Extraction of Chrosopogon zizanioides essential oil by
supercritical carbon dioxide. Luu Thai Danh, Raffaella
Mammucari, Paul Truong, Tam Tran and Neil Foster. 11th
European Meeting on Supercritical Fluids, Barcelone, Spain, May 4-7, 2008.
The
yield of supercritical carbon dioxide extraction (SCE) of essential oil from
the roots of Chrosopogon zizanioides
has been optimized with a response surface method with central composite
design. Three operating parameters
– pressure, temperature, time – were varied over 5 levels in a
dynamic extraction process utilizing carbon dioxide as extracting medium.
Analyses of multiple regression indicated that the pressure was the major
linear effect on oil yield, whilst temperature and time had a lesser impact on
the extraction yields. However,
temperature had significant effect in quadratic form and interaction with
pressure. At any extraction time, yields significantly increased with
increasing pressure and temperature.
The
empirical model predicted SCE yield for operating conditions of 220 bar, 54 � C
and 40 minutes was compared with the ones obtained by hydro-distillation and
extraction with hexane. The predicted SCE yield was over seven times higher
than that of hydrodistillation and slgithly higher than yield obtained by
hexane extraction. Compared to hydrodistillation and extraction with hexane,
SCE presented the distinctive advantages of low temperature, low operation cost
in terms of time and energy, and producing products free from residual solvent.
The high yields and purity of extracts makes SCE an attractive process for the
essential oil industry which is under pressure to produce "clean essential
oil".
Optimization of essential oil extraction from
Chrosopogon zizanioides using supercritical CO2 - Luu Thai Danh, Raffaella Mammucari, Paul Truong, Tam
Tran, and Neil Foster, American Institute of Chemical Engineers Annual Meeting
2007, Salt Lake City, Utah, USA, November 4-9.
Chrosopogon
zizanioides is a tufted, perennial and scented grass originating from India. Essential oil extracted from
the roots of Chrosopogon zizanioides
has been used in traditional medicine and perfumery as well as in other
cosmetic and aromatherapy applications. Current methods for the extraction of
oil from VZ are principally hydro-distillation, steam distillation and solvent
extraction. However, the first two methods have several drawbacks, such as
break-down of thermally-labile components, hydration reactions of certain
chemical constituents, the need for post-extraction processes to remove water
and incomplete extraction of essential oils from plant materials. The solvent
extraction presents the major disadvantage with regard to the presence of
solvent residues in extracts, which makes the process less ideal for essential
oil extraction. Supercritical fluid extraction from natural sources attracts
noticeable interest because of the inherent properties of supercritical fluids.
Extraction via supercritical fluids overcomes the drawbacks of the presence of
toxic residual solvent in the products and allows operation at moderate
conditions thus preserving the integrity of thermally-labile components, and is
capable of preserving organoleptic characteristics of plant extracts. The fluid
of choice is CO2 owning
to its availability, mild critical conditions, low cost and lack of toxicity.
In this study, the supercritical extraction of essential oil from VZ using CO2 as an extraction medium is
optimized. Response surface methodology with central composite design is
employed to optimize the process; three independent operating parameters over 5
levels have been investigated and the results are compared with hydro
distillation, steam distillation and solvent extraction (hexane). Extracts are
analysed by GC and GC-MS.
Vetiver grass, Chrosopogon
zizanioides: a choice plant for phytoremedation of heavy metals and organic
waste contaminated soils. Luu Thai Danh, Paul Truong, Raffaella Mammucari, Tam
Tran and Neil Foster. International Journal of Phytoremediation.
Soil
contamination constitutes a source of public concern about human health and
ecological threats. Conventional treatments of contaminated soils are
expensive, so there is a strong interest in research of new economical methods.
Phytoremediation is growing in importance since it is a simple, cost effective,
non-environmentally disruptive method. The application of phytoremediation,
however, is limited by slow growth, low adaptability, short root systems and
low yield of plants. Vetiveria zizanioides is one of a few plant species meeting all the criteria required for
phytoremediation. It has been demonstrated in glasshouse and field studies that
vetiver is a fast growing grass with high yield and is highly adaptable to a
wide range of environmental, soil and weather conditions. Vetiver has great
potential in accumulation of heavy metals, particularly lead and zinc. The
majority of heavy metals accumulate in roots making vetiver suitable for
phytostabilization. Vetiver can be used for phytoextraction with addition of
chelating agents. Vetiver also has the ability to uptake and promote
biodegradation of organic wastes, so it can be used for phytoremediation of
these contaminants. The potential of vetiver in phytoremediation of heavy
metals and organic wastes is superior to other plant species due to its special
characteristics.