Search Results (90)

The ever-growing global consumption of coffee generates millions of tons of spent coffee grounds (SCG) annually, posing a significant waste disposal problem. Although some SCG find use in composting or biogas production, a large portion remains underutilized. This study introduces a novel circular waste-to-energy pathway to tackle this challenge. Our proposed technology employs a cascading valorization approach, utilizing non-catalytic supercritical transesterification of pyrolytic oil derived from SCG for liquid hydrocarbon production. The process begins with pyrolysis, which converts SCG into pyrolytic oil. This oil is then upgraded via supercritical transesterification with methanol. Experiments were conducted using a 1:6 oil-to-methanol ratio at precisely controlled conditions of 239.4 °C and 1200 psi for 20 min. This optimized process yielded an impressive 96% of valuable liquid hydrocarbon product. The resulting product exhibited highly favorable characteristics, including a density of 755.7 kg/m³, a viscosity of 0.7297 mm²/s, and a high heating value (HHV) of 48.86 MJ/kg. These properties are remarkably comparable to conventional biofuels and standard fossil fuels, demonstrating the product’s potential as a viable energy source. Full article

Ensuring food safety and consumer health are crucial elements of sustainable food safety management, requiring the use of substances that inhibit the growth of undesirable microorganisms at various stages of production. The negative impact of many of these on human health and the environment has led to increased interest in alternative solutions, such as plant extracts. The aim of this study was to determine the biological activity of extracts obtained from Nigella sativa seeds using various methods, including Soxhlet and ultrasound-assisted extraction (UAE) using hexane and methanol and supercritical CO₂ extraction (SFE) assisted with methanol. The content of polyphenolic compounds, their composition, and biological activity depended on the extraction method and solvent type. All extracts exhibited antimicrobial activity against Gram-positive bacteria (Listeria monocytogenes, Priestia megaterium, and Staphylococcus aureus), Gram-negative bacteria (Salmonella Enteritidis, Pseudomonas aeruginosa, and Escherichia coli), yeasts (Candida albicans and Rhodotorula mucilaginosa), and filamentous fungi (Alternaria brassicicola, Pythium sp., Fusarium culmorum, and F. graminearum). The MIC values were in the range of <0.125 to 2 mg/mL for bacteria and 1 to 8 mg/mL for fungi, depending on the extract. Microscopic observations performed using optical and fluorescence microscopy showed changes in the viability and morphology of the fungal cells. TPC values ranged from 9.877 mg/g in hexane extract obtained by ultrasound-assisted extraction to 39.064 mg/g in extract obtained by Soxhlet method with methanol. No negative effects of the extracts on wheat seed germination were observed. Analysis of the composition of polyphenolic compounds revealed the presence of vanillic acid, hydroxybenzoic acid, syringic acid, protocatechuic acid, and p-coumaric, catechin, and epicatechin acids in all extracts. The extracts obtained with methanol, both by the Soxhlet method and by ultrasound-assisted extraction, also contained gallic acid, myricetin, luteolin, apigenin, and sinapic acid. In all extracts, thymoquinone ranged from 8.344 mg/g to 63.125 mg/g of extract, which was detected with the highest concentration in hexane extracts. Full article

Pesticides are chemical substances widely used to control, prevent, or eliminate pests in agriculture, gardening, and other sectors. However, their use poses risks to human health, and recent regulatory efforts have focused on minimizing exposure and monitoring residue levels. In this study, the separation of seven pesticides was investigated using supercritical fluid chromatography coupled to diode-array detection (SFC-DAD). The influence of six different stationary phases and various organic modifiers, as well as additional parameters such as temperature, pressure, and the presence of additives, was systematically evaluated to optimize the chromatographic conditions. The best separation performance was achieved using a LiChrospher^® 100 DIOL column with methanol as the organic modifier under a gradient program. Analyses were carried out at a flow rate of 3 mL/min, a column temperature of 35 °C, and a system back pressure of 150 bar, resulting in a total analysis time of approximately 4 min. The optimized method allowed for a faster separation of the selected agricultural pesticides by SFC-DAD compared to conventional chromatographic techniques. Full article

