Preparation of porous material from talc by mechanochemical treatment and subsequent leaching

Synthesis of porous silica via mechanochemical treatment of talc and subsequent acid leaching was investigated by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and N₂ adsorption techniques. Raw talc was ground for different times and then leached with 4 M hydrochloric acid (HCl) at 80 °C. Grinding for 6 h and subsequent leaching for 2 h of raw talc produced the porous silica with a specific surface area of 133 m²/g and total pore volume of 0.22 ml/g. The increase in specific surface area (S_BET) of the porous silica reflected the formation of micropores of 1.21.8 nm and mesopores of 4.05.5 nm in diameter inside the porous structure. The number of micropores decreased with prolonged leaching time, which can be attributed to a condensation reaction. The characteristic of hysteresis loop indicated mainly slit-shaped pores. The apparent activation energy for the leaching process was calculated to be about 21.6 kJ/mol, indicating that the kinetic process of talc leaching was the diffusion-controlled reaction. Mechanochemical treatment may promote the amorphization of talc, being greatly favorable to the subsequent leaching.     

Extraction of sage (Salvia officinalis L.) by supercritical CO2: Kinetic data, chemical composition and selectivity of diterpenes

The supercritical carbon dioxide (SFE) extraction of Dalmatian sage (Salvia officinalis L.) was investigated and compared to extraction performed by Soxhlet ethanol-water (70:30) mixture extraction (SE) and hydrodistillation (HD). The supercritical extraction allowed isolation of wide spectrum of phytochemicals, while other applied methods were limited to either volatiles (HD) or high molecular compounds isolation (SE). The kinetics of the supercritical extraction and fractionation within the pressure range of 10-30 MPa at 50 °C were also analyzed as well as the chemical compositions of total extract and partial or differential fractions isolated at different CO₂ consumption. Volatile fraction could be isolated at low pressure and low CO₂ consumption, whereby the pressures between 10 and 15 MPa followed by increased CO₂ consumption were favourable for obtaining desired selectivity of diterpenes which contain compounds with expressed antioxidative characteristics.     

Synthesis of nanocrystalline SnO2 powder from SnCl4 by mechanochemical processing

The rapid synthesis of nanocrystalline SnO₂ powder using a mechanochemical reaction of SnCl₄ (instead of the widely used tin (II) compounds) with (NH₄)₂CO₃ and the subsequent annealing of the product in air and under an H₂O/NH₃ atmosphere has been investigated using X-ray powder diffraction, TG and TEM. The reaction was complete within 5 min. Additional milling of the product at a higher milling intensity for 120 min led to the crystallisation of tetragonal SnO₂. The NH₄Cl salt matrix was removed by annealing at 300 °C. The average crystallite size of tetragonal SnO₂ was in the range of 2-48 nm and it can be controlled by variation heating temperatures and annealing atmospheres in the range of 300-700 °C.     

微波提取苹果渣中总黄酮的工艺研究

采用微波辐射技术,以乙醇提取苹果渣中黄酮类化合物。考察了乙醇浓度、微波功率、处理时间、料液比和浸泡时间对总黄酮提取率的影响。结果表明,最佳工艺条件为:70%乙醇,微波萃取2 min,微波功率为350 W,料液比1∶30(g/mL),总黄酮1次提取率0.683 7%。     

Negative pressure cavitation accelerated processing for extraction of main bioactive flavonoids from Radix Scutellariae

To enhance the extraction efficiency and reduce the energy consumption, an emerging technology named negative pressure cavitation extraction (NPCE) has been shown to be a feasible option for the extraction of bioactive compounds in agricultural crops and medicinal plants. Meanwhile, it can be applied at the pilot scale as a manufacturing process for edible and medicinal plants. Currently, NPCE was proposed for extraction of baicalin, wogonoside, baicalein and wogonin from Radix Scutellariae on the basis of a central composite design (CCD) and response surface methodology (RSM). With proper optimization (80 mesh of particle size, 40 mL/g of liquid/solid ratio, 75% aqueous ethanol as extraction solvent, 60 min extraction time and −0.07 MPa vacuum degree), NPCE was observed to have good extraction efficiency compared with other conventional extraction methods. Furthermore, the antioxidant activities of crude extracts with different extraction methods were assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay. Our results showed that NPCE extract possessed better antioxidant activity with IC₅₀ value of 3.24 μg/mL compared with the UAE, HRE and SE extracts with IC₅₀ values of 7.85, 12.14 and 11.44 μg/mL, respectively.     

