Development of bio-based chitosan films with incorporated chestnut extract

Hydrolysable tannins have prominent biological activity and thus their industrial application is gaining importance in many fields. This study explored the possibility for the utilization of a commercially available chestnut extract (CE) as an active component in chitosan-based films intended for food packaging. Therefore, a set of chitosan-based films with incorporated CE was prepared and evaluated regarding physicochemical properties. The estimated total phenolic content (TPC) has revealed a maximal value of 19.5 mgGAE gfilm-1. Moreover, the moisture content (MC) in the films has decreased (from 29.6% to 18.6%), while tensile strength (TS) has increased (from 13.5 MPa to 48.5 MPa) after the incorporation of CE. The observed coherence between TPC and evaluated properties has been confirmed by the existence of strong negative and positive linear correlations in the case of MC and TS, respectively. In large, CE extract was found to be a promising candidate as an active component in chitosan-based films

Biodegradability study of active chitosan biopolymer films enriched with Quercus polyphenol extract in different soil types

One of the recent trends within the circular economy is the development of materials derived from food processing waste and their utility as an alternative to plastic packaging. In this context, the study aims to evaluate biological causes of deterioration or degradation of chitosan-based films with and without incorporated natural Quercus polyphenol extract in three different types of soils (industrial compost, commercial garden soil, and soil from a vineyard). Degradation and active properties deterioration was followed by measurement of the loss of mass of tested active films for 14 days, and it was accompanied by other analytical techniques such as measurement of polyphenolic content, FT-IR analysis, and SEM examination of the packaging morphology. The results showed that chitosan-based film properties deteriorate in less than 3 days followed by biodegradation in all tested soils after 14 days. Films with incorporated Quercus polyphenol extract undergo deterioration of active properties in compost and garden soil in 6 days, while the fractionation and degradation process has not been complete in the vineyard soil during the 14 days. Furthermore, it has also been revealed that the addition of water to the soil decreased the rate of active chitosan film biodegradation in the terrestrial environment

Reduction in Spoilage Microbiota and Cyclopiazonic Acid Mycotoxin with Chestnut Extract Enriched Chitosan Packaging: Stability of Inoculated Gouda Cheese

Active chitosan-based films, blended with fibrous chestnut (Castanea sativa Mill.) tannin-rich extract were used to pack Gouda cheese that has been contaminated with spoilage microflora Pseudomonas fluorescens, Escherichia coli, and fungi Penicillium commune. A comprehensive experimental plan including active chitosan-based films with (i) chestnut extract (CE), (ii) tannic acid (TA), and (iii) without additives was applied to evaluate the film′s effect on induced microbiological spoilage reduction and chemical indices of commercial Gouda cheese during 37 days while stored at 4 °C and 25 °C, respectively. The cheese underwent microbiology analysis and chemical assessments of ultra-high-performance liquid chromatography (UHPLC) (cyclopiazonic acid), pH, and moisture content. The biopackaging used for packing cheese was characterized by mechanical properties before food packaging and analyzed with the same chemical analysis. The cheese microbiology showed that the bacterial counts were most efficiently decreased by the film without additives. However, active films with CE and TA were more effective as they did not break down around the cheese and showed protective properties against mycotoxin, moisture loss, and pH changes. Films themselves, when next to high-fat content food, changed their pH to less acidic, acted as absorbers, and degraded without plant-derived additives

Going Beyond Silver in Ethylene Epoxidation with First-Principles Catalyst Screening

Ethylene epoxidation is industrially and commercially one of the most important selective oxidations. Silver catalysts have been state-of-the-art for decades, their efficiency steadily improving with empirical discoveries of dopants and co-catalysts. Herein, we perform a computational screening of the metals in the periodic table, identify prospective superior catalysts and experimentally demonstrate that Ag/CuPb, Ag/CuCd and Ag/CuTl outperform the pure-Ag catalysts, while they still confer an easily scalable synthesis protocol. Furthermore, we show that to harness the potential of computationally-led discovery of catalysts fully, it is essential to include the relevant in situ conditions e.g., surface oxidation, parasitic side reactions and ethylene epoxide decomposition, as neglecting such effects leads to erroneous predictions. We combine ab initio calculations, scaling relations, and rigorous reactor microkinetic modelling, which goes beyond conventional simplified steady-state or rate-determining modelling on immutable catalyst surfaces. The modelling insights have enabled us to both synthesise novel catalysts and theoretically understand experimental findings, thus, bridging the gap between first-principles simulations and industrial applications. We show that the computational catalyst design can be easily extended to include larger reaction networks and other effects, such as surface oxidations. The feasibility was confirmed by experimental agreement

