A new solid base catalyst containing Ca12Al14O33 and CaO was prepared by chemical synthesis method and was used in the transesterification of rapeseed oil with methanol to produce biodiesel. The catalyst was characterized by Hammett indicators, X-ray diffraction (XRD), infrared spectroscopy (IR), Brunauer–Emmett–Teller (BET) and scanning electron microscopy (SEM), separately. The effect of various factors was investigated to optimize the reaction conditions. The results showed that the ME (methyl ester) content reached 90% after reacting for 3 h at 65 °C, with a methanol/oil molar ratio of 15:1, the amount of catalyst of 6 wt.% and the stirring rate of 270 rpm. Moreover, the catalyst could be used repeatedly for at least 7 cycles with the ME content over 87%, due to its high stability. In particular, this solid base catalyst can be separated from reaction system effectively and easily, as it is insoluble in both methanol and methyl esters, which may provide significant benefits for developing an environmentally benign and continuous process for synthesizing biodiesel.Highlights► A new solid catalyst containing Ca12Al14O33 and CaO was synthetically prepared. ► The catalyst has good activity with ME (methyl ester) content reached 90%. ► The catalyst can be used for at least 7 cycles with the ME content over 87%. ► The catalyst can be separated from reaction system effectively and easily. ► This study may provide benefits for developing a continuous biodiesel process.

The seeds of Jatropha curcas are a good source of oil, which can be used as a diesel substitute. In this paper, jatropha oil was extracted from the seeds with supercritical carbon dioxide (SC-CO2) at different temperatures [(308.15 to 328.15) K] and pressures [(20 to 50) MPa]. The maximum yield of 51.5 % was obtained under the optimal conditions. Eight fatty acids in the extracted jatropha oil were identified with gas chromatography/mass spectroscopy (GC-MS). The solubility of the oil in SC-CO2 at definite temperature and pressure was calculated from the initial slope of the extraction curve of yield versus volumes of SC-CO2. The Chrastil equation and a modified Chrastil equation were applied to correlate the solubility data. The values of average absolute relative deviation (AARD) were (10.1 and 3.47) %, respectively, indicating the modified Chrastil equation is much better than the Chrastil equation, mainly due to the increase of parameters.

The chemical composition and antioxidant properties of antler velvet extract prepared by supercritical CO2 extraction with co-solvent are presented in this study. The composition in different extracts was determined by radioimmunoassay analysis (RIA), high performance liquid chromatography (HPLC) and thin layer chromatographic (TLC), separately. The antioxidant properties including hydroxyl radical-scavenging by phenanthroline-Fe(II) oxidation, inhibition of lipid peroxidation from lipoprotein induced by iron and the ability of the extract to protect 2-deoxy-d-ribose against hydroxyl radical-mediated degradation were assessed. The extract mainly contained three biological bases, two sex hormones, five phospholipids and p-hydroxybenzaldehyde, which may contribute greatly to antioxidant activity. The antler velvet extracts demonstrated activity in the three antioxidant assays, and did so in a concentration-dependent fashion. The supercritical extract technology showed obvious advantage, and the inhibitory activity of SFE extract was obviously higher than that of traditional refluxing extracts.

Supercritical carbon dioxide in the presence of co-solvent was used for extraction of the active sex hormones (including estradiol and progesterone) from antler velvet. The effects of ethanol concentration, flow rate of co-solvent, extraction pressure, temperature and extraction time on the extraction yield and content of sex hormones were studied, and a optimal condition was obtained. The qualitative–quantitative analysis of components in extract was determined by radioimmunoassay analysis (RIA), high performance liquid chromatography (HPLC) and thin layer chromatographic (TLC). Three biological bases and five phospholipids in the SFE extract were identified according to their chromatographic behavior and spectral characteristics. The major components were uracil (Ur), hypoxanthine (HX), uridine (U) and p-hydroxybenzaldehyde (PHBD), sphingomyelin (SPH), phophatidylcholine (PC), phosphatidylethanolamine (PE), lysophophatidylcholine (LPC) and lysophophatidylethanolamine (LPE). The experimental results showed that, when the co-solvent was 75% ethanol, the extraction pressure was 30 MPa, the temperature was 35 °C, the extraction time was 30 min, the consumption of CO2 was 15 L/g at the flow rate of 2.0 L/min, the mean yield and content of estradiol were 87.67 pg/g and 1224.10 pg/g, respectively, while the mean yield and content of progesterone were 25.66 ng/g and 354.06 ng/g, respectively. Under these conditions, the percentages of main analytes were increased, and the recovery of estradiol and progesterone was above 88%.

