scCO2 Processing Research Articles

Outcomes of ACL Reconstruction Utilizing Supercritical CO2-Sterilized Allografts.

Allograft tendons are perceived to have a high ACL graft failure rate in primary anterior cruciate ligament (ACL) reconstruction (ACLR). Historical series may be biased by graft processing methods that degrade the biomechanical properties of donor tendons such as irradiation. Supercritical carbon dioxide (SCCO2) is a validated method of terminally sterilizing biomaterials at physiological temperatures without irradiation, but in vivo use of SCCO2-processed tendon allografts for primary ACLR has not been reported to date. ACLR with SCCO2 allografts would result in acceptable failure rates, subjective knee scores, and clinical evaluation at 2 years postoperatively. Case series; Level of evidence, 4. Patients underwent primary ACLR with terminally sterilized SCCO2-processed human gracilis, peroneus longus, semitendinosus, tibialis anterior, and tibialis posterior tendon allografts. Patient demographics were collected, along with tendon donor age and sex. At 1 year postoperatively, subjective International Knee Documentation Committee (IKDC) and ACL-Return to Sport After Injury (ACL-RSI) scores were collected, as well as clinical evaluation. At 2 years postoperatively, the IKDC and ACL-RSI scores were repeated, and return to sports and further knee injuries were recorded. A total of 144 patients with a medianage of 26 (IQR 14) years formed the study group. Patients were predominately male (58%). The loss to follow-up rate was 8% (n = 12). The mean age of allograft tendon donors was 37 (range 17-58) years, and the majority were male (83%). The mean allograft diameter was 8.9 ± 1.0 mm. At 2 years, ACL graft failureoccurred in 5% (n = 7). All graft failureswere in patients aged ≤25 years (P = .007). Neither donor age (≤40 or >40 years) nor donor sex was associated with graft failure (P > .05). The median IKDC subjective score was 95 and ACL-RSI score was 75. There were no revisions for sepsis within the first 2 years postoperatively. SCCO2 processing of allograft tendons demonstrated satisfactory clinical and patient-reported outcomes at 24 months postoperatively in a consecutive series of patients with primary ACLR, with similar ACL graft failure rates and subjective knee scores compared with those reported in published series of hamstring tendon autograft and fresh frozen nonirradiated allograft.

SARS-CoV-2 inactivation by supercritical carbon dioxide coupled with hydrogen peroxide

The recent COVID-19 pandemic has underscored the need for innovative decontamination techniques capable of treating sensitive materials potentially contaminated. Combining supercritical carbon dioxide (scCO2) with sterilant agents has shown promise in this regard. This study aimed at testing scCO2 as a virus inactivation method for biomedical materials contaminated with the Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2). The virus was inoculated on a stainless-steel carrier and treated at 45 °C and 8 MPa. No inactivation was detected when only scCO2 was used, even after long treatment times (60 min). The addition of 50 ppm of H2O2 to the process allowed the inactivation of more than 5 Log PFU (Plaque Forming Unit) of the virus by only pressurising and depressurising the vessel, while a 20-min process is needed by only using H2O2. Overall, the study demonstrates a synergistic effect when H2O2 is added to the scCO2 process for the inactivation of SARS-CoV-2.

Policosanols from grape marc: A new step towards a sustainable biorefinery for the wine industry by SC-CO2 extraction

Supercritical carbon dioxide (SC-CO2) extraction of policosanol (PC) from grape marc was investigated for the first time. Employing the broken plus intact cells (BIC) model (Sovová's model) the investigation focused on analyzing the SC-CO2 process to extract the nonpolar fraction from grape marc efficiently. Operating conditions for SC-CO2 extraction—280 bar pressure, 70 °C temperature, and a flow rate of 10 kgCO2/h—yielded the highest policosanol content. The extracted policosanol ranged between 3922 and 4083 mg/kgDM, constituting approximately 8 % of the total extraction yield. Surprisingly, this amount of PC was of the same order of magnitude found in beeswax yellow, a well-known rich natural source of PC. The primary aliphatic alcohols found in the PC from grape marc were hexacosanol, octacosanol, and triacontanol. These findings were consistent with grape marc samples from other Italian regions. Furthermore, a comparative analysis between SC-CO2 and Soxhlet extraction methods for PC was carried out.

