1. Extending the protection ability and life cycle of medical masks through the washing processJulija Volmajer Valh, Tanja Pušić, Mirjana Čurlin, Ana Knežević, 2023, original scientific article Abstract: The reuse of decontaminated disposable medical face masks can contribute to reducing the environmental burden of discarded masks. This research is focused on the effect of household and laboratory washing at 50 °C on the quality and functionality of the nonwoven structure of polypropylene medical masks by varying the washing procedure, bath composition, disinfectant agent, and number of washing cycles as a basis for reusability. The barrier properties of the medical mask were analyzed before and after the first and fifth washing cycle indirectly by measuring the contact angle of the liquid droplets with the front and back surface of the mask, further by measuring air permeability and determining antimicrobial resistance. Additional analysis included FTIR, pH of the material surface and aqueous extract, as well as the determination of residual substances—surfactants—in the aqueous extract of washed versus unwashed medical masks, while their aesthetic aspect was examined by measuring their spectral characteristics. The results showed that household washing had a stronger impact on the change of some functional properties, primarily air permeability, than laboratory washing. The addition of the disinfectant agent, didecyldimethylammonium chloride, contributes to the protective ability and supports the idea that washing of medical masks under controlled conditions can preserve barrier properties and enable reusability.
Keywords: medical masks, washing, detergent, didecyldimethylammonium chloride, air permeability, antimicrobial activity, residuals
Published in DKUM: 15.03.2024; Views: 333; Downloads: 19
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2. Sustainability-oriented surface modification of polyester knitted fabrics with chitosanTanja Pušić, Tea Bušac, Kristina Šimić, Mirjana Čurlin, Ana Šaravanja, Katia Grgić, Julija Volmajer Valh, 2024, original scientific article Abstract: The existing research deals with the process of modifying polyester knitted fabrics and polyester/cotton knitted fabrics with chitosan and the stability of functionalized surface with chitosan in the washing process according to a standard and an innovative washing procedure. The current research concept aims to evaluate the degree of progressivity and progressiveness: the modification of polyester knitted fabrics with chitosan and an innovative washing process. The polyester and polyester/cotton fabrics modified with chitosan were characterized by a staining test, microscopic analysis, zeta potential measurement, and pilling tendency of the knitted fabrics before and after five and ten washing cycles with reference detergent ECE A. The results of the zeta potential measurement of knitted fabrics functionalized with chitosan confirmed cationization of the polyester and polyester/cotton fabric with chitosan. The presence of chitosan on the washed knitted fabrics in reduced quantities is demonstrated by the staining test, the colour strength (K/S), and the zeta potential values. The staining test and surface charge of the tested knitted fabrics confirmed the research hypothesis regarding the degree of progressivity of the modification of polyester and polyester/cotton knitted fabrics with chitosan and the sustainability of the innovative washing process. The streaming potential proved to be a favorable method for monitoring the stability of chitosan in the washing process in combination with a staining test with the selected dye Remazol Red RB.
Keywords: knitted fabrics, polyester, polyester/cotton, chitosan, washing, surfaces
Published in DKUM: 05.02.2024; Views: 285; Downloads: 21
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3. Obdelava tekstilnih odpadnih voda z membranskim bioreaktorjemIrena Petrinić, Jasmina Korenak, Marjana Simonič, Mirjana Čurlin, 2010, original scientific article Abstract: Uporaba membranskega bioreaktorja (MBR), ki pomeni biološko razgradnjo odpadnih voda z aktivnim blatom v kombinaciji s fizikalnim procesom membranske filtracije, je postala zanimiva predvsem zaradi številnih prednosti pri čiščenju tekstilnih odpadnih voda in hitrega razvoja v zadnjem desetletju. Namen dela je bil očistiti modelno odpadno vodo z membranskim bioreaktorjem ter določiti njegovo učinkovitost čiščenja modelne tekstilne odpadne vode, pripravljene v laboratoriju po recepturi iz industrije. Cilj je bil vzpostaviti obratovalne razmere in stabilnost celotnega sistema, ki bi dal maksimalen izkoristek čiščenja z želeno kakovostjo očiščene vode. S spremljanjem obratovalnih parametrov, kot so pretok vhodne odpadne vode, dovajanje kisika v biološki del obdelave ter spremljanje tlaka ultrafiltracije, smo nameravali zagotoviti optimalne obratovalne razmere. S fizikalno-kemijskimi analizami smo dokazali, da so se vrednosti KPK in koncentracije barvila, izražene kot spektralni absorpcijski koeficient (SAK), znižale, in sicer za 70 do 90 odstotkov. Iz rezultatov je razvidno, da je bila učinkovitost znižanja KPK okoli 90-odstotna, učinkovitost znižanja vsebnosti barvil pa doseže do 97 odstotkov. Iz navedenega lahko povzamemo, da je tehnologija MBR, ki je kombinacija biološkega in fizikalnega čiščenja, zelo učinkovita pri čiščenju tekstilne odpadne vode.
Keywords: reaktivna azobarvila, tekstilne odpadne vode, membranski bioreaktorji, aktivno blato
Published in DKUM: 31.08.2017; Views: 2233; Downloads: 107
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4. Removal efficiency of COD, total P and total N components from municipal wastewater using hollow-fibre MBRIrena Petrinić, Mirjana Čurlin, Jasmina Korenak, Marjana Simonič, 2011, professional article Abstract: The membrane bioreactor (MBR) integrates well within the conventionally activated sludge system regarding advanced membrane separation for wastewater treatment. Over the last decade, a number of MBR systems have been constructed worldwide and this system is now accepted as a technology of choice for wastewater treatment especially for municipal wastewater. The aim of this work was to investigate and compare submerged MBR with conventionally-activated sludge system for the treatment of municipal wastewater in Maribor, Slovenia. It can be concluded from the results, that the efficiencies being determined by the parameters were satisfied, such as, chemical oxygen demand, total phosphorous, and total nitrogen, which were 97%,75%, and 90%, respectively. The efficiencies of ultrafiltration membrane for the same parameters were also determined, and compared with biological treatment. The results of this analysis show an additional effect regarding an improvement in the quality of the permeate but primary treatment is also very important. For successfully application of MBR system smaller grid for primary treatment is needed.
Keywords: municipal wastewater treatment, membrane bioreactor, membrane filtration, biological treatment
Published in DKUM: 01.06.2012; Views: 2098; Downloads: 121
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