diplomsko delo
Jan Bašič (Author), Jurij Reščič (Mentor)

Abstract

Preučevali smo stabilnost TiO$_2$ nanodelcev v medijih z različnimi dielektričnimi konstantami pri različnih vrednostih pH. Suspenzijam TiO$_2$ nanodelcev smo izmerili zeta potencial preko merjenja elektroforetske mobilnosti in hidrodinamski radij z metodo dinamičnega sipanja svetlobe (DLS). Pričakovali smo višjo stabilnost suspenzij z medijem, ki ima nižjo dielektrično konstanto. Dokazali smo, da velja ravno obratno, saj z nižanjem dielektrične konstante medija povečujemo tudi elektrostatski privlak med protiioni in nanodelcem. Protiioni se naberejo na površini nanodelcev in senčijo naboj nanodelca, ki je odgovoren za odbojno interakcijo med dvema nanodelcema. Stabilnost suspenzij je bila višja pri pH, ki je bolj oddaljen od izoelektrične točke nanodelcev, saj je bil naboj delcev večji in posledično tudi odboj med njimi. Senčenje naboja v tem primeru nima bistvenega vpliva na stabilnost kot pri dielektrični konstanti. Izvedli smo še pet Monte Carlo simulacij, kjer smo pri vsaki spremenili dielektrično konstanto medija v sistemu. Simulcije so dale rezultate, ki so v skladu z eksperimentalnimi meritvami.

Keywords

koloidna kemija;stabilnost suspenzij;Monte Carlo simulacije;zeta potencial;dinamično sipanje svetlobe;diplomska dela;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [J. Bašič]
UDC: 544.778.3:620.3:546.82-31(043.2)
COBISS: 207303427 Link will open in a new window
Views: 214
Downloads: 49
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Other data

Secondary language: English
Secondary title: Effect of solution composition on TiO$_2$ nanoparticle suspension stability
Secondary abstract: We have investigated the stability of TiO$_2$ nanoparticles in media with different dielectric constants at different pH values. The zeta potential of TiO$_2$ nanoparticle suspensions was measured by measuring the electrophoretic mobility and hydrodynamic radius using the dynamic light scattering (DLS) method. We expected a higher stability of the suspensions with a medium that has a lower dielectric constant. We proved that the opposite is true, as lowering the dielectric constant of the medium also increases the electrostatic attraction between the counterions and the nanoparticles. The counterions accumulate on the surface of the nanoparticles and shield the charge of the nanoparticle, which is responsible for the repulsive interaction between two nanoparticles. The stability of the suspensions was higher at a pH further away from the isoelectric point of the nanoparticles, as the charge of the particles was greater and consequently the repulsion between them. In this case, the charge shielding has no significant influence on the stability as in the case of the dielectric constant. We performed five more Monte Carlo simulations, in each of which we changed the dielectric constant of the medium in the system. The simulations yielded results that agree with the experimental measurements.
Secondary keywords: colloidal chemistry;stability of titanium dioxide suspensions;Monte Carlo simulations;zeta potential;dynamic light scattering;Nanodelci;Koloidi;Suspenzije (kemija);Titanov dioksid;Univerzitetna in visokošolska dela;
Type (COBISS): Bachelor thesis/paper
Study programme: 1000373
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, UNI Kemija
Pages: 1 spletni vir (1 datoteka PDF (42 str.))
ID: 24956294