Municipal solid waste (MSW) recycling is constrained by contamination, heterogeneity, and infrastructure built around material-specific pathways. We introduce effectiveness-normalized greenhouse gas (GHG) emissions as a system-level metric that adjusts reported process burdens by feedstock eligibility (Effectiveness Fraction, EF) and carbon recovery efficiency (CRE) to reflect real-world MSW conditions. Using published LCA data and engineering estimates, we benchmark six pathways, mechanical recycling, PET depolymerization, enzymatic depolymerization, pyrolysis, supercritical water gasification (SCWG), and Regenerative Robust Gasification (RRG), at the scale of mixed MSW. Normalizing for EF and CRE reveals large differences between process-level and system-level performance. Mechanical recycling and PET depolymerization show low process intensities yet high normalized impacts because they can treat only a small share of plastics in MSW. SCWG performs well at broader eligibility. RRG, a plasma-assisted molten-bath approach integrated with methanol synthesis, maintains the lowest normalized impact (~1.6 t CO₂e per ton of recycled polymer) while accepting virtually all organics in MSW and vitrifying inorganics. Modeled methanol yields are ~200–300 gal·t⁻¹ without external hydrogen and up to ~800 gal·t⁻¹ with renewable methane reforming. The metric clarifies trade-offs for policy and investment by rewarding technologies that maximize diversion and carbon retention. We discuss how effectiveness-normalized results can be incorporated into LCA practice and Extended Producer Responsibility (EPR) frameworks and outline research needs in techno-economics, regional scalability, hydrogen sourcing, and uncertainty analysis. Findings support aligning infrastructure and procurement with robust, scalable routes that deliver circular manufacturing from heterogeneous MSW. Full article

This work aims to present tes-thermo, a Python library developed to solve thermodynamic equilibrium problems using the Gibbs energy minimization approach. The library is a variant of TeS v.3, a standalone executable developed for the same purpose. The tool formulates the chemical equilibrium problem of combined phases as a nonlinear programming problem, implemented using Pyomo (Python Optimization Modeling Objects) and solved with IPOPT (Interior Point OPTimizer). To validate the tool and demonstrate its robustness, the supercritical water gasification (SCWG) of methanol and ethanol was investigated. The Peng–Robinson equation of state was employed to account for non-idealities in the gas phase. Experimental and simulated data from the literature were used for validation, and, in both cases, the results were satisfactory, with root mean square errors consistently below 0.23. The SCWG processes studied revealed that hydrogen production is favored by increasing temperature and decreasing pressure. For both methanol and ethanol, increasing the carbonaceous substrate fraction in the feed promotes hydrogen formation; however, it also leads to reduced hydrogen relative yield due to the enhanced formation of methane and carbon monoxide under these conditions. Consequently, although hydrogen production increases, the hydrogen molar fraction in the dry gas stream tends to decrease with the higher substrate content. As expected, the SCWG of methanol produces more hydrogen and less carbon monoxide compared to ethanol under similar conditions. This behavior is consistent with the higher carbon content in ethanol, which favors reactions leading to carbon oxides. In summary, tes-thermo proves to be a robust and reliable tool for conducting research and studies on topics related to thermodynamic equilibrium. Full article

Limonium gmelini (Willd.) Kuntze, a plant widely used in traditional medicine, has garnered increasing attention for its diverse pharmacological activities, including anti-inflammatory, hepatoprotective, antioxidant, and antimicrobial effects. This study aimed to explore the chemical composition and biological activities of polysaccharides and polyphenolic compounds extracted from both the roots and aboveground parts of Limonium gmelini. Several methods of extraction, including ultrasound-assisted extraction (UAE), conventional maceration (CM), and supercritical fluid extraction (SFE), were employed to obtain bioactive fractions. Chemical profiling, primarily represented by monosaccharides and polyphenolic compounds, was characterized and analyzed using proton nuclear magnetic resonance spectroscopy (¹H-NMR) and gas chromatography-mass spectrometry (GC-MS) techniques. While polyphenol-rich fractions exhibited significant antibacterial activity, particularly against Staphylococcus epidermidis, polysaccharide-rich aqueous fractions showed minimal antibacterial activity. Among the methods, CM and UAE yielded higher polyphenol content, whereas SFE provided more selective extractions. Notably, methanolic SPE fractions derived from the roots were especially enriched in active polyphenols such as gallic acid, myricetin, and naringenin, and they exhibited the highest antibacterial activity against Staphylococcus epidermidis. In contrast, extracts from the aboveground parts showed more moderate activity and a partially different chemical profile. These findings underscore the importance of plant part selection and support the targeted use of root-derived polyphenol-enriched fractions from L. gmelini as promising candidates for the development of natural antibacterial agents. Further investigation is needed to isolate and validate the most active constituents for potential therapeutic applications. Full article

