Utjecaj atmosferskog starenja na nastajanje mikroplastike u okolišu

master's thesis

• Title (english): Influence of weathering on the microplastics formation in the environment
• Author: Mirela Župan
• Mentor: Zlata Hrnjak-Murgić (mentor)
• Committee member: Zlata Hrnjak-Murgić (predsjednik povjerenstva)
• Committee member: Zvonimir Katančić (član povjerenstva)
• Committee member: Dajana Kučić Grgić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2022-09-14, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Porastom proizvodnje i uporabe plastičnih materijala, posljedično raste i količina plastičnog otpada koji nerijetko završava u okolišu. Djelovanjem atmosferskih utjecaja i sunčevog UV zračenja, plastični otpad degradira te s vremenom prelazi u mikroplastiku (MP) predstavljajući time opasnost kako za ljude, tako i za živu i neživu prirodu. U ovom radu praćeno je simulirano UV starenje polimernog materijala polipropilena (PP), pri valnoj duljini zračenja od λ = 290 nm i temperaturi od 45 ± 1°C. Uzorci PP folija debljine 0,2 cm stareni su u periodu od 14, 28, 42 i 56 dana. U svrhu praćenja procesa degradacije provedene su metode karakterizacije. Infracrvenom spektroskopijom (FTIR) određene su vrijednosti karbonilnog indeksa (C.I.), koji se javlja kao posljedica razgradnje PP molekula. Diferencijalnom pretražnom kalorimetrijom (DSC) određene su promjene temperatura: tališta (Tm), kristališta (Tc) i staklišta (Tg) te toplinskih tokova uslijed endotermnih (ΔHm) i egzotermnih (ΔHc) promjena s vremenom starenja, kao i stupanj kristalnosti (Xc). Pretražnom elektronskom mikroskopijom (SEM) praćene su promjene morfologije i površinskih svojstava starenih uzoraka. Difuznom refleksijskom spektroskopijom (DRS) potvrđen je nastanak oksidacijskih C-O skupina kao posljedica UV degradacije polimera. Tehnikom induktivno spregnute plazmom s masenom spektrometrijom (ICP-MS) provedena je identifikacija te su određene koncentracije metala nakon izluživanja. UV stareni uzorci otpuštaju veće koncentracije metala u odnosu na nestarene uzorake, zbog narušene strukture uslijed degradacije. Rezultati svih navedenih metoda dokazali su promjenu svojstava, strukture i kemijskog sastava molekula PP polimera s vremenom UV starenja te posljedično ubrzano nastajanje mikroplastike (MP).

Abstract (english)

The increasing use of plastics is accelerating their production, and the amount of plastic waste that often ends up in the environment is also increasing. Due to atmospheric influences and solar and UV radiation, plastic waste degrades and eventually turns into microplastics (MPs), thereby pose a threat to both humans and living and non-living nature. In this work, simulated UV aging of the polymer material polypropylene (PP) was performed at a radiation wavelength of λ = 290 nm and a temperature of 45 ± 1°C. Samples of PP films with a thickness of 0,2 cm were aged for 14, 28, 42, and 56 days. In order to monitor the degradation process, various characterization methods were used. Infrared spectroscopy (FTIR) was used to determine the values of carbonyl index (C.I.), which results from the degradation of PP molecules. Differential scanning calorimetry (DSC) was used to determine the melting point (Tm), crystallization point (Tc), and glass transition point (Tg), as well as the heat flows due to endothermic (ΔHm) and exothermic (ΔHc) transition and the degree of crystallinity (Xc) with aging time. The changes in morphology and surface properties of the aged samples were studied by scanning electron microscopy (SEM). Diffuse reflectance spectroscopy (DRS) confirmed the formation of oxidized C-O groups as a result of UV degradation of the polymer. Identification and concentration of residual metals were determined by inductively coupled plasma mass spectrometry (ICP-MS). The results indicate that UV aged sample released higher concentrations of metals compared to the non-aged samples, which can be attributed to the deteriorated structure as a result of degradation. The results of all methods performed indicate that the properties, structure, and chemical composition of the PP polymer molecules are changed with UV aging, leading to accelerating microplastic (MPs) formation.

• Keywords: plastični otpad; mikroplastika; polipropilen; atmosfersko starenje; UV degradacija
• Keywords (english): plastic waste; microplastics; polypropylene; weathering; UV degradation
• Language: croatian
• URN:NBN: urn:nbn:hr:149:293976
• Project: Number: IP-2020-02-6033; Title: Mikroplastika u vodi; sudbina, ponašanje i uklanjanje; Title: Microplastics in water; fate and behavior and removal; Acronym: ReMiCRO; Leader: Ana Lončarić Božić; Jurisdiction: Croatia; Funder: HRZZ; Funding stream: IP
• Study programme: Title: Materials Science and Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-03-19 17:41:18