Supercritical CO2 Extraction Technique Research Articles

Optimization of scrap tire devulcanization process using Taguchi and DEAR method in a supercritical fluid extraction pilot scale setup

Recycling of scrap tires is gaining more significance to ensure sustainable consumption and production on a commercial scale. The supercritical CO2 extraction technique has been classified as green technology under United Nation's sustainable development guidelines. Literature shows that research on scrap tire devulcanization using supercritical CO2 was performed on a laboratory-scale setup only. However, significant pilot-scale research needs to be conducted before commercial use and technology transfer. This study utilized a pilot-scale supercritical fluid extraction equipment to devulcanize waste tire-derived crumb rubber. Using Taguchi's design of experiment (DOE) model along with the Data Envelopment Analysis Based Ranking (DEAR) approach, the effect of the input process variables on response factors was examined. The input functions, devulcanizing agent's concentration, and pump pressure were discovered to be the most influential parameters in the devulcanization process. Further optimization was carried out via the DEAR-Taguchi technique. The optimal process parameters were determined to be a pump pressure of 350 bar, an extractor temperature of 80 °C, a holding time of 30 min in the extractor, a CO2 circulation of 120 min, and a devulcanizing agent concentration of 15 vol.%. Finally, a validation experiment was conducted at the optimum conditions to verify the acceptability of the model. It was noticed that the divergence for the confirmation experiment was within 10 %, indicating that the approach used for the devulcanization of crumb rubber is acceptable.

Optimization of supercritical CO2 extraction of incensole-enriched oil from Boswellia papyrifera resin using response surface methodology

Incensole is a macrocyclic diterpene naturally existing in the frankincense extracted from the trees of the genus Boswellia and possesses a wide spectrum of promising bioactivities. This study discusses for the first time the optimization of supercritical CO2 extracting incensole-enriched oil from the frankincense of Boswellia papyrifera tree. The extraction parameters of temperature, pressure, and extraction time were optimized to obtain the maximum extraction yield and incensole content simultaneously using response surface methodology (RSM) and box-Behnken design, and the compounds extracted under optimal conditions were analyzed. Under the optimal conditions of a pressure of 23.0 MPa, a temperature of 40.0 °C, and an extraction period of 3.3 h, the incensole-enriched oil yield achieved 25.0%, in which incensole content of 40.5 wt% was observed and its recovery was 59.8%. The results indicate that the supercritical CO2 extraction technique can be applied to extract incensole-enriched oil from frankincense.

Qualitative and Quantitative Comparison of Aromatic Oil Components and Antifungal Effects of Cymbopogon flexuosus Obtained with Supercritical CO2, Microwave-Ultrasonic, Steam Distillation, and Hydrodistillation Extraction Techniques.

Cymbopogon flexuosus is a highly valued botanical species with significant applications in the food and food supplement industries, medicine, and cosmetics. The effects of four extraction techniques, supercritical CO2, microwave-ultrasonic, steam distillation, and hydrodistillation techniques, on the yield, phytochemical constituents, and antifungal activity against nine fungal species of Cymbopogon flexuosus aromatic oil (AO) were explored in this investigation. Gas chromatography connected with a mass spectrometry apparatus was employed for the qualitative and quantitative analyses of the investigated plant AOs. In addition, using the broth microdilution method, minimum inhibitory concentrations (MICs) were calculated for several fungi species. The supercritical CO2 method gave the highest yield of AO (11.62 ± 0.03 (w/w)) followed by the microwave-ultrasonic method (1.55 ± 0.05% (w/w)) and the steam distillation method (1.24 ± 0.04% (w/w)), while the hydrodistillation methods gave the lowest yield (1.17 ± 0.01 (w/w)). In addition, eighteen molecules were specified in the AOs obtained with the supercritical CO2, microwave-ultrasonic, steam distillation, and hydrodistillation techniques, which constituted 99.36, 98.6, 98.21, and 98.31% (v/v) of the total oils, respectively. Additionally, linalyl acetate was the trending molecule in the microwave-ultrasonic and steam distillation methods, representing 24.61 and 24.34% (v/v), respectively, while geranial was the dominant molecule in the AOs extracted with the hydrodistillation and supercritical CO2 extraction techniques (27.01 and 25.6% (v/v), respectively). The antifungal screening results revealed that the tested C. flexuosus AOs have potential antifungal effects against all the screened fungi species. The antifungal effect of the AOs extracted with the steam distillation and microwave-ultrasonic methods was remarkable compared with that of the commercial antifungal drug Fluconazole. However, the AOs extracted with these two methods have a more potent antifungal effect against Candida parapsilosis than that of Fluconazole with MICs of 3.13 ± 0.01, 3.13 ± 0.01, and 6.25 ± 0.91 µg/mL, respectively. The same effects were also observed against Trichophyton rubrum with MICs of 6.25 ± 0.91 µg/mL, respectively. The results of this investigation demonstrated that the steam distillation and microwave-ultrasonic methods are promising processes for the extraction of C. flexuosus AO with a potent antifungal effect. This may be an advantage for the utilization of C. flexuosus AO over some antifungal synthetic agents commonly utilized as medicines, preservatives, food additives, cosmetics, and nutrient supplements.

