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Item type:Publication, Access status: with files , Continuous drying of alginate aerogel particles: Residence time measurement and process optimization under high pressure conditionsThis study advances continuous supercritical carbon dioxide (scCO₂) drying of aerogel particles by introducing a non-invasive optical method to determine particle residence time in a countercurrent extraction column. In countercurrent operation, scCO₂ flows upward while the particle suspension in ethanol enters from the top. The method enables precise, real-time residence time measurement under high pressure conditions without disturbing the process. The effects of pressure (100–150 bar), temperature (40–80 °C), CO₂ flow rate (30–80 g/min), and suspension flow rate (10–45 g/min) on residence time and drying efficiency were accordingly analyzed. Experiments were performed in a 1.25 m high extraction column, with an internal diameter of 20.5 mm, using highly spherical alginate beads with a diameter of ∼ 400 µm as a model system. Evidence of effective solvent removal throughout the whole operation range was provided by determination of the residual ethanol content in the intact aerogel beads after the drying process (0.0053–0.0341 gethanol/gaerogel). The dried products featured a specific surface area of 363 ± 27 m²/g, a mesopore volume of 3.2 ± 0.7 cm³ /g, consistent with the typical range of alginate aerogels. The combined insights provide a comprehensive picture of the countercurrent column’s operational response and allow the definition of practical operating windows. Elevated temperature and high pressure provide the most favorable trade-off between short residence time and minimized residual ethanol, maximizing the time-specific yield. Overall, the approach establishes a robust, transferable framework for optimizing continuous scCO₂ drying of aerogel particles and supports extension to other particle sizes and formulations.Publicationtype: Journal Article72 24 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Modeling cosolvent effects on solubility in supercritical CO2 using data-driven approaches(2026-04-13); ; ; Supercritical CO₂ (scCO₂) is an environmentally friendly solvent, but its low polarity limits the solubility of polar compounds. Cosolvents are commonly used to enhance solvation capability, yet comprehensive data-driven studies are scarce. We compiled the largest dataset to date — 4401 experimental solubility records with 22 cosolvents for 93 nonionic solutes, plus 4855 records in pure scCO₂ for the same solutes. Machine learning models (Random Forest, LightGBM, CatBoost, TabPFN) were trained using melting point, enthalpy of vaporization, Abraham parameters, RDKit descriptors, and solvent properties. CatBoost and TabPFN showed the best results, particularly in strict cross-validation. Including solubility data in pure scCO₂ improved predictions significantly, reducing RMSE up to 36%. High-throughput screening of 1958 solute-cosolvent pairs across 12 chemical classes revealed the strongest enhancement for polyphenols, nitrogen heterocycles, aromatic acids, and sulfonamides, with minimal effect for nonpolar compounds. Polar protic and aprotic cosolvents were the most effective, while water often showed negligible or negative effect. The results provide quantitative guidelines for cosolvent selection and demonstrate the value of integrated datasets and interpretable ML for designing supercritical fluid processes.Publicationtype: Journal Article16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Supercritical CO2 extraction of bioactives from P. halepensis petals: Process modeling, mass transfer, and bioactivity characterization(Elsevier, 2025-11-01); ; ; ; The extraction of bioactive compounds from P. halepensis petals was carried out using supercritical carbon dioxide (Sc-CO₂) under varying operational conditions, including extraction time, pressure (300–500 bar), co-solvent type (water or ethanol), and particle size (120–1400 µm), and compared to conventional techniques such as Soxhlet extraction and maceration. The results showed that Sc-CO₂ extraction at 300–500 bar achieves ∼80 % recovery of bioactive compounds within the first 30 min. Tan, Liang and Liou model successfully fitted the extraction kinetics. Furthermore, all extracts demonstrated moderate to high anticancer activity against LS174t and HCT116 cell lines compared to tamoxifen (a well-known anticancer standard). Extracts obtained by Sc-CO₂ with water as a co-solvent exhibited significant antioxidant activity against DPPH free radical; however, their antioxidant activities were notably lower than those obtained through conventional extraction methods. Finally, 38 molecules were identified by HPLC-DAD and 24 by GC-MS. The originality and novelty of this study are a) First-time application of Sc-CO₂ to extract bioactive compounds from P. halepensis petals; b) Identification of new chemical compounds (seven detected for the first time in this species) as a novel contribution.Publicationtype: Journal Article92 15 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , New insights in the morphological characterization and modelling of poly(ε-caprolactone) bone scaffolds obtained by supercritical CO₂ foaming(Elsevier, 2020-08-07); ; ; ; Hierarchically porous synthetic bone grafts (scaffolds) are gaining attention in the clinical arena. Scaffolds should combine morphological (macro- and microporosity, pore interconnectivity), mechanical and biological (biocompatibility, degradation rate) properties to fit this specific use. Supercritical (sc-) foaming is a versatile scaffold processing technology. However, the selection of the optimum operating conditions to obtain a defined scaffold structure is hampered by the lack of a single characterization technique able to fully elucidate the porous features of the resulting scaffolds. In this work, the effect of soaking time (1, 3 and 5 h) on the preparation of poly(ε-caprolactone) (PCL, 50 kDa) scaffolds by sc-foaming was evaluated by a combined X-ray microtomography (μ-CT) and mercury intrusion porosimetry (MIP) 3D-morphological analysis. Mechanical tests and in silico modelling for cell