In order to understanding of the fate and transport of TiO2 nanoparticles (NPs) in the water treatment process, this study focused on the particle surface characteristics and hydrodynamic properties at different humic acid (HA) concentration, using aluminum sulfate (AS) as a coagulant. The changes of zeta potential of humic acid capped TiO2 NPs and flocs were measured by Malvern Zetasizer nanoZS. The surface functional group of flocs was investigated using FT-IR spectra. The growth velocity of alum-TiO2 NPs flocs were determined using a small-angle light scattering technique during the coagulation process.Experimental results indicated that the zeta potential of alum-TiO2 NPs flocs surface after adsorption of humic acid was related with humic acid concentration. Adsorption of humic acid resulted in more negative electrophoresis on the surface. Size and growth velocity of alum-TiO2 NPs flocs were estimated at different humic acid concentration. It was found that the flocs growed were faster in the presence of humic acid, while humic acid had adverse influences on the growth of alum-TiO2 NPs flocs.
Binding of proton and iron to lignite humic acid size-fractions in aqueous matrix
