The effect of drying on dispersions of nano-particulate titanium dioxide in ethylene glycol

This paper first demonstrates that the UV attenuation of a well-milled aqueous dispersion of nano-particulate rutile TiO2 is 200 times greater than the attenuation of visible 550 nm light. The corresponding UV attenuation of rutile dispersions in ethylene glycol is however only ∼ 50% of that of the aqueous dispersion. It is shown that the different behaviour of suspensions in water and in ethylene glycol depends on the way in which the TiO2 was dried. If the rutile is pre-treated, by washing in ethanol before conventional oven drying, the differences between the optical properties of the aqueous and non-aqueous suspensions can be eliminated. Possible reasons for the beneficial effects of the ethanol pre-treatment are proposed.