Titania aerogels: Preparation and photocatalytic tests

Titania aerogels are suggested as promising photocatalysts [1]. In the present study aerogels were synthesised by sol-gel method combined with supercritical drying. Tetraisopropyl orthotitanate was used as a precursor, anhydrous methanol and isopropanol as solvents. Three aerogels were prepared using different ways of synthesis. Volumes and surface areas of micro- and mesopores of each aerogel were determined. XRD and SEM analyses were carried out. For comparison analyses were also performed for TiO2 P25 Degussa. Aerogels' BET surface areas ranged from 73 to 96 m2g-1. They indicate the crystalline structure of anatase. Finally photocatalytic tests were performed using water solution of p-chlorophenol and 4-hydroxybenzoic acid. Experiments were carried out in the Solar box simulating sun irradiation and on location. Aerogel Z513 prepared using 30% of precursor (tetraisopropyl orthotitanate) in isopropanol as a solvent indicates the best photocatalytic activity towards p-chlorophenol while Z516 prepared using 60% of precursor in methanol towards 4-hydroxybenzoic acid

Optimization of an active phase composition in the low-temperature nitric oxide reduction catalyst

In the first research studies series a selection of the quantitative composition of catalyst active phase composition (iron, copper and manganese) deposited on mineral-carbon support was carried out. It was found on the basis of the selection studies series that the best results were attained when copper and manganese were used as catalyst components. The quantitative composition of the denitrogention catalyst was estimated using a statistical method of experiment planning and metals content changed in the range 0.5 - 1.5wt % for both metals. Catalyst activity in nitric oxide reduction by ammonia was determined in the dependence on an active phase composition in the temperature range 100 - 200° C, at GHSV (Gas Hour Space Velocity) 6 000 and 10 000 Nm3/m3h, NO concentration 400 ppm, NH3/NO ratio 1:1. A graphic presentation of the obtained results was made using the UNIPLOT program. The highest activity in nitric oxide reduction by ammonia presented copper - manganese catalysts prepared by the impregnation of mineral-carbon support with active metals salts solutions and calcination after each metal impregnation with copper (up to 1.5 wt %) and manganese (up to 1.5 wt %)

Application of combustible wastes for the alternative fuels production

The information on the quantity of various types of combustible wastes registered in the Lower Silesia Marshal Office over the 2003 - 2005 years (waste codes - 02, 03, 04, 07, 12, 15, 16, 17, 19 and 20) was collected and then the quantities of individual wastes from different sources were summarized depending on the waste sort i.e. waste paper (cellulose), plastics, timber, textiles and rubber. The physiochemical properties and the chemical composition of the impurities in the selected waste sorts were determined and discussed while taking into account their usefulness and the necessary treatment operations for the alternative fuels production

Photodegradation of organic compounds in water

The application of photocatalytic processes for the decontamination treatment of polluted water has inspired very extensive studies. Titanium dioxide with its large band gap energy and appropriate redox potential was found as one of the most promising semiconductors for the photodegradation of pollutants in the water as well as in gas phase. The titania-silica aerogels obtained by a simple co-hydrolysis method was applied in the photodegradation of the model organic compound. Different ageing times and heat treatment temperatures were found to influence both the activity and the textural properties of the photocatalysts. The obtained aerogels are efficient photodegradation catalysts of methylene blue and allow a removal up to 98 and 78% of the model pollutant from 20 and 500 ppm solutions, respectively

Heavy metal ions removal from aqueous solutions using carbon aerogels and xerogels

Aerożele i kserożele węglowe otrzymano w procesie polikondensacji rezorcyny z formaldehydem w środowisku wodnym z wykorzystaniem wodorotlenku potasu oraz bromku cetylotrimetylowego jako katalizatorów. Zsyntezowane materiały poddano aktywacji, a następnie zbadano ich skuteczność w procesie adsorpcyjnego usuwania jonów metali ciężkich (niklu, miedzi i cynku) z roztworów wodnych. Otrzymane wyniki wskazują na istotny wpływ warunków syntezy, metody aktywacji oraz rodzaju usuwanego jonu na zdolność sorpcyjną badanych materiałów. Skuteczność usuwania niklu, miedzi i cynku z roztworów wodnych z wykorzystaniem kserożelowych i aerożelowych materiałów węglowych jest zbliżona, a w niektórych przypadkach większa, niż skuteczność komercyjnych węgli aktywnych.Carbon aerogels and xerogels were obtained by polycondensation of resorcinol and formaldehyde in the aqueous solution using potassium hydroxide and cetyltrimethylammonium bromide (CTAB) as the catalyst. Synthesised materials were activated and their effectiveness in adsorption of heavy metals ions (nickel, copper and zinc) from aqueous solutions was tested. Obtained results show essential influence of synthesis conditions, activation method and metal ion kind on adsorption capacity of tested materials. Carbon aerogel and xerogels were characterized by similar or better (in some cases) effectiveness of nickel, copper and zinc ions removal than commercial activated carbons

Catalytic combustion of trichloroethylene over TiO2-SiO2 supported catalysts

Combustion of trichloroethylene (TCE) on Cr2O3, V2O5, Pt or Pd catalysts supported on TiO2-SiO2 as a carrier has been investigated. It was found that oxide catalysts are very active but their activity quickly diminishes due to loss of the active component, especially at higher reaction temperatures and/or at high concentrations of TCE in the feed. Addition of water to the feed results in slower deactivation. The noble metal-based catalysts have a lower activity than the oxidic ones, but they are stable during the test and can be used under more severe conditions: higher temperature and high concentration of chlorine. Pt/SiO2-TiO2 is mildly and reversibly poisoned during the reaction. TiO2-SiO2 appears to be a stable and resistant support of catalysts for TCE combustion