Dynamic simulation of a supercritical fluid extraction process

The dynamic simulation of chemical processes is an indispensable and central tool for process design, analysis, and operation. Compared to a steady state simulation, the dynamic process simulation has some outstanding advantages, such as the assessment of control system reliability before its implementation on the real plant, the planning and testing of start-up and shutdown procedures, the training of operators, the possibility to investigate the causes of previous accidents, and to determine the consequences of possible accidents. In particular, as far as the accidents are concerned, it is not of minor importance that they are an economic liability to the company and the community (Fewtrell and Hirst, 1998). Fewtrell and Hirst highlighted also that high-cost accidents have some common features. The coupled dynamic simulation of process and accidents allows identifying the aforementioned deficiencies while moving towards a more safe and productive management of chemical processes. This manuscript analyzes the possible plant/accident interactions and suggests the simultaneous dynamic integration of process simulators and accident simulators. In fact, to simulate a realistic accident dynamics, both the dynamics of the plant and of the accidental event should be run simultaneously since they are biuniquely interrelated and they influence one another. The manuscript investigates the feedbacks and interactions between the process and the accident by means of a specific case study.

Improving lithium mining methods is key to furthering lithium’s use as an energy metal. Current mining methods from brines are slow and inefficient and have significant environmental impacts, providing an avenue of research toward developing more effective and less environmentally damaging methods. Supercritical fluid extraction has been evaluated in earlier research for the extraction of metals such as uranium, mercury, and several alkali and earth alkaline metals from aqueous solutions but not for lithium. This study documents the synthesis and preliminary testing of two lithium extractants for possible application in a supercritical carbon dioxide fluid extraction process to recover lithium from natural brines. Based on their high solubility in supercritical carbon dioxide and their desirable structural properties, two 14-crown-4 ethers with different functional groups were selected. In this work, solubility measurements and thermodynamic modeling were carried out to characterize their solubility behavior in the range of P = 100–300 bar with T = 60 °C and T = 85 °C. The main conclusion from this work is the experimental observation of sufficiently high solubilities of the synthesized crown ethers in supercritical carbon dioxide. The highest measured solubility of M14C4, the nonfluorinated 14-crown-4 ether, was 0.30 mol/L at 60 °C and 205 bar, and the highest measured solubility of F14C4, the fluorinated 14-crown-4 ether, was 0.27 mol/L at 60 °C and 285 bar. Another major conclusion was the observed higher solubility of M14C4 than F14C4. We also showed that equation of state modeling provides insight into the factors affecting the crown ether solubility in supercritical carbon dioxide.

Supercritical fluid extraction

The process of supercritical fluid extraction (SFE) using carbon dioxide as the mobile phase is finding increasing numbers of applications in a wide variety of industries for the extraction, separation, and cleaning of materials. This study assessed the usefulness of this approach in removing surface contaminants from a knitted polyester anterior cruciate ligament (ACL) prosthesis before packaging and sterilizing the product during manufacture. The physical, dimensional, and chemical properties of SFE treated compared with commercially scoured control samples were characterized using a number of textile test methods: electron spectroscopy for chemical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, and solvent extraction analysis. The biocompatibility of the samples was measured in terms of their ability to generate CD18 integrin expression on activated human polymorphonuclear cells, and their inflammatory response when implanted for up to 30 days in the knee joint of rats. SFE treatment was successful in removing most of the nonpolar contaminants from the ACL prosthesis and reducing the amount of residuals to a commercially acceptable level. However, some nitrogen containing compounds and polar salts were not removed by the SFE process. The results from the biocompatibility tests demonstrated that the cleaner SFE treated prosthesis induced significantly lower CD18 expression than the scoured control fabric, and was also associated with a milder inflammatory response and a more rapid rate of healing during the 30 day animal trial. Another effect of SFE processing was to cause the polyester device to shrink and lose porosity because of yarn contraction and modification of the polymer's microcrystalline structure.

Lipid material represents a potential interference for determination of nonpolar compounds (e.g., polycyclic aromatic hydrocarbons) in biological tissue samples. This study reports the development of a selective extraction method using supercritical CO2 that allows the GC/MS quantitation of PAHs in the presence of a substantial lipid background. Selective extraction of PAHs relies upon addition of C18 adsorbent beads to the initial sample slurry. The dried mixture, including C18 adsorbent, is placed in the supercritical fluid extraction (SFE) chamber. During the SFE process, lipids are preferentially retained on the C18 beads. This "SFE plus C18" procedure was developed by first optimizing SFE conditions (100 degrees C, 350 bar) for recovery of PAH standards. PAHs containing added model lipid compounds (stearic acid and cholesterol) were then subjected to SFE plus C18 treatment followed by GC/MS analysis. Using this approach, a recovery of 94-100% of PAHs was obtained while only 9-17% of the lipid material present was coextracted from the same test sample. The developed method is demonstrated to permit efficient recovery and detection of PAHs spiked into crab tissue, a matrix with a high lipid content.