Grafting of Organophosphonic Acid Monolayers on Hydrogen-Terminated Silicon Surface and Secondary Functionalization in Supercritical Carbon Dioxide Media.

The monolayer grafting on the oxide-free Si surface is challenging due to vulnerability of the surface against oxide formation in an ambient atmosphere. Most of the conventional studies focused on organic solvent-based chemistry and solvent and substrate interfaces, and residual solvents after the monolayer grafting play a key role in producing the highly stable monolayers. CO2 in its supercritical state (SCCO2) provides an elegant engineering solution for the problem faced as it can be used as inert processing environment and as carrier fluid for monolayer grafting taking up the role of organic solvents. In this work, monolayers of alkyl organophosphonic acids (OPAs) and functional OPAs were grafted on hydrogen-terminated oxide-free Si surfaces using the SCCO2 process. Grafted monolayers were physically and chemically characterized to verify the successful monolayer formation and determine the nature of the covalent binding configuration on the surface. To broaden the prospects of practical utility of the process and the OPA monolayer, the (3-bromopropyl)phosphonic acid (BPPA) monolayer was demonstrated to undergo secondary functionalization by terminal group substitution to convert the Br terminal group to the OH terminal group and secondary monolayer grafting to assemble 4-fluorothiophenol on top of the BPPA monolayer. The ability of monolayers to sustain secondary functionalization processing qualitatively hints toward ordered and stable monolayers of OPAs. The developed SCCO2 process in this work presents a single-step, green, and scalable method to graft the OPA monolayer on oxide-free Si which can employed in the future for monolayer doping, highly selective biochemical sensors, and targeted biological interactions.

Supercritical CO2 as a Valuable Tool for Aroma Technology.

This review addresses the possibilities of using supercritical carbon dioxide (SC-CO2) in the flavor industry in extraction and fractionation processes and its use as a reaction medium to generate aroma esters. The advantages and disadvantages are presented, comparing SC-CO2 processing with traditional methods. The most distinguishable features of SC-CO2 include mild reaction conditions, time savings, fewer toxicity concerns, higher sustainability, and the possibility of modulating solvent selectivity according to the process conditions (such as pressure and temperature). Thus, this review indicates the potential of using SC-CO2 to obtain a high selectivity of compounds that can be applied in aroma technology and related fields.

Chemical Composition of Vitis vinifera Leaves Essential Oil and Supercritical Carbon Dioxide Extract

Background/Objective Vitis vinifera leaves harvested from the developing canes are used in Balkan cuisines. The objective was to determine the chemical composition of the essential oil and supercritical carbon dioxide (SC CO2) extract of V. vinifera leaves harvested after the flowering of the new vine shoots. Methods The V. vinifera leaf oils were obtained by hydrodistillation and SC CO2 extraction. The application of different SC CO2 extraction parameters, determined by the Box–Behnken design, influenced the extraction yield and the chemical composition of the SC CO2 extracts. The optimal extraction conditions were set for the extraction yield and eucalyptol amount. The essential oil and SC CO2 extracts obtained were analyzed by gas chromatography–mass spectrometry. Results The most abundant compounds present in the essential oil obtained by hydrodistillation were: phytol (11.3%), α-cadinol (8.3%), trans-calamenene (8.2%), hexahydrofarnesyl acetone (7.0%), and τ-cadinol (6.6%). The extracts obtained by SC CO2 extraction consisted of twenty five compounds among which the most abundant were: phytol, squalene, eucalyptol, camphene and hexadecan-1-ol. Over the ranges of SC CO2 process parameters studied, those of pressure and extraction time had significant effect on the extraction yield and eucalyptol amount. Conclusion The results obtained determined the compounds present in V. vinifera leaves essential oil and SC CO2 extracts which contribute to the flavor and aroma of V. vinifera leaves.

