Lotaustralin from the root of Rhodiola rosea L was extracted using supercritical carbon dioxide with methanol as modifier. Response surface methodology using Box–Behnken experimental design was utilized to explore parameters for supercritical carbon dioxide extraction. The effects of various values of temperatures (50–70 °C), pressures (200--400 bar), and percentages of methanol modifier (80%–100%) on the extraction yields of lotaustralin were evaluated. Extract identification was performed using high-performance liquid chromatography. The experimental data obtained were fitted to second-order polynomial equations and assessed using analysis of variance. The highest yields predicted from the experiments were 2.05 g kg?1 lotaustralin at the optimal values, i.e. temperature 65 °C, pressure 316 bar, 88% methanol modifier at a flow rate of 0.4 mL min?1, and dynamic extraction time 90 min. 相似文献
We compare two different techniques for the extraction of biodiesel from macroalgae: the thermochemical liquefaction and the
extraction using supercritical carbon dioxide (sc-CO2). The first allows to use wet material, while sc-CO2 requires dry material and uses moderate temperature and pressure so that it can be useful for the extraction of thermolabile
compounds which may decompose at the temperature at which thermal methos are carried out. In both cases the extracted oil
was characterized quantitatively and qualitatively. The novelty of the work is that in the literature the use of macroalgae
for the production of biodiesel has not so far been described, while they are used mainly as food or other purposes. 相似文献
Photocatalytic degradation of chemical pollutants in water was investigated using semiconductor oxide catalysts, zinc oxide (ZnO) and titanium dioxide (TiO2) and phenol as the substrate. Influence of various parameters such as characteristics of the catalyst, irradiation time, substrate and catalyst concentrations, pH etc. has been studied and optimum conditions for the complete degradation of phenol in water have been identified. In terms of activity and durability TiO2 is far superior to ZnO. Mixing ZnO with TiO2 does not affect its activity significantly. The process is especially relevant in view of its potential for the treatment of wastewater containing pollutants, using solar radiation as the energy source. 相似文献
In this research, supercritical carbon dioxide extraction (SFE) showed better extraction effect when compared with Solid- liquid extraction (SLE), Soxhlet extraction (SE) and Ultrasonic extraction (UE), not only in the rate but also the time. The comparison among these three extraction modifiers, including acetone, ethanol and methanol demonstrated that ethanol was preferred to SFE due to its high extraction effect and low toxicology. In addition, parameter of SFE, influence of temperature and pressure were investigated, and the best extraction effect was achieved at the optima conditions, temperature of 40°C and the pressure of 35 MPa. Thus, SFE is a highly effective method for flavonols extraction, requiring minimum energy and producing non-toxic byproduct. SFE-GC system is applied for the evaluation on flavonols that plays a key role in plant resistance to heavy metal, with its content and synthetase gene expression significantly increasing in plant when threatened by heavy metal. Besides, results indicated that flavonols can improve plant resistance to oxidative stress by quenching the redundant ROS in matrix.