SC CO2 Research Articles

Supercritical fluid extraction of rare earth elements, thorium and uranium from monazite concentrate and phosphogypsum using carbon dioxide containing tributyl phosphate and di-(2-ethylhexyl)phosphoric acid

Supercritical fluid extraction (SCFE) using carbon dioxide containing tributyl phosphate (TBP), di-(2-ethylhexyl)phosphoric acid (D2EHPA) and their adducts with HNO3 is applied for extraction of rare earth elements (REE), thorium (Th) and uranium (U) from monazite concentrate (MC) and phosphogypsum (PG). REE extraction from MC and their separation from Th and U are carried out from the product of MC–Na2CO3 baking (MCS), which is obtained under microwave irradiation, after which the phosphates of REE, Th and U present in the MC are converted into their oxides. Up to 50% of REE can be recovered as the adducts of TBP and D2EHPA with HNO3 from the resulting powdered MCS under SCFE conditions, whereas Th and U remain in the solid phase. After a complete dissolution of the MCS residue in the mixture of 4 M HCl and 0.05 M HF, Th and U are quantitatively extracted using supercritical carbon dioxide (SC CO2) containing D2EHPA and thus separated from the REE that remain in an acidic solution. The conditions of quantitative isolation of REE, Th and U from PG are determined. The schemes for complex processing of MC and PG aimed at REE recovery and their separation from Th and U are suggested.

Preparation of anthocyanin-loaded liposomes using an improved supercritical carbon dioxide method

Abstract Anthocyanin-loaded liposomes were prepared via a single step supercritical carbon dioxide (SC-CO2) process. Phospholipid/anthocyanin suspension equilibrated with CO2 was depressurized at a constant pressure and rate. The effects of pressure, depressurization rate and temperature on the characteristics of liposomes were investigated. Liposomes obtained had a mean diameter of 160 ± 2 nm, polydispersity index of 0.26 ± 0.01, encapsulation efficiency of 52.2 ± 2.1% and zeta potential of − 44.3 ± 2.9 mV. Elevated pressure and depressurization rate generated smaller particles with higher uniformity while high temperature led to reduced sphericity. The SC-CO2 method produced liposomes with enhanced intactness, sphericity and uniformity compared to the thin film hydration method. This method offers the possibility to utilize dense phase CO2 to process the phospholipid aggregates into nano/micro particles and control their characteristics via tuning of processing parameters. SC-CO2 method shows promise in scalable production of liposomes loaded with a variety of bioactives, targeting food applications. Industrial relevance High quality anthocyanin-loaded liposomes were prepared using SC-CO2. In this process, heterogenous phospholipid aggregates suspended in an aqueous medium are transformed into unilamellar and spherical liposomes with a narrow size distribution and other characteristics that can be regulated via tuning of the processing parameters (pressure, depressurization rate and temperature). The SC-CO2 method resulted in superior particle characteristics over those prepared via the traditional thin film hydration method and also overcame some drawbacks like organic solvent residue and vesicle leakage associated with the traditional method. Anthocyanin encapsulated into liposomes can be protected from adverse external conditions with potential benefits in food and nutraceutical formulations for improved efficacy and health benefits. This improved SC–CO2 process shows great promise for potential scale up of liposome production in the industry to encapsulate a variety of bioactives, targeting food and nutraceutical applications.

Mathematical simulation of heat and mass transfer during controlled depressurization of supercritical CO2 in extraction vessels

Even after almost forty years of industrial application, companies are still reluctant to use supercritical (sc) CO2 as a solvent for extractions due to the perceived high production costs. Literature on the matter suggests that, because extraction at high pressure needs to be done in batches, using multiple extraction vessels with simulated-countercurrent flow could reduce operational costs. However, the more extraction vessels used, the less time there is to recondition them in order to have a semi-continuous operation; and if the reconditioning, and particularly the depressurization, is done too fast, the vessel could become brittle and permanently damaged. With the goal of optimizing the depressurization process in mind, numerical simulation of temperature and mass was carried considering a 1-dm3 vessel filled with a packed bed made with model materials using a mass flow function that depends on the chocked mass flux and a valve opening area. The correlation Nu=0.0777Da−0.0373Ra0.397 was obtained for convective heat transfer at the vessel wall, and temperature, pressure, and vented mass flow were simulated with about 20% improvement in predictions in comparison to our previous correlation. To explore the use of the model for practical purposes, it was used to simulate depressurization processes with volumes up to 1m3 and with different initial conditions and vessel geometries so as to have a first approach on the effect of these parameters on the depressurization time. Simulated depressurization times reached a maximum value of 54.5min for depressurizations of a 1-m3 extraction vessel starting at 60°C and 70MPa, which are very plausible extraction conditions. This model can be used to determine optimal reconditioning time in industrial plants for cost minimization.

