Synthesis of Anodized TiO₂ Nanotube Arrays as Ion Sieve for Lithium Extraction

Abstract

Titanium type lithium ion‐sieve nanotubes synthesized by the hydrothermal method were extensively explored over recent years due to its promising properties. However, on account of nanotubes′ tangled structure impeding the lithium adsorption in the interior nanotube walls, unalterable dimensions of the synthesized nanotubes, and a long period of annealing, the anodizing technique was proposed. It is shown that lithium uptake and adsorption capacity is improved because of easier mass transfer during the ion exchange process. This work focuses on a novel anodizing method for nanotube ion‐sieve synthesis. The optimum anodizing condition was discovered by altering anodizing voltage, time, and fluoride concentration to have a proper nanotube morphology and corresponding high surface area for achieving the most suitable adsorption properties. Nanotubes were grown on Ti foil in Ethylene Glycol (EG) electrolyte with different amounts of NH4F in a range of anodizing voltage (40–70 V) and time (1–4 hours). TiO2 Nanotube array morphology, dimension, and phase characterization were derived from FESEM and XRD analysis. As a result, the optimum condition discovered in this research to obtain acceptable morphology and high aspect ratio nanotubes was at 0.5 wt % NH4F, 40 V, 3 hours. Lithium titanate spinel with nanotube morphology was synthesized by chemical lithiation in the LiOH solution and then acid‐treated to obtain H4Ti5O12 adsorbent. ICP‐OES analysis revealed that the H4Ti5O12 lithium‐ion sieve with nanotube array structure obtain adsorption capacity up to 37.5 mg/g in LiOH and LiCl solutions (112 mg/L Li, pH 12), designating that the Hydrogen titanate (HTO) ion sieve could effectively extract Li+from the enriched solutions.

Stable and Reversible Lithium Storage Properties of LiTiOx Nanotubes for Electrochemical Recovery from Aqueous Solutions

“…The peaks in the two cases are very similar, but in the de‐lithiated case the intensity is lower and the peaks are slightly asymmetric and shifted to 0.5° higher. These small changes in the XRD signature of the de‐lithiated phase are in agreement with what previously reported in the literature [48,72] . Furthermore, the XRD diffractograms confirmed a change in the lithiated phase of the nanotubes after the cycling, as was seen with XPS analyses.…”

“…These small changes in the XRD signature of the de-lithiated phase are in agreement with what previously reported in the literature. [48,72] Furthermore, the XRD diffractograms confirmed a change in the lithiated phase of the nanotubes after the cycling, as was seen with XPS analyses. This change is underlined by the disappearance of the peak at 18°, the shift from 43°to 44.5°of its most intense one and the split of the one at 63°into two smaller peaks.…”

“…Titania NTs were extensively studied as primarily anode materials for lithium ion batteries and thus galvanostatically tested, but only few works are available on the use of titania NTs as lithium adsorbents. Furthermore, these only focused on batch adsorption using the NTs as ion sieves [47,48] . While Moazeni et al.…”

“…Furthermore, these only focused on batch adsorption using the NTs as ion sieves. [47,48] While Moazeni et al used disordered NTs grown by hydrothermal processes, Taghvaei et al calcinated the hydrothermally lithiated NTs grown by anodic oxidation. While the authors proved the adsorption properties through analyzing the composition of the solution pre and post adsorption, an accurate investigation of the properties of the adsorbent is still missing.…”

Ppb-Level Butanone Sensor Based on ZnO-TiO2-rGO Nanocomposites

“…Semiconductor materials such as titanium dioxide (TiO 2 ) have a wide band gap of about 3.0 eV. It is widely used in energy utilization and catalytic research because of its high catalytic activity, non-toxic, good chemical stability, and low price [21][22][23][24]. With the increasing level of scientific research, the properties of pure ZnO and TiO 2 can no longer meet the required requirements.…”