Continuous and selective separation of EGCG from tea polyphenols by fractional extraction: Experiment and simulation

A new and efficient method was explored to continuously separate (−)-epigallocatechin-3-gallate (EGCG) from tea polyphenols (TPs) by fractional extraction in centrifugal contactor separators (CCSs). The effects of different organic solvents on distribution behavior of monomers of TPs were studied, and two green extraction systems were established without reactive extractant. Based on phase equilibrium and the law of conservation of mass, a fractional extraction model was developed to investigate the influence of the process parameters such as phase ratio and the number of stages on extraction efficiency. By simulation and optimization, optimal parameters can be obtained for the separation of EGCG. EGCG can be separated by batch and continuous separation. Excellent results can be achieved by the two methods with high purity, high yield, and large output. Compared to the batch method, the continuous separation is more suitable for production in an industrial scale due to low-cost and continuous separation. © 2018 American Institute of Chemical Engineers AIChE J, 65: 259–269, 2019     

Supercritical fluid extraction of flavonoids from Maydis stigma and its nitrite-scavenging ability

Supercritical fluid carbon dioxide (SF-CO₂) extraction (SFE) of flavonoids from Maydis stigma and its nitrite-scavenging ability were investigated. The effects of extraction time, particle size and co-solvent composition in terms of water content in ethanol were first optimized. Then, a Box-Behnken design combined with response surface methodology (RSM) was employed to study the effects of three independent variables (temperature, pressure and co-solvent amount) on the extraction yield of flavonoids. A maximal extraction yield of flavonoids of approximately 4.24 mg/g of M. stigma by SFE was obtained under optimal conditions (a temperature of 50.88 °C, a pressure of 41.80 MPa, a co-solvent amount of 2.488 mL/g and an extraction time of 120 min with 0.4-mm particle sizes and 20% aqueous ethanol as the co-solvent). Furthermore, the nitrite-scavenging ability of the flavonoid-enriched SFE extracts was assessed using the Griess reagent. The flavonoid-enriched SFE extracts exhibited the highest scavenging ability on nitrite (88.1 ± 3.04%) at the concentration of 500 μg/mL and at pH 3.0. The nitrite-scavenging ability of the extracts appeared to be concentration dependent but negatively correlated with the pH.     

A novel organic gas steam-liquid extraction method for the selective extraction of cobalt from water samples

In this work, for the first time, organic gas steam-liquid extraction (OGS-LE) technique was developed as a promotion in the liquid–liquid extraction (LLE) method, by the use of a special homemade extraction cell that was designed to facilitate the traditional LLE method, without emulsification and with high extraction efficiency by a small amount of organic solvent in one step. This method is fast, simple and efficient, and was employed for the selective extraction and determination of cobalt (II) from water samples. The efficiency of the OGS-LE method was compared with the LLE method. The obtained results revealed that by using the OGS-LE technique, the extraction efficiency of cobalt from a synthetic mixture was over 90%, much higher than the traditional LLE method (34%).     