Cannabis (Cannabis sativa L.) contains numerous secondary metabolites with different bioactivities. Extraction methods differ in their efficiency in recovering metabolites from plant material, and thus cannabis extracts vary significantly in their composition and activity. We aimed to develop a repeatable and accurate HPLC-MS method for the determination of nine common cannabinoids and compare two widely used extraction techniques: ultrasound-assisted extraction (UAE) with methanol and supercritical CO₂ extraction (SFE). Inflorescences of the Kompolti cultivar were used as the plant material. On a polar C18 column, more than thirty compounds were well separated within 25 min; thirteen cannabinoids were identified and eight of them were quantified, with cannabidiol and its acidic precursor being the most abundant. Additionally, three spectrophotometric assays were employed for extract characterization: the total phenolic content, total flavonoid content, and DPPH radical scavenging capacity. The SFE extract, obtained using ethanol as a co-solvent under low pressure (<100 bar) and temperature (<45 °C), was more enriched than the UAE extract (181.62 ± 2.90 vs. 140.64 ± 13.24 mg quercetin equivalents/g of dry extract) and cannabinoids (446.29 ± 22.66 vs. 379.85 ± 17.16 mg/g of dry extract), especially cannabinoid acids. However, UAE achieved greater recovery from the plant material (cannabinoids: 83.42 ± 5.15 vs. 68.84 ± 3.49 mg/g of plant material) and showed superior antioxidant capacity (DPPH IC₅₀: 2.50 ± 0.18 vs. 3.37 ± 0.07 mg/mL). Notwithstanding the observed partial decarboxylation, the high repeatability (RSD < 15%, n = 11) of the entire analytical workflow involving UAE extraction and LC-MS analysis renders it suitable for routine analyses. This study contributes to the ongoing efforts toward the quality control and valorization of C. sativa. Full article

The removal of per- and polyfluoroalkyl substances (PFAS) from global aquatic environments is an emerging issue. However, little attention has been paid to addressing accumulated PFAS through their removal. This study demonstrates the encapsulation of perfluoroalkyl carboxylic acids (PFCAs) within polymer microspheres that dissolve in supercritical carbon dioxide (scCO₂). PFCAs were effectively captured by a hindered amine-supported monomer, 2,2,6,6-tetramethyl-4-piperidyl methacrylate (TPMA), in methanol (MeOH) through a simple acid-base reaction. The PFCA-loaded TPMA underwent dispersion polymerization in MeOH in the presence of poly(N-vinylpyrrolidone) (PVP) as a surfactant, producing microspheres with high monomer conversions. The microsphere size depended on the molecular weight and concentration of PVP, as well as the perfluoroalkyl chain length of the PFCAs. X-ray photoelectron spectroscopy (XPS) revealed that the perfluoroalkyl chains migrated from the interior to the surface of the microspheres when exposed to air. These surface perfluoroalkyl chains facilitated dissolution of the microspheres in scCO₂, with cloud points observed under relatively mild conditions. These findings suggest the potential for managing PFCA-encapsulated microspheres in the scCO₂ phase deep underground via CO₂ sequestration. Full article

Tannins are structurally diverse polyphenols prized for their antioxidant and protein-binding properties, making them valuable in leather tanning, adhesives, coatings, and water treatment. This article compares research on conventional versus supercritical fluid extraction (SFE), which is recognized as an eco-friendly and efficient technique. While SFE using supercritical CO₂ is already widely studied and commercially implemented for various botanical compounds, its application to tannin extraction remains in an earlier stage of development, with limited industrial solutions currently available. Various solvents (CO₂, water, ethanol, and methanol) and their mechanisms of action under supercritical conditions are discussed, demonstrating how adjusting parameters like pressure and temperature can selectively isolate specific tannin fractions. By reviewing multiple studies on yield, solvent choice, process efficiency, and product purity, the article highlights SFE’s advantages in preserving tannin quality while reducing energy consumption and contamination. The conclusions suggest SFE as a promising method for sustainable tannin production, offering tailored extracts that meet the growing demand for green processes in both industrial and biomedical applications. Full article