penetration and water permeability of the scaffolds were also conducted. Results evidenced the relevance of μ-CT and MIP as a synergistic analytical duo to fully elucidate the morphology of the sc-foamed scaffolds and the soaking time effect.Publicationtype: Journal ArticleScopus© Citations 18 170 338 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 141 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Protein recovery from bioethanol stillage by liquid hot water treatment(2020-01); ; Protein recovery from biogenic residues offers a high potential for increasing the added value. This paper investigates the protein recovery from bioethanol stillage by liquid hot water treatment at pH 3–11 and 110–210 °C for 10–90 min. The results show that protein solubilization starts at 89 °C and is limited by temperature. However, all amino acids except glutamic acid start to degrade at 170 °C. Especially lysine, arginine and asparagine undergo Maillard reactions, whereby degradation is favoured by bases; acids show a stabilizing effect. The highest protein yield in the hydrolysate is 75% with a concentration of 53%-DM at 170 °C and 20 min. In addition, kinetic modelling of the rate constants for protein solubilization and amino acid degradation is performed. Rate constants for amino acid degradation are about one order of magnitude higher for polar than for non-polar amino acids.Publicationtype: Journal Article281 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Alginate aerogels carrying calcium, zinc and silver cations for wound care: Fabrication and metal detectionCalcium-alginate aerogels augmented with zinc and silver can provide the next generation superabsorbent medical devices for advanced wound care with high cell and tissue tolerability and controlled compound release rates during wound healing. In this study, we addressed the fabrication and metal detection of alginate-based aerogels with these immunoactive cations. All three cations were incorporated into the alginate aerogel, albeit in different quantities, due to different magnitudes of leaching during solvent exchange step; an effect not reported previously. Silver addition led to an increase in aerogel zinc content without influencing calcium incorporation. All three metal ions were released into supernatants upon swelling aerogels in aqueous solutions, comparable to those measured for common wound dressings in human and animal injury models. The in vitro bioactivity studies showed that Zn-enriched swelling supernatants were able to suppress NO production in stimulated RAW 264.7 macrophages, indicating an effective anti-inflammatory activity.Publicationtype: Journal Article338 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Alginate and hybrid alginate-hyaluronic acid aerogel microspheres as potential carrier for pulmonary drug delivery(2019-08); ; ; ; The aim of the present study was the preparation of aerogel microspheres based on alginate and hyaluronic acid for the potential application in pulmonary drug delivery. Both polymers are commonly used in the pharmaceutical and medical fields because of their nontoxicity, biodegradability and biocompatibility characteristics. The bio-based microspheres were produced using an emulsion gelation process with a subsequent drying step by supercritical CO 2 . The microspheres were characterized by FTIR and SEM. Furthermore, their BET surface area, particle size distribution, and their aerodynamic properties were determined. The microspheres showed a low density in the range of 0.035 – 0.063 g/cm 3 and a high porosity of 97.6–98.7 %, as well as good in vitro aerodynamic properties with d A values of about 5 μm. The obtained properties of the alginate- hyaluronic acid microspheres suggest that they are potentially suitable as drug carrier for pulmonary delivery.Publicationtype: Journal Article231 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Model development for sc-drying kinetics of aerogels: Part 2. Packed bed of spherical particlesWe apply here the previously developed mass transfer model (Part 1) for drying of aerogel monoliths to the supercritical drying of particles in a packed bed. We analyzed the influence of the operating conditions, flow rate, particle and autoclave size on the drying time and consumption of carbon dioxide. Although the model requires certain improvement to quantitatively predict the experimental drying kinetics, it captures all features of the supercritical drying: (i) transition of the limiting mass transfer step between diffusion in the gel and convection in the bulk fluid; (ii) role of CO 2 density as natural variable for analysis of the CO 2 consumption; (iii) influence of the autoclave dimensions on the drying process. We suggest a unified approach towards the analysis of drying process based on a dimensionless number. Practical recommendations on the rational selection of process parameters to achieve appropriate combinations of drying time and CO 2 consumption are formulated.Publicationtype: Journal Article315 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Model development for sc-drying kinetics of aerogels: Part 1. Monoliths and single particlesA mass transport model for the supercritical drying of gels to aerogels in different sizes (monoliths or particles) and shapes (cylinder, sphere) was developed and evaluated. Physico-chemical data for the system CO2/ethanol from literature at relevant process conditions were analyzed for a precise description of relevant physical properties. In situ measurements of the supercritical drying kinetics of gel monoliths using Raman spectroscopy were used to fit the tortuosity factor of the gel network. Apart from the fitted tortuosity factor the presented model is predictive. The model was analyzed in detail for the case of spherical gel particles. Theoretical minimal drying times were found to range in seconds for microparticles. The mass transfer step limiting the overall drying kinetics was analyzed using the dimensionless Biot number. The transition Biot number can be used for rational selection of the drying conditions (pressure, temperature, mass flow) to achieve a fast drying with low CO2 consumption.Publicationtype: Journal Article299