Supercritical Fluid Application in the Oil and Gas Industry: A Comprehensive Review

The unique properties of supercritical fluid technology have found wide application in various industry sectors. Supercritical fluids allow for the obtainment of new types of products with special characteristics, or development and design of technological processes that are cost-effective and friendly to the environment. One of the promising areas where supercritical fluids, especially carbon dioxide, can be used is the oil industry. In this regard, the present review article summarizes the results of theoretical and experimental studies of the use of supercritical fluids in the oil and gas industry for supercritical extraction in the course of oil refining, increasing oil recovery in the production of heavy oil, hydraulic fracturing, as well as processing and disposal of oil sludge and asphaltenes. At the end of the present review, the issue of the impact of supercritical fluid on the corrosion of oil and gas equipment is considered. It is found that supercritical fluid technologies are very promising for the oil industry, but supercritical fluids also have disadvantages, such as expansion or incompatibility with materials (for example, rubber).

Supercritical Carbon Dioxide Effect on Lipase-Catalyzed Geranyl Acetate Synthesis

This work provides a general insight on lipase-catalyzed synthesis of geranyl acetate through esterification of geraniol with acetic acid. Although this reaction is relatively well known, the replacement of organic solvents by supercritical fluids is fairly recent and the role of CO2 is still not completely understood. Therefore, reactions were performed with Lipozyme® RM IM and Novozym® 435 as biocatalysts, and hexane and CO2 as solvents. For similar reaction conditions, geraniol conversions obtained using hexane were much higher, rather than supercritical CO2 (scCO2, 82.9% versus 12.0% after 4 h). The results obtained indicated that CO2 might help the migration of water from the enzyme surface to reaction bulk and then to the vapor phase. Thus, by increasing the vapor phase extension, the geraniol conversion enhanced to 60.5% after 4 h. Such improvement represents one step forward to comprehend the influence of CO2, a safer and greener solvent as compared to hexane.

Aquaculture and agriculture-by products as sustainable sources of omega-3 fatty acids in the food industry

The valorization of by-products is currently a matter of great concern to improve the sustainability of the food industry. High quality by-products derived from the food chain are omega-3 fatty acids, being fish the main source of docosahexaenoic acid and eicosapentaenoic acid. The search for economic and sustainable sources following the standards of circular economy had led to search for strategies that put in value new resources to obtain different omega-3 fatty acids, which could be further employed in the development of new industrial products without producing more wastes and economic losses. In this sense, seeds and vegetables, fruits and crustaceans by products can be an alternative. This review encompasses all these aspects on omega-3 fatty acids profile from marine and agri-food by-products together with their extraction and purification technologies are reported. These comprise conventional techniques like extraction with solvents, cold press, and wet pressing and, more recently proposed ones like, supercritical fluids fractionation and purification by chromatographic methods. The information collected indicates a trend to combine different conventional and emerging technologies to improve product yields and purity. This paper also addresses encapsulation strategies for their integration in novel foods to achieve maximum consumer acceptance and to ensure their effectiveness.

Characterization of Composite Nano-Bioscaffolds Based on Collagen and Supercritical Fluids-Assisted Decellularized Fibrous Extracellular Matrix

Nano-bioscaffolds obtained from decellularized tissues have been employed in several medical applications. Nano-bioscaffolds could provide structural support for cell attachment and a suitable environment with sufficient porosity for cell growth and proliferation. In this study, a new combined method constitutes a decellularization protocol to remove the tissue and cellular molecules from porcine dermis for preparation of nano-bioscaffolds with fibrous extracellular matrix via pre- and post-treatment of supercritical fluids. The supercritical fluids-assisted nano-bioscaffolds were characterized by peptide identification, infrared spectrum of absorption, morphology, histological observations, DNA quantification, and hemocompatibility. Further, the resulting nano-bioscaffolds could be employed to obtain new cross-linked composite nano-bioscaffold containing collagen and acellular matrix.

A review on Extraction of alkaloid from Nelumbo nucifera Embryos and Leaves for Production of Dietary Supplement

Lotus (Nelumbo nucifera Gaertn.) commonly distributed in low-lying and flooded areas like Southern Vietnam provides flowers, leaves, seeds, embryos, and edible rhizomes. All parts of the plant show good pharmacokinetic properties, especially lotus embryos and leaves. Studies have shown that lotus plums and leaves have many bioactive compounds such as alkaloids, flavonoids, triterpenoids, and polyphenols, in which alkaloids are one of mainly bioactive compound kinds. So that, there are many studies investigating extraction methods that increase the amount of alkaloid from lotus leaves, embryos. There are some conventional extract methods such as soak, heat reflux, Soxhlet, etc… and some modern extract methods as microwave, ultrasounds, enzyme assisted, supercritical fluids (S-CO2). At present, lotus leaves, embryos and their bioactivities can have application potential in the supplementary food such as protect-liver, anti-neurotic, etc.. The aim of this paper is to review a variety of develop methods used in the alkaloid extraction from lotus embryos, leaves. Besides, this study also introduces some pharmacokinetic properties of alkaloid which can use in functional foods.