10 Thermostat) was used maintaining steady temperatureup to ±0.05 K. At all compositions including pure components, ρ and ηwere measured in triplicate and only their averages were taken underconsideration. The average uncertainties in measured ρ and ηwere esti-mated as ±2 × 10−4 g·cm−3 and ±1 × 10−3 mPa·s, respectively.

3. Results and discussion

Densities, ρ for the systems of 1-BuOH + NM and 1-BuOH + ACNin the entire range of compositions at different temperatures (between

Table 1Experimental and literature values of densities and viscosities of pure 1-butanol (1-BuOH), nit

Sample T/K Density, ρ (g·cm−3)

This work Literature M

1-BuOH 303.15 0.8019 0.80194a, 0.802004b, 0.80195c 0308.15 0.7979 0.79793d, 0.7981e, 0.79799f 0313.15 0.7940 0.79405a, 0.794222b, 0.79410c 0318.15 0.7901 0.7902e, 0.7901f 0323.15 0.7862

NM 303.15 1.1244 1.12307d, 1.12453h, 1.1266j 0308.15 1.1176 1.11614d, 1.11686i, 1.1197j 0313.15 1.1108 1.10987i, 1.1129j, 1.11029k 0318.15 1.1040 1.1060l 0323.15 1.0972303.15 0.7713 0.77125h, 0.7710l, 0.77121o 0308.15 0.7658 0.7660n, 0.7656p, 0.76564q 0

ACN 313.15 0.7603 0.7602r, 0.7601m, 0.760370b 0318.15 0.7548323.15 0.7494 0.7495m, 0.7491r 0

a Oswal and Desai [28].b Sadeghi and Azizpour [29].c Liau et al. [30].d Troncoso et al. [27].e Aminabhavi and Gopalkrishna [31].f Sakurai and Nakagawa [32].g Pikkarainnen [33].h Weissberger et al. [34].i Ćwiklińska and Kinart [25].j García-Miaja et al. [35].k Lee and Tu [26].l Contreras and Susana [15].m Garcia and Ortega [36].n Aralaguppi et al. [19].o Iloukhani and Almasi [18].p Sandhu [11].q Saha et al. [14].r Hickey and Waghorne [37].

303.15 and 323.15 K) are as displayed in Table 2. As Table 2 shows, ρ ofthe pure components followed the order: NM ≫ 1-BuOH N ACN,whereas, for solutions the ρ varied as: 1-BuOH + NM N 1-BuOH + ACN.

From the measured ρ the excess molar volume, VmE at any composi-

tion was calculated by using the following equation:

VEm ¼ x1M1 þ x2M2

ρx1M1

ρ1þ x2M2

ρ2

� �ð1Þ

where, ρ is the density of the mixture; ρ1, M1 and x1 are the density,molar mass and mole fraction of component 1 respectively, and ρ2, M2

and x2 represent the corresponding quantities of component 2.For 1-BuOH + NM and +ACN, Vm

E at different temperatures(T = 303.15, 308.15 313.15 318.15 & 323.15 K) are as depicted inTable 2 and as a function of mole fraction of NM or ACN (x2) they aregraphically represented by Figs. 1–2. For both systems the observedVmE values were found to fit well with the Redlich–Kister polynomial

of the form:

YEm ¼ x2 1−x2ð Þ

Xni¼1

Ai 1‐2x2ð Þi‐1 ð2Þ

Here, YmE represents an excess property, x2 the mole fraction of solute(NM or ACN), Ai is the ith Redlich–Kister coefficient and n is the degree ofpolynomial. For n = 4, coefficients Ai of Eq. (2) and the relevant standarddeviation, σ for Vm

E (cm3·mol−1) at various temperatures (303.15 to323.15 K) obtained by the method of least squares are as listed in Table 3.

In their earlier investigations Torres et al. [20] and Cibulka et al.[38] both have reported that, Vm

E values were all negative foracetonitrile + methanol mixtures, but Vm

E values with respect tocomposition were sigmoid for acetonitrile + alkanols (C2–C4).Also, Vm

E values increased in a positive direction with the increment of

romethane (NM) and acetonitrile (ACN) at different temperatures.

Viscosity, η (mPa·s)

ean % deviation This work Literature Mean % deviation

.01 2.271 2.271g, 2.2896c 0.98

.01 2.008 1.998b 1.00

.01 1.779 1.784b, 1.7955c 1.08

.01 1.5831.413

.00 0.594 0.595g, 0.584i 0.45

.00 0.564 0.563i 0.10

.02 0.536 0.545i 0.90

.20 0.5100.486

.01 0.332 0.333n, 0.3254o 0.62

.00 0.317 0.3254r, 0.315b 0.64

.01 0.304 0.319n, 0.298b 1.500.292 0.2974r 0.54

.01 0.279 0.2729r 0.61

Table 2Experimental densities ρ (g·cm−3) and excess molar volumes Vm

E (cm3·mol−1) of the systems 1-butanol (x1) + nitromethane (x2) and 1-butanol (x1) + acetonitrile (x2) for differentmolar ratios at different temperatures.

