Thus, microemulsion formation using these two systems of mixed surfactants looks promising for
palm kernel oil extraction. As expected the IFT values decreased as
the salinity increased because adding salt promoted the formation
of middle phase microemulsion due to the reduction in repulsive
forces between the ionic charges of surfactants at their head
group (Tongcumpou et al., 2003a). Thus, an increase in salinity
enhanced the phase transition of Winsor type I microemulsion
toward Winsor type III microemulsion.
These twomixed surfactant systems – SystemA and System B –
with different salinities also were used for palm kernel oil extraction
using a ratio of 1 g ground palm kernel seed to 10ml of the
mixed surfactant solutions, and 30 min contact time. The efficiency
of oil extraction was plotted related to IFT values from the phase
behavior (Fig. 1). It can be seen that withNaCl addition to the system
IFT reduced and hence oil seed extraction was enhanced. However,
IFT may not be linearly correlated to oil extraction. This indicates
that IFT was not the only parameter governing the oil extraction
efficiency but other parameters also played a role in oil extraction.
These results are similar to the studies by Tongcumpou et al.
(2003b, 2006) on removal of motor oil and palm oil from fabric.
They found that while high efficiency of oil removal from fabric
resulted for the lower IFT values, other parameters (i.e. oil solubilization
and coalescence rate) also appeared to impact the overall
oil removal (or extraction) efficiency. These encouraging results on
microemulsion-based oil seed extraction motivated a preliminary
investigation on parameters that influenced the optimumefficiency
of the oil extraction and that will be described in the next aspects.
In this work we used a surfactant concentration of around
3 wt% to ascertain that the microemulsion was dominant in the
system—future work will explore lower surfactant concentration
approaching the critical microemulsion concentration (cc).