Anions influence the extraction of rutile nanoparticles from synthetic and lake water.

Due to their recent widespread use, nanoparticles (NPs) may contaminate water sources and pose a health risk. Thus, it is important to understand the fate of NPs in order to evaluate potential threats. Here we show that the presence of anions influences the stability of NPs in synthetic and lake water. Concentrations of 0.3 and 3 mM PO 4 3- exhibited stronger stabilizing effects on NPs than 30 mM. Moreover, chloride ions promoted the coagulation of TiO 2 NPs over a range of concentrations (0.3-30 mM elicited similar effects). On the other hand, phosphate was found to hinder the coagulation effect. These results are expected to contribute to novel water purification strategies for the efficient removal of NPs. Further experiments should focus on the mechanism of phosphate on the removal of NPs in the coagulation/flocculation/sedimentation (C/F/S) process.