Supercritical carbon dioxide extraction of oils from Andean lupin beans: Lab‐scale performance, process scale‐up, and economic evaluation

AbstractOil extraction from Andean lupin beans (Lupinus mutabilis SWEET) via supercritical carbon dioxide (scCO2) was studied on both lab scale and pilot scale. On the lab scale, the effect of pressure, solvent‐to‐feed ratio (S/F), sample particle size and temperature on oil yield were evaluated. The oil quality (fatty acid [FA] composition and tocopherol content) were investigated. Five‐hour scCO2 extraction yielded about 86% oil of Soxhlet extraction (using hexane as solvent). The fraction of unsaturated FA rose with extraction pressure at specific time. High tocopherol contents were detected in oils extracted at low pressure. An increase in temperature was unfavorable to oil and tocopherol yield, thereby confirming the validity for preserving oil extract quality under a mild scCO2 extraction condition. Oil quality and yield did not have identical optimum settings, opening up possibilities for producing different qualities of oils. Pilot‐scale extraction offered comparable oil yield to lab‐scale extraction at similar S/F ratio. Economic evaluation showed that it is promising to implement industrial scale scCO2 process for lupin oil extraction. It was predicted that, at a specific industrial scale of extraction (2 × 1000 L, 550 bar, 40°C and S/F of 24), the manufacturing cost of oils got close to actual commercial production cost.Practical ApplicationThis study applied an environment‐friendly high‐pressure extraction method, supercritical carbon dioxide (scCO2) extraction, to separate oils from Andean lupin beans (Lupinus mutabilis SWEET). ScCO2 extraction can serve as an alternative oil extraction method to conventional ones that use fossil‐derived organic solvents as the extractant. Up‐scaled scCO2 processing was estimated to be economically viable for commercial lupin oil production.

Oil extraction from black soldier fly (Hermetia illucens L.) larvae meal by dynamic and intermittent processes of supercritical CO2 – Global yield, oil characterization, and solvent consumption

The aim of the present study was to investigate the pressure (P) and temperature (T) conditions of sc-CO2 extraction by comparing yield and solvent consumption in two processes (dynamic and intermittent), at 25 and 30 MPa and 60 °C. The meal and oil of black soldier fly (Hermetia illucens L.) larvae were characterized to establish the carotenoid content and the profiles of total and free fatty acids, volatile and triacylglycerols (TAGs). The dynamic and intermittent processes showed similar yields and the intermittent extraction revealed lower CO2 consumption as it used half of the mass spent when compared to the dynamic process. The carotenoid levels in the oil varied from 2.05 to 4.59 mg/kg, and the main fatty acids were oleic (18:1n-9,O), lauric (12:0,La), linoleic (18:2n-6,Li), and palmitic (16:0,P). Our results showed the intermittent sc-CO2 process as a new means of oils production with high potential for application in the cosmetic and food industries.

Recovery of Al2O3 from hazardous Al waste as a reinforcement particle for high-performance Ni/Al2O3 corrosion resistance coating via ultrasonic-aided supercritical-CO2 electrodeposition

The unprocessed dumping of aluminium wastes in the landscape leads to generation of heat and toxic gases, which are detrimental to the ecosystem. Motivated by the waste-to-wealth notion, we demonstrated the recovery of aluminium oxide nanoparticles (Al2O3NPs) from domestic aluminium wastes via a sonochemical approach and synthesis of nickel/aluminium oxide (Ni/Al2O3) coating via ultrasonic-coupled supercritical carbon dioxide (US-SC-CO2) electrodeposition method for higher corrosion resistance performance. The physical characterization and material confirmation of prepared films were examined by microscopic and various spectroscopic techniques. The electrochemical corrosion resistance studies were explored via potentiodynamic polarization and electrochemical impedance spectroscopy techniques. Based on the results, the US-SC-CO2 strategy exposed an improved distribution of Al2O3 NPs assimilation in Ni matrix, higher corrosion resistance, and microhardness. The integration of ultrasonic irradiation into the SC-CO2 process promises an enhanced coating quality. Thereby, the novel US-SC-CO2 approach for Ni/Al2O3 synthesis is expected to achieve a sustainable green impact in real-world applications.

