20.500.12556/DKUM-99685 Določanje penetracijske globine UV-sevanja v kvarčnem (mikro)reaktorju Determination of UV radiation penetration depth in a quartz (micro)reactor V diplomskem delu obravnavamo vpliv absorpcijskih lastnosti izbranih spojin na prodor UV-sevanja skozi reakcijsko plast in njihov pomen pri določanju primerne globine kvarčnega mikroreaktorja. Osredotočamo se na spojine, povezane s fotoinducirano formozno reakcijo, pri kateri se zaradi nastajanja različnih intermediatov in produktov sestava ter optične lastnosti reakcijske zmesi med potekom reakcije spreminjajo. Absorpcijske lastnosti formaldehida, dimera glikolaldehida, dihidroksiacetona, piruvaldehida, glioksala, fruktoze, 5-hidroksimetilfurfurala, metanola in mesitil oksida smo določili z UV/VIS spektrofotometrijo. Izmerjene absorpcijske spektre smo primerjali glede na značilna absorpcijska območja in položaje absorpcijskih maksimumov. Za nadaljnje izračune smo za posamezne spojine v območju med 250 in 308 nm izbrali najvišjo izmerjeno absorbanco in pripadajočo valovno dolžino. Na podlagi izmerjenih absorbanc smo z uporabo Beer-Lambertovega zakona dodatno ocenili vpliv koncentracije in globine reakcijske plasti na absorbanco, prepustnost UV-sevanja ter maksimalno globino reakcijske plasti pri 80-% prepustnosti. Rezultati so pokazali, da formaldehid in fruktoza izraziteje absorbirata predvsem pri krajših UV-valovnih dolžinah, medtem ko se pri nekaterih intermediatih in produktih absorpcijski pasovi pojavljajo tudi pri daljših valovnih dolžinah. Posebej pomembno je območje med približno 250 in 300 nm, v katerem absorbirajo dimer glikolaldehida, dihidroksiaceton, piruvaldehid in 5-hidroksimetilfurfural. Izračuni so pokazali, da se z večanjem koncentracije in globine reakcijske plasti absorbanca povečuje, prepustnost UV-sevanja pa zmanjšuje. Z naraščanjem koncentracije se zmanjšuje tudi maksimalna globina reakcijske plasti pri 80-% prepustnosti. Primerjava spojin je pokazala, da lahko nekateri intermediati in produkti prodor UV-sevanja omejujejo izraziteje kot začetni formaldehid. Dobljeni rezultati kažejo, da je pri določanju ustrezne globine mikroreaktorja poleg absorpcijskih lastnosti začetnega formaldehida treba upoštevati tudi nastajajoče intermediate in produkte ter njihove koncentracije. Izračunane vrednosti predstavljajo modelno oceno na podlagi Beer-Lambertovega zakona in predpostavke približno konstantnega molarnega absorpcijskega koeficienta pri izbrani valovni dolžini posamezne spojine. In this thesis, we examine the effect of the absorption properties of selected compounds on the penetration of UV radiation through the reaction layer and their significance in determining the appropriate depth of a quartz microreactor. We focus on compounds associated with the photoinduced Formose reaction, in which the composition and optical properties of the reaction mixture change during the course of the reaction due to the formation of various intermediates and products. We determined the absorption properties of formaldehyde, glycolaldehyde dimer, dihydroxyacetone, pyruvaldehyde, glyoxal, fructose, 5-hydroxymethylfurfural, methanol, and mesityl oxide using UV/VIS spectrophotometry. We compared the measured absorption spectra based on characteristic absorption regions and the positions of absorption maxima. For further calculations, we selected the highest measured absorbance and the corresponding wavelength for each compound in the range between 250 and 308 nm. Based on the measured absorbances, we further evaluated the effect of concentration and reaction layer depth on absorbance, UV transmittance, and the maximum reaction layer depth at 80% transmittance using Beer–Lambert’s law. The results showed that formaldehyde and fructose exhibit more pronounced absorption primarily at shorter UV wavelengths, while for some intermediates and products, absorption bands also appear at longer wavelengths. Of particular importance is the range between approximately 250 and 300 nm, in which glycolaldehyde dimer, dihydroxyacetone, pyruvaldehyde, and 5-hydroxymethylfurfural absorb. Calculations have shown that as the concentration and depth of the reaction layer increase, the absorbance increases, while the transmittance of UV radiation decreases. As the concentration increases, the maximum depth of the reaction layer at 80% transmittance also decreases. A comparison of the compounds showed that certain intermediates and products can limit UV radiation penetration more significantly than the initial formaldehyde. The results obtained indicate that, when determining the appropriate depth of the microreactor, in addition to the absorption properties of the initial formaldehyde, the forming intermediates and products and their concentrations must also be taken into account. The calculated values represent a model estimate based on Beer–Lambert’s law and the assumption of an approximately constant molar absorption coefficient at the selected wavelength for each compound. UV-sevanje penetracijska globina kvarčni mikroreaktor UV/VIS spektrofotometrija Beer-Lambertov zakon formozna reakcija UV radiation penetration depth quartz microreactor UV/VIS spectrophotometry Beer-Lambert law formose reaction true true false Slovenski jezik Angleški jezik Diplomsko delo/naloga 2026-08-24 08:59:21 2026-09-10 12:20:03 2026-09-11 03:08:01 0000-00-00 00:00:00 2026 0 Maribor 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 VS_Krivec_Lorena_2026.pdf VS_Krivec_Lorena_2026.pdf 1 A0E2E6864BBF45D5614C270690301124 167ed59b8c28d1b6f57051abcc53cbfbdcf1d4771cc7920375fce106920b87d3 84d7816b-acfd-11f1-b668-00155d0001be https://dk.um.si/Dokument.php?lang=slv&id=212065 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0