ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Leaching test for calcined kaolinite and kaolinite/TiO2 photoactive composite

Michaela Tokarčíková, Kateřina Mamulová Kutláková, and Jana Seidlerová

Nanotechnology Centre

E-mail: michaela.tokarcikova@vsb.cz

Abstract: Kaolinite is a suitable material for fixing TiO₂ nanoparticles in a composite form. The kaolinite/TiO₂ composite has promising photoactive properties which are as important as is the possible impact of the composite on the environment. Accordingly, the stability of the kaolinite/TiO₂ composite dried at 105°C (KTI1) and calcined at 600°C (KTI6) and the stability of the original kaolinite treated at various temperatures (105–800°C) were studied by the leaching test in accordance with European standard BS EN 12457-2:2002 (British Standards Institution, 2002). The stability was evaluated on the basis of elements leached from the materials to extraction agents. Atomic emission spectrometry with inductively coupled plasma was used for determining the concentration of elements. In order to better understand the process of calcination and the structure changes in the kaolinite/TiO₂ composite and calcined kaolinite, the materials were evaluated using X-ray powder diffraction and infrared spectroscopy with Fourier transformation. The processes of kaolinite dehydroxylation and metakaolinite formation were observed. Kaolinite is an appropriate carrier for composite preparation due to its stability even after its treatment at high temperatures. The experiments confirmed the TiO₂ nanoparticles to be very strongly bound to the kaolinite surface. On the other hand, the experiments demonstrated that the presence of TiO₂ on the kaolinite surface caused the release of Al in high concentrations to the final extracts, especially after kaolinite/TiO₂ composite calcination.

Keywords: kaolinite – kaolinite/TiO2 photoactive composite – calcination – leaching test

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2016-0059

Chemical Papers 70 (9) 1253–1261 (2016)