Electric Charging and Colloid Stability of Fabricated Nedle-Like \(\mbox{TiO}_{2}\) Nanoparticles

Abstract

Charging and stability of needle-like TiO\(_{2}\) nanoparticles were studied. Measured isoelectric point (IEP) was pH~4 and lower than that of spherical ones pH~6. Heat treatment at 400\(\text{\r{}}\)C changed the IEP from 4 to 6. The shift is probably due to shape controller (ethylenediamine). The particles aggregate around IEP and thus are charge-stabilized. Experimental hydrodynamic diameters of needle-like particles showed a reasonably good agreement with the theoretical diameter. That is, the particles can be dispersed to primary particles. 1pK Stern and standard electrokinetic models describe electrophoretic mobility of needle-like TiO\(_{2}\), indicating that double layer relaxation is significant for needle-like TiO\(_{2}\).