Supercritical Fluid Extraction Of Lemon Verbena (Aloysia triphylla): Process Kinetics and Scale-Up,Extract Chemical Composition and Antioxidant Activity,and Economic Evaluation

The extract of lemon verbena ( Aloysia triphylla ) was obtained by supercritical fluid extraction (SFE) using laboratory and pilot scale equipments. The scale-up criterion selected (maintaining solvent to feed ratio constant) was successfully used for a 14-fold scale-up. The extract obtained in pilot scale was separated in three fractions, which were characterized as for their phytochemical profile, total flavonoids content, and antioxidant activity. The extracts obtained by SFE were compared to classical Soxhlet extraction method. Maximum yield obtained for SFE was 1.8%, and for Soxhlet, 7.1%. The chemical composition revealed different phytochemical profiles for SFE and Soxhlet extracts; the last ones presented more flavonoids, while SFE extracts were more concentrated in volatile compounds. The major compounds identified in the volatile fraction of the extracts were spathulenol, phytol and octadecatrienal. Some extracts presented pro-oxidant activity and others presented antioxidant activity. The SFE process was shown to be economically feasible for obtaining lemon verbena extracts; the minimum manufacturing cost (COM) obtained was US$ 1070.00/kg, with a payback time of 2 years.     

Supercritical fluid extraction of peach (Prunus persica) almond oil: Kinetics, mathematical modeling and scale-up

Peach almonds contain oil with important therapeutic and nutritional properties due to the presence of unsaturated fatty acids, high content of oleic acid and other substances. In this study, peach almond oil was obtained by means of supercritical fluid extraction (SFE), with yield up to 24% w/w. The objective of this work was to evaluate the effect of the operation variables in the process kinetics in order to define scale-up parameters, like extractor volume and solvent flow rate. In spite of the importance for industrial application, the definition of a scale-up methodology is difficult. Therefore, the main goal of this work was to study the kinetic aspects of the SFE by modeling the extraction curves and, with these results, suggests a scale-up methodology. The parameters evaluated were extraction pressure, CO₂ flow rate and particle size. The mass transfer models used to describe the extraction curves were logistic model, diffusion model and Sovová model. Four scale-up methodologies, based on mass transfer mechanisms, were applied. The results indicate the best curve fitting by means of Sovová’s model, while the best scale-up criterion was maintaining the ratio Q_CO2/M (solvent flow rate/raw material mass) constant. This study also indicated the convection as the dominant mass transfer mechanism, while the diffusion was the limiting factor. Moreover, the SFE of peach almond oil could be predicted by the scale-up method used.     

Scale-up studies of the supercritical fluid extraction of triterpenic acids from Eucalyptus globulus bark

The supercritical fluid extraction (SFE) of Eucalyptus globulus deciduous bark is investigated, under the context of biorefinery, aiming at the definition of a pathway for the production of enriched extracts in triterpenic acids (TTAs). Scale-up studies are performed, well supported by modeling and by experiments carried out at lab, intermediate and pilot scales (0.5, 5.0 and 80.0 L, respectively). By acknowledging the significant role played by cosolvent (ethanol) addition on the concentration of TTAs, extraction curves are measured at 200 bar and 40 °C, using two different ethanol contents, 2.5% and 5.0% (wt). Taking into account the results achieved by four distinct models, the intraparticle diffusion is confirmed as the prevailing mass transfer resistance in both conditions. Accordingly, the ratio between CO₂ flow rate and biomass weight is adopted as scale-up criterion. Despite the geometric differences between the three units, the measured extraction yields and TTAs concentration evidence good agreement, which validates the established scale-up rule. In the whole, our results legitimate the technical viability of the SFE of E. globulus deciduous bark for future exploitation at larger scales.     

