Influence of flow rate on the transport of nTiO2 and phosphate and its modeling

We studied Zeta potentials of nanoparticles titanium dioxides （nTiO2） in different concentration of NaNO3 and phosphate (P) solutions. In addition, the effect of flow rate on the transport of nTiO2 in P was investigated at pH＝6.5. Experimental results show that the Zeta potential of nTiO2 is compressed with the increasing ion concentration (IC) of NaNO3 at pH＝6.5. The negative charge increases with the augment of P. Therefore, the high P and low NaNO3 induce the stabilization of nTiO2 aggregates. The transport experiments suggest that the rapid flow rate is favorable for the transportability of nTiO2 and soluble phosphate. The breakthrough transport curves (BTCs) of nTiO2 in sand columns can be fitted well with two-site kinetic attachment model. The modeling results suggest that the values of first-order attachment rate coefficients (k2) and detachment rate coefficients (k2d) on site 2 and first-order attachment rate coefficients (k1) on site 1 are responsible to the attaching efficiency of nTiO2 on sands and their transportability.