Instituto Universitario de Investigación en Bioeconomía(BioEcoUVa)

Solubility measurements of carbon dioxide and nitrous oxide in an aqueous mixture of 2-dimethylaminoethanol and N-methyl-1,3-propanediamine

2026-04-07T19:19:32Z

Aqueous monoethanolamine (MEA) is a mature post-combustion CO2 capture technology, but it faces significant drawbacks including corrosivity, high regeneration energy (∼4 GJ/t-CO2), and reactivity with contaminants. This study investigates an aqueous blend of 2-Dimethylaminoethanol (DMAE, 30% wt.) and N-Methyl-1,3-propanediamine (MAPA, 10% wt.) as an alternative solvent to capture CO2. Given the scarcity of Vapour-Liquid Equilibrium (VLE) data for such amine blends, this research aims to expand the thermodynamic understanding of this specific aqueous DMAE + MAPA system. We thoroughly investigate its VLE with CO2 and N2O across temperatures between (313.15–393.15) K. The physical solubility of CO2 was determined using the N2O/CO2 analogy. N2O solubility measurements were conducted in a monobloc equilibrium cell from 1 to 5 MPa. The expanded relative uncertainty of the N2O solubility, expressed in molality, was estimated to be 0.8% (k = 2). Henry's constants were derived using Krichevsky-Ilinskaya analysis and CO2 solubility was determined using a static-isochoric Van Ness-type apparatus over 313.15–363.15 K and up to 7 MPa with a relative uncertainty of ur(αexp) = (0.3–5) %. Finally, speciation profiles and the heat of CO2 absorption were predicted using established thermodynamic models optimized for this system.

Upcycling post-consumer PET bottles into low-density films and 3D-printed materials

2026-04-07T07:10:39Z

Recycled polyethylene terephthalate (rPET) from mixed-color bottle waste is typically downcycled due to its variable composition and reduced melt strength, limiting their contribution to circular economy strategies and high-value applications. In this work it is proved that gas dissolution foaming enables the upcycling of two industrial rPET, light-blue PET (PET_B) and color recycled PET (PET_C) into low-density microcellular films and 3D printed-parts. A comprehensive materials characterization allows to establish the optimum processing window for these materials. This way optimized microcellular structures were produced at mild saturation conditions (15 MPa, 50 °C). PET_B shows cell sizes close to 2 μm together with relative densities of 0.2 to 0.28, outperforming virgin PET. PET_C, despite containing several non-miscible contaminants, also leads to stable cellular materials with cell sizes from 5 to 18 μm. Finally, we demonstrate for the first time that rPET 3D-printed components can be foamed while preserving their overall geometry, undergoing a controlled volumetric expansion and achieving a 40% density reduction with homogeneous microcellular structure. Overall, this study highlights the potential of gas dissolution foaming as a robust upcycling route for heterogeneous PET waste streams, enabling lightweight materials and supporting circular manufacturing strategies.

Eco-efficient hydrolysis of coconut oil: a continuous hydrothermal and water-only process for the production of oleochemicals

2026-03-25T20:02:08Z

A continuous hydrothermal process using water as reaction medium was investigated for the selective hydrolysis of triglycerides under sub- and supercritical conditions. The process was operated in continuous flow at 250–400 °C and 22–25 MPa with residence times between <1 s and <60 s, enabling controlled partial or near-complete hydrolysis without added catalysts, organic solvents and expensive enzymes. At 380 °C and 25 MPa, selective partial hydrolysis yielded up to 51 wt% mono-diglycerides and 32 wt% fatty acids at a residence time of 23 s. The process was demonstrated at a pilot scale with a throughput of 30 kg h−1 and stable operation at high oil concentrations up to 34 wt% in the reactor. Integration of counter-current heat recovery reduced the external energy demand by up to 61%, addressing the high energy intensity typically associated with supercritical water processing. Hydrolysates enriched in mono- and diglycerides exhibited strong emulsifying performance and long-term stability up to 1 year, comparable to that of a commercial emulsifier. These results show that continuous, water-only hydrothermal hydrolysis enables rapid and selective triglyceride conversion within an energy-integrated and scalable process configuration.

