Journal of Chemical & Engineering Data
Article
2
1
9.46, 29.50, 29.54, 30.05, 31.78, 35.45, 35.85, 47.08, 49.09,
the prepared dilute solutions of CGS1, CGS2, and CGS3 were
carried out separately at 293.15, 303.15, 313.15, and 233.15 K.
For the dilute solutions of CGS4, measurements were carried
out separately at 303.15, 313.15, and 233.15 K. Double
distilled deionized water was used as a solvent, and the specific
conductivity of double distilled water was measured as 1.65 μS·
22.89, 136.70, 172.88. MALDI-TOF-MS m/z calc. 779.92;
+
found: 780.68 [M-Br] .
2
.2.3.3. 3,3′-{Ethane-1,2-diylbis[oxy(2-oxoethane-2,1-
diyl)]}bis{1-[3(dodecanoylamino) propyl]-1H-imidazol-3-
−
1
ium} Dibromide (CGS3). FT-IR (υmax, cm ): N−H; 3313,
−
1
C−H; 2953, 2920, CO; 1739, 1647, CN; 1544, C−O−C;
cm at 293.15 K. The measurements were used to determine
the cmc values and to calculate some thermodynamic
parameters of the all systems. The cmc values were provided
1
1
226. H NMR (CDCl δ ppm): 0.87 (bs, 6H, CH , alkyl
3
3
chain), 1.24 (bs, 32H, CH , alkyl chain), 1.59 (bs, 4H, OC−
2
−
1
CH CH , spacer), 2.15 (bs, 4H, NH−CH CH ), 2.26 (bs, 4H,
from the break point of the specific conductivity (μS·cm )
36
2
2
2
2
OC−CH , alkyl chain), 3.22 (bs, 4H, NH−CH ), 4.44 (d,
surfactant concentration (mM) isotherms. The uncertainties
2
2
+
8
H, NCH , spacer; N−CH ), 5.60 (bs, 4H, OC−OCH ,
in the measured specific conductivity and cmc were ±0.5 μS·
2
2
2
−
1
−5
spacer), 7.71 (bs, 2H, NH), 7.80 (s, 2H, imid. H), 7.97 (s, 2H,
cm and ±1.2 × 10 M, respectively. During the specific
conductivity run, the temperature uncertainty was ±0.1 K.
2.3.2. UV−Visible Measurements. The solubilization
measurements for Sudan III were performed using a Perkin
Elmer Lamda 25 UV−Visible spectrophotometer. Mixtures of
the excess powdered Sudan III with different concentrations of
CGS solutions (above cmc) were stirred at 303.15 K at 200
rpm for 24 h. The mixture was centrifuged at 6000 rpm to
remove undissolved solutes. Afterward, solutions were filtered
to remove unsolubilized Sudan III. The amount of solubilized
Sudan III was identified by absorbance measurements
performed at 508 nm. Calibration with dilute solutions of
Sudan III dissolved in ethanol has presented gratifying Beer−
Lambert plots. The filtered solution was diluted with ethanol in
the dissolution experiment. With this dilution, the amount of
water was reduced enough to allow direct use of the calibration
plot. Molar solubilization ratios of CGSs were determined by
imid. H), 9.88 (s, 2H, imid. H). 13C NMR (DMSO-d , δ
6
ppm): 14.29, 22.56, 25.73, 29.22, 29.35, 29.48, 29.51, 29.56,
3
1
0.22, 31.78, 35.49, 35.85, 47.33, 50.14, 63.76, 122.59, 124.27,
37.87, 167.19, 173.00. MALDI-TOF-MS m/z calc. 762.88;
+
found: 762.34 [M-2Br + 2] .
2
.2.3.4. 3,3′-{Butane-1,4-diylbis[oxy(2-oxoethane-2,1-
diyl)]}bis{1-[3-(dodecanoylamino) propyl]-1H-imidazol-3-
−
1
ium} Dibromide (CGS4). FT-IR (υmax, cm ): N−H; 3315,
C−H; 2953, 2920, CO; 1739, 1648, CN; 1544, C−O−C;
1
1
226. H NMR (DMSO-d δ ppm): 0.85 (bs, 6H, CH , alkyl
6
3
chain), 1.23 (bs, 32H, CH , alkyl chain), 1.48 (bs, 4H, OC−
2
CH CH , alkyl chain), 1.70 (bs, 4H, OC−OCH CH ,
2
2
2
2
spacer), 1.93 (bs, 4H, NH−CH CH ), 2.08 (t, 4H, OC−
2
2
CH , J = 8.0 Hz, alkyl chain), 3.04 (bs, 4H, NH−CH ), 4.19
2
2
+
(
bs, 4H, N−CH ), 4.26 (bs, 4H, NCH , spacer), 5.31 (bs,
2
2
4
H, OC−OCH , spacer), 7.81 (bs, 2H, NH), 7.89 (s, 2H,
2
39
1
3
imid. H), 8.00 (s, 2H, imid. H), 9.29 (s, 2H, imid. H).
