Supercritical Fluid Extraction Process Research Articles

Recycling of Rare Earth Elements from Nickel Metal Hydride Battery Utilizing Supercritical Fluid Extraction

Nickel Metal Hydride (NiMH) batteries are widely used in hybrid vehicles. The anode of this battery consists a mischmetal alloy of lanthanum (La), cerium (Ce), praseodymium (Pr), and neodymium (Nd) [1]. These four elements are part of rare earth elements group, and among them, praseodymium and neodymium are considered critical materials, since they are in increasing high demand and facing supply uncertainty and near zero recycling. On the basis of the historic data, the annual demand for REEs has been increasing at a rate of 8.6% annually [1,4], and it is predicted that the rate could increase to above 20% annually to accommodate the increased utilization of renewable power generation (in particular wind and solar) and electrified transportation in the society [5]. To address the sustainability hurdles associated with NiMH battery and REE supply, new strategies have been initiated to mine these elements from secondary sources. Waste electrical and electronic equipment (WEEE) including NiMH batteries contain considerable amounts of REEs, which make them an attractive source.The number of NiMH batteries manufactured up to this date is significant, and the global annual production is also increasing, as Toyota plans to increase the sale of Prius hybrid model by 2020 [2]. Although REEs account for more than 30 wt% of a NiMH battery, the global recycling rates of REEs from end of life NiMH batteries is less than 1% [1,3]. Considering the great opportunity, it is essential to develop efficient processes for the recovery of REEs from this class of WEEE.Current recycling practices rely on either pyrometallurgy or hydrometallurgy. The former in highly energy intensive and the latter relies on large volumes of acids and organic solvents, generating large volumes of hazardous residues. This study is focused on developing an innovative and sustainable process for the urban mining of REEs from NiMH battery. The developed process relies on supercritical fluid extraction (SCFE) utilizing carbon dioxide as the solvent, which is inert, safe, and abundant. This process is very efficient because it runs at low temperature, and does not produce hazardous waste, while recovering about 90% of REEs. Furthermore, we proposed a mechanism for the SCFE of REEs, where we considered a trivalent REE state bonded with three Tri-n-butyl phosphate (TBP) molecules and three nitrates model for the extracted rare earth TBP complex. The SCFE process is an efficient and environmentally friendly process to valorize postconsumer NiMH battery without utilizing hazardous reagents; therefore, it minimizes the negative impacts of process tailings. This novel process proves to be a promising technique that can help realize the technological potential of REE recovery from post consumer WEEE, particularly NiMH battery

Influence of operating parameters on supercritical fluid extraction of essential oil from turmeric root

Abstract Turmeric oil was extracted from Curcuma Longa herb (turmeric root) using supercritical fluid extraction (SFE) process. Full-face central composite design was employed to optimize operating parameters of the process. These parameters were pressure, temperature, solvent flow rate, particle size and addition of co-solvent (ethanol) that varied as 20–40 MPa, 40–60 °C, 5–15 g/min, 0–0.8 mm and 0–15% of solvent rate, respectively. Turmeric oil yield found through Soxhlet extraction was 5.954 wt% of turmeric powder whereas through SFE, it varied from 2 to 5.3 wt%. Turmerone and curcumin were identified as principle compounds of turmeric essential oil, which were analyzed using Gas chromatography–mass spectrometry and Ultraviolet–visible Spectrophotometer, respectively. Experimental data of oil yield, Curcumin content and Turmerone content were fitted well in the Quadratic model. Optimized values of operating parameters for maximizing these responses were also predicted. Further, economic assessment of SFE of turmeric oil at industrial scale for 60 t/y production capacity was performed.

Integrated Supercritical Fluid Extraction and Fluid Thermal Conversion Process: Experiment Realization and Comparison of Thermal Converted Liquids

A new technology is proposed by the directly integrated supercritical fluid extraction and fluidized thermal conversion process, which was named the integrated supercritical fluid extraction and fluid thermal conversion (ISFTC) process. In the extraction unit of ISFTC, the heavy feedstock was separated into deoiled asphalt (DOA) and deasphalted oil (DAO). The DOA phase is fed to a fluidized-bed thermal convertor (FTC) without solvent separating, using hot coke to supply the heat. DAO will be qualified for fluid catalytic cracking (FCC) processing. The proposed process avoids the feedstock quality limit for both FCC and delayed coking (DC). It increased the overall liquid yield of vacuum residue (VR) upgrading and solved the problem of solvent recovery for the solvent–DOA phase at the bottom of the supercritical fluid extraction unit. A continuous laboratory apparatus was built to prove the concept. A Chinese petroleum residue was processed by the built apparatus at appropriate operating conditions. The to...

