1. Experimental and mathematical investigation of anaerobic granulate density via settling velocityAljaž Klasinc, Gregor Drago Zupančič, Matjaž Hriberšek, Aleš Hribernik, Aleksandra Lobnik, Matej Zadravec, 2022, izvirni znanstveni članek Opis: The objective of this study was to determine the density of anaerobic granules on different
heights of a full-scale Upflow Anaerobic Sludge Bed reactor. The density was defined through the
settling velocities of anaerobic granules, measured in a full-scale Upflow Anaerobic Sludge Bed
reactor. In this study, granular density was calculated with the measured settling velocities and
developed mathematical model. The developed mathematical model is based on the Stokes model.
In the experiment, granules were taken from different heights of an Upflow Anaerobic Sludge Bed
reactor, from 0.6 to 7.6 m. The granules’ diameters varied between 1 and 5 mm. The granules were
taken from six different heights through the reactor. The settling velocity of the active granules
(with gas in the granule pore and on the surface of the granule) was measured first. After the active
granules’ settling velocity measurement, the granules were placed in a vortex to obtain degassed
granules (granules without any gas in the pores or on the surface), for which the settling velocities
were also measured later. It is shown that granules’ densities at different heights are independent of
the reactor height.
Ključne besede: Upflow Anaerobic Sludge Bed reactor, microstructure, anaerobic granular sludge, settling velocity, density
Objavljeno v DKUM: 26.03.2025; Ogledov: 0; Prenosov: 0
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2. Development of fluorescence-based method for dopamine determination using o-phthaldialdehyde and 3-mercaptopropyltriethoxysilaneValeriia V. Sliesarenko, Marijana Krstić, Urban Bren, Aleksandra Lobnik, 2025, izvirni znanstveni članek Opis: Nanomaterials and sensors play an important role in modern technologies, including medical diagnostics and biochemical research. This work presents the possibility of using o-Phthaldialdehyde (OPA) in combination with 3-mercaptopropyltriethoxysilane (MPTES) to develop a dopamine-responsive sensor. During the experiment, these materials were used at different pH and ratios to determine the optimal parameters for obtaining high fluorescence intensity of the reaction product. The data obtained demonstrate a linear relationship between the fluorescence response (λex/λem = 340/460 nm) of OPA/MPTES and dopamine concentration in the range of 0.1–3.0 µM at a pH of 8, and the detection limit was 8.7 nM. The obtained results confirm the potential of OPA/MPTES as a sensing component for the detection of dopamine
Ključne besede: fluorometric method, dopamine, o-phthalaldehyde
Objavljeno v DKUM: 13.03.2025; Ogledov: 0; Prenosov: 0
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3. Dimethoate detection through a fluorescent coumarin dyeEdoardo Donà, Gerhard J. Mohr, Aleksandra Lobnik, 2024, izvirni znanstveni članek Opis: In this study, we present a straightforward and innovative approach utilizing a coumarin fluorescent dye for the detection of dimethoate in green tea. Initially, the pesticide undergoes hydrolysis in a NaOH solution, yielding our target analyte, methylamine. Following neutralization to pH 9, methylamine reacts with the dye in CH3CN for 20 min. After a careful optimization, we achieved an outstanding linear correlation (R2 = 0.999) for dimethoate, spanning concentrations from 7.8 to 292 µg/L and LOD of 3.2 µg/L. Moreover, we successfully detected dimethoate in green tea, with a recovery of 95.4% (σ = 5.7%). Organophosphates pesticides (OPs), which dimethoate is one of the most used, pose a significant threat due to their toxicity upon both high direct exposure and prolonged low-level exposure, which has been linked to cancer. Therefore, the development of a detection method that is both selective and sensitive is imperative for safeguarding both the population and the environment. This method effectively addresses the stability challenges encountered by enzyme-based fluorescent sensors, thereby opening new avenues for the detection of organophosphate pesticides.
