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Abstract: Antibiotic residues in environmental media pose a significant health, social and economic problem and require effective removal strategies. This study presents a novel approach for the removal of the antibiotic ciprofloxacin from water sources using magnetic iron oxide nanoparticles (MNPs) synthesised by co-precipitation, and subsequently functionalised with the polysaccharide carboxymethyl-dextran (CMD). The prepared nanoadsorbent was characterised extensively by various physicochemical analyses, to evaluate its morphology, crystal structure, surface chemistry, electrokinetic properties, thermogravimetric properties and magnetic features. These analyses confirmed the successful functionalisation of the MNPs with CMD highlighting its potential for effective adsorption applications. The stability of CMD coating on MNPs was evaluated in terms of total carbon content, an important, yet often overlooked factor. The adsorption performance of MNPs@CMD for ciprofloxacin was investigated systematically by studying the effects of adsorbent dosage, pH, initial ciprofloxacin concentration, ionic strength, adsorption time and kinetics, temperature, and reusability. Under optimal conditions, nanoadsorbent exhibited a satisfactory maximum adsorption capacity of 14.71 mg/g, and maintained a removal eff iciency of 79 % after four cycles, with minimal desorption of CMD layer on the MNPs. These findings demonstrate the potential of this magnetic polysaccharide nanoadsorbent for effective removal of ciprofloxacin from aqueous environments, enabling magnetic recovery and reuse.
Keywords: Carboxymethyl-dextran-MNPs, ciprofloxacin, adsorption
Published in DKUM: 26.05.2025; Views: 0; Downloads: 6
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Abstract: In this study, three locally available biomasses, namely miscanthus, hops, sewage sludge, and additionally, their mixtures, were subjected to the torrefaction process to improve their fuel properties. The torrefaction process was conducted at 250–350 ◦C and 10–60 min in a nitrogen (N2) environment. The torrefaction temperature and time were studied to evaluate the selected biomass materials; furthermore, heating values, mass and energy yields, enhancement factors, torrefaction severity indexes (TSI), and energy-mass co-benefit indexes (EMCI) were calculated. In addition, thermogravimetric (TGA) and Fourier transform infrared analyses (FTIR) were performed to characterize raw and torrefied biomass under the most stringent conditions (350 ◦C and 60 min). The results showed that with increasing torrefaction temperature and duration, mass and energy yields decreased, and heating values (HHVs) increased for all studied biomasses. The results of the TSI and EMCI indexes showed that the optimum torrefaction conditions were as follows: 260 ◦C and 10 min for pure miscanthus and hops, whilst this could not be confirmed for the sewage sludge. Furthermore, the combination of sewage sludge and the above-mentioned types of lignocellulosic biomass exhibited better fuel properties than sewage sludge alone.
Keywords: lignocellulosic biomass, sewage sludge, torrefication, thermogravimetry, TSI
Published in DKUM: 10.04.2025; Views: 0; Downloads: 14
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Abstract: The anti-viral efficacy of face mask was enhanced by applying the protein lactoferrin, the polyphenol catechin individually, and in combination. Individual solutions of protein and polyphenol were meticulously prepared and subsequently sprayed onto the inner surface of face mask layers composed of polypropylene. The functionalized mask layers were subjected to comprehensive characterization through Fourier transform infrared spectroscopy, zeta-potential measurements, and X-ray photoelectron spectroscopy. Goniometry was employed to assess the wettability of the modified surface layer, and air permeability was quantified both before and after the application of potential anti-viral agents. Bioactivity, such as anti-oxidant activity using ABTS assay and anti-viral efficiency against the model virus phi6, was followed as well. Our findings indicate the successful modification of mask with lactoferrin, while functionalization by catechin proved to be unsuccessful. The measured contact angles underscored the hydrophobic nature of the functionalized samples, ensuring reduced wettability in the presence of saliva droplets. Notably, the individual coating layers exhibited enhanced anti-oxidant activity and demonstrated anti-viral properties against the model virus phi6, when the outer layer of the mask was spray-coated. These results suggest promising technology to integrating these functionalized layers into masks for enhanced safety performance.
Keywords: catechin, lactoferrin, PP mask, spray-coating, anti-viral properties
Published in DKUM: 07.02.2025; Views: 0; Downloads: 3
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Abstract: Acid whey is derived from fresh cheese. The proteins were isolated by a monolithic ion-exchange column. The remaining whey fraction was used as a starter culture substrate of kefir grains. The aim of this work was, firstly, to study the possibility of column replacement by a UF membrane. If we succeeded, the concentrate would be used as a starter culture substrate of kefir grains. The second part of the research was to purify the remaining solution. The idea was to separate this solution to the permeate and the concentrate by nanofiltration. Further application of both filtration streams was tested as aqueous solutions or dried matter. Chemical and microbiological analyses were performed of both the permeate and the concentrate. The permeate analyses showed that lactose had been fully removed. The aqueous permeate was not stable, mainly due to an increase of total bacteria from 103 to 106 CFU/mL. Therefore, the permeate was spray-dried. The dry permeate was added to the moisture solution in different concentrations. The results showed that up to 0.5% of the dry permeate could be added to the moisturizing solution, with negligible changes in properties having the ability to inhibit acne growth. Anaerobic digestion of industrial sludge was performed with the addition of an aqueous concentrate, which showed improvement in anaerobic fermentation.
Keywords: kefir grain cultivation, remaining whey, nanofiltration
Published in DKUM: 05.12.2024; Views: 0; Downloads: 5
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Abstract: Naraščajoča skrb za zdravje in spremembe v življenjskem standardu so povečale zanimanje za razvoj protimikrobnih tekstilij, ki preprečujejo rast mikroorganizmov in delujejo preventivno proti okužbam, kot so okužbe kože in sluznic. Hitozan, naravni biopolimer, pridobljen iz hitina, se je izkazal za učinkovito protimikrobno sredstvo, saj preprečuje rast bakterij in gliv z vezavo na njihove celične stene ter zaviranjem njihovega metabolizma. Diplomsko delo obravnava vpliv plazemske obdelave celuloznih vlaken na njihovo sposobnost adsorpcije hitozana. V raziskavi smo del celuloznih vlaken obdelali s plazmo, medtem ko smo preostali del pustili neobdelan. Obe vrsti vzorcev smo nato analizirali, da bi ocenili morebitno povečanje reaktivnosti in sposobnosti vezave hitozana kot posledico plazemske obdelave v primerjavi z neobdelanimi vlakni. Cilj raziskave je bil ugotoviti, ali plazemska obdelava vpliva na izboljšanje adsorpcijskih lastnosti celuloznih vlaken. Za oceno učinkovitosti postopka smo uporablili naslednje metode: potenciometrična titracija za določanje vezave hitozana, UV-Vis analiza za merjenje koncentracije preostalega hitozana, merjenje togosti ploskih tekstilij za oceno uporabnih lastnosti obdelanih vlaken ter merjenje protimikrobnosti. Rezultati so pokazali, da plazemska obdelava bistveno izboljša adsorpcijo hitozana na celulozo. Plazemska obdelava se je izkazala kot obetavna metoda za funkcionalizacijo tekstilij, ki omogoča ustvarjanje okolju prijaznih in učinkovitih zaščitnih materialov. Diplomska naloga s svojimi ugotovitvami prispeva k napredku na področju razvoja tekstilij z dodano vrednostjo in odpira nove možnosti za raziskave v tej smeri.
Keywords: hitozan, plazma, bombaž, protimikrobnost, desorpcija
Published in DKUM: 04.10.2024; Views: 0; Downloads: 26
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