T/K 303.15 308.15 313.15 318.15 323.15

x2 ρ VmE ρ Vm

E ρ VmE ρ Vm

E ρ VmE

1-Butanol (x1) + nitromethane (x2)0.0000 0.8019 0.000 0.7979 0.000 0.7940 0.000 0.7901 0.000 0.7862 0.0000.1000 0.8199 0.190 0.8157 0.197 0.8115 0.215 0.8074 0.222 0.8032 0.2410.2000 0.8401 0.312 0.8356 0.334 0.8311 0.365 0.8267 0.387 0.8222 0.4190.2999 0.8620 0.444 0.8574 0.458 0.8528 0.480 0.8482 0.502 0.8434 0.5440.4000 0.8868 0.509 0.8820 0.521 0.8771 0.550 0.8722 0.579 0.8674 0.6000.5016 0.9156 0.489 0.9103 0.522 0.9051 0.553 0.8999 0.585 0.8946 0.6260.6017 0.9476 0.434 0.9420 0.467 0.9365 0.496 0.9310 0.527 0.9255 0.5580.6991 0.9826 0.362 0.9765 0.405 0.9705 0.445 0.9647 0.473 0.9590 0.4930.8059 1.0255 0.308 1.0192 0.335 1.0130 0.358 1.0070 0.370 1.0006 0.4070.9030 1.0711 0.186 1.0645 0.204 1.0580 0.217 1.0516 0.225 1.0453 0.2281.0000 1.1244 0.000 1.1176 0.000 1.1108 0.000 1.1040 0.000 1.0972 0.000

1-Butanol (x1) + acetonitrile (x2)0.0999 0.8000 0.007 0.7959 0.008 0.7919 0.008 0.7879 0.008 0.7839 0.0080.2000 0.7979 0.016 0.7937 0.016 0.7896 0.021 0.7854 0.025 0.7813 0.0310.2997 0.7955 0.036 0.7911 0.045 0.7868 0.053 0.7825 0.061 0.7782 0.0710.4000 0.7927 0.069 0.7882 0.077 0.7837 0.091 0.7792 0.106 0.7747 0.1240.5000 0.7896 0.103 0.7849 0.112 0.7803 0.128 0.7757 0.138 0.7710 0.1620.5998 0.7864 0.116 0.7816 0.125 0.7767 0.148 0.7719 0.163 0.7671 0.1810.6999 0.7830 0.113 0.7780 0.125 0.7730 0.140 0.7680 0.156 0.7631 0.1680.8000 0.7793 0.099 0.7741 0.111 0.7690 0.118 0.7638 0.134 0.7587 0.1460.9000 0.7753 0.070 0.7700 0.073 0.7647 0.078 0.7594 0.083 0.7541 0.0941.0000 0.7713 0.000 0.7658 0.000 0.7603 0.000 0.7548 0.000 0.7494 0.000

210 M.S. Rahman et al. / Journal of Molecular Liquids 190 (2014) 208–214

chain length of alkanols andwith temperature. However, practically forthe acetonitrile–1-butanol mixtures their Vm

E values were all positiveover the whole range as ours. But, only at very low concentrations andat low temperatures their Vm

E showed the tendency to be very smallnegative (at x2 = 0.0323, Vm

E = −0.001 cm3·mol−1 [20]).In our investigation, for both systems Vm

E are found to be positive inthe whole range of composition between 303.15 and 323.15 K. As Fig. 1shows, Vm

E for 1-BuOH + NM changed rapidly both at 1-BuOH-rich aswell as 1-BuOH-poor regions with maxima occurring near x2 = 0.425.In dealing with nitromethane + isomeric butanols, Troncoso et al.[27] also observed positive Vm

E with the maximum close to x2 = 0.5for 1-BuOH + NM. In the Vm

E vs. x2 curve their maximum was~0.35 cm3·mol−1 at 298 K compared to our value, ~0.45 cm3·mol−1

at 303 K. On the other hand, for 1-BuOH + ACN system (Fig. 2), VmE

/ cm

3 .mol

-1V

mE

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.20 0.40 0.60 0.80 1.00x2

303.15 K308.15 K313.15 K318.15 K323.15 K

Fig. 1. Excess molar volumes VmE (cm3·mol−1) for the mixtures of 1-BuOH + NM as a

function of mole fraction of NM (x2) at different temperatures: [303.15 to 323.15 K]. Thesolid lines represent fitting values with the R–K Eq. (2).

increased initially slowly up to 0.20 mole fraction of ACN followed bya rapid risewithmaximumat x2 = 0.625. Comparing Figs. 1 & 2 it is fur-ther noted that, Vm

E values for 1-BuOH + NM are relatively larger andthe heights of maxima are almost 4 times greater than those for 1-BuOH + ACN.