Extraction of phenolics from broom branches using green technologies

AbstractBACKGROUNDThe effective exploitation of plants as a biorenewable resource has very important significance for sustainable development. Broom (Cytisus scoparius) has been used and associated with healthy benefits in the Iberian Peninsula for a long time. With this in mind, different technologies, alone or in combination, have been proposed to obtain valuable compounds from broom branches.RESULTSComposition showed a seasonal variation. Periods that lead to higher content of extractives were selected to design a combined autohydrolysis and supercritical CO2 extraction process for the production of antioxidants. The autohydrolysis process leads to higher yields than conventional solvent extraction and SC–CO2 extraction produced a raffinate with radical scavenging capacity comparable with ethanolic extracts. The major bioactive compounds identified in extracts were flavonoids, phenolic acids and phenolic aldehydes.CONCLUSIONSAn extraction process resulting from a combination of solvent extraction and autohydrolysis increased the extraction yields and the recovery of extracts containing bioactive compounds suitable for use in food, cosmetic and pharmaceutical applications. The knowledge gained from this study should be helpful to further exploit and apply this resource. © 2016 Society of Chemical Industry

Ambient-dried thermal superinsulating monolithic silica-based aerogels with short cellulosic fibers

Short (<2.5 mm) cellulose fiber–silica composite aerogels were synthesized by dispersing cellulose fibers in polyethoxydisiloxane-based sol. After in situ gelation, silica phase was hydrophobized with hexamethyldisilazane, and the composites were dried either at ambient pressure or with supercritical (sc) CO2. Fiber concentration was varied from 0 to 25 wt% (corresponding to 0–2.1 vol%) of the final dried composite. Preformed cellulosic fiber network preserved the monolithic shape of the silica-based composites during ambient drying. At room conditions, thermal conductivities were 0.015 ± 0.001 W/(m K) for sc-dried aerogels and 0.017 ± 0.001 W/(m K) for their ambient-dried counterparts. Materials dried with either method exhibited large specific surface areas, from 570 to 730 m2/g, and SEM analysis did not show significant differences in the global structure of the silica network. Composite aerogels were hydrophobic with water contact angles around 138°. Based on this proof of concept, the same approach was used with a variety of natural and recycled cellulosic fibers also resulting in silica-based monoliths with low thermal conductivities in the 0.016–0.023 W/(m K) range, all produced via ambient drying.

Development of a Green Alternative Procedure for the Simultaneous Separation and Quantification of Clove Oil and Its Major Bioactive Constituents

Clove buds are a good source of oil, which can be used as a food flavor and traditional Chinese medicine. To isolate clove oil and its major bioactive constituents, a green alternative procedure employing ultrasound-assisted supercritical carbon dioxide (USC–CO2) extraction combined with gas chromatography/mass spectrometry was developed, and its performance was compared to those of conventional processes. The green USC–CO2 process saves time, solvent, energy, and raw materials without chemical waste while achieving superior yields of clove oil and major bioactive constituents. The solubility of clove oil and fictitious solubility of eugenol in SC–CO2 have been predicted for the first time at various temperatures (32–50 °C) and pressures (9.0–28.5 MPa). Furthermore, solubility data correlated well with three density-based models (Chrastil, Kumar–Johnston, and Bartle), and the overall average absolute relative deviations (AARD%) were 0.22, 0.92, and 4.91%, respectively. Using correlation results, we approx...

