Effect of generation growth on photocatalytic activity of nano TiO2-magnetic cored dendrimers

[Display omitted] •Nano TiO2 were grafted on magnetite-cored dendrimers of 0th to 3rd generations.•Mean diameters of magnetite core and nano TiO2 were 200nm and 10nm, respectively.•Generation growth increases the number of nano TiO2 groups on dendrimers.•More loss of photocatalytic activity was observed in higher generations in reuse. Titanium dioxide (TiO2) nanoparticles were individually grafted on magnetic-cored dendrimers of 0th, 1st, 2nd, and 3rd generations. Dendrimer’s fractal structure makes nano TiO2 functional group disperse well in water, so we can make full use of the surface area of each nanoparticle to improve photocatalysis. Furthermore, nano TiO2 functionalized magnetite-cored dendrimer (nano TiO2-MD) can be easily recycled by an external magnetic field. Synthesized nano TiO2-MDs of various generations were confirmed with scanning electron microscopy, energy dispersive spectroscopy analysis, X-ray diffraction, and Fourier transform-infrared spectroscopy. Pseudo first order reaction rate constants of methyl orange increased with the generation number of nano TiO2-MDs, but photocatalytic activity after five cycles of reuse was inversely proportional to the generation number. Generation growth directly increases the number of nano TiO2 functional groups to enhance the photocatalytic activity, but more loss of photocatalytic activity was observed in repeated use of higher generations of nano TiO2-MDs.