TY - JOUR AU - Hung, Do Quoc AU - Thanh, Nguyen Kim PY - 2011/12/15 TI - Preparation of NiFe2O4 - TiO2 nanoparticles and study of their photocatalytic activity JF - VNU Journal of Science: Mathematics - Physics; Vol 27 No 4 KW - N2 - Abstract. In this article, the authors describe the method for preparation of NiFe 2 O 4 – TiO 2 magnetic nanoparticles and present the results on study of their photocatalytic activity. NiFe 2 O 4 nanoparticles have been prepared by coprecipitation using spraying technique with subsequent hydrothermal processing. NiFe 2 O 4 -TiO 2 composite nanoparticles were prepared by covering thin films of TiO 2 on the surface of NiFe 2 O 4 particles using sol – gel technique. Different techniques such as XRD, TEM, SEM  were used to characterize NiFe 2 O 4 and NiFe 2 O 4 – TiO 2 composite nanoparticles obtained from the mentioned procedure. It is shown that prepared NiFe 2 O 4 – TiO 2 nanoparticles are particles of a composite material which consists of trevorite NiFe 2 O 4 and anatase TiO 2 phases. TEM study has showed that the particles size is of about 20nm. The VSM measurement has demonstrated that nickel ferrite nanoparticles and NiFe 2 O 4 – TiO 2   composite nanoparticles are superparamagnetic with saturation magnetization (Ms) of about 40 emu/g and 20 emu/g, respectively; remanences (Mr) and coercive forces (Hc) being near to zero for both the materials. The composite NiFe 2 O 4 - TiO 2 nanoparticles are used to degrade methyl orange dye. After 14 hours, methyl orange with the initial concentration of 10 -4 M is degraded 98,2%. Thanks to magnetic properties, the nanocomposite photocatalyst NiFe 2 O 4 - TiO 2 can be easily collected for reuse. Keywords: Magnetic nanoparticles, superparamagnetism, NiFe 2 O 4 -TiO 2  nanocomposite, UR - https://js.vnu.edu.vn/MaP/article/view/1531