From waste/residual marine biomass to active biopolymer-based packaging film materials for food industry applications- A review

Waste/residual marine biomass represents a vast and potentially underexplored source of biopolymers chitin/- chitosan and alginate. Their isolation and potential application in the development and production of bio-based food packaging are gaining in attractiveness due to a recent increment in plastic pollution awareness. Accordingly, a review of the latest research work was given to cover the pathway from biomass sources to biopolymers isolation and application in the development of active (antimicrobial/antioxidant) film materials intended for food packaging. Screening of the novel eco-friendly isolation processes was followed by an extensive overview of the most recent publications covering the chitosan- and alginate-based films with incorporated active agents

3D printed catalytic reactors for aerobic selective oxidation of benzyl alcohol into benzaldehyde in continuous multiphase flow

In this work, novel, patterned monolithic reactors were devised to explore more efficient routes for reactant conversion in order to investigate their potential to replace the packed bed and batch reactors conventionally employed in chemical industries. Well-defined bimetallic formulations were developed to substitute platinum group metals and critical raw materials such as palladium and cobalt, at least in part, by less active, but more sustainable and cost-effective metals such as earth-abundant iron. FePd and FeCo based monoliths were 3D printed and stacked in a continuous flow tubular reactor for testing the selective oxidation of benzyl alcohol (BA) into benzaldehyde (BZ) under mild conditions (80–100 °C and atmospheric pressure). The novel monolithic reactors were evaluated against current state-of-the-art reactor technologies, conventional packed bed and batch reactors. The FeCo- and FePd-Al2O3-supported monolithic catalyst beds showed higher conversion and TOF than their packed bed counterparts under the same operating conditions, revealing the impact of the novel design on both regular geometry and composition. What is of particular interest in the catalytic measurements shown is that the combined stacking of two monoliths in a flow reactor, Al2O3-supported Fe and GO-supported FePd catalysts, can significantly improve the performance with an increase in TOF of up to 90% in comparison to their FePd analogues. Mathematical modelling was used to obtain additional insights into the physical and chemical processes governing the rate of BA conversion. It was found that due to the flow regime inside the microchannels, an axial dispersion model was appropriate, which allowed for mapping the concentration profiles of the reactants and products within the respective monolith geometries

3D printed catalytic reactors for aerobic selective oxidation of benzyl alcohol into benzaldehyde in continuous multiphase flow

In this work, novel, patterned monolithic reactors were devised to explore more efficient routes for reactant conversion in order to investigate their potential to replace the packed bed and batch reactors conventionally employed in chemical industries. Well-defined bimetallic formulations were developed to substitute platinum group metals and critical raw materials such as palladium and cobalt, at least in part, by less active, but more sustainable and cost-effective metals such as earth-abundant iron. FePd and FeCo based monoliths were 3D printed and stacked in a continuous flow tubular reactor for testing the selective oxidation of benzyl alcohol (BA) into benzaldehyde (BZ) under mild conditions (80–100 °C and atmospheric pressure). The novel monolithic reactors were evaluated against current state-of-the-art reactor technologies, conventional packed bed and batch reactors. The FeCo- and FePd-Al2O3-supported monolithic catalyst beds showed higher conversion and TOF than their packed bed counterparts under the same operating conditions, revealing the impact of the novel design on both regular geometry and composition. What is of particular interest in the catalytic measurements shown is that the combined stacking of two monoliths in a flow reactor, Al2O3-supported Fe and GO-supported FePd catalysts, can significantly improve the performance with an increase in TOF of up to 90% in comparison to their FePd analogues. Mathematical modelling was used to obtain additional insights into the physical and chemical processes governing the rate of BA conversion. It was found that due to the flow regime inside the microchannels, an axial dispersion model was appropriate, which allowed for mapping the concentration profiles of the reactants and products within the respective monolith geometries

