Effects of grain size and structural heterogeneity on the transport and retention of nano-TiO2 in saturated porous media

Accurately predicting the fate and transport of nano-TiO2 in porous media is critical to assess its environmental impact. This study was designed to understand the effects of gain size and structural heterogeneity under different ionic strength (IS) on the fate and transport of nano-TiO2 in saturated porous media. In the columns packed homogenously with sand of different grain sizes (920, 550, 390, and 275μm), the transport of nano-TiO2 decreased when the IS increased from 0.1 to 1 or 10mM. For all the three IS conditions, the retention of the nano-TiO2 particles in the columns increased when the gain size decreased, and the mobility of the nano-TiO2 was the lowest in the sand at size of 275μm with recovery rates of…