Previously, Sandhu et al. [11] have determined VmE of 1-

BuOH + ACN at 308.15 K and their values were also all positive justlike ours. Their maximum Vm

E at 303 K was ~0.125 cm3·mol−1 nearx2 = 0.6 and that of Torres et al. [20] was 0.117 cm3·mol−1 at aboutx2 = 0.65. Our value, ~0.115 cm3·mol−1 occurring at x2 = 0.625 atthe same temperature is more close to that reported by Torres et al.[20]. Aznarez and Postigo [12] reported the Vm

E (max) as~0.106 cm3·mol−1 at 298 K. Our extrapolated value at this tempera-ture has also corresponded well to it. Like ours, other investigators

/ cm

3 .mol

-1V

mE

0.00

0.03

0.05

0.08

0.10

0.13

0.15

0.18

0.20

0.00 0.20 0.40 0.60 0.80 1.00

x2

303.15 K308.15 K313.15 K318.15 K323.15 K

Fig. 2. Excess molar volumes VmE (cm3·mol−1) for the solutions of 1-BuOH + ACN as a

function of mole fraction of ACN (x2) at different temperatures: [303.15 to 323.15 K].The solid lines represent fitting values with the R–K Eq. (2).

Table 3Fitting coefficients Ai (cm3·mol−1) of Redlich–Kister Eq. (3) and relevant σ (cm3·mol−1)for Vm

E (cm3·mol−1) for the systems 1-butanol (x1) + nitromethane (x2) and 1-butanol(x1) + acetonitrile (x2) at different temperatures.

T/K A1 A2 A3 A4 σ

1-Butanol (x1) + nitromethane (x2)303.15 1.940 −0.629 0.117 1.240 0.018308.15 2.051 −0.447 0.206 0.996 0.013313.15 2.174 −0.367 0.318 0.784 0.011318.15 2.302 −0.350 0.256 0.720 0.010323.15 2.434 −0.365 0.359 0.642 0.014

1-Butanol (x1) + acetonitrile (x2)303.15 0.384 0.472 −0.028 −0.072 0.006308.15 0.424 0.497 −0.029 −0.047 0.005313.15 0.497 0.551 −0.119 −0.109 0.005318.15 0.553 0.588 −0.130 −0.095 0.004323.15 0.632 0.583 −0.187 0.027 0.006

0.40

0.80

1.20

1.60

2.00

2.40

0.00 0.20 0.40 0.60 0.80 1.00x2

η / m

Pa•s

303.15 K

308.15 K

313.15 K

318.15 K

323.15 K

Fig. 3. Experimental viscosities, ηexp (mPa·s) for the mixtures of 1-BuOH + NM againstmole fraction of ACN (x2) at different temperatures: [303.15 to 323.15 K]. The solid linesfollowed N–G Eq. (3).

211M.S. Rahman et al. / Journal of Molecular Liquids 190 (2014) 208–214

[15,17] have reported positive VmE for the systems, CH3(CH2)n − 1

OH + ACN at n = 3,4,7 and 8 also. However, for both systems the effectof temperature on Vm

E was found to be significantly large and values ofdVE

mdT were all positive.

From the behavior of VmE vs. x2 curves it is suggested that, 1-BuOH

where the molecules exist as highly associated through H-bonds, prefer-ably undergo dissociation by the addition of either NMor ACN as a solute.As a result, for both of 1-BuOH + NMand1-BuOH + ACN systems forcesof dispersion effectively lead to steady increment in excess molar vol-umes, Vm

E up to their maxima. Subsequently, VmE start to fall sharply as in-

teraction between dissimilar components starts to occur. At very highconcentration of alkanol the curves for 1-BuOH + ACN are found to beflattened. This leads to suggest that, though dissociation of H-bondingmay take place at lower concentrations, re-association of 1-BuOH is en-hanced significantly at higher concentrations and apparently it is morefor1-BuOH + ACN.

In general, the ability of NM to disrupt H-bonding of 1-BuOH seems tobe higher than that of ACN. Again, observed progression in height ofmax-imum Vm

E suggests that, intermolecular interactions under consideration

Table 4Experimental viscosities ηexp (mPa·s) and G–N interaction parameter ε for 1-butanol (x1) + nent temperatures.