The supercritical fluid extraction (SFE) behavior of cocaine and its major metabolite benzoylecgonine (BZE) was investigated and found to be highly dependent upon the chemical nature of the matrix and the manner in which the target drug analytes are incorporated into or on the matrix. The recovery of cocaine from Teflon wool, filter paper, drug-fortified hair, and drug user hair was studied using a variety of CO2/modifier mixtures. Incorporation of a triethylamine (TEA)/water modifier mixture provided dramatic improvements in the recovery of cocaine from interactive matrixes. The results suggest that the SF extractability of cocaine is not limited by analyte solubility; rather, desorption of cocaine from hair binding sites is a rate-limiting step in the SFE process. A displacement SFE mechanism is hypothesized in which TEA (as the triethylammonium cation) competes with cocaine for negatively charged hair binding sites. The dependence of extractability on hair/drug binding interactions allows the differentiation of cocaine present at different discrete sites in hair based on differences in SFE behavior. These findings suggest the potential for distinguishing exogenous (i.e., environmental) from endogenous (i.e., physiological) sources of drugs in hair. In contrast to the results observed for cocaine, SFE recoveries of BZE were poor from all matrixes and under all conditions studied. Its increased polarity, the presence of an additional binding site, and the possibility of multiple charged states suggest that poor BZE recoveries may be due to both poor analyte solubility and failure to desorb the analyte from hair binding sites under the conditions employed.

The purpose of this work was to obtain extracts from Anacardium occidentale leaves using supercritical fluid extraction (SFE). The use of ethanol and isopropyl alcohol as co-solvents was evaluated. Mass transfer kinetics experiments were performed, and overall extraction curves were modeled. SFE process was compared with different low pressure solvent extraction processes in terms of global yield and the composition of the extract. The techniques used as low pressure solvent extraction processes were: Soxhlet extraction, agitated bed extraction, ultrasound assisted extraction using ethanol as the solvent and hydrodistillation. The extracts were analyzed by thin layer chromatography (TLC) using different eluents. Finally, the economic evaluation was conducted using the software SuperPro designer 6.0® to simulate the process and to estimate the cost of manufacturing (COM) of SFE extracts. The results indicated the presence of essential oils, flavonoids and antioxidant compounds in all the extracts. The higher yield of extract was obtained with the ultrasound assisted extraction. However, the samples with more functional compounds were verified in the SFE extracts and the extracts showed low COM. The model that best described the overall extraction curves for the SFE process was the Sovová model, which showed minimum values for the sum of the squares of the residues.

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.

In conjunction with choosing the treatment process for the new wastewater treatment plant of Espoo, Finland (400,000 P.E.), Denitrification-Nitrification (DN) and Step-Feed activated sludge processes were compared in terms of required basin volume and consumption of aeration air and methanol. The comparison was made using dynamic process simulation. The advantages of the step-feed process reported in literature – smaller volume required to treat an equal load or ability to treat a higher load in an equal volume – were questioned. In terms of consumables, the two processes were found practically equal. This is, to the best of our knowledge, the first comparison of these process configurations with dynamic simulation.

Thermochemical liquefaction of algae for bio-oil production in supercritical acetone/ethanol/isopropanol

Supercritical fluid extraction is used for producing bio-fuel from biomass. Supercritical fluid extraction process under supercritical conditions is the thermally disruption process of the lignocellulose or other organic materials at 250-400 °C temperature range under high pressure (4-5 MPa). Supercritical fluid extraction trials were performed in a cylindrical reactor (75 mL) in organic solvents (acetone, ethanol) under supercritical conditions with (calcium hydroxide, sodium carbonate) and without catalyst at the temperatures of 250, 275 and 300 °C. The produced liquids at 300 °C in supercritical liquefaction were analyzed and characterized by elemental, GC-MS and FT-IR. 36 and 37 different types of compounds were identified by GC-MS obtained in acetone and ethanol respectively.