Solubility Optimal System for Supercritical Fluid Extraction Based on a New Nonlinear Temperature-Pressure Decoupling Model Constructed with Unequal-Interval Grey Optimal Models and Peng-Robinson Models

This paper presents a new solubility optimal system to improve the efficiency of supercritical fluid extraction (SFE). The major contribution is a nonlinear temperature-pressure decoupling model constructed with unequal-interval grey optimal models (UEIGOMs) and Peng-Robinson models (PRMs). The linear parts of temperature and pressure process can be constructed with UEIGOM, respectively. The nonlinear parts of temperature and pressure process can be described by PRMs, respectively. The whole nonlinear model cannot be input-output decoupled resulting from the singularity of decoupling matrix for PRM. This problem on input-output nondecoupling can be transformed to the problem on disturbance decoupling for a class of MIMO nonlinear systems. Therefore, the whole nonlinear coupling model can be disturbance decoupled. Furthermore, solubility optimal method is presented in the paper; it can calculate the optimal pressure according to the given temperature, namely, optimal working points, to maximize solubility for SFE process. The feasibility, effectiveness, and practicality of the proposed nonlinear temperature-pressure decoupling model constructed with UEIGOMs and PRMs are verified by SFE experiments in biphenyl. Experiments using the designed solubility optimal system are carried out to demonstrate the effectiveness in control scheme, simplicity in structure, and flexibility in implementation for the proposed solubility optimal system based on a new nonlinear temperature-pressure coupling model constructed with UEIGOMs and PRMs.

Pressure control of a continuous pilot scale supercritical fluid extraction (SFE) process

Pressure control for a pilot scale continuous supercritical fluid extraction (SFE) process, has been developed for consistent extractions, overall efficiency and process safety reasons. The Internal-Model-Control (IMC) framework (specifically Skogestad’s IMC method) was employed for the design of a Proportional-Integral (PI) controller using both the actual pilot process and a hydrodynamic model of the process. Controller performance was assessed for set point changes and disturbance rejection. The best controllers lead to limited overshoot (less than 1 MPa), a response time of 200 s (within ±1% of set point) and little oscillatory behaviour. The design and performance results of the controllers generated using the hydrodynamic model were consistent with those of the actual process. Tests at alternate pressure conditions confirmed that the controller design and performance is pressure dependent owing to the nonlinear character of SFE processes.

Supercritical Fluid Extraction of Usnic Acid from Lichen of Cladonia Genus

The process of carbon dioxide supercritical fluid extraction (SFE) of secondary metabolites from the lichen of Cladonia genus is studied. The yield of solid extract during SFE with carbon dioxide is significantly higher than during the extraction with acetone, ethanol, and petroleum ether on the Soxhlet apparatus. The maximum content of the target component—usnic acid (UA)—in the extract (91%, yield—2.5% of absolutely dry raw material) is obtained under pressure of 35 MPa, temperature 40°C, and duration of the process of 40 min. Introduction of cosolvents (acetone, ethanol, methylene chloride) to carbon dioxide increases the yield of the target product to 3%.

Supercritical Fluid Extraction of Bioactive Compounds from Plant Materials.

There has been growing interest in the application of supercritical solvents over the last several years, many of the applications industrial in nature. The purpose of plant material extraction is to obtain large amounts of extract rich in the desired active compounds in a time-sensitive and cost-effective manner. The productivity and profitability of a supercritical fluid extraction (SFE) process largely depends on the selection of process parameters, which are elaborated upon in this paper. Carbon dioxide (CO2) is the most desirable solvent for the supercritical extraction of natural products. Its near-ambient critical temperature makes it suitable for the extraction of thermolabile components without degradation. A new approach has been adopted for SFE in which the solubility of nonpolar supercritical CO2 can be enhanced by the addition of small amounts of cosolvent.

Optimization of supercritical fluid extraction of steviol glycosides and total phenolic content from Stevia rebaudiana (Bertoni) leaves using response surface methodology and artificial neural network modeling

Stevia leaves include natural, non-caloric sweetening compounds known as steviol glycosides (SGs)–mainly stevioside (ST) and rebaudioside-A (Reb-A). Along with sweetness, stevia generates interest because of its dietetic and therapeutic significance related to the presence of other bioactive compounds in its leaves, such as phenolics, which in association with SGs may contribute to human health by exerting anti-inflammatory, antihyperglycemic, anticarries, chemopreventive, insulinotropic and diuretic properties. In this study, response surface methodology (RSM) and artificial neural network (ANN) modeling were compared in terms of their estimation capabilities for building effective models with maximum response values. A supercritical fluid extraction (SFE) process was optimized by employing a 5-level-3-factor central composite design to achieve maximum target response values for total extract yield, ST yield, Reb-A yield and total phenolic content of 15.85%, 95.76mg/g, 62.95mg/g and 25.76mg GAE/g, respectively. The optimized SFE parameters included a modifier concentration of 40%, an extraction temperature of 45°C, and a pressure of 225bar. The ANN model proved an attractive alternative to RSM owing to its improved estimation and predictive capabilities. SFE yielded higher target response values than conventional maceration extraction (24h) and was a faster, lower energy, and greener extraction method with reduced CO2 emissions and lower solvent consumption.