Effect of Green Food Processing Technology on the Enzyme Activity in Spelt Flour

In this research, a new approach to enzyme inactivation in flour was presented by supercritical technology, considered a sustainable technology with lower energy consumption compared to other technologies that use ultra-high temperature processing. Total protein concentration and the activity of enzymes α-amylase, lipase, peroxidase, polyphenol oxidase, and protease were determined in flour pre-treated with scCO2. During the study, it was observed that the activity of enzymes such as lipase and polyphenol oxidase, was significantly reduced under certain conditions of scCO2 treatment, while the enzymes α-amylase and protease show better stability. In particular, polyphenol oxidase was effectively inactivated below the 60% of preserved activity at 200 bar and 3 h, whereas α-amylase under the same conditions retained its activity. Additionally, the moisture content of the scCO2-treated spelt flour was reduced by 5%, and the fat content was reduced by 58%, while the quality of scCO2-treated flour was maintained. In this regard, the sustainable scCO2 process could be a valuable tool for controlling the enzymatic activity of spelt flour since the use of scCO2 technology has a positive effect on the quality of flour, which was verified by the baking performance of spelt flour with the baked spelt bread as an indicator of quality.

Dissolution Improvement of Progesterone and Testosterone via Impregnation on Mesoporous Silica Using Supercritical Carbon Dioxide

Progesterone (PRG) and testosterone (TST) were impregnated on mesoporous silica (ExP) particles via supercritical carbon dioxide (scCO2) processing at various pressures (10–18 MPa), temperatures (308.2–328.2 K), and time (30–360 min). The impact of a co-solvent on the impregnation was also studied at the best determined pressure and temperature. The properties of the drug embedded in silica particles were analysed via gas chromatography (GC), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and nitrogen adsorption. An impregnation of 1 to 82 mg/g for PRG and 0.1 to 16 mg/g for TST was obtained depending on the processing parameters. There was a significant effect of pressure, time, and co-solvent on the impregnation efficiency. Generally, an increase in time and pressure plus the use of co-solvent led to an improvement in drug adsorption. Conversely, a rise in temperature resulted in lower impregnation of both TST and PRG on ExP. There was a substantial increase in the dissolution rate (> 90% drug release within the first 2 min) of both TST and PRG impregnated in silica particles when compared to the unprocessed drugs. This dissolution enhancement was attributed to the amorphisation of both drugs due to their adsorption on mesoporous silica.Graphical

Thermodynamic behavior and crystal structure of polypropylene treated with supercritical carbon dioxide

Abstract Controlling temperature and pressure during the supercritical carbon dioxide (scCO2) process can change the mount of CO2 entered in polypropylene (PP) phase, thereby changing the mechanical properties of materials. The effect of scCO2 treatment on the crystallization behavior is different in the semi-molten and molten states. This study investigates the PP treated with scCO2 near the melting point and at various pressures, and explores the effects of temperature and pressure on the crystal structure, lamellar structure, and thermodynamic properties of PP. The results show that at a melting temperature of 165 °C, scCO2 can enhances the ability of PP molecules to makes the PP crystal region more regular, and forms larger microcrystals and lamellae. Additionally, increasing the pressure can make more CO2 enter the PP crystal region and further improve the regularity of the crystal. At a semi-melting temperature of 155 °C, scCO2 is primarily in the amorphous region because it is difficult to enter the PP crystal region. Even if increasing the pressure, it has little effect on the crystal size and lamellar thickness of PP. The research has significant implications for developing and utilizing scCO2 to remove ash from materials.

