Effect of calcination temperature and calcination time on the kaolinite/tio2 composite for photocatalytic reduction of CO2

Abstract

The kaolinite/TiO 2 composite (60 wt% of TiO 2 ) was prepared by thermal hydrolysis of a raw kaolin suspension in titanyl sulphate and calcined at different temperatures (600, 650 and 700°C) and for different times (1, 2 and 3 h). The obtained samples were characterized by XRPD, N 2 physical adsorption and SEM, and tested for photocatalytic reduction of CO 2 . The different calcination conditions did not influence TiO 2 phase composition, only slightly changed the specific surface area, and significantly affected crystallite size of kaolinite/TiO 2 composite. A higher temperature and longer duration of calcination lead to higher crystallinity of the powder. The photocatalytic results showed that the crystallite size determined the efficiency of kaolinite/TiO 2 photocatalysts. AbstraktKompozit kaolinit/TiO 2 (60 hm% TiO 2 ) byl připraven termální hydrolýzou suspenze surového kaolinu v síranu titanylu a kalcinován při různých teplotách (600, 650 a 700°C) a po různou dobu (1, 2 a 3 h). Získaný vzorek byl charakterizován pomocí XRPD, N 2 fyzikální adsorpcí a SEM, a testován na fotokatalytickou redukci CO 2 . Rozdíl kalcinačních podmínek neovlivnil složení fáze TiO 2 , pouze se mírně pozměnila specifická povrchová plocha a výrazně byla ovlivněna velikost krystalitu kompozitu kaolinit/TiO 2 . Vyšší teplota a delší doba kalcinace vedly k vyšší krystalitě prášku. Fotokatalytické výsledky ukázaly, že velikost krystality určuje účinnost fotokatalyzítoru kaolinit/TiO 2 .

Synthesis and photocatalytic activity for TiO2nanoparticles as air purification

“…means the root of the square roughness (RQ) of the surface of less than (1 nm) and increases with increasing temperature calcinations , which shows the grain of normal forms on the surface. When the temperature increases, the changes in topography and roughness of the paint TIO 2 are largely due to the phase shift of titanium Anatase to rutile and the growth of the crystal TiO 2 [27,28]. The table shows (1) that the roughness values increase with increasing temperature calcination.…”

Rare earth elements (REEs) recovery and porous silica preparation from kaolinite

“…Upon thermal activation, all kaolinite phases disappeared but showed halos at 20-25°2θ in the XRD pattern, suggesting the formation of amorphous metakaolinite as a result of dehydroxylation [17,28,61]. The weak peak at around 25°2θ was attributable to anatase, which resulted from the improved relative content due to the disappearance of kaolinite crystals [62]. Thermal activation results in the loss of structural hydroxyl groups of kaolinite.…”

Optical, photocatalytical and structural properties of TiO2 – SiO2 sol-gel coatings on high content SiO2 enamel surface

“…4 and Table 1 we can see clearly that the films annealed for 1 h have smaller particles (65 nm) and lower average roughness (82.15) then coatings that were annealed for 10 h where particles size was around (95 nm) and average roughness (110.7 nm). It is well know that crystallite size is closely related to the calcination time, increasing duration of calcination increases the crystallite growth and its size [17,18]. Fig.…”