COMPOSITE MATERIAL WITH ADSORBING/PHOTOCATALYTIC PROPERTIES IN ULTRAVIOLET AND VISIBLE SPECTRUM RANGES AND PROCESS FOR PREPARING THE SAME

摘要

The invention relates to a composite material with adsorbing and photocatalytic properties shown upon irradiation with radiation within the ultraviolet and visible spectrum range, which is made of power plant ash and semiconductor oxide of photocatalytic properties, to be employed in the process of advanced purification of industrial waste water containing complex pollutants, and to a process for preparing the same. According to the invention, the material comprises a micrometric matrix of washed power-plant fly ash and a filler of nanometric TiOpowders, having a regular zeolitic structure with a specific surface of more than 100 m/g, a crystallinity in the range of 49.5...64.0%, a specific surface in the range of 100...130 m/g, the surface loading being positive at pH values under 3.65 and negative at pH values of more than 8.14, with isoelectric points in the range 3.65...8.14, the aggregates being uniform, with submicronic dimensions, consisting of orderly arranged particles of 500...900 nm. The process, as claimed by the invention, starts by a dimensional fractioning of fly ash, upon classification, followed by the separation of the fraction having dimensions of 20...40 μm, washing thereof with distilled water for 24 h, while mechanically stirring, and separation by filtration, drying of the fraction at a temperature of 105...115°C, mixing, at the ambient temperature, of the following materials: the power plant ash fraction, TiO-Degussa P25 and NaOH, followed by grinding the same and mixing them in a ratio of 1:1:1.2, after which the mixture undergoes a heat treatment in a furnace, for 1 h, at 500°C, followed by cooling and mechanical grinding, and a hydrothermal synthesis in autoclave, at a ratio of 1 g of material : 100 ml of water from the Black Sea, while stirring continuously for 24 h, at a rate of 300...500 rpm, the composite being left to age for 4 days, without stirring, at 70°C, to end by a separation by filtration and drying at 105...115°C.