Supercritical Fluid-Assisted Fabrication of Pd Nanoparticles/Graphene Using a Choline Chloride-Oxalic Acid Deep Eutectic Solvent for Enhancing the Electrochemical Oxidation of Glycerol.

A green method for synthesizing Pd nanoparticles/graphene composites from a choline chloride–oxalic acid deep eutectic solvent (DES) without a reducing agent or a surfactant is reported. Deep eutectic solvents are usually composed of halide salts and hydrogen-bond donors, and many are biocompatible and biodegradable. The merits of deep eutectic solvents include that they serve as reducing agents and dispersants, and Pd nanoparticles are tightly anchored to graphene. The size and dispersion of Pd particles are improved when supercritical carbon dioxide (scCO2) is used because it has gaslike diffusivity and near-zero surface tension, which results in excellent wettability between the scCO2 and the carbon surface. The prepared sc-Pd NPs/GR/SPCE shows excellent activity toward glycerol oxidation compared to composites not fabricated by scCO2 processes. This study demonstrates the potential of using this scCO2-assisted protocol combined with deep eutectic solvents to further construct nanoparticles/graphene composites.

Effects of Supercritical Carbon Dioxide Extraction (SC-CO2) on the Content of Triterpenoids in the Extracts from Ganoderma Lucidum

This research investigates the effect of SC-CO2 extraction parameters on the triterpenoid recovery from G. lucidum. The SC-CO2 parameters included extraction pressure, extraction temperature, and extraction time. The extraction pressure was varied between 200, 400 and 600 bar, the extraction temperature between 30, 55 and 80 °C, and the extraction time between 30, 75 and 120 min. In this study, the SC-CO2 parameters were first optimized using a response surface methodology (RSM) for maximum triterpenoid recovery. The results showed that the optimal RSM-based SC-CO2 conditions were 430 bar extraction pressure, 54.8 °C extraction temperature and 78.90 min extraction time, achieving the maximum triterpenoid recovery of 1.56 mg/100g. The kinetic behavior of SC-CO2 process was subsequently characterized using a second-order kinetic model under variable extraction pressures and extraction temperatures, given a SC-CO2 time interval. The second-order kinetic models represented well the experimental results of triterpenoid extraction by SC-CO2 method. At these conditions, the triterpenoid extract also exhibited strong scavenging activities with IC50 values of 0.49 mg/mL for the DPPH radical scavenging activity and 0.26 mg/mL for ABTS radical scavenging activity. Thus, triterpenoids extracted from G. lucidum could be regarded as a potential agent for medicinal treatment. The results also suggest that the SC-CO2 extraction can be a useful extraction method for triterpenoid extraction from G. lucidum.

Viola odorata

This study aimed at examining the effect of supercritical carbon dioxide (ScCO2) extraction on the subsequent extraction of the Viola odorata polar bioactive components. The raw material was firs submitted to ScCO2 extraction for the extraction of the lipophilic fraction. Then the exhausted raw material was subjected to ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) in order to extract the polar components. ScCO2 extraction was performed under the pressure of 300 bar and at a temperature of 40 °C for 4 hours. In order to see the effect of ScCO2, the UAE and MAE (50% aqueous ethanol solution as solvent) were conducted on both exhausted (residue-after the ScCO2) and unexploited raw materials. Also, the impact of the various UAE and MAE conditions was tested. The UAE was conducted on two different temperatures (40 and 50 °C) at the constant extraction time (40 and 20 min). MAE was conducted on two different extraction powers (470 and 800 W) and at the constant extraction time (10 min). The results were focused on the content of total phenols, total flavonoids and antioxidant activity of the obtained extracts. The yield during the ScCO2 process was 1.43% (w/w). It was noted that the extracts obtained by applying UAE and MAE after the ScCO2 were noticeably richer in the content of total phenols. UAE conditions of 40 °C and 20 min showed the highest yield of total phenols, recording 70.38 mg GAE/g DE, while the MAE at the power of 470 W achieved 11.89% higher yield of polyphenols in residue extracts. The antioxidant activity has also been in correlation with the concentration of polyphenols.

