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Abstract: Plastic waste is steadily polluting oceans and environments. Even when collected, it is still predominantly dumped or incinerated for energy recovery at the cost of CO2. However, no simple solution exists to deal with marine litter (ML). Overcoming limitations in collection, and in the environmentally, technically and economically acceptable use of the collected material, is of paramount importance. Chemical recycling can contribute to the transition towards a circular economy but the high variety and contamination of real waste remains the biggest challenge. In my research more than 100 kg of actual benthic ML from the North Adriatic Sea, including polyolefins packaging and polyamides fishing nets, were successfully processed “as-is” without pretreatment and converted into standardized marine gas oil (MGO) compliant with the ISO8217 via the pyrolysis and the distillation process; with 8 potential harmful emissions linked to the pyrolysis process monitored and curbed to safe levels. Approximately 45 wt% yield of raw pyrolysis oil (RPO) was obtained of which 50% (v/v) being MGO. RPO and its distillates were chemically characterized via GC-MS. For all samples, more than 30% of the detected compounds were identified. 2,4-dimethyl-1-heptene, a marker of PP pyrolysis, is the most represented peak in the chemical signature of all the marine litter samples, and it differentiates commercial and pyrolysis marine gasoil. Besides, I studied the detailed composition and the steam cracking performance of distilled pyrolysis oil fractions in the naphtha-range of ML and mixed municipal plastic waste (MPW) considered unsuitable for mechanical recycling. Advanced analytical techniques including comprehensive two-dimensional gas chromatography (GC × GC) coupled with various detectors and inductively coupled plasma – mass spectrometry (ICP-MS) was applied to characterize the feedstocks and to understand how their properties affect the steam cracking performance. Both waste-derived naphtha fractions were rich in olefins and aromatics (~70% in MPW naphtha and ~51% in ML naphtha) next to traces of nitrogen, oxygen, chlorine and metals. ICP-MS analyses showed that sodium, potassium, silicon and iron were the most crucial metals that should be removed in further upgrading steps. Steam cracking of the waste-derived naphtha fractions resulted in lower light olefin yields compared to fossil naphtha used as benchmark, due to secondary reactions of aromatics and olefins. Coke formation of ML naphtha was slightly increased compared to fossil naphtha (~50%), while that of MPW naphtha was more than ~180% higher. It was concluded that mild upgrading of the waste-derived naphtha fractions or dilution with fossil feedstocks is sufficient to provide feedstocks suitable for industrial steam cracking. Waste plastics oil (WPO) obtained from a relatively large-scale batch rotary kiln pyrolysis reactor was collected and stored for 60 months in dark at 10 °C, periodically thoroughly characterized and finally tested as the drop-in fuel in internal combustion engine. It was evaluated by investigation of combustion process and emission formation phenomena under a wide range of operating parameters. The results were compared with those obtained with diesel fuel at the same injection and gas path parameters to provide a comprehensive basis for further development of control strategies. Finally, the solid residue from the pyrolysis process was evaluated for material recovery or safe disposal, thus closing the mass balance of the whole process. Due to the great contamination of the original feedstock, stabilization of solid residue is required to attain not hazardous waste criteria, but once stabilized with Portland concrete, it could even be employed as construction material, therefore transforming a problem into an opportunity.
Keywords: marine litter, marine fuel, pyrolysis, circular economy, environmental impact, chemical recycling, steam-cracking, pyrolysis char
Published in RUNG: 12.05.2023; Views: 1218; Downloads: 20
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Keywords: strateško načrtovanje, izobraževalni programi, izobraževalna tehnologija, digitalna tehnologija, management, e-learning planning, e-learning programmes, digital society, educational technology
Published in RUNG: 03.03.2023; Views: 1001; Downloads: 22
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Abstract: Nanolaminate coatings (NLC) consisting of alternated CrN coupled with either cubic tungsten nitride (β-W2N) or molybdenum nitride (γ-Mo2N) were deposited on cold worked tool steel substrates using reactive DC reactive magnetron sputtering for improved mechanical and corrosion resistance. The CrN/γ-Mo2N and CrN/β-W2N nanolaminate systems were found to perform better than the corresponding single-layer systems, with both mechanical and electrochemical properties improving by decreasing the individual layer thickness from 100 to 5 nm. The CrN/β-W2N NLC combined the high hardness value of W2N with the low corrosion current of CrN. The CrN/γ-Mo2N NLC showed synergistic improvements consisting of both higher hardness and lower corrosion currents with respect to the constituent materials alone. The dependence of mechanical and corrosion properties on the bilayer period is discussed in terms of the grain size, residual stresses and texture of the constituent materials and the nanostructured character of the multilayer architecture.
Keywords: Nanolayered coatings, Transition metal nitrides, Sputtering, Nanoindentation, Corrosion resistance, Mechanical properties
Published in RUNG: 12.01.2023; Views: 1175; Downloads: 0
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Keywords: Znanost in umetnost, biosonifikacija, raziskovanje v umetnosti, gozd, Kras
Published in RUNG: 19.12.2022; Views: 1106; Downloads: 0
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Abstract: Diplomsko delo obravnava nekaj ključnih vprašanja političnega filma, katerega prav tako definira ter kontekstualizira. Na začetku se posvetimo tipologiji političnega, ki presega zgolj obravnavanje vladajočega razreda, politikov kot oseb in izvajanje oblasti. Razločevanje med zgoraj opisanim in sfero skupnih zadev, ki se dotikajo naših življenj na vseh nivojih povežemo s filmom in za boljše razumevanje razširimo s temami, kot so žanr, teorija avtorstva, metode potujitve in realizem. Vsi ti dejavniki namreč vplivajo na definicijo političnega filma. Ključen faktor političnega filma je lahko prav produkcija filma, in sicer z rušenjem tradicionalnih hierarhij v procesu zasnove in produkcije filma. Prav politika je tisto, kar neposredno vpliva na naša življenja. Če film prikazuje perspektivo upornikov in ljudi, ki sicer ne bi imeli besede, če daje gledalcu možnost kritičnega razmišljanja o subjektu, temi ali sistemu in če je realističen, govorimo o političnem filmu. Za lažje razumevanje politične filme različnih klasifikacij razporedimo v kategorije in v nadaljevanju tudi razložimo, kako se tema povezuje s praktičnim delom diplomske naloge, ki ga predstavlja diplomski film z naslovom Ni vsak dan nedelja.
Keywords: politični film, žanrski film, avtorski film, teorija avtorstva, francoski novi val, realizem, diplomske naloge
Published in RUNG: 08.08.2022; Views: 1638; Downloads: 55
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