Supercritical fluid extraction (SFE) of the monoamine oxidase (MAO) inhibitor from antler velvet with CO2 was explored. The effect of different parameters, such as particle size, the kind of co-solvent, extraction temperature and pressure, on the extraction yield (Y) and the total inhibitory activity (TI) on MAO-B were investigated using three-level orthogonal array design. The experimental results show that when the absolute ethanol as co-solvent was used and the particle size was 120 μm, the extraction temperature was 70 °C, the extraction pressure was 30 MPa, the extract yield reached 3.58% and the TI of the extract was 3319.13 U/g. Evaluation of the inhibitory activity of extract on MAO indicated that the extracts had strong inhibitory effects on MAO-B, but had slight effects on MAO-A. The MAO-B activity was inhibited by 93.77% at the concentration of 278.15 mg/L, which was much higher than that of water extract and ethanol extracts. The compositions of estradiol, uracil, hypoxanthine, p-hydroxybenzaldehyde and phospholipids in the SFE extracts were identified, which were reported to have the inhibitory effect on MAO.

The solubility of triphenyltin chloride (TPT) and triphenylmethyl chloride (TPC) in supercritical carbon dioxide (SC-CO2) was measured with a dynamic method at temperatures from 308.15 K to 338.15 K and pressures ranging from 15 MPa to 40 MPa. The two compounds displayed a similar mole fraction solubility in SC-CO2 of about 10−3 to 10−4 with a relative uncertainty of about 6 % over the range of experimental conditions. The experimental solubility data were correlated with both empirical Gordillo and semiempirical Chrastil models. The correlation results indicated that the values of average relative deviations (ARD) with the Gordillo model for TPT and TPC were 5 % and 12 %, and those of with the Chrastil model were 9 % and 6 % respectively.

The extraction of flavonoids from Houttuynia cordata Thunb by pressurized liquid extraction has been studied in this article. The effects of several important factors such as the concentration of slovent ethanol, solvent rate, temperature and pressure were investigated by orthogonal array design experiment. Both a high flavonoids yield of 3.152% and a high flavoniods content of 23.962% were obtained with solvent ethanol concentration of 50%, solvent rate of 1.8 mL/min, temperature of 70 °C and pressure of 8 MPa. The results are favorable to that of traditional methods of hot soaking and ultrasound-assisted extraction.

The heterogeneous base catalyst, γ-Al2O3 loaded with KOH and K (K/KOH/γ-Al2O3) was first prepared and used in the transesterification of rapeseed oil with methanol to produce biodiesel. The prepared catalyst was characterized by X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller method, infrared spectroscopy and X-ray photoelectron spectroscopy. It was found that when γ-Al2O3 is loaded with KOH and K, the Al–O–K species is produced, resulting in an increase in the catalytic activity. The impacts of catalyst preparation conditions on the catalytic activities of K/KOH/γ-Al2O3 were investigated. The results demonstrate that the catalyst K/KOH/γ-Al2O3 has high catalytic activity when the added amounts of KOH and K are 20 and 7.5 wt% respectively. The transesterification of rapeseed oil to biodiesel with the prepared heterogeneous base catalyst was optimized. It was found that the yield of biodiesel can reach as high as 84.52% after 1 h reaction at 60°C, with a 9:1 molar ratio of methanol to oil, a catalyst amount of 4 wt%, and a stirring rate of 270 g.

