In the present work, we accomplish the boosting of photocatalytic performance by the synergistic effect of acid treatment and transition metal oxide co-catalysts on molten salt rutile TiO nanorods. FT-IR and XPS (oxygen deconvolution) results confirmed that the amount of hydroxyl groups increased on the surface of rutile TiO nanorods (TO-NRs) after acid treatment. HR-TEM analysis revealed fine dispersion of metal oxide on the surface of acid treated TiO nanorods (ATO-NRs). The photocatalytic activities of as-prepared (TO-NRs), acid treated (ATO-NRs), metal oxide loaded (MTO-NRs), and both acid treated and metal oxide loaded (MATO-NRs) nanorods were compared based on the rate kinetics and dye degradation efficiencies. Cobalt oxide (1 wt %) loaded and 1.0 M acid treated TiO nanorods (Co/ATO-NR) exhibited the higher photocatalytic degradation efficiency for Orange-II dye degradation and inactivation of S. typhimurium pathogen compared to other photocatalysts under solar irradiation. Photoelectrochemical analysis demonstrated that the charge transfer process in Co/ATO-NR is significantly higher than that in the untreated samples. The improved photocatalytic activity of inactive TO-NRs might be due to enhanced charge transfer of finely dispersed metal oxides on the OH-rich surface of acid treated TiO nanorods.

Vertically aligned titanate nanotubes (VA-TNTs) are prepared for the repeated and effective recovery of Sr ions. Two-electrode electrochemical anodization with a 50 V potential was used to prepare the TiO2 nanotube arrays on a Ti metal foil. The growth and inner diameters of the TiO2 nanotubes were measured as a function of the anodization potential and reaction time. VA-TNTs structures are synthesized via one-step alkaline hydrothermal (HT) reaction of the as-prepared anodized TiO2 nanotube arrays (anodic TiNA). The titanate nanotube synthesis is successfully optimized, revealing that a low calcination temperature and a low HT reaction time allowed for the synthesis of a vertically aligned homogeneously dispersed “Grass”-type morphology among the titanate nanotubes. The equilibrium isotherm and kinetic data are used for model fitting. High-resolution transmission electron microscopy images and X-ray energy dispersive spectroscopy elemental characterizations provided a detailed chemical composition and surface analysis of the VA-TNTs. The recyclability of the VA-TNTs for repeated metal ion adsorption–desorption is demonstrated successfully. The crystallinity of the VA-TNTs after each repeated desorption cycle was dramatically improved by Na treatment. This structural reformation (Na treatment) step increased the number of possible high-yield metal ion recovery cycles. Also, the VA-TNTs have great potential for removing toxic heavy metal ions in an easy, economic, and environmentally friendly way.

TNT-2D material prepared via molten salt NRs for efficient Sr2+ adsorption.

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