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Iskalni niz: "avtor" (Romana Cerc Korošec) .

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1.
SBA-15 mesoporous particles with adsorbed cresol red dye and functionalized with 3-aminopropyl groups : materials properties and dye release studies
Erika Švara Fabjan, Romana Cerc Korošec, Klara Šifrer, Andrijana Sever Škapin, Ramon Martinez Manez, 2024, izvirni znanstveni članek

Povzetek: Research in the field of sensing has focused on tailoring the responsiveness of materials through the variation in materials properties achieved via functionalization of the mesoporous matrix. pH indicator dyes capable of protonation/deprotonation reactions are known to display different forms, resulting in changes in colour. This research focused on the preparation of mesoporous substrates SBA-15 with integrated pH indicator dye o-cresolsulphonephtalein (cresol red) grafted with (3-aminopropy) trimethoxysilane (gaining functionalized-SBA-15 material) in order to gain a colour change response following release of the dye. UV-Vis reflectance and absorbance spectra were used to evaluate forms of cresol red. The textural properties, including specific surface area, pore size distribution and pore volume were evaluated using nitrogen sorption, and XRD analysis was conducted to evaluate crystallinity of the material and pore ordering. The presence of 3-aminopropyl groups was determined by thermal decomposition using TGA–DSC/MS. The functionalized SBA-15 materials loaded with cresol red mostly retained ordering of the pores and showed a slight reduction in surface area. Functionalization changed the surface properties of the material. In the non-functionalized SBA-15, cresol red was present in both double (H2L) and single (HL−) protonated forms, whereas in the functionalized SBA-15 the deprotonated L2−form prevailed. Through desorption experiments cresol red was successfully desorbed from selected sample to different media. The change of colour caused by alterations in the form of the dye once released from the mesoporous silica material into the medium was confirmed. The form of cresol red released was determined by the pH of the medium.
Ključne besede: mezoporozni materiali, SBA-15, funkcionalizacija, uravnavanje odzivnosti, zaznavanje
Objavljeno v DiRROS: 13.02.2024; Ogledov: 114; Prenosov: 59
.pdf Celotno besedilo (10,52 MB)
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Quality control of thermally modified timber using dynamic vapor sorption (DVS) analysis
Miha Humar, Rožle Repič, Davor Kržišnik, Boštjan Lesar, Romana Cerc Korošec, Christian Brischke, Lukas Emmerich, Gregor Rep, 2020, izvirni znanstveni članek

Povzetek: The importance of thermal modification is increasing worldwide. Increased use of thermally modified timber (TMT) has resulted in a need for reliable quality control, comprising control of variation of the production within defined limits, allowing third-party control in the case of certification and the regulation of customer complaints and claims. Techniques are thus needed to characterise the modification of quality in terms of improved target properties of TMT during industrial production, and of TMT products that have been in service for an arbitrary time. In this study, we aimed to utilise dynamic vapor sorption (DVS) for this purpose. Norway spruce (Picea abies) and European beech (Fagus sylvatica) samples were thermally modified at different temperatures according to different heat treatment techniques: (1) the Silvapro process based on an initial vacuum; (2) an air heat treatment, whereby samples were wrapped in aluminium foil; (3) thermal modification of wood samples in the ambient atmosphere in a laboratory oven. Wood samples from closed processes were analysed for validation. TMT was characterised with respect to mass loss, colour and density. Mass loss of wood due to modification (MLTM) was correlated with factors derived from DVS analysis. The present DVS measurements suggest that the equilibrium wood moisture content (EMC95% RH), the time to reach 10% wood moisture content (t10% MC), and the elongation factor, c, derived from a logarithmic function, can serve as alternative parameters to characterise the quality of several thermal modification processes. Further studies are recommended using other wood species, different modification processes and further parameters gained from DVS measurements to understand the robustness and the predictive power of the applied technique
Ključne besede: thermal modification, quality control, dynamic vapour sorption, wood, moisture content
Objavljeno v DiRROS: 31.08.2023; Ogledov: 258; Prenosov: 133
.pdf Celotno besedilo (1,91 MB)
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4.
Metal and non-metal modified titania : the effect of phase composition and surface area on photocatalytic activity
Boštjan Žener, Lev Matoh, Martin Reli, Andrijana Sever Škapin, Romana Cerc Korošec, 2022, izvirni znanstveni članek

Povzetek: The application of TiO 2 photocatalysis in various environmental fields has been extensively studied in the last decades due to its ability to induce the degradation of adsorbed organic pollutants. In the present work, TiO 2 powders doped and co-doped with sulfur and nitrogen and modified with platinum were prepared by particulate sol-gel synthesis. PXRD measurements revealed that the replacement of HCl with H 2SO4 during synthesis reduced the size of the crystallites from ~ 30 nm to ~20 nm, increasing the surface area from ~44 m2/g to ~80 m2/g. This is consistent with the photocatalytic activity of the samples and the measured photocurrent behavior of the photocatalysts. The results showed that the prop- erties of the powders (i.e., surface area, crystallite size, photocurrent behavior) depend strongly not only on the type but also on the amount of acid and dopants used in the synthesis. Doping, co-doping and modification of TiO 2 samples with nitrogen, sulfur and platinum increased their photocatalytic activity up to 6 times.
Ključne besede: titanium dioxide, powders, doping, photocatalysis, photocurrent, SEM
Objavljeno v DiRROS: 04.05.2023; Ogledov: 284; Prenosov: 122
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5.
Improved synthetic route of incorporation of nanosilicon species into phenol-formaldehyde resin and preparation of novel ZnAl-layered double-hydroxide hybrid phenol-formaldehyde resin
Ana Dremelj, Romana Cerc Korošec, Andreja Pondelak, Branka Mušič, 2022, izvirni znanstveni članek

Povzetek: Hybrid phenol-formaldehyde (PF) resins represent one of the most important niche groups of binding systems for composites. New industrial needs, environmental requirements, and price fluctuations have led to further research on materials with enhanced mechanical and thermal properties. The preparation of novel hybrid materials can be achieved by inclusion of various elements or functional groups in the organic polymer phenolic framework. Herein, we report the synthesis and characterization of a PF-based hybrid material with different nanoscale silicone species and ZnAl-layered double hydroxide (LDH). The main goals of this study were to improve the synthetic pathways of hybrid resin, as well as to prepare granulated composite materials and test samples and determine their characterization. Added inorganic species increased the glass-transition temperature by a minimum of 8 °C, which was determined using differential scanning calorimetry (DSC). Rheological properties (melting viscosity and flow distance) of the hybrid resin were measured. The homogeneity of distribution of added species across the organic matrix was evaluated with scanning electron microscopy (SEM). With synthesized new hybrid-binding systems, we prepared different granulated composite materials and evaluated them with the measurements of rheological properties (flow curing characteristics). Tensile strength of samples, prepared from granulated composite material, improved by more than 5%.
Ključne besede: phenol-formaldehyde hybrid resins, nano-SiO2, ZnAl-LDH, composites, glass-transition temperature, mechanical properties
Objavljeno v DiRROS: 03.05.2023; Ogledov: 347; Prenosov: 152
.pdf Celotno besedilo (1,92 MB)
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