Removal of Rhodamine B Dye with Fe/Mn Co-Doped Titania Nanotubes

Fe/Mn co-doped titania nanotubes has been synthesized by solution combustion followed by the hydrothermal treatment. Combustion synthesis has emerged as a facile and economically viable technique for the preparation of advanced ceramics, catalysts and nanomaterials. Stoichiometric amounts of transition metal nitrates and fuel (Glycine) are mixed in a solution for the preparation of nanomaterials by using the single step solution combustion method at 350° C. The Fe_xMn_yTi₀.₉O_(2-δ) (x,y ranges from 0.01-0.09, with x+y = 0.1) nanomaterials are made in the anatase phase by the solution combustion synthesis. The nanotubes are then fabricated using the hydrothermal method using 10 N NaOH at temperature of 130°C for 24 hours.

Characterization of the prepared co-doped titania nanotubes were performed using transmission and scanning electron microscopy (TEM and SEM), XRD analysis, and BET specific surface area analysis. The co-doped titania nanotubes thus prepared contain both monoclinic and anatase phases as evidenced by the XRD and EDX results. STEM analysis shows the formation of nanotubes. BET analyses show that the surface area for both the nanopowders and nanotubes increases with Mn doping and surface area increases when the nanostructure changes from a powder form to a tube form.

Degussa P-25, Titania nanotubes synthesized @ 180°C, co-doped Titania nanotubes (Fe_0.01Mn_0.09Ti_0.9O_(2-δ) , Fe_0.05Mn_0.05Ti_0.9O_(2-δ) & Fe_0.09Mn_0.01Ti_0.9O_(2-δ)), co-doped titania nanopowders (Fe_0.01Mn_0.09Ti_0.9O_(2-δ) & Fe_0.09Mn_0.01Ti_0.9O_(2-δ)), and Activated carbon were tested and compared for the adsorbtion of Rhodamine B. With adsorbent loading of 100 mg (0.06 wt%) in 150 ml beaker, the suspension was stirred using the magnetic stirrer. Adsorption of Rhodamine B was found to be the highest for the Fe_0.01Mn_0.09Ti_0.9O_(2-δ) nanotubes. The adsorption of Rhodamine B was found to increase with the adsorbent loading. Influence of pH was studied over a pH range of 2.5 – 10.5 and found that the removal of Rhodamine B is the highest at pH = 2.54. Adsorption of Rhodamine B was found to increase with temperature from 25 to 50° C.