Uranium uptake from wastewater by the novel MnxTi1-xOy composite materials: Performance and mechanism

Highlights: • The porous Mn_xTi_1-xO_y composites with recyclability were prepared. • The Mn_0.5Ti_0.5O_y showed the wonderful adsorption property for uranium(VI). • The adsorption capacity of uranium on the Mn_0.5Ti_0.5O_y reached 695.2 mg/g. • The maximum percentage of uranium on the Mn_0.5Ti_0.5O_y was 98.6%. • The removal efficiency remained above 90% after five cycles. The novel Mn_xTi_1-xO_y composite materials with different mole ratios (Mn to Ti = 3:7, 5:5 and 7:3) were prepared to remove uranium species from wastewater. These composite materials were characterized by various techniques, such as thermogravimetric analysis (TG), X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) and scanning electron microscopy (SEM). It was found that the chitosan in Mn_xTi_1-x-Chi were completely removed after calcination at 650 °C and Mn_xTi_1-xO_y composites possessed uniform distribution of the porous structure as well as plentiful hydroxyl-containing groups. Moreover, the as-prepared Mn_xTi_1-xO_y composite materials were applied to remove uranium from solution to evaluate the adsorption performance. It was found that the Mn_0.5Ti_0.5O_y possessed relatively excellent uptake performance for uranium comparing with the Mn_0.3Ti_0.7O_y and Mn_0.7Ti_0.3O_y and its maximum uptake capacity and efficiency reach 695.2 mg/g and 98.6% (pH = 4, m/V = 0.1 g/L, T = 298 K), respectively, which were much superior than most of reported materials based on titanium oxide or manganese oxide. Besides, the uranium uptake on Mn_0.5Ti_0.5O_y was independent on ionic strength and it had considerable reusability, which might be the necessary condition for Mn_0.5Ti_0.5O_y to be applied in uranium uptake from uranium-containing wastewater. As a candidate adsorbent, Mn_0.5Ti_0.5O_y possessed a high potentiality to remove uranium from wastewater.