Pilot‐scale supercritical CO2 extraction of edible insect oil from Tenebrio molitor L. larvae – Influence of extraction conditions on kinetics, defatting performance and compositional properties

In view of industrial fractionation processes for edible insects, supercritical CO2 extraction of Tenebrio molitor larval oil was studied. The influence of extraction parameters on defatting of larvae was investigated using a full factorial design. Furthermore, the effect of operating conditions on extraction kinetics, fatty acid composition, and acidity of mealworm oil was evaluated. Pressure, time, and their interaction showed the most significant effects on defatting. Maximal defatting (95%) was achieved at 400/250 bar, 45°C, and 105 min. Extraction kinetics revealed that incrementing pressure increased the solubility of mealworm oil in SC–CO2 enabling faster extraction. Extracted oils contained 72% unsaturated fatty acids, and oleic acid accounted for 42% of total FAME. Oil composition and acidity were found to be affected by extraction parameters showing the highest amount of low molecular and free fatty acids after slow extraction at 250 bar and 65°C. Use of selective extraction conditions enabled simple time‐dependent fractionation and deacidification yielding fractions with tailored fatty acid profiles or facilitating subsequent refining processes, respectively. Defatting performance and oil composition were not substantially different when using hexane as a solvent in comparison to SC–CO2. Mealworm larvae can be effectively defatted using SC–CO2 at high pressure and moderate temperature, yielding two valuable fractions: oil‐ and protein‐rich residue.Practical applications: Mealworm larvae are promising candidates for the inclusion of edible insects in the western food and feed industry due to modest breeding demands, existing rearing knowledge, and high contents of protein and fat. The development of fractionation processes for the production of standardized insect bulk materials and incorporation in feed or food in analogy to soy and other plant raw materials rich in fat and protein will help gain industrial applicability and enhance consumer acceptance. Depending on the processing approach, a defatting step is crucial prior to protein extraction. The results of this study indicate that SC–CO2 extraction is suitable for achieving a high yield of solvent‐free oil and a protein‐enriched, solvent‐free residue at low extraction temperatures. Both fractions can be further refined and purified in order to achieve valuable intermediates for food and feed applications.The SC–CO2 extraction of mealworms yielded highly unsaturated oil and a defatted residue containing protein and chitin. The operating parameters clearly affected the defatting performance and the extraction rate.

Facile preparation of lightweight high-strength biodegradable polymer/multi-walled carbon nanotubes nanocomposite foams for electromagnetic interference shielding

Lightweight conductive polymer composites (CPCs) have been considered as the most promising alternatives to metal-based shields for electromagnetic interference (EMI) shielding application but still face non-degradation issues. We report a facile, inexpensive and green method to implement lightweight biodegradable poly (l-lactic acid) (PLLA)-multiwalled carbon nanotubes (MWCNTs) nanocomposite foams using a combinatorial technology of pressure-induced flow (PIF) processing and supercritical carbon dioxide (Sc–CO2) foaming. Such low-density (∼0.3 g/cm3), low thickness (∼2.5 mm), high compressive strength (∼54 MPa g−1 cm3)) and highly conductive (∼3.4 S m−1) PLLA-MWCNT nanocomposite foams were first reported as an EMI shielding material: it presents high performance EMI shielding with a remarkable effectiveness and a corresponding average specific EMI SE of ∼23 dB and ∼77 dB g−1 cm3, respectively, with less reflection in the measured X-band frequency region. Considering the simple, low-cost and eco-friendly fabrication process, the lightweight, high-strength and highly conductive biodegradable polymer composite foams are expected to be used as high-performance EMI shielding materials in areas such as electronics, automobiles and packaging.

Extraction of α-humulene-enriched oil from clove using ultrasound-assisted supercritical carbon dioxide extraction and studies of its fictitious solubility

Clove buds are used as a spice and food flavoring. In this study, clove oil and α-humulene was extracted from cloves using supercritical carbon dioxide extraction with and without ultrasound assistance (USC–CO2 and SC–CO2, respectively) at different temperatures (32–50°C) and pressures (9.0–25.0MPa). The results of these extractions were compared with those of heat reflux extraction and steam distillation methods conducted in parallel. The extracts obtained using these four techniques were analyzed using gas chromatography and gas chromatography/mass spectrometry (GC/MS). The results demonstrated that the USC–CO2 extraction procedure may extract clove oil and α-humulene from clove buds with better yields and shorter extraction times than conventional extraction techniques while utilizing less severe operating parameters. Furthermore, the experimental fictitious solubility data obtained using the dynamic method were well correlated with density-based models, including the Chrastil model, the Bartle model and the Kumar and Johnston model.

Use of Non-Conventional Cell Disruption Method for Extraction of Proteins from Black Yeasts.

