3.6. Kinetic of oil extraction
Tables 1 and 2 shows the calculated values of the mass transfer
coefficients using Eq. (3) and the yield of oil, for both soxhlet and
batch extractor respectively at equilibrium at various temperatures,
particle size diameter, type of solvent and solvent to solid ratio.
Parameters of kinetic model, YAi and ka were estimated by non
linear square fit from equation to experimental data using Origin-
Lab 8.5. It is found that the mass transfer coefficients increase with
the increase in the temperature of extraction. The ka (s1) value
varies from 0.89 to 1.43 for soxhlet extractor and from 1.23 to
2.06 for batch extraction. The plotted graph shows a linear relationship
with R2 values were above 0.9879 for soxhlet and batch
extraction. Increasing the temperature causes the reaction time
to be reduced as reaction occurs faster. The final concentration increases
with temperature because of the effect of thermodynamic
on the solubilization of oil inside the solid (Liauw et al., 2008). The
ka also increases around 23% when hexane was used when compared
with petroleum ether and extraction occurs significantly.
This proves that higher yield is achieved using hexane in the soxhlet
extractor. This is in agreement with Giri and Sharma, 2000 that
particle size and extracting and solubilising power of the solvent
affects the mass transfer (Giri and Sharma, 2000). Table 3 shows
the comparison value of mass transfer coefficient with previous
work. In this study, the mass transfer coefficient obtained was
0.386 103 s1 using particle size of 0.5 mm. Liauw et al