Components interactions and stability factors in terpenes oil-in-water emulsions stabilized with hydrolyzed soybean lecithin

2026-03-23T20:01:35Z

R-(+)-limonene, eucalyptol, and linalool are natural compounds with promising antifungal activity but limited practical applicability due to high volatility, low water solubility, and photodegradability. This study investigates the formulation of stable oil-in-water emulsions using a low-energy phase inversion method and exclusively naturally derived components. The influence of the surfactant concentration (0.5–1.1 wt% hydrolyzed soybean lecithin), the addition of a co-surfactant (2.6 wt% isoeugenol), thickener concentration (0.05–0.50 wt% guar gum), continuous-phase pH (3, 5, & 7), and active compound physicochemical properties was systematically evaluated. Emulsions containing 11 wt% terpene were prepared by water titration. Stable formulations were obtained at neutral pH using 1.1 wt% lecithin, 2.6 wt% isoeugenol and 0.5 wt% guar gum. Acidification reduced stability, associated with pH-dependent variations in surface charge and intermolecular interactions affecting both interfacial organization and bulk rheology. Differences in droplet size distribution and viscosity among terpenes highlight the role of active compound polar character in governing emulsion microstructure. Overall, this work demonstrates that stable, fully natural terpene-based emulsions can be rationally designed using low- energy methods, providing a formulation framework relevant to sustainable phytosanitary applications.

Development of a new polymeric formulation of rutin by supercritical antisolvent precipitation and evaluation of its nephroprotective capacity against cisplatin nephrotoxicity in rats

2026-03-11T09:36:47Z

Nephrotoxicity associated with antitumor drugs such as cisplatin is a well-documented clinical challenge. The intrinsic toxicity of these drugs is driving the search for renoprotective strategies. Currently, one of the most popular is the use of natural substances with antioxidant properties, such as flavonoids. Rutin is a member of this family whose nephroprotective properties have already been studied. However, its bioavailability is very low due to its high lipophilicity. Polymeric nanoparticle design is one of the possible strategies used to solve pharmacokinetic problems. The aim of this work was to design and develop a new polymeric formulation of rutin and to evaluate its nephroprotective capacity against cisplatin toxicity in an experimental rat model. Rutin was processed and coated with Eudragit® polymers using the Supercritical Anti Solvent (SAS) process. A successful micronization and coating of rutin was achieved. In vitro release studies of the formulations obtained demonstrated that pure SAS-processed rutin showed a higher solubility and dissolution rate that unprocessed rutin, and that rutin coated with Eudragit® polymers combined this increased solubilization with a controlled release. However, after administration of the formulation with the best in vivo properties obtained in rats, they did not show a significant nephroprotective capacity. The histological study confirmed the negative results obtained in the functional study. Although this formulation did not show significant nephroprotective effects in vivo, the study provides valuable insights into the limitations of current polymeric encapsulation strategies for rutin.

Molecular basis of changes in pasting and rheological properties of starches physically modified by microwave radiation

2026-03-05T20:01:57Z

This study investigates the effects of controlled microwave treatment (100 ◦C, 25% moisture, 30 min) on the molecular and rheological properties of pure starches (normal and waxy maize, normal and waxy rice, wheat, potato and tapioca). Structural changes were assessed through high-performance anion exchange chromatog- raphy with pulsed amperometric detection (HPAEC/PAD) to resolve amylopectin chain-length distributions, and size-exclusion chromatography with multi-angle light scattering, differential refractive index, and viscometric multi-detection (SEC/MALS-dRI-Visco) to determine amylose and amylopectin molecular parameters for both debranched and whole molecules. The impact of these changes on the pasting properties of starches and the viscoelasticity of their gels was established. Microwave treatment induced source-specific responses. Waxy starches showed increases in very short amylopectin chains and molecular degradation, with minimal rheological impact due to their low viscometric profile. Potato starch experienced the most pronounced rheological modi- fications despite minimal molecular degradation, suggesting supramolecular reorganisation, supported by an increase in amylopectin intrinsic viscosity. Wheat and tapioca starches exhibited moderate structural changes and enhanced gel stability, attributed to an increase of fractions comparable in size to long amylopectin chains. Rice starches displayed similar pasting and rheological responses, having amylopectin fine structure a pre- dominant role, while the absence of amylose in waxy rice favoured greater amylopectin hydrolysis. Correlation analyses linked amylose short/medium chains to parameters related to stronger and firmer gels. In contrast, short amylopectin chains correlated with weaker gels. These findings offer mechanistic insight into the potential of controlled microwave processing to tailor starch functionality in food systems.

