Hierarchical layered titanate microspherulite: formation by electrochemical spark discharge spallation and application in aqueous pollutant treatment

Abstract

An ultrafast and template-free method to synthesize three-dimensional (3D) hierarchical layered titanate microspherulite (TMS) particles with high surface area is reported. The synthesis makes use of an electrochemical spark discharge spallation (ESDS) process, during which a fast anodic reaction on the titanium surface creates a layer of titanium dioxide that instantly breaks down by the applied electrical field into the solution in the form of titanium oxide particles. The spalled particles readily react with the heated NaOH electrolyte to form the titanate particles. A typical as-prepared TMS with a diameter of 0.4 similar to 1.5 mu m is synthesized by ESDS of Ti foils in 10 M NaOH solution under an applied current density of 0.5 A cm(-2), leading to a reaction yield of approximately 0.10 similar to 0.15 g per square centimetre of exposed Ti foil within 20 min. After hydrogen ion exchange, the surface area can reach as high as similar to 406 m(2) g(-1). On the Ti surface, a crystalline rutile TiO2 nanosheet structure is formed, which is attributed to the local exothermic heat caused by the spark discharge. A formation mechanism of the TMS is discussed based on field emission scanning electron microscopy (FESEM), a transmission electron microscopy (TEM) study and Raman scattering spectroscopy analysis. The as-prepared TMS shows excellent adsorption performance compared with a titanate micro-particle (TMP), nanowire (TNW) and nanotube (TNT) when methylene blue (MB) and Pb-II ions are used as representative organic and inorganic pollutants. The mechanism of adsorption has also been discussed.National Research Foundation of Singapore Government [MEWR651/06/160

A one-step thermal decomposition method to prepare anatase TiO2 nanosheets with improved adsorption capacities and enhanced photocatalytic activities

“…The values compare very favorably to adsorption capacities of several common adsorbents reported in the literature, such as zeolite (16.37 mg g −1 , MB), activated sewage char (120 mg g −1 , MB), titania (6 mg g −1 , MB), H 3 PO 4 -activated various micro-mesoporous carbons (138-190 mg g −1 , MB) [68,69]. The value (186 mg g −1 ) is also comparable to data reported for other layered titanate products, for example, hollow spheres (154 mg g −1 , MB) and microspherulites (236 mg g −1 , MB) [70][71][72]. The high adsorption capacity of TiO 2 NSs are assigned to the high surface area [73], and mesopore structures of the materials.…”

“…It can be concluded that the adsorption of MB on TiO 2 NSs follows the pseudo-second-order kinetic model which relies on the assumption that chemisorption and effective electrostatic interactions play a major role in the adsorption process [74]. Comparing the adsorption capacities of the adsorbents mentioned above (references [68][69][70][71][72]), we can conclude that TiO 2 NSs shows efficient adsorption properties and is a promising candidate for environmentally friendly adsorbents in water treatment.…”

Blue colloidal nanoparticles of molybdenum oxide by simple anodizing method: decolorization by PdCl2 and observation of in-liquid gasochromic coloration

“…It is noteworthy that hydrate forms of metal oxides, which have been obtained by anodizing method, are good candidates owing to their property of high proton transportation. The method of anodizing has been also used in a few papers for synthesis of metal oxides of other elements such as titanium compounds [33,34]. Although people are familiar with this process in electrochemistry or corrosion science, less attention has been paid to it as a method for generation of colloidal solutions and nanoparticles.…”

Synthesis of dual-phase titanate/anatase with controllable morphology doped with nitrogen from a bola-amphiphile amine surfactant as template

“…However, the adsorptive properties of anatase are not ideal either. In contrast, titanate materials have recently been identified as superior adsorbents for, for example, organic dyes and heavy metal ions [12,13]. Its layered crystal structure makes it possess large specific surface area, the pollutants and intermediates around the catalyst.…”