Extraction Process Optimization of Curcumin from Curcuma xanthorrhiza Roxb. with Supercritical Carbon Dioxide Using Ethanol as a Cosolvent.

Curcuma xanthorrhiza Roxb., known as temulawak, Javanese ginger, or Javanese turmeric, is a plant species belonging to the ginger family. This plant originated in Indonesia, more specifically on Java Island, and is usually used as medicine. It contains a high amount of a phenolic compound, namely, curcumin. A supercritical carbon dioxide extraction technique was employed to extract curcumin from C. xanthorrhiza. The objective of this work was to investigate the effects of temperature, pressure, and CO2 flow rate on the extraction yield and curcumin recovery from C. xanthorrhiza, which was extracted using supercritical carbon dioxide and ethanol as a cosolvent. The Box-Behnken design (BBD) experimental design and response surface methodology were used to optimize the extraction yield and curcumin recovery. The extraction conditions at a temperature of 40 °C, a pressure of 25 MPa, and a CO2 flow rate of 5.34 mL/min produced the optimum extraction yield of 10.4% and curcumin recovery of 3.2%. From Fourier transform infrared analysis, although the physical-chemical structure in the residue of the starting material was almost similar, the quantity of all functional groups in the residue decreased from the starting material. From scanning electron microscopy analysis, it was confirmed that the cell was broken due to the high-pressure effect, so that the extraction process runs easily.

Oil removal from spent bleaching earth of vegetable oil refinery plant using supercritical carbon dioxide.

The oil in the spent bleaching earth (SBE) matrix was successfully removed by applying the supercritical carbon dioxide (SCCO2) extraction technique in a semi-continuous flow-type system. The SCCO2 extraction process was conducted at 40-80 °C and 20-30 MPa with extraction time of ∼180 min. The color of SBE matrix changes from the dark to dark-pale color after the SCCO2 extraction treatment exhibiting the substances including oil in the SBE matrix were successfully removed. The extracted oil yield was around 95% when the SCCO2 extraction process was performed at 40 °C and 30 MPa with 10% ethanol addition as a co-solvent. The GC analysis showed that the prominent fatty acid constituents in the extracted oil are palmitic and oleic acids, furthermore it can be fed as a feedstock to produce biodiesel fuel. Next, it can be proposed that SCCO2 extraction system is a viable way to extract oil from the SBE matrix.

Enhancement of Curcuma xanthorrhiza Roxb Phytochemical Dissolution via Micronization Using a Supercritical Antisolvent Technique.

Fine particles comprising Curcuma xanthorrhiza Roxb (C. xanthorrhiza) rhizome extract were successfully generated using a supercritical carbon dioxide (SCCO2) antisolvent technique. The SCCO2 antisolvent process was performed at 40 °C with 8-16 MPa operating pressures. The CO2 and feed solution flow rates were 15 and 0.25 mL min-1, respectively. The mixture of C. xanthorrhiza rhizome extract and a polyvinylpyrrolidone (PVP) polymer in acetone-ethanol was used as a feed solution. The collected particle products seemed to possess spherical and spherical-like morphologies with a diameter of less than 500 nm. The infrared spectroscopy analysis showed that the structural properties of C. xanthorrhiza rhizome extract did not change after treatment with the SCCO2 antisolvent. Furthermore, the addition of the PVP polymer in the C. xanthorrhiza rhizome extract particle products may improve their dissolution significantly in an aqueous solution medium.

Formation of Fine Particles from Curcumin/PVP by the Supercritical Antisolvent Process with a Coaxial Nozzle.

The production of fine particles via the supercritical carbon dioxide (SC-CO2) antisolvent process was carried out. The experiments were conducted at temperatures of 40-60 °C and pressures of 8-12 MPa with a 15 mL min-1 carbon dioxide (CO2) and 0.5 mL min-1 feed solution flow rate. As a feed solution, the curcumin and the polyvinylpyrrolidone (PVP) powder were dissolved in acetone and ethanol at concentrations of 1.0 mg mL-1 and 2.0-4.0% in weight, respectively. Scanning electron microscopy (SEM) images described that most of the precipitated particle products have spherical morphologies with a size of less than 1 µm. The Fourier transform infrared spectroscopy (FT-IR) spectra exhibited that the curcumin structural properties did not shift after the SC-CO2 antisolvent process. Moreover, the PVP addition in the curcumin particle products can enhance the curcumin dissolution in distilled water significantly.

Hexagonal hollow silica plate particles with high transmittance under ultraviolet-visible light.

Creating hollow structures is one strategy for tuning the optical properties of materials. The current study aimed to increase the optical transmittance of silica (SiO2) particles. To this end, hexagonal-shaped hollow silica plate (HHSP) particles were synthesized from tetraethyl orthosilicate (TEOS) and zinc oxide (ZnO) template particles, using a microwave-assisted hydrothermal method. The size and shell thickness of the HHSP particles could be adjusted by using different TEOS/ZnO molar ratios and different ZnO template sizes, respectively. The optical transmittance of the HHSP particles depended on the shell thickness and particle size. The highest transmittance was 99% in the ultraviolet and visible region (300-800 nm) and was exhibited by HHSP particles with the thinnest shell thickness of 6.3 nm. This transmittance was higher than that exhibited by spherical hollow silica particles with a similar shell thickness. This suggested morphology-dependent transmittance for the semiconducting material. These preliminary results illustrate the promising features of the HHSP particles and suggest their potential application in future transparent devices.