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Helichrysum italicum presents a valuable source of natural bioactive compounds. In this work, a literature review of terpenes, phenolic compounds, and other less common phytochemicals from H. italicum with regard to application of different separation methods is presented. Data including extraction/separation methods and experimental conditions applied, obtained yields, number of identified compounds, content of different compound groups, and analytical techniques applied are shown as corresponding tables. Numerous biological activities of both isolates and individual compounds are emphasized. In addition, the data reported are discussed, and the directions for further investigations are proposed. [ABSTRACT FROM AUTHOR]

The solid catalyst La/Mn oxide was prepared using co-precipitation method. The catalytic behavior for catalyzing transesterification of soybean oil with methanol under subcritical conditions was investigated in a batch reactor; optimization of several parameters for catalyst preparation and transesterification reaction was also performed. The triglyceride (TG) conversion of above 99% was obtained using La/Mn oxide catalyst prepared with La:Mn molar ratio of 2:1 and calcined at 600 °C for 90 min, under such reaction conditions as 3 wt.% of catalyst, methanol/oil molar ratio of 12:1, reaction temperature and time of 180 °C and 60 min, respectively. The catalyst shows good reusability, and can resist FFA to some extent. However, it is sensitive to water. The mechanisms of catalytic activity and deactivation were discussed according to the characterization of the fresh and used catalysts using basic strength, BET surface area, scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS), and X-ray diffraction (XRD). Results demonstrated that the complex oxide LaMnO 3.15 was the dominant component. The crystalline structure of the catalyst after use changed remarkably and the active sites might be occupied by organics, which led to the deactivation or diminished activity of the catalyst in the repeated use process. [ABSTRACT FROM AUTHOR]

Highlights: [•] New solid base catalyst MnCO3/ZnO shows high activity for biodiesel production in subcritical methanol. [•] Optimum conditions for catalyst preparation and biodiesel production were determined. [•] High catalyst activity maintained after reused for 17 cycles. [•] Deactivation of the catalyst is discussed. [Copyright &y& Elsevier]

Abstract: Kinetics and selectivity of supercritical carbon dioxide (SC CO2) extraction of Helichrysum italicum flowers were analyzed at pressures in the range of 10–20MPa and temperatures of 40°C and 60°C (density of SC CO2 from 290 to 841kg/m3) and also at 10MPa and 40°C using flowers with different moisture contents (10.5% and 28.4%). Increased moisture content of H. italicum flowers resulted in enchased solubility of solute enabling decrease of SC CO2 consumption necessary for achieving desired extraction yield. The most abundant compounds in the supercritical extracts are sesquiterpenes and waxes while monoterpenes and sesquiterpenes are the main constituents of essential oil obtained by hydrodistillation. The optimal set of working parameters with respect to extraction yield, SC CO2 consumption and chemical composition of extract were defined related to moisture content of raw material and SC CO2 density. [Copyright &y& Elsevier]

Abstract: A wide spectrum of phytochemicals could be isolated from sage (Salvia officinalis L.) using different extraction or distillation technique: the supercritical fluid extraction (SFE), the volatiles compounds (monoterpenes and sesquiterpenes) isolation using hydrodistillation or higher molecular compounds with Soxhlet extraction or ultrasound-assisted extraction. The combination of ultrasound-assisted extraction followed by re-extraction of obtained extract with supercritical CO2 was performed in this study. The goal of performed investigation was to concentrate diterpenes present in sage extract which are generally considered to be responsible for antioxidant activity of extracted compounds. The fractionation using the supercritical CO2, and different combination of the ultrasound-assisted solvent extractions (water–ethanol mixture or only water) followed by supercritical CO2 re-extraction of obtained extract or treated plant material were analyzed and compared. Based on the results of these investigations it could be proposed the best extraction procedure: the ultrasound pretreatment of plant material with distilled water and re-extraction of plant material (residue) using supercritical CO2. That procedure gives two valuable products: the ultrasound extract which is rich in sugars and possess the immunomodulatory activity and supercritical extract which is rich in diterpenes and sesquiterpenes. [Copyright &y& Elsevier]

Abstract: Analysis of several different schemes for industrial FAME production at higher pressure and temperature (catalytic or non-catalytic synthesis) was realized with the aim to find the best route to reduce the energy consumption (EC) and to improve the life cycle energy efficiency. Obtained results indicated that the EC (MJ/kg FAME) mainly depends on degree of conversion of triglycerides being almost 25% smaller if degree of conversion increase from 97 mass% to complete conversion. Further significant decrease of EC might be obtained at subcritical conditions but only after substantial decrease of methanol to oil molar ratio (from 42 to 15) which requires use of appropriate catalyst. On account of that, the kinetics of heterogeneous catalyzed methanolysis of triglycerides was analyzed using data published in literature (CaO) as well as own experimental data (K2CO3/Al–O–Si) with a goal to obtain reliable kinetic rate constant which might be used for process simulation. This study shows that if heterogeneous process of biodiesel synthesis is realized at subcritical conditions then further decrease of EC is possible. [Copyright &y& Elsevier]