Advances in microwave-induced physical modification of flours: From structural changes to product development

2025-12-15T09:30:20Z

Cereal-based products are staple foods in most human diets worldwide. Starch, the main component of cereals, is commonly modified to enhance its functionality and overcome its functional limitations. Physical hydrothermal treatment assisted by microwave (MW) radiation has recently gained considerable attention as an energy-efficient and cost-efficient alternative to traditional thermal methods. While most studies have focused on starch modification, the direct modification of flours and whole grains has emerged as a promising strategy for producing more nutrient-dense ingredients with enhanced functionality. In this context, the role of proteins, the second major biopolymers, and the interplay between endogenous components in determining the behaviour of complex starchy matrices is of great interest. This review explores recent advances in MW treatment of flours and grains, with particular emphasis on the structural and functional changes in starch and proteins, and the implications of these changes for product development. MW treatment has been shown to effectively alter the morphology and structure of both biopolymers. This led to modifications in functionality that varied depending on the botanical source and treatment conditions. These modifications effectively enhance the quality of cereal-based food products, particularly gluten-free bread. Overall, MW technology offers a promising green strategy for developing customised, functional ingredients tailored to specific dietary needs, with growing relevance to broader applications in the food industry.

Advanced characterization in molecularly imprinted Polypyrrole for potentiometric lactose sensing

2026-01-22T11:50:48Z

The motivation behind this study comes from the necessity to monitor lactose levels in milk for quality control and public health, as existing methods are often complex, time-consuming, and expensive. This research aims to develop a specific and sensitive potentiometric sensor for lactose detection using electropolymerised polypyrrole- based molecularly imprinted polymers (MIPs). MIP sensors were developed through chronoamperometric elec- tropolymerisation of pyrrole in the presence of lactose, creating specific binding sites. Raman spectroscopy, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM) were used to assess surface morphology confirming the presence of imprinted cavities and surface changes after lactose removal. The electrochemical performance of the sensors was evaluated by EIS spectroscopy demonstrating the influence of MIP cavities on the electron transfer of the sensor compared to non-imprinted polymer (NIP). Finally, open circuit potentials (OCP) in various lactose concentrations and real milk samples confirmed the high sensitivity and selectivity of the MIP sensors. Moreover, Principal Component Analysis (PCA), Partial Least Square Regression (PLS), and Support Vector Machine (SVM) models were satisfactorily employed to establish corre- lations between OCP measurements and lactose content, allowing its prediction in milk samples with an average error of 6 %. The results demonstrated that the MIP sensors exhibited high selectivity and sensitivity towards lactose, with improved responses compared to NIP sensors. The study concludes that polypyrrole-based MIPs provide a robust and effective approach for lactose detection and prediction in dairy products, offering a promising tool for quality control and ensuring consumer safety

Multilayer microcellular structures by steam-assisted one-step supercritical CO₂ foaming of PMMA

2025-10-14T19:01:15Z

In this work, we introduce a one-step steam-assisted supercritical CO₂ foaming process to create multilayer PMMA foams with tunable pore structures. The method operates entirely above the polymer’s effective glass transition temperature (125 ◦C), allowing saturation and foaming to take place simultaneously in a matter of minutes. By adding subcritical water before saturation, the system triggers a steam explosion during depres- surization, leading to much faster pressure drops (up to 40 % faster), improved nucleation, and a notable reduction in structural defects. As a result, foams with more uniform cells, finer pore sizes (2.3 μm), and lower densities (91 kg / m3; +10 X expansion) are obtained even at moderate pressures. A particularly interesting outcome is the formation of multilayer architectures: polymer pellets with different levels of CO₂ uptake fuse naturally into foams with distinct porosities across layers. This opens new opportunities for designing multi- functional materials, where different layers could be tailored for specific mechanical, thermal, or acoustic roles. The creation of multilayer is mostly attributed by the combination of one-step foaming above the Tg of the polymer together with a pellet sudden ejection from the autoclave while foaming and freezing the structure. Overall, the steam-assisted approach offers a scalable and energy-efficient pathway to produce polymer foams with customized microstructures and properties.