Ključne besede: organophosphate pesticide, methylamine, coumarin, fluorescence detection, dimethoate, TICT, twisted intramolecular charge transfer
Objavljeno v DKUM: 20.12.2024; Ogledov: 0; Prenosov: 3
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4. Microfibres and coliforms determination and removal from wastewater treatment effluentJolanda Rihter Pikl, Aleksandra Lobnik, Milenko Roš, Hakim El Khiar, Nataša Uranjek, 2024, izvirni znanstveni članek Opis: The research aim was to remove as many microfibres, microplastics and harmful bacteria as possible from the
polluted water to produce suitable water for reuse. The test water was the effluent from the municipal wastewater treatment plant in Shalek Valley. A pilot plant with a ceramic SiC filter for membrane filtration and
ozonation of filtered water was set up to remove suspended solids, micro-fibres, microplastics, and harmful
microorganisms. The Microfibers Detection System was developed to identify microfibers on-site. The results
showed that the microfiltration system combined with ozone treatment effectively removed total suspended
solids, microfibres, microplastics and microorganisms. A detection system method for identifying microfibres and
microplastic particles was used to determine how many microfibres and microorganisms were identified by
membrane filtration and ozonation. The study showed that membrane filtration successfully removed all
microfibres, 88% of total coliforms and 93% of E. coli. After additional ozonation, we achieved a 100% removal
rate of total coliforms and a 100% removal rate of E. coli. The treated water (effluent from the municipal
wastewater treatment plant) can be used for specific purposes, such as agricultural irrigation or enhancing
bathing waters near the plant’s water effluent.
Ključne besede: microfibres removal, microplastics, microfiltration, ozonation, water reuse
Objavljeno v DKUM: 26.09.2024; Ogledov: 0; Prenosov: 11
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5. Sustainable All-Cellulose Biocomposites from Renewable Biomass Resources Fabricated in a Water-Based Processing System by the Vacuum-Filtration-Assisted Impregnation MethodÖzkan Yapar, Petteri Piltonen, Ajra Hadela, Aleksandra Lobnik, 2024, izvirni znanstveni članek Ključne besede: all-cellulose composites, NaOH/urea/water solvent system, full dissolution of cellulose, dissolving pulp, regenerated cellulose
Objavljeno v DKUM: 16.07.2024; Ogledov: 125; Prenosov: 30
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6. Fluorescence based dopamine detectionValeriia V. Sliesarenko, Urban Bren, Aleksandra Lobnik, 2024, izvirni znanstveni članek Opis: Dopamine is an important hormone and neurotransmitter, and its levels in human fluids can indicate stress, depression, and various mental disorders. Food products, as well as medications, affect its level in the human body greatly. Therefore, dopamine monitoring is crucial, and necessary for improving the quality of life. The priority is to search for simple and environmentally friendly sensor systems for the in vitro detection of dopamine, enabling mass utilization. In this study, we explored the use of o-phthalaldehyde (OPA) as an indicator for the detection of dopamine, with fluorescence in the visible range (λex/λem = 390/455 nm), while direct dopamine fluorescence measurement was in the UV range (λex/λem = 280/320 nm). The longer excitation/emission wavelengths of dopamine-OPA complex, as well as lower detection limits, are useful for developing a simple detection method using LEDs. Three types of poloxamers were tested as additives to improve the fluorescence signal from the reaction between dopamine and OPA. Pluronic F127 led to a 16-fold increase in the fluorescence. Utilizing 4% Pluronic F127 with OPA at pH 7 resulted in a linear response within concentration ranges of dopamine (0.5–3 µM), achieving a limit of detection of 0.015 µM. In contrast, a direct detection of dopamine within the same range exhibited a detection limit of 0.13 µM.
