Fig. 1.

The measurements of the size distribution and the zeta potential of the nanoparticles suspended in aqueous medium were performed on a Zetasizer nano zs (Malvern Instruments, United Kingdom) using laser He-Ne (633 nm). The zeta potential was determined directly in solution containing NaCl (0.01 mM). The zeta potential of the TiO2 nanoparticles is about – 20 mV (at pH = 7). (A) The DLS analysis indicated that the mode and dispersion around the mode of nanoparticles was 52 ± 15 nm. (B) The maximal luminous transmission after 24 h for the suspension treated with sonotrod was evaluated to 32%. (C) Characterisation (size and shape) of nanoparticle aggregates was also performed by transmission electron microscopy (TEM). The mean size of aggregates was calculated on 10 microscopic fields picked at random. Mean nanoparticle size evaluated by this method was 34 ± 9 nm.