title: Aggregation of TiO2-graphene nanocomposites in aqueous environment: Influence of environmental factors and UV irradiation.
abstract: The aggregation kinetics of TiO2-graphene nanocomposites in aqueous solution affected by solution pH, salt types (NaCl, CaCl2) and concentrations of electrolytes, and stability induced by UV irradiation was investigated in this study. The zeta potentials and hydrodynamic diameter of the nanoparticles were used as bases to assess the aggregation behavior, and stability of nanocomposites exposed to UV irradiation was expressed in terms of supernatant concentration. The aggregation of TiO2-graphene nanoparticles in aqueous media followed the colloidal theory. TiO2-graphene nanoparticles were significantly aggregated in the presence of a diavalent cation compared with monovalent cation because the former was more capable of effective charge screening and neutralization. The calculated Hamaker constant of the TiO2-graphene nanocomposites in aqueous solution prepared in the lab was 2.31×10(-20)J. The stability of this composite nanoparticles was between those of pure TiO2 and graphene. A known intensity of UV irradiation was beneficial in the formation of TiO2-graphene nanoparticle aggregates. However, prolonged UV irradiation may stabilize the nanoparticles. These results provided critical information about the colloidal properties of the new TiO2-graphene nanocomposites and were useful in predicting the fate and transport of TiO2-graphene nanocomposites in natural water environments.
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Zulin
authors.initials: Z
authors.lastname: Hua
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Jianan
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China. Electronic address: baixue@hhu.edu.cn.
authors.forename: Xue
authors.initials: X
authors.lastname: Bai
authors.affiliation: Key Laboratory of Water and Sediment Sciences of the Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871, China.
authors.forename: Zhengfang
authors.initials: Z
authors.lastname: Ye
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Tang
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Liang
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Yuqi
authors.initials: Y
authors.lastname: Liu
mesh_terms: D006108:Graphite / Q000032:analysis / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D053761:Nanocomposites / Q000032:analysis / Q000737:chemistry*; D014025:Titanium / Q000032:analysis / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D006108:Graphite; D014025:Titanium
keywords: Aggregation; DLVO theory; TiO(2)–graphene; UV irradiation