Optimiranje i modeliranje enzimatske sinteze nanočestica željezovih oksida

master's thesis

• Title (english): Optimization and modelling of enzymatic synthesis of iron oxides nanoparticles
• Author: Martina Burštinski
• Mentor: Ana Vrsalović Presečki (mentor)
• Committee member: Ana Vrsalović Presečki (predsjednik povjerenstva)
• Committee member: Martina Sudar (član povjerenstva)
• Committee member: Hrvoje Kušić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2018-11-30, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Reaction Engineering

Abstract

U ovom radu provedena je biokatalitička sinteza nanočestica željezovih oksida hidrolizom uree uz enzim ureazu, te uz dodatak željezova (II) klorida. Provedena je optimizacija procesa korištenjem statističke metode Dizajna eksperimenata u svrhu određivanja optimalnih uvjeta sinteze nanočestica najmanje veličine i najveće koncentracije. Ispitivan je utjecaj promjene temperature (25°C – 40°C) i koncentracije enzima ureaze (0,5 – 3 mg mL^-1) uz konstantnu koncentraciju uree i željezovog (II) klorida. Ispitana je kinetika enzima ureaze u reakciji hidrolize uree praćenjem porasta koncentracije amonijevih iona pri različitim koncentracijama uree, uz stalnu koncentraciju enzima ureaze. Kinetika reakcije opisana je jednosupstratnom Michaelis – Menteničinom kinetikom. Ispitan je utjecaj željezovih iona na aktivnost enzima mjerenjem specifične aktivnosti ureaze u ovisnosti o različitim koncentracijama željezova (II) klorida te pri konstantnim koncentracijama uree i ureaze. Ustanovljeno je da željezovi ioni inhibiraju enzim nekompetitivnom inhibicijom, te da se inhibicija povećava porastom temperature. Validacija pretpostavljenog matematičkog modela provedena je u kotlastom reaktoru. Sva ispitivanja provedena su u redestiliranoj vodi pri temperaturama T = 25 °C, T = 32,5 °C i T = 40 °C. Sintetizirane nanočestice željezovih oksida karakterizirane su analizom na pretražnom elektronskom mikroskopu s energetski disperzivnom rendgenskom spektroskopijom i NTA metodom.

Abstract (english)

In this study, biocatalytic synthesis of iron oxide nanoparticles was carried out by urea hydrolysis catalyzed by enzyme urease and with the addition of iron (II) chloride. Optimization of the process using a statistical method of Design of Experiments was performed in order to determine optimal conditions for the synthesis of nanoparticles with the smallest size and the highest concentration. Influence of temperature change (25°C – 40°C) and concentration of urease (0,5 – 3 mg mL^-1) with constant concentration of urea and iron (II) chloride was examined. Kinetics of enzyme urease was studied in the reaction of urea hydrolysis by measuring the concentration of ammonium ions at different concentrations of urea with constant concentration of urease. Kinetics of the reaction was described with Michaelis – Menten kinetic model. Influence of iron ions on enzymatic activity was examined by measuring the specific activity of urease at different concentrations of iron (II) chloride and at constant concentrations of urea and urease. It has been found that iron ions inhibit urease by non-competitive inhibition and that the inhibition is increased with temperature increase Assumed mathematical model of the process was validated in a batch reactor. All experiments were carried out in redistilled water at temperatures T = 25 °C, T = 32,5 °C and T = 40 °C. Synthesized iron oxide nanoparticles were characterized with a scanning electron microscope with energy dispersive spectroscopy and nanoparticle tracking analysis.

• Keywords: nanočestice; željezovi oksidi; urea; ureaza; biokatalitička sinteza
• Keywords (english): nanoparticles; iron oxides; urea; urease; biocatalytic synthesis
• Language: croatian
• URN:NBN: urn:nbn:hr:149:252134
• 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: Open access
• Created on: 2022-02-16 13:44:52