Acellular Porcine Cornea Produced by Supercritical Carbon Dioxide Extraction: A Potential Substitute for Human Corneal Regeneration.

The aim of this study was to develop a non-cytotoxic, biocompatible innovative acellular porcine cornea (APC) for corneal wound healing and corneal blindness treatment. APC was produced by using supercritical carbon dioxide (SCCO2) to decellularize the porcine cornea. Decellularization of the porcine cornea was examined by hematoxylin and eosin staining and 4,6-diamidino-2-phenylindole, dihydrochloride staining. The residual DNA content of APC was analyzed in comparison with the native porcine cornea. Virus inactivation up to at least 6 log10 was confirmed for the stepwise process of APC for 4 different model viruses. In addition, a series of in vitro and in vivo tests in accordance with ISO-10993 biocompatibility assay and animal performance tests were performed. APC produced by the SCCO2 process revealed complete decellularization, without any residual non-collagenous proteins. The scanning electron microscopy structural features of the decellularized cornea were similar to those of human. APC was found to be nontoxic and exhibited excellent biocompatibility in both in vitro and in vivo studies. The animal performance test proved that APC exerted excellent adaptability on the cornea and no sign of irritation and good compatibility in lamellar corneal transplantation. APC manufactured by SCCO2 technology revealed complete cells and non-collagenous protein removal compared with the Triton-sodium dodecyl sulfate decellularization process. APC showed excellent biocompatibility in rabbit lamellar corneal transplantation with a follow-up to 1 year. APC can be a potential substitute for human-donated cornea for corneal transplantation in the near future.

Polylactide, Processed by a Foaming Method Using Compressed Freon R134a, for Tissue Engineering.

Fabricating polymeric scaffolds using cost-effective manufacturing processes is still challenging. Gas foaming techniques using supercritical carbon dioxide (scCO2) have attracted attention for producing synthetic polymer matrices; however, the high-pressure requirements are often a technological barrier for its widespread use. Compressed 1,1,1,2-tetrafluoroethane, known as Freon R134a, offers advantages over CO2 in manufacturing processes in terms of lower pressure and temperature conditions and the use of low-cost equipment. Here, we report for the first time the use of Freon R134a for generating porous polymer matrices, specifically polylactide (PLA). PLA scaffolds processed with Freon R134a exhibited larger pore sizes, and total porosity, and appropriate mechanical properties compared with those achieved by scCO2 processing. PLGA scaffolds processed with Freon R134a were highly porous and showed a relatively fragile structure. Human mesenchymal stem cells (MSCs) attached to PLA scaffolds processed with Freon R134a, and their metabolic activity increased during culturing. In addition, MSCs displayed spread morphology on the PLA scaffolds processed with Freon R134a, with a well-organized actin cytoskeleton and a dense matrix of fibronectin fibrils. Functionalization of Freon R134a-processed PLA scaffolds with protein nanoparticles, used as bioactive factors, enhanced the scaffolds’ cytocompatibility. These findings indicate that gas foaming using compressed Freon R134a could represent a cost-effective and environmentally friendly fabrication technology to produce polymeric scaffolds for tissue engineering approaches.

Preparation of Solid Dispersions of Simvastatin and Soluplus Using a Single-Step Organic Solvent-Free Supercritical Fluid Process for the Drug Solubility and Dissolution Rate Enhancement.

