Capturing of Nano-TiO2 from Complex Mixtures by Bisphosphonate-Functionalized Fe3O4 Nanoparticles

Abstract

Selectively capturing nanosized titanium dioxide (nano-TiO2) from complex mixtures is a very significant but very formidable task both for enriching the analytical methodology and removing/recycling of nano-TiO2. We presented a novel sustainable strategy for such a task by using the bisphosphonate-functionalized Fe3O4 (BP-Fe3O4) nanoparticles as the highly selective adsorbents toward nano-TiO2. The BP-Fe3O4 exhibited high equilibrium adsorption capacity (Qe) toward nano-TiO2 (2.45 g g–1 for 60 nm anatase TiO2) but negligible Qe toward nano-SiO2 (0.01 g g–1 for 15 nm SiO2). The BP-Fe3O4 also had good adsorption capability toward nano-TiO2 in complex liquid media, or in the solid mixtures containing 10−500 times of coexisting nano-SiO2. This capturing strategy enables the green pretreatment for quantitative analysis of nano-TiO2 in complex real samples with the spike recoveries of 69.9–99.0% and low detection limit of 0.02 ppm. Furthermore, this strategy offers great convenience for identification of the crystal forms and even the morphology of nano-TiO2 existing in complex real samples. Besides, this capturing strategy holds great potential for separating or removing nano-TiO2 from the environment and the sustainable recycling of nano-TiO2.