The influence of pressure and treatment time on cells disruption of different black yeasts and on activities of extracted proteins using supercritical carbon dioxide process was studied. The cells of three different black yeasts Phaeotheca triangularis, Trimatostroma salinum, and Wallemia ichthyophaga were exposed to supercritical carbon dioxide (SC CO2) by varying pressure at fixed temperature (35°C). The black yeasts cell walls were disrupted, and the content of the cells was spilled into the liquid medium. The impact of SC CO2 conditions on secretion of enzymes and proteins from black yeast cells suspension was studied. The residual activity of the enzymes cellulase, β-glucosidase, α-amylase, and protease was studied by enzymatic assay. The viability of black yeast cells was determined by measuring the optical density of the cell suspension at 600 nm. The total protein concentration in the suspension was determined on UV–Vis spectrophotometer at 595 nm. The release of intracellular and extracellular products from black yeast cells was achieved. Also, the observation by an environmental scanning electron microscopy shows major morphological changes with SC CO2-treated cells. The advantages of the proposed method are in a simple use, which is also possible for heat-sensitive materials on one hand and on the other hand integration of the extraction of enzymes and their use in biocatalytical reactions.

Enhanced β Crystalline Phase in Poly(vinylidene fluoride) via the Incorporation of Graphene Oxide Sheets assisted by Supercritical CO2 Treatment

ABSTRACTGraphene oxide (GO) sheets were pre-modified with a typical piezoelectric polymer, poly(vinylidene fluoride) (PVDF), using a simple supercritical carbon dioxide (SC CO2) method, and then the PVDF-decorated GO was added into a PVDF matrix by solution blending. Transmission electron microscopy (TEM) revealed that the decorating degree of PVDF on the surface of the GO increased significantly with increasing of SC CO2 pressure and PVDF concentration. The mechanism of the polymer adsorption on the GO sheets through favorable interaction between the GO and PVDF chains was identified via Fourier transform infrared spectroscopy (FTIR). Further, the crystallization behavior of PVDF/GO composites was investigated by differential scanning calorimetry (DSC), FTIR and polarized optical microscopy (POM). Interestingly, the composite with PVDF-decorated GO as the filler showed higher β-phase content compared to the composite with pristine GO as the filler. The study showed that the supercritical fluid-induced epitaxial crystallization process has significant potential for fabricating functional GO-based nanocomposties containing piezoelectric or conducting materials.

A Simple Method To Calculate the Viscosity of Heavy Oil Saturated with Supercritical CO2 Using Correlations

Supercritical carbon dioxide (sc CO2) could greatly reduce the viscosity of heavy oils and consequently increases their fluidity on account of its special properties, whose density is close to that of the liquid while viscosity is similar to that of the gas. No matter if under reservoir conditions or in the pipelines, the fluidity of heavy-oil/sc CO2 is of major concern, especially for the process of CO2 injection development in deep heavy oil reservoirs and the transportation of heavy oil diluted by sc CO2. In this Article, a method to calculate viscosities of heavy-oil/CO2 mixtures is introduced, which is based on the Lederer equation. Contrary to earlier reports, this Article has calculated the parameters with empirical correlations especially for the viscosity of sc CO2, which was calculated with a computing procedure using equation of state in previous references. In addition, the viscosity of dead-heavy-oil at high-pressure and high-temperature (HPHT) and the volume factor, Fo, are also calculated u...

Easy Preparation and Photoelectrochemical Properties of CdS Nanoparticle/Graphene Nanosheet Nanocomposites Using Supercritical Carbon Dioxide.

Graphene nanosheets (GNSs) were modified with CdS nanoparticles (NPs) using supercritical CO2 (SC CO2), which has gas-like diffusivity, low viscosity, and near-zero surface tension. The resulting CdS NP/GNS nanocomposites were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. Distinct morphologies of CdS NP/GNS nanocomposites decorated on the GNS surface were obtained at different SC CO2 pressures, temperatures, and durations and in different sources. Results showed that the sources and SC CO2 significantly influenced the aggregation or assembly behavior of the CdS NP/GNS nanocomposites on the GNSs. The formation mechanism of the distinct nanohybrid structures was studied by Raman mapping. A difference was noted between the Raman spectra of pristine graphene nanosheets and CdS NP/GNS nanocomposites. This result can be ascribed to the CdS NPs anchored onto the GNS defects and to the improved quality of the GNSs under SC CO2. The photo-current densities of CdS NP/GNS nanocomposites were at least three times higher than that of the pristine CdS NPs at the same applied voltage for photoelectrochemical water splitting. The findings suggested that highly efficient graphene-supported NP photoelectrocatalysts can be fabricated by the supercritical fluid method and that graphene can serve as a favorable photoelectrocatalytic carrier, with promising potential applications in environmental and energy fields. Keywords: Graphene Nanosheets, Cadmium Sulfide, Raman Spectroscopy, Photoelectrochemical.