Conventional mild hydrotreatment processes of bio-oil present significant challenges of a high degree of polymerization, a low oil yield, high coke formation, and poor catalyst recovery. To address these challenges, the current study looked into investigating and enhancing the properties of raw bio-oil organic phase samples via a solvent-assisted stabilization approach using methanol (METH), ethanol (ETH), isopropyl alcohol (IPA), and ethyl ether (DME). Solvents like methanol (METH) and ethanol (ETH), which are highly polar, yielded higher oil fractions (64% and 62%, respectively) compared to less polar solvents like ethyl ether (DME) at 59%. Isopropyl alcohol (IPA), with intermediate polarity, achieved a balanced oil yield of 63%, indicating its ability to dissolve both polar and non-polar components. Moisture reduction in stabilized bio-oils followed the order IPA > ETH > METH > DME, with IPA showing the highest reduction due to its structural characteristics facilitating dehydration. Viscosity reduction varied, with IPA > ETH > DME > METH. Carbon recovery in stabilized bio-oils ranged from 65% to 75% for DME, ETH, and METH and was 71% for IPA. The heating values of stabilized bio-oils ranged from 28 to 29 MJ/kg, with IPA-stabilized bio-oil showing the highest value (29.05 ± 0.06 MJ/kg). METH demonstrated high efficiency (74.8%) in stabilizing bio-oil, attributed to its strong hydrogen-donating capability. ETH followed closely at 69.5%, indicating its comparable performance in bio-oil stabilization. With moderate efficiency (69.3%), IPA presents a balanced alternative considering its molecular structure and hydrogen solubility. In contrast, DME exhibited lower efficiency (63.6%) due to its weaker hydrogenation capability and propensity for undesired side reactions. The current study suggests that subcritical conditions up to 200 °C are adequate for METH, ETH, and IPA in bio-oil stabilization, comparable to results obtained under supercritical conditions. Full article

The HERMES project investigates the utilization of surplus wind and solar energy to produce renewable fuels such as hydrogen, methane, and methanol for seasonal storage, thereby supporting carbon neutrality and the energy transition. This initiative aims to create a closed-loop, zero-emission energy system with efficiencies of up to 65%, employing a low-pressure (≤30 bar) synthesis process—specifically, sorption-enhanced methanol synthesis—integrated into the power system. Excess renewable electricity is harnessed for chemical synthesis, beginning with electrolysis to generate hydrogen, which is then converted into methanol using CO₂ sourced from a biogas plant. This methanol, biomethane, or a hybrid fuel blend powers a supercritical gas turbine, providing a flexible and reliable energy supply. Optimization analysis indicates that a combined wind and photovoltaic system can meet 62% of electricity demand, while the proposed storage system can handle over 90%. Remarkably, liquid methanol storage requires a compact 313 m³ tank, significantly smaller than storage requirements for hydrogen or methane in gas form. The project entails a total investment of 105 M EUR and annual operation and maintenance costs of 3.1 M EUR, with the levelized cost of electricity expected to decrease by 43% in the short term and 69% in the long term as future investment costs decline. Full article

(1) Background: Over 90% of hop crops are currently used in beer production, with a small part used in the cosmetics and pharmaceutical industries. Spent hops as a waste product contain one of the strongest antioxidants, xanthohumol. The aim of the study was to purify spent hop extracts by magnetic dispersive extraction using iron oxide nanoparticles (IONP) to obtain pure xanthohumol; (2) Methods: The extract from the waste product obtained after supercritical carbon dioxide extraction of hops was prepared by ultrasound-assisted extraction utilizing different solvents, i.e., ethyl acetate, propanol, acetone, 80% methanol, ethyl acetate-methanol (1:1, v/v), and propanol-methanol (1:1, v/v). The hydrodynamic diameters and zeta potential of IONPs before and after incubation were measured by dynamic light scattering (DLS). The extracts were analyzed by reversed-phase high-performance liquid chromatography (HPLC). Isolated xanthohumol was identified based on the DAD spectrum in the range of 200–600 nm and by Fourier transform infrared spectroscopy/attenuated total reflectance (FT-IR/ATR); The antioxidant activity of extracts before and after incubation with IONPs was assessed using SNPAC (Silver Nanoparticle Antioxidant Capacity), DPPH (2,2-diphenyl-1-picrylhydrazyl radical), and FRAP (Ferric Reducing Antioxidant Power) assays, as well as total phenolic content (TPC) and total flavonoid content (TFC). (3) Results: The amount of added IONPs, the kind of solvent, and the contact time of the extract with nanoparticles were optimized. We found that 80% MeOH extract after incubation with IONPs (865 µg IONPs/g of spent hops) at room temperature for 48 h contains 74.61% of initial xanthohumol content, providing a final xanthohumol concentration of 43 µg mL⁻¹. (4) Conclusions: The proposed method of magnetic dispersive extraction using IONPs allows for the purification of spent hops extract and obtaining a pure product, namely xanthohumol, with a wide potential for practical applications in medicine, pharmacy, cosmetics, and agriculture. This is clear evidence of the usefulness of IONP as an effective sorbent. The method allows the use of residues from the brewing industry, i.e., the biomass of used hop cones to obtain a valuable substance. Full article