Structural and electrical properties of 0.57PSN-0.43PT ceramics prepared by mechanochemical synthesis and sintered at low temperature

In this investigation we show that the dielectric, ferroelectric and piezoelectric properties of stoichiometric 0.57Pb(Sc_1/2Nb_1/2)O₃-0.43PbTiO₃ (0.57PSN-0.43PT) ceramics prepared by mechanochemical synthesis are comparable or even better than the properties of 0.57PSN-0.43PT ceramics with Nb doping, which was proposed to enhance the electrical properties. Here, the stoichiometric ceramic was sintered to 97% of theoretical density at a temperature of 1000 °C, which is 200-300 °C lower than previously reported. The dielectric constant ?, remnant polarization P_r, piezoelectric coefficient d₃₃, coupling coefficients k_p and k_t and mechanical quality factor Q_m of the ceramics prepared by mechanochemical synthesis were 2200, 43 μC/cm², 570 pC/N, 0.71, 0.56 and 38, respectively.The effects of the poling field on the structural and electrical properties of the 0.57PSN-0.43PT ceramics were investigated. The results show that the ratio of the monoclinic to the tetragonal phases is influenced by the application of the poling electric field. The non-poled ceramics contain 71% of the monoclinic phase and 29% of the tetragonal phase. The highest d₃₃, k_p and k_t were measured for ceramics poled at an electric field of 3 kV/mm. For these poled ceramics a phase determination of 86% monoclinic phase and 14% tetragonal phase was obtained from Rietveld refinements.     

Kinetic study of pilot-scale supercritical CO2 extraction of rosemary (Rosmarinus officinalis) leaves

Rosmarinus officinalis (rosemary) extracts were obtained in a supercritical pilot-scale plant. Based on experimental information available in the literature for analytical or low-scale processes, extraction temperature and pressure were selected to be 313 K and 30 MPa. At these extraction conditions, the kinetic behavior of the pilot-scale overall extraction curve were determined with respect to yield, antioxidant activity and carnosic acid content. The overall extraction curve was represented using Sovova's model; the average deviation between measured and calculated yields was lower than 2%. Mass transfer coefficients in the fluid and solid phases were determined and were compared with previous data reported in the literature for low-scale rosemary supercritical extraction.A two-stage depressurization procedure was accomplished and the effect of both on-line fractionation and extraction time on the antioxidant activity of the samples collected was studied. The antioxidant activity of the different fractions could be straight correlated with the carnosic acid content with a regression coefficient of 0.92.     

Comparison of different extraction methods for the extraction of major bioactive flavonoid compounds from spearmint (Mentha spicata L.) leaves

Different bioactive flavonoid compounds including catechin, epicatechin, rutin, myricetin, luteolin, apigenin and naringenin were obtained from spearmint (Mentha spicata L.) leaves by using conventional soxhlet extraction (CSE) and supercritical carbon dioxide (SC-CO₂) extraction at different extraction schemes and parameters. The effect of different parameters such as temperature (40, 50 and 60 °C), pressure (100, 200 and 300 bar) and dynamic extraction time (30, 60 and 90 min) on the supercritical carbon dioxide (SC-CO₂) extraction of spearmint flavonoids was investigated using full factorial arrangement in a completely randomized design (CRD). The extracts of spearmint leaves obtained by CSE and optimal SC-CO₂ extraction conditions were further analyzed by high performance liquid chromatography (HPLC) to identify and quantify major bioactive flavonoid compounds profile. Comparable results were obtained by optimum SC-CO₂ extraction condition (60 °C, 200 bar, 60 min) and 70% ethanol soxhlet extraction. As revealed by the results, soxhlet extraction had a higher crude extract yield (257.67 mg/g) comparing to the SC-CO₂ extraction (60.57 mg/g). Supercritical carbon dioxide extract (optimum condition) was found to have more main flavonoid compounds (seven bioactive flavonoids) with high concentration comparing to the 70% ethanol soxhlet extraction (five bioactive flavonoids). Therefore, SC-CO₂ extraction is considered as an alternative process compared to the CSE for obtaining the bioactive flavonoid compounds with high concentration from spearmint leaves.     