Collaborative Online International Learning (COIL) in chemical engineering: Preparing students for multicultural and international work environments

2025-10-08T19:01:25Z

In today’s interconnected society, chemical engineering students must be prepared to work in international and multicultural environments. However, in our experience, current chemical engineering curricula often fail to develop these competencies. This study aims to demonstrate the benefits of Collaborative Online International Learning (COIL) in chemical engineering education. For the first time, the COIL approach has been implemented in a simulation course. In addition to preparing students for international and multicultural work environments, this experience enhances their problem-solving and critical-thinking skills. Unlike other COIL applications, this project allows for multiple valid solutions, though not all are necessarily optimal. After two successful COIL projects involving chemical engineering students from the Universidad de Valladolid (Spain), the Universidad Nacional de Colombia, and the Universidad Aut´onoma de Nuevo Le´on (Mexico), students reported feeling more confident in their knowledge and abilities, better prepared for multicultural and international work environ- ments, and more capable of performing well in their first job. In both project editions, survey responses to related questions averaged above 4 out of 5. Key takeaways from this work are that, to accomplish the objectives of a COIL, it is essential to define the project timeline in advance, ensure a similar level of knowledge among students, confirm software access, establish a unified communication platform, and conduct individual kickoff meetings for each team. Additionally, effective international collaboration is more likely when no more than 50 % of a team’s members come from the same institution

Pulp and peel breadfruit flours as techno-functional ingredients. Rheological and staling behavior of their gels

2026-01-15T08:08:43Z

Breadfruit represents an exceptional nutritional source. However, its potential as a techno-functional food ingredient remains largely unexplored. In this context, this study aimed to produce and characterize flours derived from breadfruit (BF) pulp and peel in terms of their physical, techno-functional, pasting and rheological properties. Banana flour was used as a reference for comparison purpose. BF flours formed heat-stable gels at a 4 % concentration, double the threshold required for banana flour, with higher water absorption capacity (+68 %), swelling power (+75 %), and five-fold lower solubility than banana flour. BF-pulp flour demonstrated 10 % higher emulsifying activity and 60 % higher emulsion stability. Additionally, it showed a higher pasting tem- perature, increased final viscosity (+24 %), and substantially lower breakdown viscosity ( 75 %) compared to banana. All gels exhibited pseudoplastic flow behavior, with BF-pulp presenting the highest consistency index and thixotropy. Dynamic oscillatory tests revealed superior viscoelastic properties in BF-gels, with storage and loss moduli exceeding those of banana gel at equivalent concentrations. Retrogradation kinetics showed faster amylopectin recrystallization in BF gels, in particular those from BF-pulp flour, compared to banana gel, sug- gesting an earlier achievement of structural stability during storage. In contrast, banana gels exhibited a higher leveling-off retrogradation enthalpy, reflecting a firmer and more stable texture over long-term storage. These findings position BF-pulp flour as a high-performance hydrocolloid, offering enhanced gel strength and emulsion stability, suitable for gluten-free sauces or bakery fillings. Meanwhile, the lower viscosity and unique shear rheology of BF-peel flour may benefit low-viscosity applications. The distinct viscometric and staling profiles exhibited by BF-samples enable the design of novel foods with a wide range of textures.

Molecular and structural changes in starch and proteins induced by microwave treatment and their effect on pasting properties. A study on amaranth, buckwheat, quinoa, and sorghum in grain and flour form

2026-01-14T12:28:52Z

This study investigated the effects of microwave treatment (MWT) on the molecular structure and properties of starch and proteins, as well as on the pasting properties of flours. MWT was performed under uniform conditions (25 % moisture, 100 ◦C, 30 min) for amaranth, buckwheat, quinoa, and sorghum in two forms: grain and flour. MWT generally caused fragmentation of amylose and amylopectin, reducing amylopectin molar mass by up to 39 % and amylose long chains by up to 18 %, disrupting protein secondary structure (α-helix content up to 5 %), and altering morphology of starch granules and protein. All flours presented an orthorhombic crystal structure that was maintained after MWT. MWT changes were generally more pronounced in flour than in grain treatments, with amaranth showing the greatest change and buckwheat the least. Microwave-induced changes in pasting properties depended on intrinsic flour properties and structural modifications. Principal component analysis revealed a consistent change in all treated samples, but to varying degrees depending on botanical origin and treatment form. This study contributes to a deeper understanding of structural changes of starch and proteins by MWT and their contribution to altered pasting properties depending on whether the treatment is applied to grain or flour.

