Effects of Cerium, Iron and Copper Incorporation on the Structural Properties and Activities of Ti-Pillared Bentonites

Abstract

Ti-pillared bentonite (Ti-PB) using bentonite from the Middle Anatolia region (Hançılı) was synthesized. Iron or copper was impregnated to Ti-PB from the solution and subsequent cerium incorporation was done by wet impregnation. The hydrothermal syntheses were carried out with a Cu/(Cu+Ti) ratios of 0.1 and 0.2. The anatase phase of titanium dioxide was found for all of the samples. The Ti-PB calcined at 500 °C gave a basal spacing value of 4.41 nm, a specific BET surface area of 348 m2 g-1, and a micropore volume of 0.093 cm3g-1. While the post incorporation of copper and iron caused decrease in the micropore properties, the hydrothermally synthesized copper titanium samples reflected the similar behavior with Ti-PB. Energy dispersive X-ray spectroscopy (EDS) analyses indicated that TiO2 content of all PBs was near 40 wt % and metal incorporation to Ti-PB was succesfully performed by the impregnation method. Ti-PB exhibited both the Lewis and Brønsted acidities. The copper impregnation resulted in an increase in the Lewis acidity. The hydrotermally synthesised copper containing sample and cerium-iron and cerium-copper impregnated samples yielded an increase in the Brønsted acidity. Approximately 90 % phenol conversion at 30 °C in an hour was achived with the cerium and iron containing sample and the completion of photocatalytic oxidation was reached at 2 hours. An increase of temperature rised the conversion of phenol, and the iron containing sample resulted in approximately 100 % conversion at an hour at 50 °C. Hydroquinone, benzoquinone and catechol and formic, malic, fumaric acids were observed as the reaction intermediates. The leaching of metals was observed at low values and the stability of iron was found six times higher than the copper.