Zs. Pap

Pt/N–TiO2 Aerogel Composites Used for Hydrogen Production Via Photocatalysis Process

Pt/N–TiO2 aerogel photocatalysts were obtained by means of sol–gel process followed by low temperature supercritical drying. Urea and guanidine-HCl were used as nitrogen sources. Pt clusters were loaded on photocatalysts surface by photoreduction process. Enhanced photocatalytic activities and H2 evolution rates were obtained on photocatalysts containing nitrogen impurities.Graphical Abstract

Important Aspects on the Removal of Humic Acid and Phenolic Compounds with Clay Minerals. “Synergism Provided by the Pollutants, Efficiency Given by the Media”

Adsorptive water purification methods were studied for the removal of phenol-type compounds (such as phenol/thymol) and humic acid applying sodium bentonite modified by cationic surfactant hexadecyltrimethylammonium bromide (HTAB). The effect of humic acid on adsorption of phenols was examined in pure and model thermal water. It was found that the efficiency of the removal of individual pollutants can be highly influenced if another pollutant is present. The main reason for the increased efficiency was identified by the means of infrared spectroscopy which proved that each pollutant modifies decisively the organophilicity of the clay surface. Furthermore, the studies performed in model thermal waters revealed that the presence of specific cations could further increase the removability of these pollutants.

New insights regarding the calcination as a critical parameter in the synthesis of sol–gel made titania powders

The number of studies regarding sol–gel made titania powders is quite high, and nearly all of them use the calcination as the crystallization process. However, several papers are not providing crucial information regarding the calcination parameters, such as, heat treatment atmosphere, heating rate or heat treatment time. Furthermore, nearly no investigations were done regarding short calcination times and fast heating rates. The present paper points out the missing or under-evaluated aspects in the literature and demonstrates their importance throughout simple experiments. First of all, the influence of the calcination atmosphere and the applied flow rate (in tubular furnaces) was proven by demonstrating the inhomogeneity of the obtained samples. Secondly, the major influence of the chosen calcination time and rate was proven by obtaining fast heat treated titania powders. Their activity varied significantly with the applied calcination time, achieving two activity maxima. Also, the obtained activity trend shows that by varying the calcination time highly active titanias can be obtained (more active than Evonik Aeroxide P25).