T/K 303.15 308.15 313.1

x2 ηexp ε ηexp ε ηexp

1-Butanol (x1) + nitromethane (x2)0.0000 2.271 – 2.008 – 1.7790.1000 1.815 −1.064 1.607 −1.064 1.4380.2000 1.448 −1.106 1.305 −1.106 1.1720.2999 1.218 −1.022 1.107 −1.022 0.9960.4000 1.052 −0.980 0.955 −0.980 0.8680.5016 0.918 −0.967 0.834 −0.967 0.7620.6017 0.802 −1.034 0.730 −1.034 0.6720.6991 0.706 −1.113 0.654 −1.113 0.6050.8059 0.624 −1.364 0.583 −1.364 0.5490.9030 0.586 −1.631 0.553 −1.631 0.5241.0000 0.594 – 0.564 – 0.536

1-Butanol (x1) + acetonitrile (x2)0.0999 1.696 −1.110 1.517 −1.068 1.3640.2000 1.322 −0.978 1.197 −0.926 1.0850.2997 1.054 −0.912 0.957 −0.895 0.8760.4000 0.842 −0.929 0.781 −0.858 0.7230.5000 0.695 −0.891 0.643 −0.863 0.6010.5998 0.574 −0.925 0.536 −0.890 0.5020.6999 0.482 −0.972 0.453 −0.938 0.4270.8000 0.413 −1.039 0.391 −0.996 0.3740.9000 0.362 −1.175 0.345 −1.111 0.3291.0000 0.332 – 0.317 – 0.304

are weaker in 1-BuOH + NM than those in 1-BuOH + ACN. Also, as theheight of the maximum Vm

E decreases with Gutmann's donor numbers(2.7 and 14.1 kcal·mol−1 for NM and ACN, respectively) [39],donor–acceptor interaction is expected to be less in 1-BuOH + NMcompared to 1-BuOH + ACN. Hence, as expected the resulting posi-tive Vm

E for 1-BuOH + NM is higher than that for 1-BuOH + ACN.Though molecules of both NM and ACN are smaller in size, dipole

moments are quite large (μNM = 3.1D and μACN = 3.37). As a result,self-association of weaker type due to dipole–dipole interaction is con-sidered to stabilize NM and ACN in their liquid state. As evidence,Toshiyuki et al. [40] have already suggested for strong parallel andanti-parallel clustered structures of pure ACN. However, it is supposedthat interactions likely to exist within the dissimilar components of 1-BuOH + NM or 1-BuOH + ACN should basically be due to the

itromethane.(x2) and 1-butanol (x1) + acetonitrile (x2) for different molar ratios at differ-

5 318.15 323.15

ε ηexp ε ηexp ε

– 1.583 – 1.413 –

−1.031 1.283 −1.076 1.156 −1.045−1.109 1.067 −1.050 0.968 −1.030−1.049 0.906 −1.040 0.828 −1.021−0.991 0.800 −0.956 0.730 −0.973−0.984 0.700 −0.991 0.646 −0.989−1.050 0.622 −1.054 0.578 −1.050−1.140 0.565 −1.133 0.527 −1.142−1.335 0.518 −1.306 0.488 −1.298−1.587 0.499 −1.503 0.474 −1.467– 0.510 – 0.486 –

−0.991 1.231 −0.919 1.111 −0.872−0.882 0.986 −0.846 0.900 −0.791−0.853 0.803 −0.820 0.738 −0.778−0.807 0.667 −0.784 0.619 −0.735−0.807 0.555 −0.812 0.519 −0.762−0.856 0.470 −0.835 0.442 −0.788−0.907 0.402 −0.893 0.381 −0.834−0.913 0.354 −0.910 0.336 −0.866−1.085 0.315 −1.036 0.301 −0.959– 0.292 – 0.279 –

0.20

0.60

1.00

1.40

1.80

2.20

2.60

0.00 0.20 0.40 0.60 0.80 1.00x2

η / m

Pa•s

303.15 K308.15 K313.15 K318.15 K323.15 K

Fig. 4. Experimental viscosities ηexp (mPa·s) for the mixtures of 1-BuOH + ACN againstmole fraction of ACN (x2) at different temperatures: [303.15 to 323.15 K]. The solid linesfollowed N–G Eq. (3).

212 M.S. Rahman et al. / Journal of Molecular Liquids 190 (2014) 208–214

formation of intermolecular H-bonding between\NO2 of NMand\CNof ACN with the\OH of 1-BuOH of the following type:

It is also probable that significant intermolecular dipole–dipole in-teraction of the following form may exist between the N of \NO2

group and C of \CN group with the O of \OH group.

Table 5Experimental kinematic viscosities υexp (m2·s−1) for the systems of 1-butanol (x1) 1-butanol (xperatures.