Optimization of coffee oil flavor encapsulation using response surface methodology

This study aimed the encapsulation of coffee oil flavor and optimizing the process conditions which affect the encapsulation efficiency (EE). Oil was extracted from roasted Coffea arabica, (Yrigachefe, Ethiopia) using supercritical carbon dioxide (Sc–CO2). Then, the extracted oil was encapsulated by polyethyleneglycol (PEG) using particles from gas-saturated solutions (PGSS) process. Process parameters which affect the EE such as, temperature (T, 40–50 °C), pressure (P, 200–300 bar) and polymer-oil ratios (R, 5:1–10:1 g/g) were optimized via Box Behnken design (BBD). The optimal conditions were (T, 40.0 °C, P, 260.14 bar and R, 6.57:1 g/g) with a maximum EE of 79.78%. The encapsulated oil showed peroxide value of 4.56 meq peroxide/kg oil after 12 weeks of storage. Less than 2% loss of fatty acid composition was observed after encapsulation. Moreover, flavor profiles of particles obtained using optimal condition showed very good preservation of flavors. Therefore, microencapsulation using PGSS process could be employed for production of freely flowing powdered particles that can be used in food processing industries.

Formation of solid lipid microparticles from fully hydrogenated canola oil using supercritical carbon dioxide

A simple and green process based on supercritical carbon dioxide (SC–CO2) technology was used to produce solid lipid microparticles from fully hydrogenated canola oil (FHCO). The effects of pressure (122, 211 and 300 bar) and nozzle diameter (0.1, 0.3 and 14.3 mm) on the particle size, morphology, thermal properties and polymorphism were investigated. Then, the essential oil loading capacity of the particles obtained under optimum conditions was evaluated. Smaller nozzle diameter (0.1 mm) and lower pressure (122 bar) produced spherical particles with narrower particle size distribution and a mean diameter of 1.27 μm. Melting point of all particles decreased to 65 °C from 69 °C for the FHCO. The main polymorphic form of the particles obtained at lower pressures and larger nozzle diameters was α, whereas it was β at higher pressures and smaller nozzle diameters. Essential oil loading efficiency of 96% was achieved when FHCO blended with 40% essential oil was used as the feed material. SC-CO2 process is a promising technology for solid lipid particle formation as delivery vehicles for bioactives.

Effect of Nano-clay on Rheological and Extrusion Foaming Process of a Block-Copolymerized Polypropylene

The effects of nano-clay and the corresponding coupling agent maleic anhydride grafted polypropylene (PP-g-MAH) on thermal properties, rheological properties and extrusion foaming process of a block-copolymerized polypropylene (B-PP) were studied. Supercritical CO 2 (SC CO 2 ) was used as the foaming agent with a concentration of 5wt%. Each step of foamed B-PP/ PP-g-MAH/ nano-clay composites processing is addressed, including mixing of the composites, manufacture of the composites, foaming process of the composites and characterization of the cell structure. The results showed that incorporation of nano-clay and PP-g-MAH caused reduced melt strength and complex viscosity of B-PP. However, the heterogeneous nucleation induced by nano-clay and PP-g-MAH improved the maximum foaming expansion ratio and cell-population density of B-PP foam.