Whey Beverage Emulsified System as Carrying Matrix of Fennel Seed Extract Obtained by Supercritical CO2 Extraction: Impact of Thermosonication Processing and Addition of Prebiotic Fibers.

Whey beverages that were enriched with fructooligosaccharides (FOS) and xylooligosaccharides (XOS) were used for carrying Foeniculum vulgare extract that was obtained by the supercritical CO2 extraction technique to produce novel functional products. Fennel-based whey beverages were subjected to thermosonication processing (100, 200, and 300 W at 60 °C for 15 min) to verify the performance of the dairy colloidal system for protecting the bioactive fennel compounds. The impacts of thermosonication processing on the quality attributes of the functional whey beverages were examined according to their droplet size distribution, microstructure, kinetic stability, color parameters, browning index, total phenolic content (TPC), and antioxidant capacity by DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2-Azino-bis-(3-ethylbenzothiazoline)-6-sulphonic acid) assays. The enrichment of the whey beverages with FOS and XOS did not affect their kinetic stability. However, the addition of prebiotic dietary fibers contributed to reducing the mean droplet size due to the formation of whey protein–FOS/XOS conjugates. The thermosonication treatments did not promote color changes that were discernible to the human eye. On the other hand, the thermosonication processing reduced the kinetic stability of the beverages. Overall, the colloidal dairy systems preserved the antioxidant capacity of the fennel seed extract, regardless of thermosonication treatment intensity. The whey beverages enriched with FOS and XOS proved to be effective carrying matrices for protecting the lipophilic bioactive fennel compounds.

Supercritical CO 2 extraction of residual oil from pressed sesame seed cake: Optimization and its physicochemical properties

Supercritical CO2 extraction was selected to extract oil from pressed sesame seed cake. The effect of extraction parameters on the quantity and quality of extracted oil, namely temperature (40–60℃), pressure (175–225 bar) and time (1–5 hr), was studied. By using response surface methodology with the Box–Behnken design, the optimal extraction condition was achieved at 50℃, 220 bar, and 5 hr and provided 29.80% db of the oil yield. The extracted oil contained sesamin (225.79 mg/100 g cake), sesamolin (75.57 mg/100 g cake), tocopherols (7.03 mg/100 g cake) and Folin–Ciocalteu reducing capacity (29.11 mg GAE/100 g cake). Main fatty acids observed in the extracted oil were linoleic acid (36.18%–45.38%) and oleic acid (31.84%–39.40%). The experimental results indicated that supercritical CO2 extraction could be a viable technique to extract the residual oil from pressed sesame seed cake. Practical applications It is obvious that supercritical CO2 extraction technique could be used to recover a residual oil efficiently from pressed sesame seed cake. The extracted oil was obtained at the optimum extraction temperature of 50℃, extraction pressure of 220 bar and extraction time of 5 hr. The extracted oil samples had high scavenging activity containing bioactive compounds including tocopherols, sesamin, and sesamolin. The fatty acid compositions of extracted oil from pressed sesame seed cake by supercritical CO2 extraction were linoleic acid and oleic acid. It was implied that the unsaturated fatty acid of the sesame oil was more than the saturated fatty acid. On the basis of this result, the extracted oil from pressed sesame seed cake can be considered as potential source of linoleic acid and oleic acid and alternative source of edible vegetable oil.