Supercritical fluid extraction of vegetable matrices: Applications,trends and future perspectives of a convincing green technology

Along more than a decade, R&D on supercritical fluid extraction (SFE) of vegetable matrices has been increasingly reported in the literature. Aiming at portraying the current state of this field and its evolution in terms of raw materials, products, modes of operation, optimization, modeling techniques, and closeness to industrial application, a large compilation of almost 600 essays from 2000 to 2013 has been deeply analyzed in order to unveil those indicators and their trends. Furthermore, strengths and weaknesses are identified, and some remarks that may drive upcoming research are provided.Globally, more than 300 species are reported in the literature, with prevalence of the extraction of seeds (28% of works) and leaves (17%). The main families of extracted compounds, cosolvents and operating conditions adopted are critically examined, being possible to conclude that researchers investigate many times working regions far from the optimum due to practical limitations or absence of experimental optimization. Current phenomenological, statistical and semi-empirical approaches are reviewed, along with scale-up studies, and economic analysis. In the whole, the most comprehensive picture over SFE of vegetable matrices is provided in this review, highlighting pertinent aspects and opportunities that may further consolidate the convincing route of this technology for the next years.     

Investigation and scale-up of hot-melt coating of pharmaceuticals in fluidized beds

This study was performed to investigate and scale-up the hot-melt coating process in fluidized beds. A series of well-designed experiments was carried out in a pilot scale unit with 20 kg product capacity to investigate the effects of process variables on the efficiency of the coating of Cefuroxime Axetil with stearic acid. Results showed that the efficiency is at the highest when the fluidization air flow rate is adjusted by considering the changes in the amount of materials present in the unit as well as the changes in the terminal velocities of particles during the process.With the objective to scale-up the hot-melt coating process from pilot to production scale, a dynamic thermodynamic model based on conservation equations of mass and energy was developed. Predictive accuracy of the model was assessed by applying it to the pilot scale unit and comparing its predictions with the online measurements taken on the same unit. Results showed that the predictions of the model agree well with the measurements. Utilizing this model and taking several experiments performed in the pilot scale unit as a basis, scaling up of the hot-melt coating process was carried out. Comparisons of the model predictions with the measurements taken on the production scale unit (200 kg product capacity) revealed that the model is able to reproduce the product attributes and the outlet air temperatures across scales. Therefore, it proves to be a promising tool that can be used in the scale-up of the hot-melt coating processes in fluidized beds.     

A hydrodynamic model of a continuous supercritical fluid extraction system for the treatment of oil contaminated solids

Supercritical fluid extraction (SFE) has the potential to recover compounds from a range of solid matrices if a fully continuous process can be commercialized. This paper presents the development of a hydrodynamic model for a continuous pilot scale SFE process, involving countercurrent flow of a slurry and a supercritical fluid. The model developed is based on first principles and focuses on predicting pressure and slurry level within the extraction vessel. The model was validated using pilot scale system data. Using adjusted parameters, the model accurately predicted steady state pressure and provided a good estimate of slurry level.     

Scale-up of binder agglomeration processes

This review article describes scale-up of batch and continuous granulation processes where liquid binder is added to fine powder in order to form a granular product. The technical goal of scale-up is to maintain similarity of critical product attributes as the production scale and/or throughput of a manufacturing process is increased. This paper provides a framework for scaling-up that considers critical process transformations in relation to the desired product attributes. A similar approach can be taken in developing process control strategies. In any agglomeration process, transformations can be used to describe how raw materials (typically fine powders and liquid binders) are converted into a granular product. Often the critical product attributes are characterized on the scale of individual granules (e.g., size, shape, porosity, mechanical strength, etc.). On the other hand, industrial scale-up requires predictive relations for the sizing, design and operation of process equipment. Considering scale-up on the basis of transformations is one way to link the macro-scale equipment decisions with micro-scale product attributes. This approach can be applied to the scale-up of batch and/or continuous granulation processes as well as transitioning from small batch prototypes to continuous production circuits.     

