Aggregation of TiO and Ag nanoparticles in soil solution - Effects of primary nanoparticle size and dissolved organic matter characteristics.

The colloidal stability of nanoparticles NP in soil solution is important to assess their potential effects on ecosystems. The aim of this work was to elucidate the interactions between initial particle size d, particle number concentration (N) as well as the characteristics of dissolved organic matter (DOM) for stabilizing Ag NP and TiO NP. In batch experiments using time-resolved dynamic light scattering (DLS), we investigated the aggregation of TiO NP (79 nm, 164 nm) and citrate-stabilised Ag NP (73 nm, 180 nm) in Ca solution (2 mM) and two soil solutions, one extracted from a farmland and one from a floodplain soil (each containing 2 mM Ca).