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( NaCl,CaCl2; 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.
Xin DuJici ZhangJinna ZhangKe WangShijie YouXiuheng Wang
The present work aims to ascertain the mechanisms of surfactant（dodecylbenzene sulfonate; DBS） effects on the aggregation behaviors of TiO2 nanoparticles（TiO2-NPs） in natural water samples. Aggregation experiments were conducted at a TiO2-NPs concentration of 10 mg/L in deionized water and in natural water samples via dynamic light scattering and Zeta potential determination. Average attachment efficiency was calculated to compare the aggregation behaviors of nanoparticles in the two aqueous media. Results showed that the effects of DBS on aggregation could be interpreted by both Derjaguin–Landau–Verwey–Overbeek（DLVO） and non-DLVO mechanisms. In natural water samples,aggregation did not occur rapidly and was able to develop slowly under all conditions, and the roles of DBS were obvious at high DBS concentration owing to the impacts of inherent components of natural water samples, such as colloids and natural organic compounds.Future aggregation studies should concentrate on multi-factor, multi-colloidal and dynamic aspects under similar environmental conditions.
