NTiO2 mass transfer and deposition behavior in an aquatic environment

Abstract

Nano-TiO2 (nTiO2) is widely used in industry, and some of it is inevitably released into natural aquatic environments. nTiO2 can be deposited on the streambed or transported along the stream and streambed, and it can also undergo exchange-transfer processes in these systems. The behavior of nTiO2 in rivers includes deposition-transfer processes in the stream and exchange-transfer processes between the stream and streambed. In this work, the deposition, mass transfer, exchange, and aggregation behavior of nTiO2 in a simulated river were studied as a function of the solution pH, stream velocity, and anionic, cationic, and neutral surfactant concentrations. In these experiments, a recirculating flume was used to simulate a natural stream. The nTiO2 deposition and aggregation phenomena in the river and streambed were characterized. Of the three surfactants studied, the anionic surfactant enhanced the nTiO2 stability in the river and limited its aggregation most effectively, resulting in slow nTiO2 deposition and nTiO2 transport over long distances. This study provides information about nanoparticle transport phenomena in simulated natural aquatic systems.