T/K 303.15 308.15

x2 106·υexpm2/s 106·υexpm2/s

1-Butanol (x1) + nitromethane (x2)0.0000 2.832 2.5170.1000 2.214 1.9700.2000 1.724 1.5620.2999 1.413 1.2910.4000 1.186 1.0830.5016 1.003 0.9160.6017 0.846 0.7750.6991 0.719 0.6700.8059 0.608 0.5720.9030 0.547 0.5191.0000 0.528 0.505

1-Butanol (x1) + acetonitrile (x2)0.0999 2.120 1.9060.2000 1.657 1.5080.2997 1.325 1.2100.4000 1.062 0.9910.5000 0.880 0.8190.5998 0.730 0.6860.6999 0.616 0.5820.8000 0.530 0.5050.9000 0.467 0.4481.0000 0.430 0.414

Interactions of the above types as well as geometric fittings, wheresmaller component molecules (NM or ACN) incorporate into the voidswithin H-bonded structures of 1-BuOH are supposed to cause volumecontraction, that may contribute negatively towards Vm

E . Nevertheless,observed positive Vm

E in the entire range and at all temperatures leadto suggest that, for both systems the combined effect due to factorscausing volume expansion simply outweighed all those causing volumecontraction.

Viscosities, η for 1-BuOH + NM and 1-BuOH + ACN in the wholerange between 303.15 and 323.15 K are as displayed in Table 4.Figs. 3–4 represent the η as a function of mole fraction of NM and ACN,respectively. As Table 4 shows, the η of pure 1-BuOH between 303.15and 323.15 K are almost 4 times higher than NM and 7 times thanACN. Also, η follow the order: 1-BuOH ≫ NM N ACN. As Figs. 3–4show, viscous behavior is strikingly similar for both systems — all the ηvs. x2 curves falling rapidly in the alkanol-rich region, followed by rathera slower fall as the concentration of NM or ACN increases. For both sys-tems though effect of temperature on η is not so significant in 1-BuOH-poor regions, it is quite large for the 1-BuOH-rich mixtures.

It is anticipated that the addition of NM or ACN to highly associated1-BuOH in fact causes dissociation of the alkanol into monomers/small-er multimers. Consequently, as all mixtures experience lesser resistanceto flow, η falls drastically. Again, though polarity of NM and ACN is ex-pected to have certain effect on η of the mixtures particularly on itsmagnitude, it behaves differently. Compared to NM, ACN is less effectivein increasing solution viscosities even with its greater dipole moment.As a result, rate of decrement in η for 1-BuOH + ACN is larger thanthat of 1-BuOH + NM at all temperatures. During flow, hetero-

1) + nitromethane (x2) and + acetonitrile (x2) for differentmolar ratios at different tem-

313.15 318.15 323.15

106·υexp m2/s 106·υexp m2/s 106·υexp m2/s

2.241 2.004 1.7971.772 1.589 1.4391.410 1.291 1.1771.168 1.068 0.9820.990 0.917 0.8420.842 0.778 0.7220.718 0.668 0.6250.623 0.586 0.5500.542 0.514 0.4880.495 0.475 0.4530.483 0.462 0.488

1.722 1.562 1.4171.374 1.255 1.1521.113 1.026 0.9480.923 0.856 0.7990.770 0.715 0.6730.646 0.609 0.5760.552 0.523 0.4990.486 0.463 0.4430.430 0.415 0.3990.400 0.387 0.372

0.20

0.60

1.00

1.40

1.80

2.20

2.60

3.00

0.00 0.20 0.40 0.60 0.80 1.00x2

10-6

•υ /

m2 •s

-1303.15 K308.15 K313.15 K318.15 K323.15 K

Fig. 5.Kinematic viscosities υ (m2 s−1) for the solutions of 1-BuOH + NMas a function ofmole fraction of ACN (x2) at different temperatures: [303.15 to 323.15 K]. The lines: — at303.15; – – at 308.15;… at 313.15; –∙– at 318. 15 and –∙∙– at 323.15 K represent the calcu-lated υ values by UNIFAC–VISCO model.

Table 6Average absolute deviation (AAD %) in comparison of experimental and calculatedkinematic viscosities for 1-butanol (x1) + nitromethane (x2) and 1-butanol (x1) + -

acetonitrile (x2) at different temperatures.

T/K AAD%

1-BuOH (x1) + NM (x2) 1-BuOH (x1) + ACN (x2)

303.15 7.69 10.44308.15 7.31 10.74313.15 7.05 11.13318.15 7.09 11.20323.15 7.00 11.64

Table 7Excess Gibbs energy of activation Δ⁎gEexp, Δ⁎gEcal, Δ⁎gEC and Δ⁎gER for the systems of 1-

213M.S. Rahman et al. / Journal of Molecular Liquids 190 (2014) 208–214

molecular species formed by ACN with 1-BuOH possibly become morelabile than those existing between MN and 1-BuOH. Nonetheless, forboth systems the effect of temperature on η is significantly large andthe respective dη/dT values are negative.

