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Abstract: Cellulose nanofibrils (CNFs) are promising materials for flexible and green supercapacitor electrodes, while Ti3C2Tx MXene exhibits high specific capacitance. However, the diffusion limitation of ions and chemical instability in the generally used highly basic (KOH, MXene oxidation) or acidic (H2SO4, CNF degradation) electrolytes limits their performance and durability. Herein, freestanding CNF/MXene cryogel membranes were prepared by deep freeze-casting (at −50 and −80 ◦C), using different weight percentages of components (10, 50, 90), and evaluated for their structural and physico-chemical stability in other less aggressive aqueous electrolyte solutions (Na2/Mg/Mn/K2-SO4, Na2CO3), to examine the influence of the ions transport on their pseudocapacitive properties. While the membrane prepared with 50 wt% (2.5 mg/cm2 ) of MXene loading at −80 ◦C shrank in a basic Na2CO3 electrolyte, the capacitance was performed via the forming of an electroactive layer on its interface, giving it high stability (90% after 3 days of cycling) but lower capacitance (8 F/g at 2 mV/s) than in H2SO4 (25 F/g). On the contrary, slightly acidic electrolytes extended the cations’ transport path due to excessive but still size-limited diffusion of the hydrated ions (SO4 2− > Na+ > Mn2+ > Mg2+) during membrane swelling, which blocked it, reducing the electroactive surface area and lowering conductivities (<3 F/g).
Keywords: cellulose nanofibrils, Ti3C2Tx MXene, freeze-casting, aqueous electrolytes, physico-chemical properties, electric double layer, pseudocapacitance
Published in DKUM: 07.04.2025; Views: 0; Downloads: 5
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Abstract: Low-cost, readily available, or even disposable membranes in water purification or downstream biopharma processes are becoming attractive alternatives to expensive polymeric columns or filters. In this article, the potential of microfiltration membranes prepared from differently orientated viscose fibre slivers, infused with ultrafine quaternised (qCNF) and amino-hydrophobised (aCNF) cellulose nanofibrils, were investigated for capturing and deactivating the bacteria from water during vacuum filtration. The morphology and capturing mechanism of the single- and multi-layer structured membranes were evaluated using microscopic imaging and colloidal particles. They were assessed for antibacterial efficacy and the retention of selected bacterial species (Escherichia coli, Staphylococcus aureus, Micrococcus luteus), differing in the cell envelope structure, hydrodynamic biovolume (shape and size) and their clustering. The aCNF increased biocidal efficacy significantly when compared to qCNF-integrated membrane, although the latter retained bacteria equally effectively by a thicker multi-layer structured membrane. The retention of bacterial cells occurred through electrostatic and hydrophobic interactions, as well as via interfibrous pore diffusion, depending on their physicochemical properties. For all bacterial strains, the highest retention (up to 100% or log 6 reduction) at >50 L/h∗bar∗m2 flow rate was achieved with a 4-layer gradient-structured membrane containing different aCNF content, thereby matching the performance of industrial polymeric filters used for removing bacteria.
Keywords: fibrous membrane, cationised cellulose nanofibrils, amino-hydrophobised cellulose nanofibrils, antibacterial activity, multi-layer structure, flux, bacteria retention
Published in DKUM: 28.03.2024; Views: 220; Downloads: 12
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Keywords: tekstilni materiali, funkcionalno gradientni materiali, barierne membrane, bioaktivne membrane, protimikrobne lastnosti
Published in DKUM: 27.05.2020; Views: 1266; Downloads: 54
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Abstract: World is facing numerous environmental challenges, one of them being the increasing pollution both in the atmosphere and landfills. After the goods have been used, they are either buried or burnt. Both ways of disposal are detrimental and hazardous to the environment. The term biodegradation is becoming more and more important, as it converts materials into water, carbon dioxide and biomass, which present no harm to the environment. Nowadays, a lot of research is performed on the development of biodegradable polymers, which can “vanish” from the Earth surface after being used. In this respect, this research work was conducted in order to study the biodegradation phenomenon of cellulosic and non-cellulosic textile materials when buried in soil, for them to be used in our daily lives with maximum efficiency and after their use, to be disposed of easily with no harmful effects to the environment. This research indicates the time span of the use life of various cellulosic and non-cellulosic materials such as cotton, jute, linen, flax, wool when used for the reinforcement of soil. The visual observations and applied microscopic methods revealed that the biodegradation of cellulose textile materials proceeded in a similar way as for non-cellulosic materials, the only difference being the time of biodegradation. The non-cellulosic textile material (wool) was relatively more resistant to microorganisms due to its molecular structure and surface.
Keywords: biodegradation, composting, natural textile materials, FT-IR
Published in DKUM: 21.12.2015; Views: 1431; Downloads: 415
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Published in DKUM: 10.07.2015; Views: 2424; Downloads: 37
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