Vertically Aligned Titanate Nanotubes Hydrothermally Synthesized from Anodized TiO₂ Nanotube Arrays: An Efficient Adsorbent for the Repeatable Recovery of Sr Ions

Abstract

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.

Study of 1D Titanate‐Based Materials –New Modification of the Synthesis Procedure and Surface Properties‐Recent Applications

“…TiNTs have potential applications in several fields; they are found in biomaterials, gas sensors, adsorbents, heterogeneous catalysis ( photocatalysis, oxidation reactions, organic synthesis, biomass,…), biological activities to remove bacteria from water, solar cells, Li battery production, and many others. In particular, TiNTs have been used as a catalytic support for different active species (metals, oxides and sulfides).…”

Rational Regulation of Surface Free Radicals on TiO2 Nanotube Arrays via Ag2O–AgBiO3 towards Enhanced Selective Photoelectrochemical Detection

“…The nanostructure of the as-prepared samples in each step was investigated by using scanning electron microscopy (SEM). An orderly hollow 1D TiO 2 NTA was first grown on a Ti substrate via the anodization method [ 28 , 29 ] (see Figure 1 b). By comparison, two significantly different morphologies of reaction products can be observed on the surface of the NTAs after the reaction of one-step precipitation ( Figure 1 c).…”

Sr2+ sorption property of seaweed-like sodium titanate mats: effects of crystallographic properties

“…13 Numerous efforts have been undertaken to develop purication methods that can remove strontium from water effectively. For instance, purication materials used for water purication include layered titanate, [14][15][16][17] zeolite, 18,19 hydroxyapatite, [20][21][22] organic materials, 23,24 and others. Among these materials, sodium titanate is established as an efficient strontium removal material.…”

“…31,32,34 The removal efficiency of sodium titanates for several cations, including heavy metals and radionuclides, has been reported. 9,[14][15][16][17] Recently, the Sr 2+ adsorption selectivity of sodium nonatitanate (Na 4 Ti 9 O 20 ) and sodium trititanate (Na 2 Ti 3 O 7 ) were investigated by Kunishi et al 35 Although several references have reported on the mechanism of sodium titanate sorption, it is interesting to note that the ion-exchange reaction has been the focus for the cation removal by sodium titanates, while other reactions, such as precipitation or surface adsorption, have been overlooked. Recently, we reported the synthesis of a unique seaweed-like sodium titanate mat (SST), which is composed of randomly distributed layered-sodium titanate nanobers, using a template-free alkaline hydrothermal process.…”