The solubility of uracil in supercritical carbon dioxide (SC-CO2) was determined with dynamic method at temperatures (308, 318, 328, 338, and 348) K and various pressures in the range of (15 to 40) MPa. The mole fraction solubilities of uracil ranged from (0.769 to 14.98)·10−8. The solvent capacity of SC-CO2 to dissolve uracil increases by increasing the pressure at a constant temperature. The crossover point was observed around a pressure of 15 MPa. Experimental data of the solubility of uracil were correlated by the Chrastil model and the modified Chrastil model. The results indicated that the two models were able to successfully correlate the experimental solid uracil + SC-CO2 solubility data, and the values of average absolute relative deviation (AARD) were 12.8 % and 10.1 %, respectively.

Supercritical fluid extraction (SFE) of essential oil from clove buds with CO2 was explored. The effect of different parameters, such as temperature (30 °C, 40 °C, 50 °C), pressure(10 MPa, 20 MPa, 30 MPa) and particle size (three degree index), on the extraction yield and the content of eugenol in extracts was investigated using three-level orthogonal array design. The experimental results show that the temperature has the largest effect on the eugenol content of the extracts, and particle size has the maximum effect on the oil yield. The essential oil of 19.56% yield, in which the maximum content of eugenol in extracts is 58.77%, can be extracted from clove buds at pressure of 10 MPa and temperature of 50 °C. Essential oil of clove buds obtained by SFE, hydrodistillation, steam distillation and Soxhlet extraction were further analyzed by gas chromatography/mass spectrometric detection to compare the extraction methods. Twenty three compounds in the clove oils have been identified, showing that the composition of the clove oil extracted by different methods is mostly similar, whereas relative concentration of the identified compounds is apparently different. General characteristics of the clove oils obtained by different methods were further compared, and SFE is considered as the optimum process among the four processes for obtaining clove oil with high quality.

A method involving the simultaneous extraction and clean-up of nine organochlorine pesticides (OCPs) from the actual ginseng was developed using supercritical fluid extraction (SFE) and off-line solid-phase extraction (SPE) cartridge. The pesticides in the study consisted of α-, β-, γ- and δ-benzene hexachloride (BHC), pentchloronitrobenzene and DDT and its metabolites. The target analytes extracted were collected with an off-line commercial solid-phase extraction cartridge, recovered with eluting solvent and quantified by gas chromatography-electron-capture detection together with mass spectrometric confirmation. The optimal extraction conditions was obtained from a series of experiments in which samples preloaded by 10 wt.% ethanol–H2O solutions, 300 bar extraction pressure, 60 °C extraction temperature, with C18 as trap adsorbent and n-hexane as eluting solvent. Additionally, Soxhlet extraction of organochlorine pesticides in actual ginseng was also carried out. Experimental results showed that SFE was more rapid and more effective than Soxhlet extraction.

Supercritical CO2 (SC-CO2) extraction technology and ultrasonic technology were used to extract two active sex hormones, estradiol and progesterone, and insulin-like growth factor-1 (IGF-1) from antler velvet. The effects of SC-CO2 extraction condition on the extraction yield and content of sex hormones, the ultrasonic extraction condition on the content of IGF-1 and the SC-CO2 extraction condition on the activity remaining of IGF-1 were studied. The optimal conditions were obtained. The experimental results showed that, in presence of 75% ethanol as the co-solvent, the mean yield and content of estradiol and progesterone were 87.67 pg·g−1 and 1224.10 pg·g−1, 12.38 ng·g−1 and 354.06 ng·g−1, respectively, with extraction pressure of 30 MPa, temperature of 35°C, extraction time of 30 min and CO2 consumption of 15 L·g−1 at the flow rate of 2.0 L·min−1. The highest content of IGF-1 was 7425.75 ng·g−1 antler velvet residue, when the pH10 ammonia-ammonium chloride buffer solution was used as the solvent, the ratio of solvent to sample was 20/1 (volume/mass), the extraction temperature was 0-35°C, and the extraction time was 4 × 15 min. Under these conditions, 93.68% activity remaining of IGF-1 in the residue was obtained, while little IGF-1 activity exists in traditional residue. The experimental results indicate that the technology of SC-CO2 with co-solvent is of advantage for getting high content sexual hormones and keeping high activity of IGF-1 in the residue, which can not be achieved by traditional extraction methods.