HALLOYSITE-TiO2 NANOCOMPOSITES: SYNTHESIS AND CHARACTERIZATION

In this paper we describe the synthesis and characterization of nano-sized TiO2 particles supported on Halloysite with halloysite to TiO2 weight ratios of 30:70. Two halloysite-TiO2 nanocomposites were prepared using two different halloysites (from Limnos island Greece and from Utah, USA). Both halloysite - TiO2 nanocomposites were prepared by deposition of anatase form of TiO2 on the halloysite surfaces using a sol-gel method with titanium isopropoxide as a precursor under hydrothermal treatment at 180 degrees C. Phase composition, particle morphology and physical properties of these samples were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Attenuated Total Reflection using Fourier Transform Infrared spectroscopy (ATR-FTIR) and N-2 specific surface area (SSA) analysis by BET. Preparation of halloysite-TiO2 nanocomposites led to good dispersion of 3-10nm TiO2 particles on halloysite surfaces. ATR-FTIR results indicated the formation of hydrogen bonding between the outer surfaces of halloysite tubes and TiO2. After compositing with TiO2 both halloysite samples largely showed interparticle mesopores of about 5.7nm, while halloysite from Utah, USA retained a higher SSA compared to the one from Limnos island Greece.