Ključne besede: fluorometric method, dopamine, O-phthalaldehyde, Pluronic F127
Objavljeno v DKUM: 28.05.2024; Ogledov: 317; Prenosov: 20
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7. Comparison of surface and spectral properties of optical sensor layers prepared by spin/spray coating and printing techniquesNena Dimitrušev, Polonca Nedeljko, Allwin Mabes Raj, Aleksandra Lobnik, 2023, izvirni znanstveni članek Ključne besede: optical sensor layers preparation, spin coating, spray coating, inkjet printing, SFE, XPS, NH3, response, real-time response
Objavljeno v DKUM: 28.03.2024; Ogledov: 198; Prenosov: 13
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8. Vpliv predobdelave PA tekstilnega odpada na učinkovitost njegove razgradnjeLaura Berglez, 2023, magistrsko delo Opis: Cilj magistrske naloge, je ugotoviti vpliv predobdelave poliamidnega materiala iz tekstilnega odpada na učinkovitost njegove razgradnje. Razgradnja je potekala z nevtralno hidrolizo, pri čemer smo želeli v rezultatu čim večjo prisotnost monomera ε – kaprolaktam. Uporabili smo vzorce, ki so bili obarvani v svetlih in temnih tonih ter surovi ne-obarvan odpad poliamidne preje. Obarvane vzorce smo pred razgradnjo razbarvali in nato ročno oprali z neionskim pralnim sredstvom (NPS). Surove vzorce smo oprali ročno in industrijsko, prav tako z NPS. Po končani razgradnji smo vzorec ločili na tekočo in trdno fazo ter izvedli analize s FTIR spektroskopijo in LC-MC kromatografijo, da smo videli katera vrsta predobdelave je bila najučinkovitejša pri pridobitvi čim več tekoče faze v rezultatu in čim višjega absolutnega deleža monomera. Najvišji delež monomera je bil pri vzorcu temno obarvane preje, ki smo jo dvakrat razbarvali in nato ročno oprali z NPS in pri surovem vzorcu, ročno opranem in razgrajenem na reaktorju, ki stabilno vzdržuje pogoje razgradnje.
Ključne besede: poliamid 6, nevtralna hidroliza, tekstilni odpad, recikliranje
Objavljeno v DKUM: 02.10.2023; Ogledov: 371; Prenosov: 0
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9. Optical detection of stress parameters : diploma thesisMarijana Krstić, 2023, diplomsko delo Opis: In this thesis we developed the optical method of dopamine detection at pH 9, by creating DA-OPA complex. O–phthaldehyde was used as the indicator for fluorescent detection of dopamine with (3-Mercaptopropyl)-triethoxysilane as an additional reagent. The fluorescent product reached its maximum after 2 minutes, wavelengths of emission and excitation were λex/λem=340 nm/460 nm. The determination of dopamine was linear within a concentration range between 0.5∙10–6 and 3∙10–6 M. Limit of detection was 3.38∙10–6 M. Urea and norepinephrine can interfere dopamine detection, under examined parameters: ratio DA:OPA was 1:100, OPA:MPTES was 1:1, buffer was at pH 9.
Ključne besede: dopamine, fluorescence, o-phthaldehyde, optical method
Objavljeno v DKUM: 13.09.2023; Ogledov: 252; Prenosov: 16
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10. Analiza učinkovitosti delovanja čistilne naprave Veržej : diplomsko deloVito Nahberger, 2021, diplomsko delo Opis: Komunalne čistilne naprave so nepogrešljiv del sodobnih strategij čiščenja odpadnih voda. Ena izmed njih je tudi čistilna naprava Veržej, ki deluje že 14 let. Zanimalo nas je, ali ČN še vedno ustreza sodobnim zakonskim smernicam in ali bi bilo mogoče sam proces čiščenja še izboljšati. Slednje smo ugotavljali s pomočjo proučevanja že znanih dejstev in analiz, ki smo jih izvedli v lastni zasedbi. Izsledki so pokazali, da ČN v glavnem še vedno dobro opravlja svoje delo, vendar pa bi bilo določene segmente kljub temu dobro preurediti. Bolje bi se lahko uredilo ravnanje z odpadnim blatom in odvajanje obdelane vode v naravo. Posodabljanje ČN Veržej ovira predvsem skromna količina sredstev, ki se v ta namen usmerjajo, težavo pa predstavlja tudi dejstvo, da objekt ni upravičen do sofinanciranja s strani Evropske unije, saj ne presega mejne kapacitete 2000 PE.
Ključne besede: Biološko čiščenje, čistilna naprava Veržej, komunalna odpadna voda, učinek čiščenja, izboljšave delovanja ČN, odpadno blato
Objavljeno v DKUM: 16.02.2022; Ogledov: 1158; Prenosov: 126
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