Extraction of Chrosopogon zizanioides essential oil by supercritical carbon dioxide. Luu Thai Danh, Raffaella Mammucari, Paul Truong, Tam Tran and Neil Foster. 11^th 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.