Recovery of oil from palm oil mill effluent using polypropylene micro/nanofiber

Residual palm oil that goes into the river untreated can become detrimental to the environment. Residual oil discharge during milling process into palm oil mill effluent (POME) is unavoidable. About 1 wt% of residual oil in POME causes major problems to the mills, in terms of environment, wastewater treatment and economy losses. This paper reports the recovery of residual oil from POME by adsorption on polypropylene micro/nanofiber (PP-MNF) and desorption of oil by hands pressing, and oil extraction from the PP-MNF using solvent and supercritical-CO2 extraction techniques. The characterization of the PP-MNF and the quality of oil extracted were analyzed using analytical instruments. The reusability of the PP-MNF was also investigated. The experimental results showed the adsorption capacity of the PP-MNF was 28.65 g of oil/g of PP-MNF on average using refined palm oil, whilst recovery of oil from POME was 10.93 g of oil/g of PP-MNF. The extraction yield of oil from PP-MNF using hand pressing was 89.62%. The extraction of residual oil from the pressed PP-MNF showed comparable yield between solvent and supercritical CO2 techniques. The quality of recovered oil was similar with the quality of the crude oil, and no trace of polypropylene contamination was detected in the oil recovered. The PP-MNF showed no significant physical change after the extraction process. In conclusion, the PP-MNF has great potential to be used commercially in residual oil recovery from POME.

Surfactant removal from mesoporous TiO 2 nanocrystals by supercritical CO 2 fluid extraction

In this study, mesoporous TiO 2 crystals were synthesized with a sol–gel process in the presence of hexadecylamine which was used as a structure-directing agent. The neutral template was removed by either supercritical CO 2 extraction (SCE) or conventional calcinations to produce mesopores, and the pore characteristics of mesoporous TiO 2 were investigated with TGA, XRD, FT-IR, SEM and N 2 sorption analysis. The results showed that hexadecylamine was completely combusted by a thermal treatment above 400 °C, whereas SCE successfully removed more than 62% of the surfactant with methanol used as a modifier. However, in contrast to SCE, calcination at 400 °C accompanied a reduction in surface area and pore volume, as well as the partial collapse of the mesostructure. The combination of SCE and subsequent heat treatment at 400 °C not only improved the porosity but also retarded the structure destruction due to much less exothermal behavior. The SCE approach provided mesoporous TiO 2 nanocrystals with remarkably high mesoporosity. The SCE technique can result in numerous advantages such as high mesoporosity, short processing time, low energy consumption, and environmental benefit.

Variabilidade química de compostos orgânicos voláteis e semivoláteis de populações nativas de Maytenus ilicifolia

This work is focused on the chemical distribution of volatile and semi-volatile compounds of 18 native populations of Maytenus ilicifolia collected all over Brazil. The extracts of bulk samples (30 plants) of each population were obtained by supercritical CO2 extraction technique, and analyzed by GC/MS. The quantification of compounds (phytol, squalene, vitamin E, limonene, stigmasterol, friedelan-3-ol, friedelin, fridelan-3-one, palmitic acid and geranyl acetate) showed significant variations within the different populations, which could be related tom microclimate characteristics.

Extraction of Aucubin from Seeds of Eucommia ulmoides Oliv. Using Supercritical Carbon Dioxide

Supercritical CO2 was used as solvent for the extraction of aucubin from the seeds of Eucommia ulmoides Oliv. The co-solvent composition was tested and extraction conditions were optimized. Results showed that the best co-solvent was a water-ethanol mixture (1 + 3, v/v), and the highest yield was obtained when the extraction was performed under 26 MPa at extraction and separation temperatures of 55 and 30 degrees C for 120 min, using 6 mL co-solvent/g material at a CO2 flow rate of 20 L/h. In a comparison of the supercritical CO2 and Soxhlet extraction methods, the Soxhlet method needed 3 h to extract 10 g material, whereas the supercritical CO2 extraction technique needed only 2 h to extract 100 g material, thus showing a high extraction capability. The supercritical CO2 extraction produced a higher yield, with a lower cost for the extraction. Owing to the advantages of low extraction temperature, high yield, and ease of separating the product from the solvent, supercritical CO2 extraction is likely to be developed into an ideal technique for the extraction of aucubin, a compound with thermal instability, from the seeds of this plant.