The continuous biodiesel production from soybean oil was carried out under the subcritical condition of methanol with MnCO 3 /Na-silicate as a heterogeneous catalyst. The transesterification rate was first investigated in a set of experiments performed in a batch autoclave at 448 K using methanol-to-oil molar ratio of 18:1 and various catalyst loadings (5, 10 and 20 wt% based on the oil mass). The results from these experiments, as well as the experimental data and the appropriate kinetic model recently reported in the literature were used for designing a packed bed tubular reactor (PBTR), a main unit of the pilot plant with the capacity of 100 L of biodiesel per day. The pilot plant was constructed and tested under various operating conditions. The first 11 h of the pilot-plant operation was realized in the tubular reactor packed with inert glass beads (i.e. without the catalyst) in order to analyze the effect of the non-catalyzed subcritical biodiesel (fatty acid methyl esters, FAME) production. Then, glass beads were replaced with a mix of MnCO 3 /Na-silicate catalyst particles and glass beads, and the catalytic biodiesel production was continuously run under the subcritical methanol condition for 85 h. Two mass balance tests during the continuous pilot plant operation were performed. [ABSTRACT FROM AUTHOR]

A heterogeneous cerium–manganese oxide catalyst was synthesized by a co-precipitation method, characterized and tested in soybean oil transesterification with methanol under subcritical condition for methanol. Conversion of triglycerides after 40 min of transesterification in a batch process was over 99% with a fatty acid methyl ester (FAME) yield of 91.6% when 3 wt.% of catalyst based on oil, and 18:1 methanol/oil molar ratio were applied. The same amount of catalyst was used in 12 cycles of transesterification with catalyst regeneration performed only after the 7th cycle. The catalyst exhibited good tolerance toward soybean oil containing below 1.5 wt.% of water or 4 wt.% of free fatty acids. The mechanisms of Ce/Mn catalytic activity and its deactivation were discussed according to the characterization of the fresh and used catalyst according to results of different analytical methods: the Hammett titration, BET surface area, scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS), FTIR, X-ray diffraction (XRD), ICP-AAS and TG-DSC. It was assumed that deactivation of catalyst was mainly a consequence of manganese solubility in methanol and glycerol. [ABSTRACT FROM AUTHOR]

Calcium-containing perovskites CaTiO 3 , CaMnO 3 , CaZrO 3 and Ca 2 Fe 2 O 5 were synthesized by calcination of mechanochemically treated stoichiometric mixtures of CaCO 3 and either TiO 2 , MnO 2 , ZrO 2 or Fe 2 O 3 powders. X-ray diffraction analysis revealed a pure single perovskite phase for all four samples after calcination. This study proved that the pure perovskite phase exhibited low or no catalytic activity at 60 °C for the methanolysis of sunflower oil. However, at 165 °C FAME yield of more than 90% was reached after 2 h using CaTiO 3 , CaMnO 3 and CaZrO 3 as catalyst. Contrary to inactive pure perovskites at 60 °C, the CaTiO 3 and Ca 2 Fe 2 O 5 samples containing a very small amount of “free” CaO also showed methanolysis activity at 60 °C. This fact can be used to explain some contradictory statements reported in literature related to the perovskites as catalyst for biodiesel synthesis at mild temperatures. [ABSTRACT FROM AUTHOR]

In the present work, calcium diglyceroxide (CaDG) was synthesized by mechanochemical treatment of CaO dispersed in glycerol, and characterized by X-ray diffraction (XRD), thermal analysis (TGA/DTA), infrared spectroscopy (FTIR), and Hammett indicator method for base strength determination. The obtained CaDG was tested as a catalyst in the methanolysis of sunflower oil under different working conditions: catalyst amount, agitation speed, temperature and methanol to oil molar ratio. The main advantage of CaDG used as a catalyst in methanolysis is related to the initial rate of methanolysis. According to many previously reported data in literature the mass transfer resistance controls the overall rate of methanolysis, but it is not observed with CaDG used as catalyst. Recently developed kinetic model that describes the complex methanolysis process was successfully applied for this system and model parameters were determined, supporting the explanation of the physical effect of the CaDG catalyst on the reduction of mass transfer resistance and increasing the rate of methanolysis. The absence of mass transfer rate at the beginning of process is a consequence of the nature of the CaDG, which is adsorbed at the droplet interfaces between methanol and oil leading to the formation of fine dispersion of these two immiscible liquids. [ABSTRACT FROM AUTHOR]

