14 research outputs found

    Effect of copper and titanium-exchanged montmorillonite nanostructures on the packaging performance of chitosan/poly-vinyl-alcohol-based active packaging nanocomposite films

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    In this study, CuMt and TiMt montmorillonites were produced via an ion-exchange process with Cu+ and Ti4+ ions. These nanostructured materials were characterized with X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) measurements and added as nanoreinforcements and active agents in chitosan (CS)/poly-vinyl-alcohol (PVOH)-based packaging films. The developed films were characterized by XRD and FTIR measurements. The antimicrobial, tensile, and oxygen/water-barrier measurements for the evaluation of the packaging performance were carried out to the obtained CS/PVOH/CuMt and CS/PVOH/TiMt films. The results of this study indicated that CS/PVOH/CuMt film is a stronger intercalated nanocomposite structure compared to the CS/PVOH/TiMt film. This fact reflected higher tensile strength and water/oxygen-barrier properties. The antibacterial activity of these films was tested against four food pathogenic bacteria: Escherichia coli, Staphylococcus aureus, Salmonella enterica and Listeria monocytogenes. Results showed that in most cases, the antibacterial activity was generated by the CuMt and TiMt nanostructures. Thus, both CS/PVOH/CuMt and CS/PVOH/TiMt films are nanocomposite candidates with very good perspectives for future applications on food edible active packaging. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

    Efficient and Rapid Photocatalytic Reduction of Hexavalent Chromium Achieved by a Phloroglucinol-Derived Microporous Polymeric Organic Framework Solid

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    A microporous polymeric organic framework (POF) based on phloroglucinol (phlo-POF) was for the first time evaluated on photoreduction and removal processes of hexavalent chromium (Cr6+) from aqueous solutions. The phlo-POF synthesis was based on reaction of phloroglucinol and terephthalaldehyde under hydrothermal conditions. Structural and chemical characterization was performed using UV-vis-NIR diffuse reflectance spectroscopy (DRS), FT-infrared spectroscopy, and thermogravimetric methods, while surface area analysis was employed to determine other physical and surface properties. Batch experiments were conducted on contaminated water to determine the rate and extent of Cr6+ removal and its immobilization by the phlo-POF material. The kinetic studies showed a rapid removal of Cr6+ ions from the water in the presence of the phlo-POF, best described by the zero-order kinetic model. The efficiency of the material with UV-C irradiation on Cr6+ reduction was compared with a well-studied material, the Degussa P-25 TiO2 catalyst, and found to be ∼200% higher. Cycle experiments verify the successful reuse of the phlo-POF photocatalyst for at least ten times for Cr6+ reduction

    The use of activated bio-carbon derived from “Posidonia oceanica” sea-waste for Lithium-Sulfur batteries development

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    Lithium-Sulfur Batteries is promising energy storage systems due to their superior capacity and energy density. A promising solution for drawbacks such as low sulfur utilization and cycling stability is the use of porous carbon as sulfur carrier. On the other hand, cyclic economy and green ideas is of great importance nowadays. Carbon-sulfur cathodes from waste valorization, abundant, and low-cost precursors is an attractive approach. Herein, an activated carbon (AC-Poc) derived from "Posidonia oceanica" sea-waste, was studied as a matrix for the development of a novel carbon-sulfur composite cathode (AC-Poc/S) for the first time. AC-Poc can be used as an effective sulfur host, due to its high specific BET surface area (1264 m(2).g(-1)) hierarchical porous structure, and total pore volume 0.81 cm(3).g(-1). AC-Poc/S reveals an outstanding initial capacity of 1539 mAh.g(-1) as cathode material, combined with high reversible capacity at 0.2 C. Furthermore, the discharge capacity of 390 mAh/g at 2 C reveals good rate capability, even at increased C-rate. AC-Poc/S composite exhibits excellent sulfur utilization (92 %) alongside with sufficiently well electrochemical performance. These results combined with the easy synthesis method of the activated carbon from an abundant and low-cost precursor make AC-Poc/S a very promising material for LSBs applications.Web of Science53art. no. 10274

    Performance of Thyme Oil@Na-Montmorillonite and Thyme Oil@Organo-Modified Montmorillonite Nanostructures on the Development of Melt-Extruded Poly-L-lactic Acid Antioxidant Active Packaging Films

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    Today, the use of natural biodegradable materials in the production processes is more and more adopted by industry to achieve cyclic economy targets and to improve environmental and human health indexes. Active packaging is the latest trend for food preservation. In this work, nanostructures were prepared by incorporation of thyme oil with natural natrium-montmorillonite and organo-montmorillonite with two different techniques, direct impregnation and the green evaporation–adsorption process. Such nanostructures were mixed with poly-L-lactic-acid for the first time via an extrusion molding process to develop a new packaging film. Comparisons of mor-phological, mechanical, and other basic properties for food packaging were carried out via XRD, FTIR, TG, SEM/EDS, oxygen and water vapor permeation, and antimicrobial and antioxidant activity for the first time. Results showed that poly-L-lactic-acid could be modified with clays and essential oils to produce improved active packaging films. The final product exhibits food odor prevention characteristics and shelf-life extension capabilities, and it could be used for active packaging. The films based on OrgMt clay seems to be more promising, while the thyme oil addition improves their behavior as active packaging. The PLLA/3%TO@OrgMt and PLLA/5%TO@OrgMt films were qualified between the tested samples as the most promising materials for this purpose. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
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