Selection of suitable model for different matrices of raw materials used in supercritical fluid extraction process

ABSTRACTSupercritical fluid extraction (SFE) process is the sustainable green process for the extraction. Mathematical modeling of SFE process is carried out using mass transfer resistances, which vary with the types of solute. In this paper, the effect of matrices such as leaves, flower concrete, flower bud, herb plant, shrub seed and vegetable matter is studied on extraction yield through different models. These models are solved using COMSOL Multiphysics 5.2 solver and results are validated with that of literature. Experimental data of each type of solute matrix are fitted in various models and best suited model is predicted.

Obtaining bixin from semi-defatted annatto seeds by a mechanical method and solvent extraction: Process integration and economic evaluation

This work involves the application of physical separation methods to concentrate the pigment of semi-defatted annatto seeds, a noble vegetal biomass rich in bixin pigments. Semi-defatted annatto seeds are the residue produced after the extraction of the lipid fraction from annatto seeds using supercritical fluid extraction (SFE). Semi-defatted annatto seeds are use in this work due to three important reasons: i) previous lipid extraction is necessary to recovery the tocotrienol-rich oil present in the annatto seeds, ii) an initial removal of the oil via SFE process favors bixin separation and iii) the cost of raw material is null. Physical methods including i) the mechanical fractionation method and ii) an integrated process of mechanical fractionation method and low-pressure solvent extraction (LPSE) were studied. The integrated process was proposed for processing two different semi-defatted annatto materials denoted Batches 1 and 2. The cost of manufacture (COM) was calculated for two different production scales (5 and 50L) considering the integrated process vs. only the mechanical fractionation method. The integrated process showed a significantly higher COM than mechanical fractionation method. This work suggests that mechanical fractionation method is an adequate and low-cost process to obtain a rich-pigment product from semi-defatted annatto seeds.

A Simplified Method to Estimate Sc-CO2 Extraction of Bioactive Compounds from Different Matrices: Chili Pepper vs. Tomato By-Products

In the last few decades, the search for bioactive compounds or “target molecules” from natural sources or their by-products has become the most important application of the supercritical fluid extraction (SFE) process. In this context, the present research had two main objectives: (i) to verify the effectiveness of a two-step SFE process (namely, a preliminary Sc-CO2 extraction of carotenoids followed by the recovery of polyphenols by ethanol coupled with Sc-CO2) in order to obtain bioactive extracts from two widespread different matrices (chili pepper and tomato by-products), and (ii) to test the validity of the mathematical model proposed to describe the kinetics of SFE of carotenoids from different matrices, the knowledge of which is required also for the definition of the role played in the extraction process by the characteristics of the sample matrix. On the basis of the results obtained, it was possible to introduce a simplified kinetic model that was able to describe the time evolution of the extraction of bioactive compounds (mainly carotenoids and phenols) from different substrates. In particular, while both chili pepper and tomato were confirmed to be good sources of bioactive antioxidant compounds, the extraction process from chili pepper was faster than from tomato under identical operating conditions.

Supercritical fluid extraction of coriander seeds: Kinetics modelling and ANN optimization

The main goal of this research was mathematical modelling and numerical simulation of the supercritical fluid extraction (SFE) process of coriander (Coriandrum sativum L.) seeds. SFE was performed at different set of process parameters: pressure (100, 150 and 200bar), temperature (40, 55 and 70°C) and CO2 flow rate (0.2, 0.3 and 0.4kg/h). Both applied empirical models, derived from models developed by Brunner and Esquivel et al., adequately described SFE process. Second objective was to determine effects of investigated SFE parameters on total extraction yield. Furthermore, calculated parameters from the empirical models were used for the calculation of initial slope, which was successfully used for optimization using artificial neural network (ANN). Optimized SFE conditions for maximized initial slope, i.e. initial rate of the solubility-controlled extraction phase, were pressure of 200bar, temperature of 40°C and CO2 flow rate of 0.4kg/h.