In order to get at least qualitative information about the molecularinteraction, our experimental viscosity data were initially fitted to theGrunberg–Nissan equation of the following form [41]:

ηexp ¼ exp x1ln η1 þ x2ln η2 þ x1x2εð Þ: ð3Þ

Here, ε is designated as Grunberg–Nissan interaction parameter. εprimarily depends upon the types of components used as well as tem-perature, and it is frequently considered as a measure of interaction be-tween the component liquids. According to Fort and Moore [42] εbecomes positive in the mixtures with components having specific in-teraction,while it is negative if the interaction is either weak or nonspe-cific. As Table 4 shows, for both the systems ε are all negative and theirmagnitudes decrease further at rising temperatures. This leads to

0.20

0.60

1.00

1.40

1.80

2.20

2.60

3.00

0.00 0.20 0.40 0.60 0.80 1.00

x2

10-6

•υ /

m2 •s

-1

303.15 K308.15 K313.15 K318.15 K323.15 K

Fig. 6.Kinematic viscosities υ (m2 s−1) for themixtures of 1-BuOH + ACNas a function ofmole fraction of ACN (x2) at different temperatures: [303.15 to 323.15 K]. The lines: — at303.15, at 308.15 … at 313.15, at 318. 15 and –∙∙– at 323.15 K represent the calculated υvalues by UNIFAC–VISCO model.

suggest that, during flow the interaction existing between either ACNor CN and 1-BuOH is merely due to weaker forces. However, as valuesof ε are more negative for 1-BuOH + NM, dispersive forces dominatemore in 1-BuOH + NM than in 1-BuOH + ACN.

For the present systems an attempt is also made to predict the mix-ture viscosity, ηm by using the UNIFAC–VISCO model. Earlier, Gaston–Bonhomme, Petrino and Chevalier [43,44] have modified the UNIFACactivity coefficient method to predict viscosities of mixtures. In theUNIFAC–VISCO model, relationship between the mixture viscosity, ηm

and excess Gibbs free energy of activation, Δ*gE is expressed as:

lnηm ¼Xi

xi ln ηiVið Þ− lnVm þ Δ�gE

RTð4aÞ

Δ�gE ¼ Δ�gEC þ Δ�gER ð4bÞ

where, Vm refers to the molar volume of mixtures, ηi and Vi are the vis-cosity and molar volume of the ith component respectively, and Δ*gEC

and Δ*gER respectively are the combinatorial and the residual terms ofexcess Gibbs energy of activation. In UNIFAC–VISCO model, while thecombinatorial term accounts for the contribution due to shape differ-ences among the component molecules, the residual part arises fromgroup–group interactions/enthalpy effect caused by mixing them up.However, unlike others due to the non-availability of group contribu-tions for N-containing compounds in the conventional UNIFAC–VISCOlist, in this particular method for prediction all the groups under

butanol (x1) 1-butanol (x1) + nitromethane (x2) and + acetonitrile (x2) for differentmolar ratios at 303.15 K.

x2 Δ⁎gEexp/RT Δ⁎gEcal/RT Δ⁎gEC/RT Δ⁎gER/RT

1-Butanol (x1) + nitromethane (x2)0.0000 0.000 0.000 0.000 0.0000.1000 −0.077 −0.124 −0.017 −0.1070.2000 −0.158 −0.223 −0.031 −0.1920.2999 −0.188 −0.296 −0.042 −0.2540.4000 −0.194 −0.344 −0.051 −0.2940.5016 −0.191 −0.364 −0.055 −0.3090.6017 −0.193 −0.355 −0.055 −0.3000.6991 −0.194 −0.318 −0.051 −0.2670.8059 −0.182 −0.241 −0.040 −0.2010.9030 −0.126 −0.138 −0.023 −0.1141.0000 0.000 0.000 0.000 0.000

1-Butanol (x1) + acetonitrile (x2)0.0000 0.000 0.000 0.000 0.0000.0999 −0.088 −0.126 −0.020 −0.1050.2000 −0.135 −0.229 −0.037 −0.1920.2997 −0.161 −0.308 −0.051 −0.2570.4000 −0.187 −0.362 −0.061 −0.3000.5000 −0.184 −0.387 −0.067 −0.3210.5998 −0.183 −0.383 −0.067 −0.3160.6999 −0.168 −0.347 −0.062 −0.2850.8000 −0.138 −0.273 −0.050 −0.2230.9000 −0.089 −0.160 −0.030 −0.1301.0000 0.000 0.000 0.000 0.000

214 M.S. Rahman et al. / Journal of Molecular Liquids 190 (2014) 208–214

consideration were chosen just similar to those in the UNIFAC methodreported by Hansen et al. [45], Wittig et al. [46] and also by Balslevand Abildskov [47]. Moreover, all the UNIFAC group–group interactionparameters, anm, used were in Kelvin and for similar groups they wereconsidered as identical.