Optimization of total alkannin yields of Alkanna tinctoria by using sub- and supercritical carbon dioxide extraction

The effects of supercritical carbondioxide extraction was investigated to compare previously validated extraction methods on total alkannin yield with Alkanna tinctoria collected form Antalya, Turkey. A two-step process was used; extraction of alkannin derivatives with supercritical CO₂ followed by alkaline hydrolysis of alkannin derivatives. A Box-Behnken exprerimental design was used to evaluate the effect of three variables, pressure (50-350 bar), temperature (30-80 °C) and CO₂ flow (5-20 g min⁻¹) at 1:30 ratio of alkanna root:CO₂ amount. Response surface analysis revealed that the data were adequately fitted to a second-order polynomial model with R² 0.9665 and the most effective variable was pressure (P ≤ 0.05). Optimum conditions were determined as 80 °C, 175 bar, 5 g min⁻¹ CO₂ flow yielding the highest total alkannins (1.47%) which was higher than conventional hexane extraction (1.24%) providing a solvent-free alternative for industrial production.     

Supercritical CO2 extraction of lipids and astaxanthin from Brazilian redspotted shrimp waste (Farfantepenaeus paulensis)

Brazilian redspotted shrimp (Farfantepenaeus paulensis) waste is an important source of carotenoids such as astaxanthin and lipids with a high ω−3 fatty acids content, mainly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). In order to establish an efficient and environmental friendly recovery process, the lipids and astaxanthin were extracted from the freeze-dried redspotted shrimp waste (including head, tail and shell) using supercritical carbon dioxide. The effects of the extraction conditions of pressure (200-400 bar) and temperature (40-60 °C) on the global yield (X₀), astaxanthin extraction yield and astaxanthin concentration in the extract were evaluated. It was found that the pressure and temperature showed a very low significant effect on the lipid extraction yield using supercritical CO₂. In comparison with lipid extraction by solvents, maximum efficiency of supercritical fluid extraction achieved 64% of hexane extraction yield. On the other hand, temperature and pressure had significant effects on astaxanthin extraction yield. Thegreatest amount of extract was obtained at 43 °C and 370 bar, with 39% of recovery.     

乙醇/碳酸钾双水相萃取盾叶薯蓣发酵液中的2,3-丁二醇

实验考察了乙醇/碳酸钾双水相萃取盾叶薯蓣发酵液中2,3-丁二醇的分配情况,并对其工艺条件进行了优化。结果表明,当乙醇22%(质量)、碳酸钾26%(质量)时,发酵液中2,3-丁二醇的回收率达到最高值97%,此时,乙偶姻和残余还原糖的回收率为97%和87%,菌体和蛋白的去除率分别为99%和94%,而丙酮酸、柠檬酸、苹果酸、延胡索酸和琥珀酸的去除率高达100%,这为2,3-丁二醇的工业分离提供了一种新的技术。     

Selective extraction of phosphatidylcholine from lecithin by supercritical carbon dioxide/ethanol mixture

Selective extraction of phosphatidylcholine (PC) from deoiled soybean lecithin using supercritical fluid (SCF) mixtures of carbon dioxide (CO₂) and ethanol was studied at moderate pressures. Temperature was varied between 60 and 80°C at pressures of 17.2 and 20.7 MPa. Ethanol was added as co-solvent to supercritical CO₂ at the levels of 10 and 12.5 wt%. Constant rate of extraction of the individual phospholipids (PL) was observed for 150 min during which the extractions were carried out. Pressure and ethanol fraction had a positive effect on the selective extraction of PC, whereas temperature had a negative effect. Under all the conditions studied, the extracts were mainly composed of PC while the extraction of the other PL was very low. Extraction at 60°C and 20.7 MPa with 10 wt% ethanol/90 wt% CO₂ SCF mixture resulted in 95% selectivity to PC.     

Supercritical carbon dioxide extraction of triglycerides from Jatropha curcas L. seeds

This study examines the effects of pressure, temperature and solvent to solid ratio (SSR) on extraction efficiency of triglycerides from powdered Jatropha seeds by using supercritical carbon dioxide extraction. Supercritical extractions were designed for pressures ranging from 250 to 350 bar, temperatures ranging from 313 to 333 K and SSR values ranging from 65:1 to 125:1. All values were selected using response surface methodology in order to determine their effects on the concentration of triglycerides from the extracted oil. Using 3750 g of carbon dioxide over 5 h, a supercritical carbon dioxide extraction (at 350 bar, 333 K and an SSR value of 125:1) yielded 43.51% oil. The concentration and extraction efficiency (i.e. recovery) of triglycerides in the extract reached 657.1 mg/g and 97.62%, respectively. Changes in pressure presented more effective in increasing the recovery of triglycerides, but both temperature and the SSR value are important in obtaining high concentration of triglycerides from the Jatropha seeds that are useful for biodiesel materials.     