Supercritical CO2Assisted Synthesis of EDTA-Fe3O4Nanocomposite with High Adsorption Capacity for Hexavalent Chromium

Efficiency of EDTA functionalized nanoparticles in adsorption of chromium (VI) from water was investigated in this study. Magnetic iron oxide nanoparticles (IONPs) were synthesized by a simple chemical coprecipitation route and EDTA coating onto IONPs was attained via supercritical carbon dioxide (Sc CO2), a technology with green sustainable properties. The obtained nanoparticles were then characterized by UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and vibrating magnetometric analysis (VSM). The synthesized nanoparticle and its modified variant were evaluated as adsorbent for chromium (VI) removal from water through batch adsorption technique and the effect of analytic concentration; contact time and adsorbent concentration were studied at pH 2. The results showed higher removal efficiency for modified magnetic iron oxide nanoparticles (MIONPs) (i.e., 99.9%) than their nonmodified variant IONPs, that is, 34.06% for the same concentration after 18 hours of incubation. Also maximum adsorption capacity (qe= 452.26 mg/g) of MIONPs attained can be related to their preparation in Sc CO2asqecalculated from IONPs, that is, 170.33 mg/g, is lower than that of MIONPs. The adsorption data fit well with Freundlich isotherm equation while kinetic adsorption studies of chromium (VI) were modeled by pseudo-second-order model.

Exploring the selectivity of supercritical CO2 to obtain nonpolar fractions of passion fruit bagasse extracts

The contents of tocols, unsaturated fatty acids and carotenoids make the passion fruit bagasse an interesting source for extraction. In this study the selectivity of supercritical carbon dioxide (SC–CO2) as solvent was explored to obtain extract fractions concentrated in such compounds from passion fruit bagasse. The study was divided into two stages. The first stage identified the conditions of temperature and pressure that achieved extracts with different chemical compositions. In the second stage, such conditions were applied in a sequential supercritical fluid extraction (SFE) process composed by three steps (60°C and 17MPa; 50°C and 17MPa; e 60°C and 26MPa). Only the first step recovered tocols, the second step extracted fatty acids without tocols and low carotenoid content, and the third step concentrated carotenoids. The sequential SFE process achieved extracts 1.5 and 5.8 times more concentrated in tocols and carotenoids, respectively, than the single-stage condition that achieved bigger global yield (40°C, 35MPa).

High-efficiency exfoliation of layered materials into 2D nanosheets in switchable CO2/Surfactant/H2O system

Layered materials present attractive and important properties due to their two-dimensional (2D) structure, allowing potential applications including electronics, optoelectronics, and catalysis. However, fully exploiting the outstanding properties will require a method for their efficient exfoliation. Here we present that a series of layered materials can be successfully exfoliated into single- and few-layer nanosheets using the driving forces coming from the phase inversion, i.e., from micelles to reverse micelles in the emulsion microenvironment built by supercritical carbon dioxide (SC CO2). The effect of variable experimental parameters including CO2 pressure, ethanol/water ratio, and initial concentration of bulk materials on the exfoliation yield have been investigated. Moreover, we demonstrate that the exfoliated 2D nanosheets have their worthwhile applications, for example, graphene can be used to prepare conductive paper, MoS2 can be used as fluorescent label to perform cellular labelling, and BN can effectively reinforce polymers leading to the promising mechanical properties.

A combined procedure of ultrasound-assisted and supercritical carbon dioxide for extraction and quantitation oleanolic and ursolic acids from Hedyotis corymbosa

Hedyotis corymbosa is a good source of oleanolic acid (OA) and ursolic acid (UA), which have many beneficial effects on human health and are two interesting compounds that are widely utilized in medicine and functional food. To isolate OA and UA from the plant, a novel procedure employing ultrasound-assisted supercritical carbon dioxide (USC–CO2) extraction was developed, and its performance was compared with that of conventional processes. HPLC analysis of the obtained extracts revealed that the highest yields of OA (2.316mg/g dry plant) and UA (9.284mg/g dry plant) were achieved by USC–CO2 extraction using a dried sample with a mean particle size of 0.355mm at a CO2 flow rate of 2.1mL/min, temperature of 53°C and pressure of 26.5MPa. The static extraction time was 15min and the dynamic extraction time was 80min with 11.0% aqueous ethanol (80% (v/v) ethanol in water) as a cosolvent. The yields obtained with USC–CO2 extraction were higher than those obtained with conventional SC–CO2 extraction and heat-reflux extraction for the two discussed compounds. With the newly developed process, these results were obtained faster and at a lower temperature and pressure; additionally, less organic solvent was used. Therefore, USC–CO2 extraction, as performed under the above-mentioned conditions, is a more effective and selective method for extraction of OA and UA from H. corymbosa compared with the other two techniques. USC–CO2 extraction is efficient and environmentally friendly for using in the pharmaceutical industry.