The study was designed to investigate the feasibility of supercritical carbon dioxide (scCO2) processing for the preparation of simvastatin (SIM) solid dispersions (SDs) in Soluplus® (SOL) at temperatures below polymer’s glass transition. The SIM content in the SDs experimental design was kept at 10, 20 and 30% to study the effect of the drug–polymer ratio on the successful preparation of SDs. The SIM–SOL formulations, physical mixtures (PMs) and SDs were evaluated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and dissolution studies. The scCO2 processing conditions and drug–polymer ratio were found to influence the physicochemical properties of the drug in formulated SDs. SIM is a highly crystalline drug; however, physicochemical characterisation carried out by SEM, DSC, and XRD demonstrated the presence of SIM in amorphous nature within the SDs. The SIM–SOL SDs showed enhanced drug dissolution rates, with 100% being released within 45 min. Moreover, the drug dissolution from SDs was faster and higher in comparison to PMs. In conclusion, this study shows that SIM–SOL dispersions can be successfully prepared using a solvent-free supercritical fluid process to enhance dissolution rate of the drug.

Supercritical CO2‐Assisted SiOx/Carbon Multi‐Layer Coating on Si Anode for Lithium‐Ion Batteries

AbstractSupercritical CO2 (SCCO2), characterized by gas‐like diffusivity, low surface tension, and excellent mass transfer properties, is applied to create a SiOx/carbon multi‐layer coating on Si particles. Interaction of SCCO2 with Si produces a continuous SiOx layer, which can buffer Si volume change during lithiation/delithiation. In addition, a conformal carbon film is deposited around the Si@SiOx core. Compared to the carbon film produced via a conventional wet‐chemical method, the SCCO2‐deposited carbon has significantly fewer oxygen‐containing functional groups and thus higher electronic conductivity. Three types of carbon precursors, namely, glucose, sucrose, and citric acid, in the SCCO2 syntheses are compared. An eco‐friendly, cost‐effective, and scalable SCCO2 process is thus developed for the single‐step production of a unique Si@SiOx@C anode for Li‐ion batteries. The sample prepared using the glucose precursor shows the highest tap density, the lowest charge transfer resistance, and the best Li+ transport kinetics among the electrodes, resulting in a high specific capacity of 918 mAh g−1 at 5 A g−1. After 300 charge–discharge cycles, the electrode retains its integrity and the accumulation of the solid electrolyte interphase is low. The great potential of the proposed SCCO2 synthesis and composite anode for Li‐ion battery applications is demonstrated.

Brominated flame retardants extraction from waste electrical and electronic equipment-derived ABS using supercritical carbon dioxide.

Persistent organic pollutants such as brominated flame retardants represent a major problem in the end-of-life of polymer materials. This study investigates the extraction of brominated flame retardants (BFR) from real waste electrical and electronic equipment (WEEE) using supercritical carbon dioxide (sc-CO2). Sc-CO2 is a non-toxic solvent which possesses intermediate properties between liquids and gases which confer it high diffusivity and solubility. A batch of WEEE-derived acrylonitrile-butadienestyrene (ABS) was first characterized to determine its bromine and BFR composition which was found to be four times higher than the regulation limit set in 2019. Then, different parameters of the sc-CO2 process such as temperature, pressure, granulometry and the use of a co-solvent were studied to estimate the effect of each one on the BFR extraction efficiency. With the view to determine the recyclability of the treated polymer, the impact of the extraction process on the polymer material was also studied by Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Size Exclusion Chromatography (SEC). The extraction process performed on <500µm particle size sample at 40°C and 500 bars during 6h and using ethanol as a co-solvent allowed to remove 43.5±0.9% of bromine, which was the maximum extraction rate obtained. Sc-CO2 extraction was found to be an efficient technique to remove tetrabromobisphenol A (TBBPA) but the tested conditions did not allow to remove enough polybromodiphenylethers (PBDE) to satisfy the regulation. Sc-CO2 process seems to be a promising pre-treatment method prior to mechanical recycling as no degradation effect on the polymer matrix was observed.