TiO 2/montmorillonite nanocomposite for removal of organic pollutant

Abstract

In order to improve the adsorption and photocatalytic performance of TiO 2 modified clay composite, a new method of immobilization of nano-scaled TiO 2 on the layer surface of montmorillonite (MT) clay was designed and carried out in two steps in this work. The first step was to prepare a nano-scaled TiO 2 dispersion by a hydrothermal method with the addition of organic dispersant into an aqueous solution of TiCl 4; and then the assemblies of nano-scaled TiO 2 with CTAB (cetyltrimethylammonium bromide) were applied to regulate the process of immobilization of nano-scaled TiO 2 on the layer surface of MT clay. The results indicated that well pre-dispersed nano-TiO 2 was obtained with the application of diethanolamine (DEA) as a dispersant, which could interact with CTAB to form assemblies of nano-scaled TiO 2 particles and CTAB molecules (CTAB–DEA–TiO 2), and then became self-anchored on the layer surface of MT clay to produce well-distributed TiO 2/MT nanocomposites. After calcination at 500 °C, the modified composites showed much higher values for specific surface area, average pore size and pore volume than the raw MT clay. The adsorption and photocatalytic performance of the composite TCM-500 was evaluated by using methyl orange (MO). The comparative photocatalytic degradation of MO indicated that the composite gave 10% higher photocatalytic efficiency than P25 due to its optimal structural conformation tailored by surfactant assembly. Therefore, the new method of immobilization of pre-dispersed nano-scaled TiO 2 assembly with a surfactant was a good alternative to prepare a TiO 2/MT nanocomposite and was effective to improve its adsorption capacity and photocatalytic performance.