For the present systems of 1-BuOH + ACN and 1-BuOH + NM, ex-perimental kinematic viscosities νexp (=ηexp/ρ) obtained are as summa-rized in Table 5. The νcal values as predicted by the UNIFAC–VISCOmodel,were then comparedwithνexp as in Figs. 5&6. It is striking tonote that, allthe values of νcal were smaller than νexp. In a recent study, variationof similar type has also been observed for the phenylmethanol + 2-butanone system [48]. The relative errors (Eν,i) and respective absoluteaverage deviations (AAD) were then calculated as:

Eν;i ¼ν exp;i−νcal;i

ν exp;i� 100 ð5aÞ

AAD ¼ 1n

Xni

Eν;i�� �� ð5bÞ

where, i denotes the ith data and n is the total number experimental dataat any temperature. As Table 6 shows, estimated AAD values are found tobe smaller for 1-BuOH + NM than those of 1-BuOH + ACN. However, allthese AAD values were slightly smaller when compared with those re-ported for phenylmethanol + 2-butanone [48].

Furthermore, to explore the cause of deviation each of Δ*gE, Δ*gEC

andΔ*gER predicted by themodel was comparedwith the experimentalΔ*gE. The experimental Δ*gE follows:

Δ�gE

RTjexp

¼ ln ηmVmð Þ−XNi

xi ln ηiVið Þ ð6Þ

where, N denotes the number of components in a mixture and all theother terms have their usual significance. For comparison, experimentalΔ*gE at 303.15 K and those obtained by the model are summarized inTable 7. As this table shows, for both systems absolute values |Δ*gexpE |were found to be smaller than those predicted. Again, magnitude ofΔ*gER (due to residual term) was reasonably greater compared to Δ*gEC

(combinatorial term). This leads to suggest that, possiblyΔ*gER ismore re-sponsible for larger deviation. Perhaps, individual contribution of some ofthe constituent groups under present considerationmight have also beenoverestimated by the UNIFAC–VISCO model in a similar manner as re-ported for the phenylmethanol + 2-butanone system [48].

4. Conclusion

Densities and viscosities of mixtures of 1-BuOH + NM and 1-BuOH + ACN have been measured over the entire range of concentra-tion at temperatures between 303.15 and 323.15 K. The experimentalρ of the pure liquids followed the order: NM ≫ 1-BuOH N ACN, whilefor the systems: 1-BuOH + NM N 1-BuOH + ACN. At temperatures be-tween 303.15 and 323.15 K, Vm

E for both the systems were found to bepositive in their entire range of composition. The isotherms of Vm

E

have been fitted to the Redlich–Kister equation and they followed theorder: 1-BuOH + NM N 1-BuOH + ACN.

However, η of pure components varied as: 1-BuOH ≫ NM N CANand for themixturesη as a function of composition formed convex curvesfollowing the order: 1-BuOH + NM N 1-BuOH + ACN. Furthermore, themagnitudes as well as the sign of the G–N parameters ε indicate that,though heteromolecular species were likely to form on mixing up of 1-BuOH with NM or ACN, forces due to dispersion dominate as a whole.

Kinematic viscosities, νwere predicted by the UNIFAC–VISCOmodeland when compared with experimental values they were found to besmaller within the studied range of temperature. For both systems,|Δ*gexpE | were smaller than those predicted from the model. It has alsobeen found that, the contribution due to the residual term is greaterthan that of the combinatorial term, and hence, the residual term is tobe considered as more responsible for any larger deviation.

Acknowledgment

The authors gratefully acknowledge the financial grant from theMinistry of Science, Information and Communication Technology, Gov-ernment of the People's Republic of Bangladesh, for theproject “PhysicalProperties and Molecular Interactions in Liquid Systems”.

References

[1] M.K.M.Z. Hyder, M.A. Saleh, S. Akhtar, J. Mol. Liq. 159 (2011) 204.[2] M.A. Rahaman, M.S.I. Aziz, S. Akhtar, J. Mol. Liq. 162 (2011) 26.[3] F.I. Chowdhury, S. Akhtar, M.A. Saleh, J. Mol. Liq. 155 (2010) 1.[4] F.I. Chowdhury, S. Akhtar, M.A. Saleh, Phys. Chem. Liq. 47 (2009) 681.[5] S. Akhtar, K.M.S. Hossain, M.A. Saleh, Phys. Chem. Liq. 40 (2002) 435.[6] M.A. Chowdhury, M.A. Majid, M.A. Saleh, J. Chem. Thermodyn. 33 (2001) 347.[7] M.A. Saleh, M. Habibullah, M.S. Ahmed, M.A. Uddin, S.M.H. Uddin, M.A. Uddin, F.M.

Khan, Phys. Chem. Liq. 44 (2006) 31.[8] M.A. Saleh, M. Habibullah, M.S. Ahmed, M.A. Uddin, S.M.H. Uddin, M.A. Uddin, F.M.

Khan, Phys. Chem. Liq. 43 (2005) 485.[9] M.A. Saleh, S. Begum, M.H. Uddin, Phys. Chem. Liq. 39 (2001) 465.

[10] C.M. Kinart, W.J. Kinart, A. Wikliaska, D. Chciaska, T. Dzikowski, Phys. Chem. Liq. 41(2003) 197.

