Improved production of titanate nanotubes by hydrothermal method for adsorption of organic dyes

Background Increasing the yield of nanomaterials using the same reactor size and fixing most of the reactants and conditions will greatly improve the production process by saving time, energy and efforts. Titanate nanotubes are mainly prepared by hydrothermal process, in which TiO2 powder reacts with NaOH at certain conditions to form the desired nanotubes. It was reported that it is a must to use high concentrations of NaOH (10 N) to enable the tubular form formation, and the amount of NaOH from the stoichiometry point of view is much higher than that of TiO2; this means excess amounts of NaOH are not used and washed off. This work was designed to improve the production yield by making use of this excess amount of NaOH. Results More than 60 g of sodium titanate nanotubes was prepared using simple hydrothermal method. The prepared nanotubes were characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, Fourier-transform infrared spectroscopy and BET surface area analysis. The adsorption capacity of these nanotubes was tested against three commonly used dyes: methyl orange, crystal violet and thymol blue. The samples showed great affinity toward crystal violet and lower activity toward methyl orange and thymol blue, where they achieved more than 90% removal efficiency under different experimental conditions. Conclusions Sodium titanate nanotubes were prepared in large amounts using modified hydrothermal method. The obtained nanotubes efficiently removed crystal violet from water. This improved synthesis of titanate nanotubes will reduce the total cost of nanomaterials production, and subsequently the treatment process, since titanate nanotubes are used in adsorption and photocatalysis processes.

Titanate Nanotubes as Futuristic Catalyst Support Material

Titanate Nanotubes (TNT) were synthesized by aging commercial titanium dioxide (TiO2 - Degussa P25) with an alkali (KOH) solution at different time intervals. The prepared materials were investigated for their surface composition and textural behaviour by X-ray powder diffraction (XRD), Raman spectroscopy, Gas (N2 and CO2) adsorption measurements, and Transmission electron microscopy (TEM). The X-ray diffraction spectra revealed the decrease in the crystalline nature of the materials decreased by exposing them for a longer duration in the base solution. Raman spectra results showed that ageing time affected the structural properties. The specific surface area and the pore size of the newly synthesised materials were affected by the ageing process. The TEM images showed the influence of ageing during the formation of titanate nanotubes. HRTEM revealed that Pd particle sizes of <1 nm was present inside the tubes.

Titanate Nanotubes as Futuristic Catalyst Support Material

Titanate Nanotubes (TNT) were synthesized by aging commercial titanium dioxide (TiO2 - Degussa P25) with an alkali (KOH) solution at different time intervals. The prepared materials were investigated for their surface composition and textural behaviour by X-ray powder diffraction (XRD), Raman spectroscopy, Gas (N2 and CO2) adsorption measurements, and Transmission electron microscopy (TEM). The X-ray diffraction spectra revealed the decrease in the crystalline nature of the materials decreased by exposing them for a longer duration in the base solution. Raman spectra results showed that ageing time affected the structural properties. The specific surface area and the pore size of the newly synthesised materials were affected by the ageing process. The TEM images showed the influence of ageing during the formation of titanate nanotubes. HRTEM revealed that Pd particle sizes of <1 nm was present inside the tubes.

Removal of Cd2+ from Water Containing Ca2+, Mg2+ using Titanate Nanotubes Modified by Carbon

Ca2+ and Mg2+ usually exist in natural water. When Cd2+ is removed from water by adsorption, it will be inhibited by these two ions. Titanate nanotubes (TNTs) have an effective adsorption capacity for Cd2+ due to extraordinary ion-exchange property. However, TNTs also adsorb Ca2+ and Mg2+ in water. In this study, carbon-modified TNT (TNT/C or TNT/HC) was synthesized by hydrothermal synthesis. The transmission electron microscope (TEM) images show that TNT/C or TNT/HC still keep nanotube morphology. The experimental results show the order of adsorption amount to Cd2+ is TNT > TNT/C > TNT/HC when there is no Ca2+ or Mg2+. But when there is Ca2+ or Mg2+ in the water, the order of Cd2+ adsorption capacity becomes TNT/HC > TNT/C > TNT. It indicates that the surface carbon-modification can alleviate the hindrance of Ca2+ or Mg2+ to Cd2+ removal. This is because the carbon on the surface of TNT captured part of Ca2+ or Mg2+, it made more Cd2+ be successfully absorbed by TNT through ion exchange. This mechanism was confirmed by XPS spectra analysis. The results of this paper can provide ideas for the adsorption and removal of Cd2+ in water in the presence of Ca2+ or Mg2+.

About the Influence of PEG Spacers on the Cytotoxicity of Titanate Nanotubes-Docetaxel Nanohybrids against a Prostate Cancer Cell Line

The association between chemotherapeutic drugs and metal oxide nanoparticles has sparked a rapidly growing interest in cancer nanomedicine. The elaboration of new engineered docetaxel (DTX)‑nanocarriers based on titanate nanotubes (TiONts) was reported. The idea was to maintain the drug inside cancer cells and avoid multidrug resistance mechanisms, which often limit drug efficacy by decreasing their intracellular concentrations in tumor cells. HS‑PEGn‑COOH (PEG: polyethylene glycol, n = 3000, 5000, 10,000) was conjugated, in an organic medium by covalent linkages, on TiONts surface. This study aimed to investigate the influence of different PEG derivatives chain lengths on the TiONts colloidal stability, on the PEGn density and conformation, as well as on the DTX biological activity in a prostate cancer model (human PC‑3 prostate adenocarcinoma cells). In vitro tests highlighted significant cytotoxicities of the drug after loading DTX on PEGn‑modified TiONts (TiONts‑PEGn‑DTX). Higher grafting densities for shorter PEGylated chains were most favorable on DTX cytotoxicity by promoting both colloidal stability in biological media and cells internalization. This promising strategy involves a better understanding of nanohybrid engineering, particularly on the PEGylated chain length influence, and can thus become a potent tool in nanomedicine to fight against cancer.