The continuous sunflower oil methanolysis catalyzed by quicklime in a packed-bed tubular reactor of 60 cm height was studied at 60 °C using methanol-to-oil molar ratios from 6:1 to 18:1 and weight hourly space velocities from 0.188 to 0.376 (kg/kg cat h). The main goal was to establish the effect of the process variables on the fatty acid methyl esters (FAME) synthesis. A full factorial design was used to evaluate the significance of the three process factors (methanol-to-oil molar ratio, flow rate of the reactants and bed height) statistically. Moreover, the recently reported kinetic model of methanolysis was used to describe variations of FAME and triacylglycerols (TAG) concentrations along the reactor length. The kinetic model predicted the axial concentration profiles of TAG and FAME in the reactor with acceptable accuracy. A high FAME content (98.5%) could be achieved at the two thirds of the bed of quicklime bits without loss of catalytic activity within 30 h of continuous operation. [ABSTRACT FROM AUTHOR]

The Strontium doped cinder was prepared using the wet impregnation method and analyzed as catalyst for biodiesel synthesis. Different procedure for cinder impregnation were investigated (temperature and duration of catalyst calcinations, the concentration of SrCl 2 solution) and optimal condition was established: impregnation 20 g of cinder 2–5 mm particles with 0.2 M SrCl 2 solution followed by calcinations at 1000 °C for 4 h. The Sr-cinder activity was tested at 90–200 °C using 1–5% mass of catalyst with different molar ratio of methanol to soybean oil (from 9 to 36). The maximum triglycerides (TG) conversion of 99.0% with the Fatty Acid Methyl Esters (FAME) yield of 97.1% was obtained by using 4% catalyst at 180 °C, for 1 h, and methanol/oil molar ratio 24:1. Influence of free fatty acid (FFA) and water in soybean oil on catalyst activity was analyzed, too. The catalyst could be used for 14 times with TG conversion and FAME yield above 90% and 80% respectively. The Sr-doped cinder catalysts before and after transesterification were characterized using BET surface area, basic strength, X-ray diffraction (XRD), scanning electron microscopy (SEM) and ICP-AAS. Results showed that the formation of SrAl 2 Si 2 O 8 and Sr 5 Al 8 O 17 complexes should be the main reason for the catalytic activity of prepared catalyst. Slow decrease of catalyst activity during its repeated use is result of Sr–Al-glycerolate formation in reaction between Sr–Al complexes and glycerol. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mechanochemical synthesis of CaO·ZnO catalyst and its testing in methanolysis of virgin sunflower and used vegetable oil. [•] Determination of heterogeneous methanolysis kinetics and kinetic parameters evaluation. [•] Definition of the overall volumetric mass transfer coefficient as a function of triglycerides conversion. [•] Proposal of the kinetic model to describe the heterogeneous methanolysis kinetics. [ABSTRACT FROM AUTHOR]

Abstract: A difficulty of biodiesel synthesis based on alkaline catalysts obviously exists if free fatty acids (FFAs) content in vegetable oil is above 0.5wt.%. In this study, the ferric sulfate supported on silica (Fe2(SO4)3/SiO2) was synthesized, activated (at different temperature: 120–600°C) and tested for heterogeneous esterification of FFA (oleic acid) present in sunflower oil (5wt.%). The catalyst samples were characterized by BET, TG/DTG, XRD and FTIR analyses. Obtained results showed that catalyst activated at 500°C for 2h in air atmosphere gave the maximal conversion of oleic acid (∼97%). Repeated use of catalyst without additional catalyst treatment or re-activation indicated that catalyst posses desired stability and activity. A pseudo-homogeneous kinetic model was proposed with good agreement between calculated and experimental data. [Copyright &y& Elsevier]

