Komparativna karakterizacija geopolimera dobivenih kiselom i lužnatom aktivacijom

master's thesis

• Title (english): A comparative characterization of geopolymers obtained by acidic and basis activation
• Author: Ana Marija Đerek
• Mentor: Vladimir Dananić (mentor)
• Committee member: Vladimir Dananić (predsjednik povjerenstva)
• Committee member: Stanislav Kurajica (član povjerenstva)
• Committee member: Juraj Šipušić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2021-09-30, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Sintetizirani su geopolimeri na temelju metakaolina s pomoću dvije različite aktivatorske otopine, natrijevog silikata (Na2SiO3) i otopine fosforne kiseline (H3PO4). Odrađeno je komparativno istraživanje karakteristika alkalnih i kiselih geopolimera pri čemu su se prvenstveno uspoređivali spektrometrijski podaci dobiveni na sintentiziranim geopolimernim uzorcima pomoću FTIR-a i Ramana te kvantnokemijski izračun oligomerne strukture geopolimernih matrica. Također, u radu je ispitana i mehanička stabilnost dobivenih geopolimernih materijala. Nakon vremena njegovanja od 14 dana dobiveni rezultati pokazuju da je tlačna čvrstoća geopolimernog morta na bazi natrijevog silikata veća (30,2 MPa) u odnosu na onu dobivenu u kiselom mediju (9,4 MPa). Geopolimerne paste posjeduju manje tlačne čvrstoće zbog nedostatka punila. Fosfatni geopolimerni sustavi pokazali su određenu ograničenost u svojoj sintezi. Fosfatna pasta bila je izrazito krhka, dok fosfatni mort zahtjeva agregat visoke čistoće i inertnosti zbog reakcije fosfatne kiseline i agregata (nastanak plinova zatim pora). U radu su se pokazala odlična slaganja između kvantnokemijskog modela i eksperimentalnih podataka (FTIR i Raman) što ukazuje na uspješnost geopolimerne sinteze u alkalnom i kiselom sustavu. FTIR se pokazao kao odlična karakterizacijska tehnika za geopolimerne sustave na bazi metakaolina. Raman se pokazao kao neprikladna strukturna karakterizacijska metoda zbog prisutnosti anatasa visoke kristaliničnosti u metakaolinskom sastavu te zbog pojave fluorescencije.

Abstract (english)

Metakaolin-based geopolymers were synthesized using two different activator solutions, sodium silicate (Na2SiO3) and phosphoric acid solution (H3PO4). A comparative study of the characteristics of alkaline and acidic geopolymers was performed using FTIR, Raman and quantum chemical calculation of the oligomeric structure of geopolymer matrices with a focus on the comparison of the spectrometric data obtained from synthesized geopolymer samples. The mechanical stability of the obtained geopolymer materials was also examined. After a 14-day period of nurturing the results obtained show that the compressive strength of geopolymer mortar based on sodium silicate is greater (30,2 MPa) than that obtained in an acidic medium (9,4 MPa). Geopolymer pastes have lower compressive strength due to lack of filler. Phosphate geopolymer systems have shown a certain limitation in their synthesis The phosphate paste was extremely brittle, while phosphate mortar requires a high purity aggregate due to phosphoric acid and aggregate reactions (gas formation causes higher porosity). The paper showed excellent agreement between the quantum chemical model and experimental data (FTIR and Raman), which indicates the success of geopolymer synthesis in alkaline and acidic systems. FTIR has proven to be an excellent characterization technique for metakaolin-based geopolymer systems. Raman proved to be an inappropriate structural characterization method due to the presence of high crystallinity anatase in the metakaolin system and due to the occurrence of fluorescence.

• Keywords: geopolimer; alkalna aktivacija; kisela aktivacija; tlačna čvrstoća; FTIR; Raman
• Keywords (english): geopolymer; alkaline activation; acid activation; compressive strength; FTIR; Raman
• Language: croatian
• URN:NBN: urn:nbn:hr:149:264903
• Study programme: Title: Environmental Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka ekoinženjerstva (magistar/magistra inženjer/inženjerka ekoinženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2023-04-21 12:18:18