Aggregation and toxicity of titanium dioxide nanoparticles in aquatic environment-A Review

The use of nanoparticles-particles with size similar to 1-100 nm is increasing worldwide. This is particularly the case for applications of titanium dioxide nanoparticles (nano-TiO2) in consumer products, which have expanded at a fast rate in the last decade. The properties of nano-TiO2 differ significantly from bulk-TiO2 of the same composition because of an increase in surface area. A release of nano-TiO2 from application sources to the aquatic environment may pose possible risks due to their bioavailability and toxicity. The aggregation of nano-TiO2 plays an important role in the environmental effects of nanoparticles because the size and shape of nanoparticles will determine the magnitude of any potentially toxic effect. Aggregation is affected by pH, ionic strength, and ionic identity (inorganic and organic) of aqueous suspensions and is reviewed in this paper. The current information on the evaluation of ecotoxicological hazards of nano-TiO2 to bacteria, algae, invertebrates, nematodes, and rainbow trout is also given.