Supercritical carbon dioxide extraction of oil from Mexican chia seed (Salvia hispanica L.): Characterization and process optimization

Supercritical carbon dioxide (SC-CO₂) was employed to extract oil rich in omega-3 fatty acids (FAs) from chia seeds, and the physicochemical properties of the oil were determined. A central composite rotatable design was used to analyze the impact of temperature (40 °C, 60 °C and 80 °C), pressure (250 bar, 350 bar and 450 bar) and time (60 min, 150 min and 240 min) on oil extraction yield, and a response surface methodology (RSM) was applied. The extraction time and pressure had the greatest effects on oil. The highest oil yield was 92.8% after 300 min of extraction time at 450 bar. The FA composition varied depending on operating conditions but had a high content of α-linolenic acid (44.4-63.4%) and linoleic acid (19.6-35.0%). The rheological evaluation of the oils indicated a Newtonian behavior. The viscosity of the oil decreased with the increase in temperature following an Arrhenius-type relationship.     

盐析-萃取工艺分离2-甲基咪唑母液的研究

研究了2-甲基咪唑母液的盐析-萃取法分离工艺.考察了NaOH、NaCl的浓度、萃取温度3个因素对2-甲基咪唑萃取率的影响,通过单因素实验和正交实验确定最佳分离条件为:NaOH浓度为2.5mol·L-1(NaOH的摩尔数:母液浓缩后体积,下同),NaCl浓度为2.6mol·L-1,萃取温度为70℃,此时,萃取率为83.7...     

Supercritical CO2 extraction of Persea indica: Effect of extraction parameters, modelling and bioactivity of its extracts

The objective of the work was to optimize the extraction of Persea indica L. bioactive compounds by means of supercritical fluid extraction (SFE) and analyze their insecticidal effects. P. indica L. is one of the dominant species of the Canarian laurel forest, a relict of the Tertiary flora. Different extraction conditions (pressure, plant material particle size, temperature, CO₂ flow) and the influence of entrainer were tested and the evolution of the extracted compounds was screened by HPLC-MS. A comparison with conventional techniques such as hydrodistillation (HD) or organic solvent extraction (OSE) was also presented. Particularly, four CO₂ densities ranging from 628.61 kg/m³ to 839.81 kg/m³ were studied in the range of 10.0-20.0 MPa and 40-50 °C. The extracts contained insecticidal ryanodanes of great interest, previously described as insecticidal components of P. indica. The insecticidal antifeedant activity of selected extracts was inspected. A model based on mass transfer equations, the Sovová model, was successfully applied to correlate the experimental data.     

Supercritical CO2 extraction of oil, carotenoids, squalene and sterols from lotus (Nelumbo nucifera Gaertn) bee pollen

The high-quality oil, abundant in carotenoids, squalene and sterols (mainly consisting of campesterol, stigmasterol, β-sitosterol and β-amyrin), was extracted by supercritical CO₂ from lotus bee pollen for its potential nutraceutical use. The effects of extraction pressure and temperature on the yields and the compositions of the extracts were investigated by using a two-factor central composite rotatable design experiment. ANOVA for response surface model demonstrated that the data were adequately fitted into four polynomial models. The yields of the oil, carotenoids, squalene and sterols were significantly influenced by the experimental variables. It was predicted that maximum oil yield obtained at the extraction pressure of 38.2 MPa and temperature of 49.7 °C contained the maximum amount of carotenoids, squalene and sterols. GC-FID analysis of the fatty acid composition of lotus bee pollen oil showed that polyunsaturated fatty acids accounted for approximately 22% of the total fatty acids.