Določanje nečistot v ogljikovih materialih

Vojska, Tine (avtor), Genorio, Boštjan (mentor)

Ogljikovi materiali, predvsem grafenski dosegajo izjemno raznolike lastnosti, ki bi lahko omogočile njihovo široko uporabo v različnih aplikacijah. Kljub velikemu napredku na tem področju pa komercialni preboj še vedno ni bil dosežen. Eden od razlogov za neuspeh je, da industrijska proizvodnja homogenih in brezkovinskih ogljikovih materialov ostaja težava. Kovinske nečistote bistveno vplivajo na lastnosti ogljikovih materialov, tudi če so prisotne le v zelo nizkih koncentracijah (ppm), kar omejuje njihovo uporabnost. Razvoj zanesljive in hitre metode za določanje kovinskih nečistot je tako pomemben za njihovo širšo uporabo. Določanje nečistot v ogljikovih materialih ni preprosta naloga. Glavna težava je povezana s korakom predpriprave vzorca za analizo, saj je ogljikove materiale izjemno težko razgraditi, zaradi njihove stabilne strukture in odpornosti na kisline. V magistrskemu delu sem določil vsebnost kovinskih nečistot v grafitu, grafen oksidu in reduciranem grafen oksidu. Kot začetni material sem uporabil grafit, iz katerega sem po izboljšani Hummersovi metodi sintetiziral grafen oksid. Sintetizirani grafen oksid sem nato kemijsko reduciral z uporabo hidrazina in pridobil reducirani grafen oksid. Oba sintetizirana vzorca in začetni material, sem razklopil na tri različne načine in sicer z izluževanjem s kislino, s suhim razklopom in z mikrovalovnim kislinskim razklopom. Vsebnost elementov razklopljenih vzorcev sem določil z metodo optične emisijske spektroskopije z induktivno sklopljeno plazmo (ICP-OES). Vzorce sem dodatno analiziral s sledečimi metodami: vrstično elektronsko mikroskopije (SEM), termogravimetrično analizo (TGA), rentgensko fotoelektronsko spektroskopijo (XPS), BET analizo specifične površine in Ramansko spektroskopijo. Rezultati so pokazali, da je mikrovalovni kislinski razklop najprimernejša metoda za razgradnjo ogljikovih materialov. Čeprav je bil pri sintezi uporabljen grafit in kemikalije z visoko stopnjo čistosti, so kovinske nečistote še vedno prisotne v končnih materialih. Zaradi njihove prisotnosti je pred določevanjem lastnosti ogljikovih materialov potrebno določiti vsebnost kovinskih nečistot, saj te lahko bistveno vplivajo na lastnosti ogljikovih materialov.

• Jezik: Slovenski jezik
• Ključne besede: ICP-OES, ogljikovi materiali, kovinske nečistote, mikrovalovni kislinski razklop
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2025
• PID: 20.500.12556/RUL-170371
• COBISS.SI-ID: 243864835
• Datum objave v RUL: 04.07.2025

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Determination of impurities in carbon materials

Izvleček

Carbon materials exhibit exceptionally diverse properties, which could enable their widespread application in various fields. Despite significant advancements in this area, a commercial breakthrough has yet to be achieved. One reason for this limitation lies in the challenge of industrially producing homogeneous and metal-free carbon materials. Metallic impurities significantly affect the properties of carbon materials, even when present only in ppm levels, which restricts their usability. Developing reliable and rapid methods for determining metallic impurities is therefore crucial for broader applications. Determining elemental impurities in carbon materials is not a straightforward task. The primary difficulty lies in the sample preparation process, as carbon materials are exceptionally challenging to decompose due to their stable structure and resistance to acids. In my master’s thesis, I determined the content of metallic impurities in graphite, graphene oxide and reduced graphene oxide. Graphite was used as the starting material, from which I synthesized graphene oxide using an improved Hummers’ method. The synthesized graphene oxide was then chemically reduced using hydrazine to produce reduced graphene oxide. Both synthesized samples and the starting material were decomposed using three different methods: acid leaching, dry ashing, and microwave-assisted acid digestion. The elemental content in the decomposed samples was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). The samples were also analyzed using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), BET surface area analysis, and Raman spectroscopy. The results showed that microwave-assisted acid digestion is the most suitable method for decomposing carbon materials. Although graphite and high-purity chemicals were used during synthesis, metallic impurities were still present in the final materials. Due to their presence, it is necessary to determine the content of metallic impurities before assessing the properties of carbon materials, as these impurities can significantly influence their characteristics.

• Ključne besede: ICP-OES, carbon materials, metallic impurities, microwave-assisted acid digestion