Handbook of Solvents - George Wypych - ChemTech - Ventech!

946 Phillip J. Wakelyn, Peter J. Wan
miscella refining facility which was constructed in 1988 with a designed capacity of 500
tons/day but operated at only 270 tons/day due to limited delinting capacity. After week
long testing with commercial isohexane, this plant experienced more than 20% natural gas
usage and easily increased the throughput rate by close to 10% when compared with commercial
hexane. This energy savings with commercial isohexane over commercial hexane
may be largely attributed to the difference in the amount of water present in their corresponding
azeotropes. Isohexane requires an additional step - isomerization to manufacture
and will always be priced higher than hexane. But based on the two cottonseed oil mill trials,
isohexane can be a cost efficient solvent. 99 One additional benefit, the shorter residence
time of the extracted cottonseed marc in the desolventizer/toaster because of the lower boiling
range of isohexane will likely preserve more vegetable protein in the final meals which
has been observed by both plants during the tests. 7,45 The benefit in improved quality of oils
were not obvious in both plant trials but might be realized with extended trials.
Further evaluation of hydrocarbon solvents: As indicated in the study conducted by
Wan et al., 85 the commercial cyclic hydrocarbons are the least effective extraction solvent
than the branched and linear hydrocarbons. The comparison of extraction efficiency of pure
isomers of hexane was conducted with the same single stage extractor as displayed in Figure
14.10.3. This was done to identify any unique structure-function characteristics of these
pure components of commercial hexane and provide some guidance to the selection and tailored
formulation for future commercial isohexane for the oilseed extraction industry. The
extraction results for various pure isomers of six carbon paraffins using the single stage extractor
indicated the following: (a) cyclohexane is noticeably less efficient in extracting cottonseed
flake than all the other isomers; (b) slightly branched isomers, such as, 2-methyl
and 3-methyl pentane, and methyl-cyclopentane are very slightly less efficient than n-hexane;
and (c) highly branched isomers, 2,2-dimethyl and 2,3-dimethyl butane, are slightly
less efficient than slightly branched isomers in extraction (Unpublished data).
14.10.5 FUTURE TRENDS
In the future there most likely will be new demands for highly specialized extraction solvents
as newly domesticated species that make useful novel oils 30 and other products and
new or altered biological products with enhanced nutritional and industrial properties will
be developed through conventional breeding and genetic engineering for use as “functional
foods” 31 (e.g., phytosterols to achieve cholesterol lowering); as oils with altered lipid
profiles 32 (e.g., for lower saturated fat) or with more vitamin E; new drugs/nutraceuticals,
industrial chemicals (e.g., fatty acids for lubricants, as cosmetics, coatings, detergents, surfactants,
flavors, polymers, etc.); as sources for specialty chemicals; as value added products;
etc. 31-38
Genetically enhanced (GE) /biotech crops make up a growing share of the agricultural
output. 39 Biotechnology is the most powerful tool ever put in the hands of agricultural scientists.
The ability to breed desirable traits or eliminate problematic ones can yield potentially
spectacular benefits, such as various chemicals of importance including improved fats and
oils, and vaccines and medicine, improved nutrition (e.g., in casaba, oilseeds, rice, sweet
potatoes), and improved yields with the use of less agricultural chemicals. GE/biotech crops
could be increasingly developed as biofactories for a wide range of products, including nutrients
pharmaceuticals, and plastics. There is much promise for being able to produce products
that would protect millions from disease, starvation, and death. However
biotechnology and GM crops have become very controversial, and have run into serious