Estimating the solubility of different solutes in supercritical CO2 covering a wide range of operating conditions by using neural network models

A new neural network-based model is proposed for solute solubility in supercritical carbon dioxide (CO2). The solubility of fifteen solutes in supercritical carbon dioxide at different temperatures and pressures are estimated. Four neural network models have been tested to investigate the generalize-ability of each network. The results from different semi-empirical models, namely Chrastil, Kumar and Johnston, Bartle, Mendez-Santiago and Teja, the Peng–Robinson and Soave–Redlich–Kwong equation of state models are compared to the one estimated by using the proposed neural network model. The average absolute deviation (AAD) of 5.42% compared to those of density-based and equation of state models, representing the reasonable accuracy of the developed model for estimating the solubility of solutes in supercritical fluid extraction process.

Extraction of bioactive alkaloids from Melocactus zehntneri using supercritical fluid

The purpose of this study was to extract alkaloids from Melocactus zehntneri aerial parts using supercritical fluid extraction (SFE) and to evaluate their cytotoxic action. SFE process was compared to different classical low pressure solvent extraction processes in terms of global yield, extract profile and biological activity. Two specimens of M. zehntneri were evaluated: young and adult aerial parts. The extracts were analyzed by HPLC-UV/DAD as well as they were evaluated against HMVII and Trichomonas vaginalis. The results indicated a qualitative difference in chromatographic profile of the extracts. Finally, the results point out the potential of the extract obtained from aerial parts of young specimens (Y-RM) through SFE at 300bar/55°C against T. vaginalis and HMVII, presenting relevant information for development of new studies about cytotoxic.

On-line coupling of supercritical fluid extraction and chromatographic techniques.

This review summarizes and discusses recent advances and applications of on-line supercritical fluid extraction coupled to liquid chromatography, gas chromatography, and supercritical fluid chromatographic techniques. Supercritical fluids, due to their exceptional physical properties, provide unique opportunities not only during the extraction step but also in the separation process. Although supercritical fluid extraction is especially suitable for recovery of non-polar organic compounds, this technique can also be successfully applied to the extraction of polar analytes by the aid of modifiers. Supercritical fluid extraction process can be performed following "off-line" or "on-line" approaches and their main features are contrasted herein. Besides, the parameters affecting the supercritical fluid extraction process are explained and a "decision tree" is for the first time presented in this review work as a guide tool for method development. The general principles (instrumental and methodological) of the different on-line couplings of supercritical fluid extraction with chromatographic techniques are described. Advantages and shortcomings of supercritical fluid extraction as hyphenated technique are discussed. Besides, an update of the most recent applications (from 2005 up to now) of the mentioned couplings is also presented in this review.

Supercritical fluid extraction as a tool to valorize underexploited freshwater green algae

Water reservoirs in Poland such as rivers, lakes and ponds are a rich source of freshwater green macroalgae that can be exploited as a good source of biologically active compounds, once an appropriate process has been developed and the metabolites and biological activity of the different species have been demonstrated. With this goal, in the present work a supercritical fluid extraction process (SFE) has been studied to extract carotenoids and phenolic compounds from Cladophora glomerata, Ulva flexuosa and Chara fragilis. Optimization of the parameters involved in the SFE process (temperature, pressure and % ethanol as co-solvent) has been carried out by using a 3-level factorial experimental design and different responses have been evaluated simultaneously (extraction yield, total carotenoids, total phenols and antioxidant activity). Optimized conditions include the use of 40°C, 300bar and 11.4% ethanol as co-solvent. Under these conditions, C. fragilis extracts were the richest in total carotenoids and total phenols (24.90mg fucoxanthin equivalents g−1 extract and 30.20mg gallic acid equivalents g−1 extract, respectively), whereas those produced from U. flexuosa possessed the highest antioxidant activity (0.944mmol trolox equivalents g−1 extract). The chemical characterization of the different extracts, carried out by HPLC-DAD-MS, allowed the tentative assignment of diverse carotenoids, chlorophylls and related compounds in the studied algae; among them some described for the first time on these species. Hence, extracts obtained from the studied algae using SFE can be considered of potential interest in cosmetic, food and pharmaceutical industry as a way to valorize these underexploited materials.

