Određivanje naboja i veličine čestica akustičnom spektroskopijom

Ovaj rad opisuje metode određivanja veličine i naboja čestica u disperznim sustavima, posebno onima u kojima su čestice disperzne faze koloidne veličine. Detaljno je opisana primjena ultrazvuka u te svrhe kao i temelji akustične spektroskopije. Tom suvremenom metodom određena je veličina i raspodjela veličine čestica tri različita uzorka titanijevog dioksida, TiO2. Jedan od tih uzoraka očito je namijenjen primjeni u proizvodnji sredstava za sunčanje dok je drugi primjenjiv u proizvodnji boja (čestice su veće). Treći uzorak je pokazao gotovo monodisperzne čestice nanometarske veličine (31 nm) i svakako je namijenjen za neke specijalne namjene. Izmjerena je i promjena zeta potencijala čestica s promjenom pH. Uočena je promjena karakteristična za okside metala: pozitivan zeta potencija pri niskim i negativan pri visokim vrijednostima pH.This work describes various techniques for particle size and particle charge determination in disperse systems, particularly in those where particles are colloidal in size. The application of ultrasound for these purpose is described in details as well as the fundamentals ofAcoustic Spectroscopy. By using this modern technique, particle sizes and distributions of three different titania samples were determined. One of them is clearly used in preparation of sunscreens while the other for applications in paints (particles are much larger and size distribution is wider). The third samples exhibited almost monodispersed nanosized particles (31 nm) and it is undoubtedly prepared for some special applications. The variation of zeta potential with change in pH was also determined. As usual for metal oxide particles, zeta potential is positive at low pH values and negative at higher (iep is at pH 2.5)