Optical properties of TiO2 suspensions: Influence of pH and powder concentration on mean particle size

The optical properties of photocatalytic suspensions, that is, the absorption and scattering coefficients, depend on the effective size of particle agglomerates. This work aimed to investigate if the pH and powder concentration affect the particle size and eventually the optical properties of suspensions. Aqueous suspensions of commercial TiO2 powders irradiated by monochromatic light have been optically characterized by measuring the transimitted photon flow as a function of catalyst mass and by applying an asymptotic form of the Kubelka-Munk solution of the radiative transfer equation. It was found that equal masses of catalyst at different pH and concentration values show different particle size distributions and therefore different optical properties. Moreover, the quantum yield for the photocatalytic reaction of phenol was determined for each catalyst and pH