Chemical Composition, Anti‐oxidant, and Antimicrobial Activities of Four Saline‐Tolerant Plant Seed Oils Extracted by SFC

AbstractThe supercritical CO2 fluid extraction process was used to obtain seed oils. The compositional analyses of the seed oils of Amorpha fruticosa L., Caragana microphylla Lam and Elaeagnus angustifolia L. were performed by GC–MS, from which 18–22 fatty acid compositions were identified, and their main components were linoleic acid (49.10–66.39 %) and oleic acid (11.95–41.10 %). The seed oils were rich in unsaturated fatty acids, which accounted for 79.75–91.19 %. The in vitro anti‐oxidant activities of the seed oils were measured by the DPPH, ABTS and phosphomolybdenum complex assays. The IC50s of the seed oils were 6.5110–12.6599 mg/mL tested by DPPH assay, and the IC50s were in the range of 0.6872–1.9310 mg/mL tested by ABTS assay. The anti‐oxidant activities of seed oils decreased in the order of A. fruticosa > C. microphylla > E. angustifolia (A) > E. angustifolia (D). In vitro antimicrobial activities of seed oils against five bacteria were tested by microdilution method. The MIC values of the oils against Bacillus subtilis, E. coli, S. aureus, P. solanacearum and B. thuringiensis were in the range of 26–36, 30–38, 58, 56–58 and 56–58 mg/mL, respectively, while the MBC values were in the range of 30–40, 34–42, 58, 56–58 and 58 mg/mL, respectively. In vitro antifungal properties of the seed oils against four plant pathogenic fungi were tested by the mycelial growth rate method. The EC50s of seed oils against V. mali, C. gloeosporioides, F. graminearum and B. cinerea were in the range of 17.51–19.25, 15.58–19.12, 8.00–17.12 and 18.76–19.14 mg/mL, respectively. The seed oils showed moderate anti‐oxidant and antimicrobial activities.

High-Efficiency Extraction and Modification on the Coal Liquefaction Residue Using Supercritical Fluid with Different Types of Solvents

This study aims to systematically illustrate the mechanism of supercritical fluid extraction (SFE) and modification on the coal liquefaction residue (CLR) and to identify the evolution and characteristics of the mesophase produced from the carbonization of SFE extracts. Results show that the extraction performance of SFE and the properties of the mesophase precursor were strongly dependent upon the selection of operating conditions and solvents. The SFE process using acetone and isopropanol presented excellent extraction performance, owning to the effect of solvent polarity on the degradation or supercritical reaction, achieving their respective CLR extraction yields of 45.85 and 30.12 wt %, while an extraction yield of 53.78 wt % was attained when using benzene, benefiting from its strong affinity to condensed aromatic hydrocarbons. More practically, quinoline-insoluble (QI) fraction decreased from 48.84 to 1.13 wt % after SFE processing, which significantly upgraded the quality of the mesophase precurso...

Fluid phase equilibria and mass transfer studies applied to supercritical fluid extraction of Illicium verum volatile oil

Supercritical fluid extraction (SFE) is one of the techniques used to obtain Illicium verum volatile oil, however, solubility of the volatile oil in CO2, one of the most important process variables from the SFE, is still unknown. In this work, vapor liquid equilibria experiments (VLE) were conducted in order to verify solubility of the major compound in the I. verum volatile oil, E-anethole, in CO2. In addition, SFE was carried with 750 g/h and 1500 g/h of CO2 at 308.15 K and 8000 kPa, 9000 kPa, 10,000 kPa and the antioxidant activity of the volatile oil accessed by the DPPH method. The VLE experimental data was modeled using the Peng–Robinson EOS (PR-EOS) with three mixing rules (vdW1, vdW2 and MKP). Moreover, SFE process was simulated using the equation proposed by Sovová and solubility data was compared with the values obtained by the PR-EOS.

Molecular dynamics simulation study: The reactivation of NaX zeolite contaminated by bi and tri aromatics using supercritical fluid extraction

In the present work, the supercritical fluid extraction (SFE) process was utilized to reactivate deactivated NaX zeolite with bi and tri aromatic contaminants (naphthalene and anthracene). In this direction, different parameters including extraction static time (30–120min), extraction pressure (80–350bar), extraction temperature (323.15–373.15K) and using two common and polar modifiers, methanol and dichloromethane, were investigated. The obtained results show that the optimum parameters were extraction pressure and temperature of 350bar and 373.15, respectively as well as static time of 90min to have the highest extraction value. However, modifiers did not display any significant influence on extraction efficiency. In addition, molecular dynamics simulations have been carried out to provide an atomic description of the supercritical carbon dioxide behavior with contaminants trapped inside NaX zeolite. The force field parameters were chosen carefully to examine self-diffusion coefficient of sorbates over a wide range of loading, temperature, and pressure. The simulated self-diffusivity was found to be in a reasonable agreement with the corresponding experimental data which evaluate the effectiveness of proposed calculation method and force field accuracy. All involved calculations were performed in time period 6ns and repeated calculations have been done at least two times to confirm the results and applied average values, which made the results being reliable.