Entwicklung eines Simulationsprogramms zum Scale-up von Hydrierreaktoren

Development of a simulation program for the scale-up of hydrogenation reactors. The scale-up of trickle-bed reactors to pilot and production scale has been difficult and necessitated considerable over-dimensioning. Therefore a simulation program based on a cell model has been developed in which the dimensions of a cell are directly related to the dimensions of the catalyst particles used. The kinetic equation is formulated with an effective rate coefficient as the only key parameter to be adjusted. With this coefficient the intrinsic rate coefficient, the mass transfer, and the incomplete catalyst particle wetting are considered. The model was applied to the hardening of fatty acids and the hydrogenation of fatty acid methyl esters in laboratory reactors. Comparison with experimental results of pilot and industrial scale is favourable. Thus the model can be used for the scale-up of trickle-bed reactors.     

Supercritical fluid extraction of wormwood (Artemisia absinthium L.)

The objective of the work was to optimize the extraction of wormwood oil by supercritical fluid extraction (SFE) of growth-controlled plant material. Different extraction conditions, two growth techniques and various crops were tested and the evolution of the extracted oil composition was screened chromatographically. A comparison with conventional techniques such as hydrodistillation (HD) or organic solvent extraction (OSE) was also presented. Particularly, six CO₂ densities ranging from 285.0 kg/m³ to 819.5 kg/m³ were studied in the range of 9.0-18.0 MPa and 40-50 °C. A systematic study was carried out with plant material from 2005, while SFE of 2006, 2008 and aeroponically grown crops was performed for comparative purposes. The effect of ethanol as a modifier of the supercritical fluid extraction was also studied. The major compounds found in the SFE extracts as well as in the HD essential oils were Z-epoxyocimene, chrysanthenol and chrysanthenyl acetate. A model based on mass transfer equations, the Sovová model, was successfully applied to correlate the experimental data.     

超临界流体萃取固态物料数值模拟的研究进展

介绍了超临界流体萃取固态物料的数值模拟方法 ,对固体物料萃取的经验动力学模型、热质类比模型、质量守恒模型的原理及传质特性进行了评述     

Experimental study on the scale-up effect of gas storage in the form of hydrate in a quiescent reactor

This paper presents the experimental study on the scale-up effect of natural gas storage in the form of hydrates in a quiescent reactor. The hydrate formation experiments with respect to gas storage in the presence of sodium dodecyl sulfate (SDS) were initially performed in a 10 L reactor to study the scale-up effect by adjusting the mass of water loaded. The results demonstrated that the scale-up effect was very obvious, i.e., the specific hydrate formation rate, the moles of gas consumed per unit mass of water and time, decreased rapidly with the increasing mass of water loaded in the reactor. A multi-deck cell-type vessel was devised as the internals of the reactor to eliminate the scale-up effect, where water was loaded in each cell of the vessel instead of being loaded in the reactor directly and the hydrate formed in all cells of the vessel simultaneously. A double-deck cell-type vessel was set-up and a series of hydrate formation experiments were performed to study the influence of the number of deck and the size of each cell upon the specific formation rate and the storage capacity. The experimental results proved the feasibility of the multi-deck cell-type vessel. The influence of water quality was also studied and the results demonstrated that tap water could be used instead of the expensive distilled water in the formation of hydrates and the most suitable concentration of SDS in tap water was 2000 mg/L.     

On-Site Recovery of Hemicelluloses from Thermomechanical Pulp Mill Process Water by Microfiltration and Ultrafiltration

During mechanical defibration of wood, a minor fraction of the wood mass is dissolved in the process water. These dissolved substances represent an extra energy demand when they are treated in the mill’s wastewater treatment plant. Galactoglucomannan, the main hemicellulose in spruce, can be recovered from thermomechanical pulp mill process water by a process based on microfiltration (MF) and ultrafiltration (UF). The purpose of this work was to study the scale-up of the process from laboratory scale to continuous industrial scale. MF was first studied in the laboratory, and then combined with UF in a continuous pilot process on-site at a pulp mill. The data obtained were used to estimate the cost of the membrane processes for galactoglucomannan recovery which was found to be about €1160 per ton hemicelluloses.     

