چكيده به لاتين
Photocatalytic cements contain a photocatalytic substance such as TiO2 and exhibit photocatalytic behavior. In most of the researches that have been done so far, for making photocatalytic cements, titanium oxide in powder form has been added to the cement base and then the properties of the resulting samples have been investigated. In this research, the synthesized sol containing Titania is added to the cement field simultaneously and its effect on the properties of cement and its photocatalytic properties are investigated. First, stable Titania sols were synthesized and prepared by three methods of polymeric, colloidal and aging, then by adding solls containing different amounts of titanium to cement, cement mixtures containing photocatalytic material were prepared, cast and then dried.
The phases in the mentioned cement samples and synthesized sols were investigated using X-ray diffraction (XRD) method. The morphology and microstructure of the samples were also examined using scanning electron microscopy (FESEM). Some properties of cement samples were investigated using density and porosity tests and compressive strength test. Then the photocatalytic behavior of the samples was measured by performing the degradation test of methylene blue and the nitrogen oxide degradation test for different amounts of titanium in the presence of ultraviolet waves (UV lamp). The results showed that the samples containing stable Titania sols, despite the simplification of the production process and their economic justification, had almost similar properties to the samples containing Titania nanoparticles.
According to the results of XRD and FESEM, it was observed that cement samples containing colloidal titania sol, similar to cement samples containing titanium nanoparticles, have phases resulting from hydration of cement such as CH and CSH and no cement clotting disorder has occurred. The density of pure cement sample was gradually reduced from 3% by weight to 8% by weight of titanium with the addition of colloidal titanium sol and from 1.67 to 1.16, while the sample of pure cement was added from 3% by weight to 8% by weight of titania. It decreased from 1.67 to 1.45. The strength of pure cement sample decreased from 11.8 MPa to 3.2 MPa by adding titanium in colloidal titanium sol from 3% by weight to 8% by weight. However, the strength of the pure cement sample increased from 11.84 to 8.84 by adding commercial nano-titania suspension from 3% by weight to 8% by weight of titania.
The results of photocatalytic test showed that the synthesized colloidal titania sol, like the purchased titania nanoparticles in about 4 hours, led to the degradation of methylene blue up to about 70-80%. However, the degradation rates of methylene blue were about 10% for polymeric sol and about 50% for aged sol. The cement sample containing colloidal titanium sol showed almost the same degradation as the titanium nanoparticle cement sample purchased at 5% by weight of titania, with degradation of up to 60% for both Cem-TiO2 and Cem-Col samples. Therefore, in the end, the Cem-Col 5% sample was selected as the optimal sample.
