Are supercritical fluids solvents for the future?

Knez, Željko; Pantić, Milica; Cör, Darija; Novak, Zoran; Chen, Lin

doi:10.1016/j.cep.2019.107532

Cited by 130 publications

(60 citation statements)

References 50 publications

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“…CO 2 has a moderate critical temperature and pressure (31.1 °C and 7.4 MPa) [23] and can be dissolved in most organic solvents for solvent expansion. Moreover, CO 2 is readily available, inexpensive, nontoxic, and easy to separate from the precipitated materials by depressurization [24,25]. Consequently, it is frequently used as an antisolvent.…”

Section: Introductionmentioning

confidence: 99%

Purification of Polybutylene Terephthalate by Oligomer Removal Using a Compressed CO2 Antisolvent

Huang

Tan

2019

Polymers

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In this study, the cyclic oligomers in the highly chemically resistant polyester polybutylene terephthalate (PBT) were effectively removed using a compressed CO2 antisolvent technique in which 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was used as the solvent. In addition to the oligomers, tetrahydrofuran was completely removed because of its low molecular weight and liquid state. The effects of the operating variables, including temperature, pressure, and the PBT concentration in HFIP, on the degree of removal of the oligomers were systematically studied using experimental design and the response surface methodology. The most appropriate operating conditions for the purification of PBT were 8.3 MPa and 23.4 °C when using 4.5 wt % PBT in HFIP. Under these conditions, the cyclic trimers and dimers could be removed by up to 81.4% and 95.7%, respectively, in a very short operating time.

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Section: Introductionmentioning

confidence: 99%

Purification of Polybutylene Terephthalate by Oligomer Removal Using a Compressed CO2 Antisolvent

Huang

Tan

2019

Polymers

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“…The utilization of sub- and supercritical fluids may replace many environmentally harmful solvents currently used in industry, such as organic solvents. Therefore, high-pressure technologies involving sub- and supercritical fluids serve the opportunity to obtain new products with specific properties or to design new processes that are environmentally friendly and sustainable [ 47 , 48 ]. Figure 3 shows a phase diagram of water with marked sub- and supercritical regions [ 49 ].…”

Section: Utilization Of Sub- and Supercritical Fluidsmentioning

confidence: 99%

Recycling of Carbon Fiber-Reinforced Composites—Difficulties and Future Perspectives

Borjan

Knez

2021

Materials

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Carbon fiber-reinforced composites present an exciting combination of properties and offer clear advantages that make them a perfect replacement for a spread of materials. Consequently, in recent years, their production has dramatically increased as well as the quantity of waste materials. As future legislations are likely to prevent the use of landfills and incineration to dispose of composite waste, alternative solutions such as recycling are considered as one of the urgent problems to be settled. This study presents the leading technologies for recycling carbon fiber-reinforced composites, focusing on chemical recycling using sub- and supercritical fluids. These new reaction media have been demonstrated to be more manageable and efficient in recovering clean fibers with good mechanical properties. The conventional technologies of carbon fibers recycling have also been reviewed and described with both advantages and drawbacks.

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“…Extraction with supercritical fluids represents a valid alternative to conventional solvent extraction systems. Supercritical fluids (SCF) are substances for which both pressure and temperature are higher than their critical values assuming physical characteristics intermediate between those of a liquid and those of a gas [ 148 , 149 ]. Therefore, the synergism among density, low viscosity, diffusivity, near-zero surface tension, pressure, and temperature dependence allow supercritical fluids to easily penetrate a microporous matrix to extract intracellular compounds [ 150 ].…”

Section: Green Extraction Process: Synergism Between Solvents and Technologymentioning

confidence: 99%

Emerging Green Techniques for the Extraction of Antioxidants from Agri-Food By-Products as Promising Ingredients for the Food Industry

et al. 2021

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Nowadays, the food industry is heavily involved in searching for green sources of valuable compounds, to be employed as potential food ingredients, to cater to the evolving consumers’ requirements for health-beneficial food ingredients. In this frame, agri-food by-products represent a low-cost source of natural bioactive compounds, including antioxidants. However, to effectively recover these intracellular compounds, it is necessary to reduce the mass transfer resistances represented by the cellular envelope, within which they are localized, to enhance their extractability. To this purpose, emerging extraction technologies, have been proposed, including Supercritical Fluid Extraction, Microwave-Assisted Extraction, Ultrasound-Assisted Extraction, High-Pressure Homogenization, Pulsed Electric Fields, High Voltage Electrical Discharges. These technologies demonstrated to be a sustainable alternative to conventional extraction, showing the potential to increase the extraction yield, decrease the extraction time and solvent consumption. Additionally, in green extraction processes, also the contribution of solvent selection, as well as environmental and economic aspects, represent a key factor. Therefore, this review focused on critically analyzing the main findings on the synergistic effect of low environmental impact technologies and green solvents towards the green extraction of antioxidants from food by-products, by discussing the main associated advantages and drawbacks, and the criteria of selection for process sustainability.

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Are supercritical fluids solvents for the future?

Cited by 130 publications

References 50 publications

Purification of Polybutylene Terephthalate by Oligomer Removal Using a Compressed CO2 Antisolvent

Purification of Polybutylene Terephthalate by Oligomer Removal Using a Compressed CO2 Antisolvent

Recycling of Carbon Fiber-Reinforced Composites—Difficulties and Future Perspectives

Emerging Green Techniques for the Extraction of Antioxidants from Agri-Food By-Products as Promising Ingredients for the Food Industry

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