超临界流体萃取技术的发展及应用

超临界流体萃取技术(Supercritical fluid extraction technology,简称:SFE)是利用流体在超临界状态下具有选择性溶解能力的特性对不同的物料进行分离。超临界流体萃取技术在天然有机物质的提取方面有着巨大的优势。随着现代化工业工程技术的发展,超临界流体萃取技术在食品、石油、化工、医药等各个领域显示出广阔的发展前景。     

Extraction of phenolic fraction from guava seeds (Psidium guajava L.) using supercritical carbon dioxide and co-solvents

In this work the supercritical fluid extraction (SFE) with carbon dioxide (CO₂) and with ethyl acetate (EtAc) and ethanol (EtOH) as co-solvents was applied to obtain the phenolic fraction from guava seeds (Psidium guajava L.). The extraction was explored at various operating conditions, using 10, 20 and 30 MPa and 40, 50 and 60 °C. The use of EtAc and EtOH as co-solvents in SFE was also studied. The supercritical process was compared with traditional techniques such as Soxhlet extraction using EtAc and EtOH as solvents. The quality of the different extracts, obtained using SFE and Soxhlet methods and different solvents, was evaluated through the antioxidant activity, obtained by the collection methods of scavenging DPPH and bleaching of β-carotene, and also through the total phenolic content (TPC) of the samples, by the Folin-Ciocalteu method. The antioxidant potential indicates the use of ethanol as co-solvent as the best modifier in SFE, used in concentration of 10% (w/w) at 50 °C and 30 MPa. The quality of the extracts obtained by SFE with EtOH varied with the operating conditions of temperature and pressure, with higher values obtained at 10 and 20 MPa for TPC results and also antioxidant methods. The process yield of the phenolic fraction was also evaluated for all the extraction procedures studied (SFE and Soxhlet), with results varying from 0.380 to 1.738% (w/w).     

Scale-up and design of a continuous microwave treatment system for the processing of oil-contaminated drill cuttings

A continuous microwave treatment system has been developed for the remediation of contaminated drill cuttings at pilot scale. Using the mechanisms of oil removal as a basis, a design was produced using electromagnetic simulations to find the optimum microwave applicator geometry which yielded the most favourable power density distribution. Bulk materials handling and process engineering principles were systematically integrated with the electromagnetic design to produce a system capable of treating 500 kg/h of material. The effects of the key design parameters are simulated, and a number of the simulations are verified with experimental data. It is shown that the environmental discharge threshold of 1% oil can be achieved in continuous operation, and the sensitivity of the system to changing feedstock properties is also highlighted. The parity between the simulations and experimental results in this paper highlights the necessity of electromagnetic modelling in the design and scale-up microwave processing equipment.     

Industrial experience in the scale-up of reactive distillation with examples from C4-chemistry

The objective of this paper is to illustrate process design from the industrial point of view for a heterogeneous reactive distillation exemplified by the decomposition of MTBE. Based on thermodynamics a plausible column concept is suggested. Open questions concerning scale-up of structured catalytic packings are discussed on the basis of experiments in the lab and pilot plant scale. Lab scale experiments were modelled satisfactorily with an equilibrium stage approach. In order to perform the scale-up from lab to pilot scale with the equilibrium stage approach the reaction rate constant had to be reduced significantly. Incomplete catalyst wetting due to maldistribution effects or mass transfer phenomena might be possible reasons.     