Molecular modifications in cereal and tuber starches induced by microwave treatment: A comprehensive analysis using asymmetric flow field-flow fractionation

2025-12-03T07:49:43Z

This study investigated the impact of microwave treatment (MWT) on the molecular structure of starches from cereal (normal and waxy rice, normal and waxy maize, and wheat) and tuber (potato and tapioca) sources using asymmetric flow field-flow fractionation (AF4) coupled with multi-angle light scattering and differential refractive index detectors. The starches were treated under the same conditions (7.5 W/g, 25 % moisture, 100 ◦C, 30 min). In addition to conventional parameters such as number- and weight-average molecular masses, radii, and dispersity, novel metrics, including mass-to-radius ratios, apparent density, and concentration profiles related to molecular mass, were employed to elucidate structural transformations. The results revealed that non- waxy cereal starches exhibited greater resistance to hydrolysis owing to higher structural compaction, whereas waxy cereals experienced homogenisation of molecular radii and apparent density. In contrast, tuber starches, particularly potato, underwent molecular aggregation, forming homogeneous structures with low dispersity and a high concentration of large particles. This study introduces a novel approach for evaluating and understanding the molecular structural modifications in starch induced by MWT and how the original matrix affects these modifications, providing valuable insights for future research and applications of this physical modification process

Measurement of high-pressure properties for aqueous solutions of amines: Densities and isobaric heat capacities of 3-(methylamino)propylamine and 1-methylpiperazine binary mixtures

2025-11-25T07:49:26Z

The density and isobaric heat capacity of 3-(methylamino)propylamine (MAPA) + H2O and 1-methylpiperazine (1-MPZ) + H2O mixtures were measured using a vibrating tube densimeter and a flow calorimeter, respectively. Density measurements were carried out with a relative expanded uncertainty of 0.1 % (k = 2) over a wide range of temperatures (from 293.15 K to 393.15 K), pressure up to 100 MPa, and amine mass fractions of 0.1, 0.2, 0.3, and 0.4. Isobaric heat capacity experimental data was acquired with a relative expanded uncertainty better than 1 % (k = 2). These measurements reached pressures up to 25 MPa and temperatures from 293.15 K to 353.15 K, in the same amine mass fractions compositions. A modified Tammann-Tait empirical equation was used to develop density correlation as a function of temperature, pressure, and molality. Additionally, an empirical function of temperature and amine mass fraction was used to fit the isobaric heat capacity data. Both correlations showed good agreement with the experimental data of the aqueous amine solutions under study, within 0.1 % for density correlation and 1 % for isobaric heat capacity correlation. Compared to the limited experimental data found in literature, the deviations observed were smaller than the reported uncertainties.

On the use of neural networks for the structural characterization of polymeric porous materials

2025-02-26T10:43:55Z

The structural characterization is an essential task in the study of porous materials. To achieve reliable results, it requires to evaluate images with hundreds of pores. Current methods require large time amounts and are subjected to human errors and subjectivity. A completely automatic tool would not only speed up the process but also enhance its reliability and reproducibility. Therefore, the main objective of this article is the study of a deep-learning-based technique for the structural characterization of porous materials, through the use of a convolutional neural network. Several fine-tuned Mask R–CNN models are evaluated using different training configurations in four separate datasets each composed of numerous SEM images of diverse polymeric porous materials: closed-pore extruded polystyrene (XPS), polyurethane (PU), and poly(methyl methacrylate) (PMMA), and open-pore PU. Results prove the tool capable of providing very accurate results, equivalent to those achieved by time-consuming manual methods, in a matter of seconds.

Effect of nanoclays on the electrochemical performance of LbL catechol sensors

2024-02-08T20:03:00Z

Halloysite nanotubes (HNTs) are excellent candidates to improve the immobilization of electroactive materials or enzymes due to their tubular structure and properties. In this work, an improved LbL based catechol sensor has been developed using a combination of sensing materials with complementary activity. These include sulfonated copper phthalocyanine (CuPcSO3−) acting as electrocatalytic material, poly(ethyleneimine) (PEI) to increase the charge injection efficiency and the increase of the surface provided by HNTs. The LbL film has been used as the sensing platform to deposit tyrosinase in order to further enhance the performance of the developed sensor towards catechol. The LbL films were characterized by using UV–Vis, FTIR and cyclic voltammetry. The limits of detection, repeatability and reproducibility of the sensors and the biosensor were evaluated. The limits of detection were 1.23 μmol·L−1 for the optimized (PEI/CuPcSO3−) sensor, 0.987 μmol·L−1 for the (PEI/HNT/PEI/CuPcSO3−) sensor and 0.938 μmol·L−1 for the (PEI/HNT/PEI/CuPcSO3−)-Tyrosinase sensor.