Page 129 - EER-2-2

Explora: Environment
and Resource Microemulsion-based canola oil extraction

Figure 4. Comparison of the visual appearance of pellets after treatment with pure solvents or premixes (from left to right: Extracted by n-hexane,
1-propanol, and premix #1 – 3 from Table 3)

efficiency of 1-propanol was reasonably higher than that et al. 15,16 also examined the capability of Tween 80 and
of ethanol. This can be attributed to the better solubility of n-butanol on microemulsification of kerosene and hexane
both lecithin and canola oil in 1-propanol, despite ethanol as oil phases. They identified different Winsor types (I,
being less toxic and more soluble in water. II, III, and IV) but noted that in the Winsor III domain,
increasing the temperature caused the turbid phase to
3.3. Efficacy of Tween-based ME systems separate into three different phases. They suggested that
In the present study, the capabilities of Tween 20 and this behavior could be potentially used as a mass transfer
Tween 80 in recovering residual oil from CPC were technique. This likely occurred in the present study, and for
investigated under various concentrations (0 – 22 wt%), further details, readers are referred to a recently published
premix: CPC ratios (1:1 – 16: 1), and with and without review. 7
co-surfactants (ethanol and 1-propanol). Based on the
To improve the extraction rate under natural pH (~6.1),
observations, Tween 80 (0.83 wt %, pH~6.1) was capable different ratios of Span 80:Tween 80 (10:90, 30:70, 50:50,
of recovering only a small portion (<10%) of the residual 70:30, and 90:10) were also mixed, and their effects were
oil. However, when combined with ethanol (Tween investigated. Through numerous trials, it was found that
80:ethanol at a 1:8 ratio, 0.83:6.66 wt%), under optimal
temperature conditions (70°C) and an 8:1 premix: CPC using higher ratios of Span 80 significantly increased the
ratio, the system recovered nearly a quarter (~27%) of the size of the oil phase. Surprisingly, further investigations
residual oil as free oil. Due to the significant role of ethanol revealed that the increase in the oil extraction rate was
in improving oil recovery and the hygroscopicity nature of due to Span 80 being much more soluble in oil than in
CPC, another set of experiments was conducted. In this water; therefore, most of it transferred from the premix
case, the required amount of ethanol (2.66 g) was first solution into the extracted oil phase, causing the oil phase
mixed with CPC (5 g), heated (55°C, 30 min), and then to increase visually in size. In line with our findings, Zhang
23
cooled. Afterward, a Tween solution (37.34 g, containing and Wang have already attributed the increase in free
0.33 g Tween 80) was mixed with the ethanol-CPC oil yield in the presence of high Span concentrations to
mixture, heated (70°C, 30 min), cooled, and centrifuged. the partial dissolution of Span in the oil. It appears that
Visual observations showed only a slight improvement in a similar phenomenon occurred in other studies, but
the oil recovery rate. they mistakenly reported that Spans led to improved
oil recovery. 18,21,22 In contrast to these reports, 21,22 it can
These findings demonstrate that Tween 80, as a be clearly concluded that Span 80 is not an appropriate
synthetic, non-ionic, food-grade, biodegradable surfactant surfactant to be used individually or in combination with
with a reasonably low cost, can potentially release part Tween 80 or other Tweens for oil extraction purposes.
of the remaining oils from CPC. These findings are in
line with a previous report in which 0.5 wt% Tween 80, Despite the non-ionic nature of Tween 80, another
6% NaCl, and a 25:1 ratio of Tween 80:palm pressed fiber set of experiments examined the influence of alkaline
(PPF), heated at 60°C, recovered nearly 39% of the residual pH (~10.0) as well as surfactant concentration (0.0 – 2.0
palm oil from PPF. They reported that under these wt%) under a constant CPC: surfactant solution ratio
18
conditions, the extracted oil was emulsified (Figure 1), and (1:4) on the oil extraction rate. It is worth noting that
no free oil phase or Winsor type III domain was observed. the natural pH of the mixtures was around 6.0 ± 0.1, but
However, in the present study, despite the structural and when the pH was adjusted to the target value (pH = 10.0),
compositional differences between CPC and PPF, most of the color of the mixtures visibly turned brownish, likely
the released oil was in the form of free oil, likely due to the due to the ionization of amino acids, structural changes,
presence of the co-surfactant. In addition, the amount of solubilization, and denaturation of proteins. These
Tween 80 solution used in the present study was one-third mixtures were also mildly heated (55°C, 45 min) before
of that utilized by Ramly et al. (1:8 vs. 1:25). Mukherjee centrifugation. Upon centrifugation, no free oil phase
18

Volume 2 Issue 2 (2025) 8 doi: 10.36922/eer.6562