Supercritical fluid extraction combined with dispersive liquid-liquid microextraction as a sensitive and efficient sample preparation method for determination of organic compounds in solid samples

The supercritical fluid extraction (SFE) followed by the dispersive liquid-liquid microextraction (DLLME) has been developed for extraction and determination of polycyclic aromatic hydrocarbons (PAHs) in marine sediments. PAHs were employed as model compounds to assess the extraction procedure and were determined by gas chromatography-flame ionization detection (GC-FID). SFE of PAHs was performed at 313 K and 253.2 bar, at static and dynamic times 10 and 30 min, respectively. The extracted PAHs were collected in 1 mL of acetonitrile. Subsequently, 16 μL of chlorobenzene (as extraction solvent) was added to collecting solvent (1.0 mL of acetonitrile). Then, the resulted mixture was injected into 5.0 mL of aqueous solution, rapidly. After centrifugation, the PAHs in the sedimented phase were analyzed by GC-FID. Effects of significant parameters on the extraction in SFE and DLLME methods were investigated. Under the optimum conditions, the calibration plots were linear in the range of 0.4-41.6 mg kg⁻¹ and the limits of detection (LODs) were 0.2 mg kg⁻¹ for all of the analytes. Analysis of PAHs in different solid samples showed that the improved technique has great potential for PAHs analysis in marine sediments. SFE-DLLME leads to high preconcentration factor, easy use of DLLME in solid samples and solving the main problem of SFE that is the extra step (vaporization of large volume of toxic organic solvent) after extraction needed prior to final analysis.     

Obtaining phenolic compounds from jatoba (Hymenaea courbaril L.) bark by supercritical fluid extraction

The extraction of polyphenol compounds from jatoba (Hymenaea courbaril L. var stilbocarpa) bark using supercritical fluid extraction (SFE) with CO₂ and cosolvents has been investigated. Among the solvent systems studied, SFE using CO₂ and water (9:1, v/v), at 323 K and 35 MPa, presented the best results, with extract yield of 24%, and with high antioxidant activity (IC₅₀ of 0.2 mg/cm³). This solvent system was used to determine global yield isotherms, which were built at 323 and 333 K, and 15, 25, and 35 MPa, using a second lot of jatoba. The highest yield was 11.5% at 15 MPa and 323 K, with maximum total phenolic compounds (TPC) of 335.00 mg TAE/g extract (d.b.) and total tannins content of 1.8 g/100 g raw material. A kinetic experiment was performed using optimized conditions, yielding 18% extract, and the kinetic parameters were used to scale-up the process from laboratory to pilot scale. Chemical analyses showed high content of phenolic compounds in the extracts of jatoba bark mostly due to the presence of procyanidins.     

Scale-Up Study of Dye RB-19 Ozonation in a New Gas-Inducing Reactor

The purpose of this research was to study the scale-up behavior of dye RB-19 ozonation in a new gas-inducing reactor, which has been used in the NTUST laboratory on various ozonation studies over the past few years. In this scale-up study, three geometrically similar gas-inducing reactors with different diameters (D _t =0.17, 0.29, and 0.51m) were employed. Three common scale-up criteria (i.e., equal liquid surface motion, equal specific power consumption, and equal impeller tip velocity) were investigated in this research. Under the equal liquid surface motion criterion, the scale-up exponent value and constant K of the modified onset Froude number were determined to be 0.5 and 0.61, respectively. The equal specific power consumption criterion was studied under gas input condition and the scale-up exponent was found to be 0.65. The regression equation for the power number of the three different scale reactors was also obtained. The scale-up exponent of equal impeller tip velocity was determined by theory to be 1.0. The scale-up investigation of dye RB-19 ozonation was then carried out in reactors with three different diameters under the same operating conditions (e.g., initial dye concentration, initial dye/ozone molar ratio, superficial gas velocity, temperature and pH value). From the experimental results, the best-fit scale-up exponent was found to be 1.18, resulting in same dye removal rate in reactors with different diameters. The enhancement factors and chemical ozone mass transfer coefficients were also obtained for these sets of ozonation experiments.