A multi-scale study of 3D printed Co-Al2O3 catalyst monoliths versus spheres

This study demonstrates the characteristics of two model packing configurations: 3D printed (3DP) catalyst monoliths on the one hand, and their conventional counterparts, packed beds of spheres, on the other. Cobalt deposited on alumina is selected as a convenient model system for this work, due to its wide spread use in many catalytic reactions. 3DP constructs were produced from alumina powder impregnated with cobalt nitrate while the alumina spheres were directly impregnated with the same cobalt nitrate precursor. The form of the catalyst, the impregnation process, as well as the thermal history, were found to have a significant effect on the resulting cobalt phases. Probing the catalyst bodies in situ by XRD-CT indicated that the level of dispersion of identified Co phases (Co3O4 reduced to CoO) across the support is maintained under reduction conditions. The packed bed of spheres exhibits a non-uniform distribution of cobalt phases, including a core-shell morphology with an average crystallite size of 10–14 nm across the sphere, while the 3DP monolith exhibits a uniform distribution of cobalt phases with an average crystallite size of 5–12 nm upon reduction from Co3O4 to CoO. Computational Fluid Dynamics (CFD) modelling was carried out to develop digital twins and assess the effect of the geometry of both configurations on the pressure drop and velocity profiles. Finally, the activity of both Cobalt-based catalyst geometries was assessed in terms of their conversion, selectivity and turn over frequencies under model multiphase (selective oxidation) reaction conditions, which showed that the desired 3D printed monolithic geometries can offer distinct advantages to the reactor design

3D printed SrNbO2N photocatalyst for degradation of organic pollutants in water

Organic pollutants in water are a major concern for the environment and human health, and require urgent attention. Here, we developed for the first time monolithic structures by 3D printing of perovskite metal oxynitride, SrNbO2N, for photocatalytic degradation of organic pollutant in water. Advanced, synchrotron-based XRD-CT measurements were employed to gain structural insight into photocatalyst formulation and assess the fidelity of design in terms of both the chemical and physical form of the photocatalysts to be imaged. Our 3D printed material showed excellent photocatalytic activity, degrading 100% of methylene blue (MB) as well as good stability for three cycle operations. This is due to high adsorption of the 3D printed oxynitride towards MB which enhanced its photoredox reactivity. It is also evident from the excellent charge transfer demonstrating a charge transfer rate of (1.5 ± 0.2) × 108 s−1. We performed Time-Dependent Density Functional Theory (TD-DFT) calculations to understand the photocatalyst structure and degradation pathways. Our calculated band gap (at Γ) of 1.88 eV is in good agreement with the experimental values. We found that the highest valence bands were contributed by N p orbitals and the lowest conduction bands corresponded to Nb d orbitals offering avenues for fine-tuning the band gap. Hence, the ability to tailor photocatalyst monoliths by 3D printing renders their water treatment application more facile compared to their powder suspension counterparts

3D printed SrNbO₂N photocatalyst for degradation of organic pollutants in water

Organic pollutants in water are a major concern for the environment and human health, and require urgent attention. Here, we developed for the first time monolithic structures by 3D printing of perovskite metal oxynitride, SrNbO2N, for photocatalytic degradation of organic pollutant in water. Advanced, synchrotron-based XRD-CT measurements were employed to gain structural insight into photocatalyst formulation and assess the fidelity of design in terms of both the chemical and physical form of the photocatalysts to be imaged. Our 3D printed material showed excellent photocatalytic activity, degrading 100% of methylene blue (MB) as well as good stability for three cycle operations. This is due to high adsorption of the 3D printed oxynitride towards MB which enhanced its photoredox reactivity. It is also evident from the excellent charge transfer demonstrating a charge transfer rate of (1.5 ± 0.2) × 108 s−1. We performed Time-Dependent Density Functional Theory (TD-DFT) calculations to understand the photocatalyst structure and degradation pathways. Our calculated band gap (at Γ) of 1.88 eV is in good agreement with the experimental values. We found that the highest valence bands were contributed by N p orbitals and the lowest conduction bands corresponded to Nb d orbitals offering avenues for fine-tuning the band gap. Hence, the ability to tailor photocatalyst monoliths by 3D printing renders their water treatment application more facile compared to their powder suspension counterparts