Browsing by Subject "Composite membranes"

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    Process intensification through enzymatic decomposition of urea with simultaneous recovery of ammonia
    (Elsevier Ltd, 2024) Yurekli Y.; Zhang T.; Qiu F.
    Urea in the human body and in municipal wastewater discharges above safe limit can impair the human health and adversely affect the environment. Innovative technologies for sustainable urea recovery are widely recognized as a necessity. In this study, multifunctional enzymatic composite membranes comprised of zeolite nanoparticles dispersed in sulfonated polysulfone (S2PSf) ultrafiltration membranes and urease enzyme deposited by layer-by-layer self-assembly method on the rear surface and in the pores have been fabricated. The proposed architecture offers biocatalytic reaction, ion exchange, and filtration mechanisms sequentially to first degrade urea by the urease catalyzed reaction and recover the released ammonium cations by the zeolite nanoparticles (NPs) within the membrane under continuous flow mode. Zeolite (NaX) NPs were synthesized with environmentally friendly approach and then characterized in detail. The batch mode of adsorption results revealed that the NaX NPs had an uptake of 62.3 mg/g for NH4+-N. It was also found that the mixed matrix membrane (MMM) was more effective than the powdered NaX under similar batch operation. The hydraulic permeability of the MMM compared to the PSf membrane (0.3 L/m2.h.bar) was significantly improved to 335 L/m2.h.bar, but the addition of polyethyleneimine and urease in subsequent modifications reduced the permeability to 152 L/m2.h.bar. The continuous removal of ammonium cations during filtration resulted in a higher catalytic activity of the S2PSf-10Z-PEI-URE membrane compared to the batch mode under similar conditions. However, due to the short residence time in the flow-through mode, the sorption capacity of the membrane was greatly reduced. This study demonstrates a practical tool for the complete recycling of urea contained wastewater, and further development for the applications in hemodialysis and recycling of the astronaut urine during long-term space flight. © 2024 Elsevier Ltd
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    Biological and mechanical evaluation of cinnamaldehyde doped liquid crystal-polymer composite membranes
    (Taylor and Francis Ltd., 2024) Seylan Akış M.; Kemiklioglu E.; Kemiklioğlu U.
    In this study cinnamaldehyde (CA) doped polyurethane cholesteryl pelargonate cholesteric liquid crystal composite membranes were produced and their properties were examined for use in biological applications. The relationship between the blood coagulation and protein adsorption was studied and the results showed that increasing CA concentration allowed an improvement in biological properties of them. Additionally, the effect of CA on the hyrophobicity of these membranes was investigated by determining water holding capacity, contact angles. The mechanical strength of these membranes were determined and it was found that their strength increased and the ability to elongate decreased with an increasing CA dopant concentration. © 2023 Taylor & Francis Group, LLC.