Reactive Extraction Technology - Process Intensification for Green Chemistry - page 280

extract more oil trapped deep inside the core of the seeds than conventional 24-hour
Soxhlet extraction using n-hexane. Another significant finding was that the unsieved
jatropha oil seeds, which contained different solid particle sizes, tended to inhibit
FAME conversion in the supercritical reactive extraction process. The varying particle
sizes were expected to render the reaction rate inconsistent, while larger solid particle
sizes, which were easier to settle, reduced the oil-methanol contact area for the
transesterification process. Consequently, screening of blended Jatropha curcas L.
seeds to a smaller particle size through sieving is important to maximizing the

FAME or biodiesel output.

10.2.2.3 Conclusion

This experimental study has confirmed the feasibility of supercritical reactive extraction
technology for the commercial production of biodiesel from oil seeds. Almost 100.0%
FAME yield can be achieved in a relatively short time, even when skipping the
conventional oil extraction stage, which might take up to 24 hours. At higher tempera-
tures and pressures (300 C and 240MPa), the extraction of oil from seeds has a higher
efficiency than conventional oil extraction, whether by chemical solvent or by mechani-
cal pressing. Moreover, no addition of catalyst is required, which will greatly simplify
downstream processes such as catalyst separation and washing. The solid particle size
has been found to be a significant factor, with the optimum at 1.0mm.

10.3 Impact on Green Processing and Process Intensification

As shown in Table 10.1, solid-liquid or liquid-liquid reactive extraction is an attractive
method for the production of biodiesel since it is a simple process with fewer processing
steps than other processes and provides a similarly high FAME yield and quality.
Consequently, reactive extraction has significant revolutionary potential for the process
and plant design of green processing technology and process intensification (PI). First, this
novel technology provides a more efficient extraction method, especially for solid
biomaterials. It can effectively reduce the mass-transfer limitation inherent in conventional
bioprocessing technology by a large margin. This can increase the final product yield at a
lower cost. Moreover, combining the extraction and reaction processes in a single
processing unit can reduce the number of waste streams generated, which will reduce
the extra cost for transportation to centralized waste treatment. The final products produced
from reactive extraction have also been proven to contain fewer impurities. This will
reduce the separation intensity in the downstream processes and allow higher-quality
products to be obtained. A reduction of the processing unit and volume will directly help to
lower the capital and production costs in conventional green processing plants. Indirect
reduction costs will include lower energy usage due to less operating equipment and
inherently safer operation due to a decrease in the use of hazardous chemicals such as
hexane. The total reduction in cost will essentially render products of conventional
bioprocessing more economically competitive than their counterparts in the market.
This in turn will garner greater corporate interest in providing monetary capital to drive
its development.