Abstract: Hydrodynamics of a continuous cocurrent two-phase upflow reciprocating plate reactor (RPR) for homogeneously base-catalyzed methanolysis of sunflower oil was studied. Here, methanol constituted the dispersed phase and sunflower oil was the continuous phase. The measurements were performed in both the non-reactive (methanol–sunflower oil) and reactive (sunflower oil–methanol–KOH) systems. The main goal was to define the effects of the vibration intensity and the important reaction operating conditions on the pressure fluctuation at the reactor bottom, the power consumption, the dispersed phase holdup, the Sauter-mean drop diameter and the specific interfacial area. The power consumption under batch, single- and two-phase flow was proved to depend on the vibration intensity. The Sauter-mean drop diameter was found to depend on the specific power consumption in accordance with the turbulent model due to the turbulent energy dissipation in well-mixed regions around perforated plates. The simplified correlation of Kumar and Hartland could be used for estimating the Sauter-mean drop diameter. The energy dissipation due to reciprocating plate motion and the superficial dispersed phase velocity affected the dispersed phase holdup and the specific interfacial area. The present results are crucial for designing RPRs for application in continuous base-catalyzed methanolysis of vegetable oils. [Copyright &y& Elsevier]

Abstract: The kinetics of Ca(OH)2-catalyzed methanolysis of sunflower oil was studied at a moderate temperature (60°C), a methanol-to-oil molar ratio (6:1) and different catalyst amounts (from 1% to 10% based on oil weight). The methanolysis process was shown to involve the initial triglyceride (TG) mass transfer controlled region, followed by the chemical reaction controlled region in the latter period. The TG mass transfer limitation was caused by the low available active specific catalyst surface due to the high adsorbed methanol concentration. Both the TG mass transfer and chemical reaction rates increased with increasing the catalyst amount. [Copyright &y& Elsevier]

Abstract: 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 10–30MPa 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 15MPa followed by increased CO2 consumption were favourable for obtaining desired selectivity of diterpenes which contain compounds with expressed antioxidative characteristics. [Copyright &y& Elsevier]

Abstract: The methanolysis of sunflower oil was studied in the presence of CaO previously calcined at various temperatures and the optimal temperature for CaO calcination was determined. The sigmoidal process kinetics was explained by the initial triglyceride (TG) mass transfer controlled region, followed by the chemical reaction controlled region in the latter reaction period. The TG mass transfer limitation was due to the small available active specific catalyst surface, which was mainly covered by adsorbed molecules of methanol. In the later phase, the adsorbed methanol concentration decreased, causing the increase of both the available active specific catalyst surface and the TG mass transfer rate, and the chemical reaction rate become smaller than the TG mass transfer rate. [Copyright &y& Elsevier]

Abstract: The kinetics of the sunflower oil methanolysis process was studied at lower temperatures (10–30°C). The sigmoidal kinetics of the process was explained by the mass transfer controlled region in the initial heterogenous regime, followed by the chemical reaction controlled region in the pseudo-homogenous regime. A simple kinetic model, which did not require complex computation of the kinetic constants, was used for simulation of the TG conversion and the FAME formation in the latter regime: the fast irreversible second-order reaction was followed by the slow reversible second-order reaction close to the completion of the methanolysis reaction. The mass transfer was related to the drop size of the dispersed (methanol) phase, which reduced rapidly with the progress of the methanolysis reaction. This was attributed to the formation of the emulsifying agents stabilizing the emulsion of methanol drops into the oil. [Copyright &y& Elsevier]

Abstract: Isolation of carrot fruit (Daucus carrota L., cultivar “Chanteney”) essential oil by supercritical carbon dioxide was investigated from the pretreatment of herbaceous matrix and extraction conditions to the chemical composition of obtained extract and its antimicrobial activity. The qualitative and quantitative analyses of the supercritical extract, as well as of the essential oil obtained by hydrodistillation, were done by GC/FID and GC/MS methods. Antimicrobial properties of both samples were investigated against ten species of microorganisms. Experimental results showed that the particle size had no influence on the extraction process. The highest yield was obtained at 40°C and 10MPa. The main component of the supercritical extract, as well as of the essential oil was carotol. The supercritical extract was characterized by the presence of heavier molecular weight compounds, while some lighter compounds, e.g. pinenes, were not detected. The supercritical extract and the essential oil were the most effective against Gram-positive bacteria. [Copyright &y& Elsevier]

Abstract: In this paper the essential oil supercritical carbon dioxide extraction from leaves of Lamiaceae family species was studied. Recent investigations of Lamiaceae family essential oil storage have shown that most of the oil is found in peltate glandular trichomes on the leaf surface. The effect of supercritical on the peltate glands was investigated by Scanning Electron Microscopy. It was observed that exposure to supercritical led to disruption of the peltate glands and essential oil release. This phenomenon was used as a basic hypothesis of the mathematical model of the supercritical fluid extraction with . The model was applied to simulate basil, rosemary, marjoram and pennyroyal supercritical extraction on the existing experimental data. An average deviation from the experimental data was less than 0.83%. The model results indicated a possibility of a decrease in the supercritical consumption by modified and optimized processing of Lamiaceae family herbaceous material. [Copyright &y& Elsevier]