Aggregation of natural colloidal particles under solar irradiation

Aggregation/agglomeration of nanoparticles affects their fate and transport in natural waters. Although nanoparticles behave as colloidal matter expressing aggregation/agglomeration properties under natural water conditions, the role of aggregation/agglomeration during photocatalysis has not been demonstrated clearly so far. The main objective of this study could be described as assessment of the colloidal behavior of the binary system i.e., NOM representative organics and nanoparticles representative of photocatalyst specimens described by following basic experimental procedures prior to, during and under post photo-treatment conditions. To fulfill this aim, dynamic light scattering, sedimentation and turbidity experiments were performed. Aggregation and/or agglomeration of TiO2 nanoparticles were assessed by using the above indicated physico-chemical parameters in relation to water matrix effects as well as photocatalytic removal efficiencies. Aggregation and/or agglomeration behavior of both matrix components provided information on expected reactivity under irradiation during photocatalysis. Overall evaluation of the systems provided information both during photocatalysis as well as light induced reactions under environmental conditions. Therefore, a broader insight was deduced on the fate of nanoparticles through photocatalysis.