Plant engineering workflow consists of different phases and engineering disciplines. Dynamic process simulation can be utilized to mitigate risks and improve quality of design in the engineering workflow. Earlier and more extensive utilization of simulation is proposed in this paper using an integrated simulation-assisted engineering workflow. In this paper, basic automation design and tests are conducted in dynamic process simulation software Apros. The basic automation design is delivered to detailed design for implementation. Usually engineering projects utilize multiple non-interoperable software tools requiring significant manual data transfer. Standard engineering data interfaces provide reusable and automatic transfer features for engineering software. In this paper, standard-based integration of automation and simulation engineering is demonstrated by transferring automation design data in PLCopen XML format to detailed design. The integration and its benefits are demonstrated and some limitations and challenges for wider utilization are recognized.

Polyphenolic compounds in bark are resources of great interest to produce renewable chemicals and several different technologies are available or under early development for the extraction of these types of compounds. Since critical environmental effects of a product are often set during the design phase, it is important to use life cycle assessment (LCA) to identify the steps resulting in the largest environmental burdens and the overall performance of the various technologies at an early stage during technology development. In addition, for a better understanding of the environmental impact of the future system, it is needed to consider an up-scaled process already in early process development. In the current study, LCAs of three different technologies; hot water extraction (HWE), ultrasound assisted extraction (UAE), and supercritical fluid extraction (SFE) for the extraction of phenolic compounds from spruce bark were compared in a large-scale production scenario. The study includes industrially relevant heat sources and heating technologies, downstream separations, solvent recovery, and heat recovery within the processes. The LCA shows that the simpler HWE process has a lower environmental impact per amount of phenolic compound extracted than UAE and SFE unless the extraction yields of the latter are more than about 5 times that of HWE. The reason for this result is mainly the environmental burden caused by the consumption of ethanol in the UAE and SFE processes, which accounts for more than 70% of the total environmental burden in most impact categories. Even if bioethanol produced with a particularly low carbon footprint would be used, the impact from ethanol use in the extractions would be considerable. UAE and SFE were also more dependent on the use of electricity. In the base case scenario, electricity produced with a low share of fossil resources was used, and electricity was in this case not one of the main contributors to the environmental impact of the processes. However, if the production of electricity is largely fossil-based, it comes out as a significant factor. Furthermore, the heat recovery in an up-scaled process is very important and accounts for a reduction of 35–60% net heat demand. As a complement to LCAs, future studies of promising polyphenolic compound production systems should also include economic aspects and performance.

The objective of this research was to investigate and compare the results obtained in the intensification and integration of (sc-CO2) under different pressure conditions (25 and 30 MPa) at 60 °C. When intensifying the process, ethanol (10%) was used as a co-solvent (sc-CO2 + EtOH). In the process integration, black soldier fly larvae flour, defatted via supercritical extraction (SFE), was the raw material for pressurized liquid extraction (PLE) using ethanol as solvent. The extract yields, fatty acid profile, free fatty acids, triacylglycerols (TAGs), oxidative stability, and nutritional quality of the oil obtained using sc-CO2 + EtOH were evaluated. The composition of bioactive compounds (carotenoids, acidity, antioxidant compounds, tocopherols, and phospholipids) was determined in both extracts. The yields of the extracts were different by 32.5 to 53.9%. In the extracts obtained with sc-CO2 + EtOH (10%), the predominant fatty acids were oleic, palmitic, and linoleic, with considerable levels of desirable fatty acids (DFA), tocopherols, and phospholipids. The nutritional indices showed good values for polyunsaturated and saturated fatty acids (PUFAs/SFAs), above 0.45%. Extracts from larvae meal defatted with SFE showed carotenoids, phenolic compounds, and antioxidant activity. HPTLC and HPLC analyses indicated the presence of amino acids, sugars, phenolics, and organic acids in their composition. This study revealed that the supercritical fluid extraction (SFE) process, or its conditions, can modify the fatty acid composition and the presence of minor bioactive compounds in the obtained extracts.

The teaching of higher mathematics is fundamentally challenged by its abstract and logical nature, while traditional instructional methods show significant limitations in visualizing and dynamizing core concepts. The rise of artificial intelligence has brought revolutionary breakthroughs to the visualization teaching of higher mathematics, largely due to its powerful capabilities in image generation, natural language interaction, and dynamic simulation. This paper focuses on the application of AI technology in this field and systematically constructs three teaching models, “intelligent diagram generation” “interactive experimental exploration”, and “dynamic process simulation”. These models are supported by in-depth analysis of typical cases such as saddle surfaces, vector fields, and integrals. Furthermore, the paper discusses the theoretical foundations and practical pathways of AI visualization teaching, aiming to provide theoretical guidance for promoting the paradigm shift in higher mathematics education from static abstraction to dynamic intuition.