[11] J.S. Sandhu, A.K. Sharma, R.K. Wadi, J. Chem. Eng. Data 31 (1986) 152.[12] S.B. Aznarez, M.A. Postigo, J. Solution Chem. 27 (1998) 1045.[13] P.S. Nikam, L.N. Shirsat, M. Hasan, J. Chem. Eng. Data 43 (1998) 732.[14] N. Saha, B. Das, D.K. Hazra, J. Chem. Eng. Data 40 (1995) 1264.[15] M. Contreras, P. Susana, J. Chem. Eng. Data 34 (1989) 455.[16] H.-C. Ku, C.-H. Tu, J. Chem. Eng. Data 43 (1998) 465.[17] C.G. Pina, A.Z. Francesconi, Fluid Phase Equilib. 143 (1998) 143.[18] H. Iloukhani, M. Almasi, Thermochim. Acta 495 (2009) 139.[19] M.I. Aralaguppi, C.V. Jadar, T.M. Aminabhavi, J. Chem. Eng. Data 41 (1996) 1307.[20] R.B. Tôrres, A.Z. Francesconi, P.L.O. Volpe, Fluid Phase Equilib. 210 (2003) 287.[21] C.-H. Tu, S.-L. Lee, I.-H. Peng, J. Chem. Eng. Data 46 (2001) 151.[22] C.A. Cerdeirina, C.A. Tovar, J. Troncoso, E. Carballo, L. Roman, Fluid Phase Equilib. 157

(1999) 93.[23] C.A. Cerdeirina, C.A. Tovar, D. Gonzalez, E. Carballo, L. Romani, Fluid Phase Equilib.

179 (2001) 101.[24] H. Piekarski, G. Somsen, J. Solution Chem. 21 (1992) 557.[25] A. Ćwiklińska, C.M. Kinart, J. Chem. Thermodyn. 43 (2011) 420.[26] S.-L. Lee, C.-H. Tu, J. Chem. Eng. Data 44 (1999) 108.[27] J. Troncoso, C.A. Tovar, C.A. Cerdeiriña, E. Carballo, L. Romaní, J. Chem. Eng. Data 46

(2001) 312.[28] S.L. Oswal, H.S. Desai, Fluid Phase Equilib. 161 (1999) 191.[29] R. Sadeghi, S. Azizpour, J. Chem. Eng. Data 56 (2011) 240.[30] W.-R. Liau, M. Tang, Y.-P. Chen, J. Chem. Eng. Data 43 (1998) 826.[31] T.M. Aminabhavi, B. Gopalkrishna, J. Chem. Eng. Data 39 (1994) 865.[32] M. Sakurai, T. Nakagawa, J. Chem. Thermodyn. 16 (1984) 171.[33] L. Pikkarainnen, J. Chem. Eng. Data 28 (1983) 345.[34] A. Weissberger, E.S. Proskauer, J.A. Riddick, E.E. Toops Jr., Organic Solvents: Physical

Properties and Methods of Purification, Interscience, New York, 1955.[35] G. García-Miaja, J. Troncoso, Luis Romaní, J. Chem. Eng. Data 52 (2007) 261.[36] B. Garcia, J.C. Ortega, J. Chem. Eng. Data 33 (1988) 200.[37] K. Hickey, W.E. Waghorne, J. Chem. Eng. Data 46 (2001) 851.[38] I. Cibulka, V.D. Nguyen, R. Holub, J. Chem. Thermodyn. 16 (1984) 159–164.[39] Y. Marcus, I. Solvation. Ed. Wiley, New York, (1985).[40] T. Toshiyuki, M. Tabata, A. Yamaguchi, J. Nishimoto, M. Kumamoto, H. Wakita, T.

Yamaguchi, J. Phys. Chem. B 102 (1998) 8880.[41] L. Grunberg, A.H. Nissan, Nature 164 (1949) 799.[42] R.J. Fort, W.R. Moore, Trans. Faraday Soc. 62 (1966) 1112.[43] J.L. Chevalier, P. Petrino, Y. Gaston-Bonhomme, Chem. Eng. Sci. 43 (1988) 303.[44] Y. Gaston-Bonhomme, P. Petrino, J.L. Chevalier, Chem. Eng. Sci. 49 (1994) 1799.[45] H.K. Hansen, P. Rasmussen, A. Fredenslund, M. Schiller, J. Gmehling, Ind. Eng. Chem.

Res. 30 (1991) 2352.[46] R. Wittig, J. Lohmann, J. Gmehling, Ind. Eng. Chem. Res. 42 (2003) 183.[47] K. Balslev, J. Abildskov, Ind. Eng. Chem. Res. 41 (2002) 2047.[48] M. Habibullah, I.M.M. Rahman, M.A. Uddin, K. Iwakabe, A. Azam, H. Hasegawa, J.

Chem. Eng. Data 56 (2011) 3323.