Adsorptive and Photocatalytic Removal of Phenol by Layered Niobates Organically Modified Through Intercalation and Silylation

Abstract

Layered hexaniobate K4Nb6O17 was modified with dodecylammonium ions and octadecyltrimethoxysilane molecules, which were held in the interlayer spaces by electrostatic interactions and covalent attachment to the layers, respectively. Interlayer spacing of the niobate was expanded by incorporation of the bulky organic species. Vapor adsorption isotherms of benzene and water indicated hydrophobic interlayer microenvironments of the organically modified niobates. Both of the modified niobates fairly adsorbed phenol dissolved in water. The photocatalytic activity of hexaniobate allowed the organically modified materials to photocatalytically decompose phenol upon UV irradiation. Decomposition time courses and quantitative analysis of phenol present in the system indicated that the phenol molecules adsorbed on the niobates were preferentially degraded. XRD and IR analyses of the modified niobates indicated that the silylated niobate was more durable than the ion-exchanged sample; the former kept the structure during the photocatalytic process while the latter was partly collapsed.

Pickering Emulsions Prepared by Layered Niobate K4Nb6O17 Intercalated with Organic Cations and Photocatalytic Dye Decomposition in the Emulsions

“…Here, we report Pickering emulsions prepared with layered hexaniobate K 4 Nb 6 O 17 that is a photocatalytically active wide band gap semiconductor , and is intercalated with organic cations through ion exchange. − The photocatalytic activity allows decomposition of organic species that is adsorbed on the material or dissolved in the surrounding liquid upon UV irradiation. − Hydrophobicity of the material is broadly modified by intercalation of alkylammonium ions whereas bare K 4 Nb 6 O 17 is hydrophilic. − We have obtained both w/o and o/w emulsions depending on the intercalated alkylammonium species with different chain length. In addition, the niobate particles located at the water–oil interface photocatalytically decompose dyes dissolved in both oil and water phases.…”