In this study, we performed supercritical CO₂ extraction of oleoresin from Peruvian ginger, focusing on the extraction yield, total polyphenol content, antioxidant capacity, and contents of gingerol and shogaol. The temperature (40 to 50 °C), pressure (80 to 250 bar), CO₂ flow rate (2 and 8 ft³/h) and extraction time (10 to 360 min) were evaluated in three steps. The extraction yield was influenced by the temperature, pressure, flow rate and extraction time. Oleoresin extracts were obtained from 150 to 250 bar. The supercritical extraction conditions selected for the recovery of the oleoresin extract were 50 °C, 250 bar, 8 ft³/h and 360 min, resulting in an extraction yield of 25.99 ± 0.13 mg extracts/g dry basis, a total polyphenol content of 171.65 ± 2.12 mg of gallic acid equivalent (GAE)/g extract, an antioxidant capacity expressed as a half-maximal inhibitory concentration (IC₅₀) of 1.02 ± 0.01 mg extract/mL methanol and a Ferric Reducing Antioxidant Power (FRAP) value of 368.14 ± 60.95 mg Trolox/g extract. The contents of gingerols and shogaols in the supercritical extract were 254.71 ± 33.79 mg of 6-gingerol/g extract, 24.46 ± 3.41 mg of 6-shogaol/g extract, 9.63 ± 2.51 mg of 8-gingerol/g extract, 51.01 ± 9.39 mg of 8-shogaol/g extract, 27.47 ± 5.06 mg of 10-gingerol/g extract and 20.11 ± 4.62 mg of 10-shogaol/g extract. There was no reduction in the total polyphenol content or antioxidant capacity according to the IC₅₀ and FRAP assays, under storage conditions of 0 °C, 20 °C and 40 °C after 180 days; this indicates that the oleoresin obtained using supercritical CO₂ extraction could be used as an additive in food products. Full article

Lignin is considered a renewable source for the production of valuable aromatic chemicals and liquid fuel. Solvent depolymerization of lignin is a fruitful strategy for the valorization of lignin. However, Kraft lignin is highly prone to produce char (a by-product) during the hydrothermal depolymerization process due to its poor solubility in organic solvents. Therefore, the minimization of char formation remains challenging. The purpose of the present study was to fractionate Kraft lignin in methanol to obtain low-molecular-weight fractions that could be further depolymerized in supercritical methanol to produce aromatic monomers and to suppress char formation. The results showed that the use of methanol-soluble lignin achieved a bio-oil yield of 45.04% and a char yield of 39.6% at 280 °C for 2 h compared to 28.57% and 57.73%, respectively, when using raw Kraft lignin. Elemental analysis revealed a high heating value of 30.13 MJ kg⁻¹ and a sulfur content of only 0.09% for the bio-oil derived from methanol-soluble lignin. The methanol extraction process reduced the oxygen content and increased the hydrogen and carbon contents in the modified lignin and bio-oil, indicating that the extracted lignin fraction had an enhanced deoxygenation capability and a higher energy content. These findings highlight the potential of methanol-soluble Kraft lignin as a valuable resource for sustainable energy production and the production of aromatic compounds. Full article

Background/Objectives: This study investigates the impact of supercritical antisolvent (SAS) process parameters on the particle formation of telmisartan, a poorly water-soluble drug. Methods: A fractional factorial design was employed to examine the influence of the SAS process parameters, including solvent ratio, drug solution concentration, temperature, pressure, injection rate of drug solution, and CO₂ flow rate, on particle formation. Solid-state characterizations of the SAS process particles using XRD and FT-IR confirmed their amorphous nature. The effect of particle size on the kinetic solubility, dissolution, and oral bioavailability of telmisartan was also assessed. Results: Using a mixture of dichloromethane and methanol, telmisartan amorphous nano-microparticles with sizes between 200 and 2000 nm were produced. The key parameters, particularly drug solution concentration and temperature, significantly affected the particle size. Interestingly, the ratio of the solvent mixture also had a significant effect on the particle morphology. Further experiments were performed to determine the conditions for preparing telmisartan amorphous nano-microparticles with various sizes by controlling the solvent mixture ratio and the concentration of the drug solution. It was revealed that a reduction in the amorphous particle size enhanced both the kinetic solubility and dissolution rates, leading to a significantly increased in vivo oral bioavailability in rats compared to unprocessed telmisartan. Conclusions: These findings suggest that SAS processing, utilizing adjustments of process parameters, offers an effective strategy for enhancing the bioavailability of poorly soluble drugs by generating amorphous spherical nano-microparticles with optimized particle size. Full article