Effects of phosphate on the dispersion stability and coagulation/flocculation/sedimentation removal efficiency of anatase nanoparticles

This study investigates the behavior and fate of TiO2 NPs in conventional water treatment (coagulation/flocculation/sedimentation) under the influence of waterborne phosphate, focusing on the phosphate uptake rate, surface interactions, and dispersion stability and removal efficiency of TiO2 NPs. The adsorption of HPO42- ions on TiO2 NPs (i.e., surface complexation in solution) causes displacement of carbonate species. Moreover, adsorption experiments indicates that complexation of inorganic anions on the surfaces of TiO2 NPs can occur rapidly, within a 5 min time frame. This study confirmed that phosphate would affect the surface charge of the TiO2 NPs; thus, the bridging effect during coagulation may also be hindered by phosphate becoming attached to TiO2 NP surfaces. This information will contribute to nanotechnology-related water safety and water treatment technology. (C) 2019 Elsevier Ltd. All rights reserved.