C
using eq1
NMR (DMSO-d , δ ppm): 14.41, 22.56, 24.95, 25.71, 29.19,
6
MSR = (S − S )/(C − Ccmc)
(1)
T
cmc
T
2
5
9.29, 29.42, 29.47, 29.51, 30.31, 31.76, 35.50, 35.86, 47.36,
0.06, 65.66, 122.67, 124.35, 137.88, 167.32, 172.94. MALDI-
In this equation, C is a particular total CGS concentration,
T
+
TOF-MS m/z calc. 867.94; found: 867.92 [M] .
ST is the total apparent solubility of Sudan III in the CGS
solution at C , and C is the cmc value of CGS. Scmc can be
1
13
The H NMR spectra, C NMR spectra, and MALDI-TOF
T
cmc
MS of CGS4 are given in Figures 1−3, respectively.
taken as the water solubility (S) due to its small change up to
the cmc of the surfactant.
2
.3. Physicochemical Properties. 2.3.1. Specific Con-
ductivity Measurements. 2.3.1.1. Determination of Krafft
Temperature. Krafft temperatures of CGSs were determined
2.4. Emulsification Power. To determine the emulsifica-
tion power, 10 mL (0.1% by weight) of each of the different
CGS solutions was individually placed into a 100 mL cylinder,
and then 10 mL of paraffin oil was added at 303.15 K. The
cylinder was shaken vigorously for 10 min and then settled.
The time needed to separate 9 mL of pure CGS solution was
recorded (average of three readings) and was taken as an
indication of the emulsification power (emulsion stability) of
38
by a specific conductivity method. Aqueous solutions of
surfactants (1 wt %) were prepared, and then these solutions
were kept refrigerated at ∼277.15 K for at least 48 h. At the
end of this period, the hydrate surfactant crystals were
precipitated. Then, hydrate surfactant crystals were taken out
of the refrigerator, and after, the temperature of systems was
increased gradually under constant stirring. Conductivity data
of systems were measured with a WTW Terminal 740
40
each CGS.
−
1
3. RESULTS AND DISCUSSION
conductometer (cell constant = 0.485 cm ). Krafft temper-
atures were taken as the temperature at which the conductivity
vs temperature plots represented a sudden break. During the
specific conductivity run, the temperature uncertainty was
3.1. Krafft Temperature. T is an important feature of an
K
ionic surfactant that is firmly connected to the surfactant
molecular structure. Micelle formations are only seen in
±
0.1 K.
.3.1.2. Determination of Critical Micelle Concentration.
aqueous solution above T . When the temperature is lower
K
2
than T , hydration heat energy and the crystal lattice energy
K
The specific conductivity data of CGS solutions were
will have an effect on the solubility of ionic surfactants. At
measured with the WTW Terminal 740 conductometer (cell
higher temperatures than T , solubility increases considerably
K
−
1
constant = 0.485 cm ). The stock solutions of CGSs were
prepared in molar concentration units at room temperature. A
known volume of stock CGS solution was added incrementally
into the volumetric flask containing double distilled deionized
water, and thus, dilute solutions in different concentrations
were obtained. The specific conductivity measurements of
these solutions were performed in a temperature-controlled
Thermo Scientific thermostatic water bath. Measurements for
because a hydrated surfactant crystal melts and generates
41
micelles in solution. Figure 4 shows that the conductivity
values increase gradually at low temperatures due to the very
limited solubility of CGSs. There is a sudden increase in
conductivity values until the T point is reached.
K
When the T values obtained have been examined, it has
K
been observed that they have risen as usual with a rise in the
number of carbon atoms contained in both hydrophilic and
1
526
J. Chem. Eng. Data 2021, 66, 1522−1532
Bilgen, Sel?uk
