Effects of Linear Alkylbenzene Sulfonate on Aggregation Behaviors of Titanium Dioxide Nanoparticles in Aqueous Environment

In aqueous environment, organic matters may exert impacts on the aggregation behaviors of titanium dioxide nanoparticles （TiO2-NPs）. Owing to the deficiency of studies on the aggregation of TiO2-NPs in the presence of synthetic organic compound, this study used linear alkylbenzene sulfonate （LAS） as a representative to evaluate the effects of TiO2-NPs concentration （1-10 mg/L）, LAS concentration （0-1 mg/L）, pH （4-8 ） and ionic strength （ NaC1, CaC12 ; 5 - 20 mM ） during aggregation of TiO2-NPs suspensions based on the detection of hydrodynamic diameters and electrophoretic mobilities and the calculation of interaction energies. The results showed that the TiO2-NPs in the presence of LAS are more stable than that in the absence of LAS. With the increase of ionic strength, the hydrodynamic diameter of NPs decreases, and the existence of LAS changes the point of zero charge from 5.4 to a lower value and thus alteres the aggregation behaviors of TiO2- NPs. The present study suggests that the LAS has a significant impact to the transportation and transformation of nanoparticles in aqueous environment.