Synthesis of Nanosilica from paddy husk ash and their surface functionalization

Nanosilica was synthesized by a chemical precipitation process from paddy husk ash (PHA) efficiently and effectively. Surface functionalization of the silica nanoparticles was carried out with oleic acid (C18H34O2). Scanning electron micrographs (SEM) data showed that the nanosilica particle size was in the range of 50-70 nm and they were in the agglomerate form. X-ray diffraction (XRD) analysis data revealed that synthesized nanosilica was in amorphous form showing a strong broad peak at 22.14o (2). Fourier transform infrared spectroscopy (FT-IR) data supported the presence of hydrogen bonded silanol group and siloxane groups in nanosilica. Surface functionalized nanosilica with oleic acid was characterized using thermogravimetric analysis (TGA) and FT-IR methods. FT-IR experimental data showed that the modified nanosilica formed the ester bonding between silanol group in nanosilica and the carboxylic group of oleic acid with a successful functionalization

Photocatalytic activity of nano-tio2 on glass in building envelope

Titanium dioxide is manufactured by processing naturally occurring titanium containing rutile (TiO2) or ilmenite (FeTiO3) minerals. Sri Lanka has vast deposits of ilmenite which is the major raw material in TiO2 production. However, Sri Lanka currently does not produce any type of value added TiO2 pigments. With the growth of nanotechnology, nano-TiO2 is now produced worldwide using different methods varying the particle size from 1 nm to 100 nm. Nano-TiO2 has the tightly controlled particle size that increases both the refractive index and light scattering properties as a result of the uniform particle size distribution and additional surface area. Nano-TiO2 is particularly interesting in UV resistant surface coatings where it can act as a UV reflector. Because of the higher photocatalytic activity nano-TiO2 can be used for anti-fogging coatings where nano-TiO2 incorporated into outdoor building materials can substantially reduce concentrations of airborne pollutants such as volatile organic compounds and nitrogen oxides and as photocatalyst coating which assist in deactivation of bio-contaminants. In this investigation nano-TiO2 and pigmentary TiO2 were synthesized using titanyl sulfate precursor, which can easily be produced by Sri Lankan ilmenite with sulfuric acid according to the sulfate process. Synthesized nano-TiO2 was characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning transmission electron microscopy (STEM) and scanning electron microscopy (SEM) methods. The photocatalytic activity of nano-TiO2 was assessed by the degradation of bromothymol blue in aqueous solution. Nano-TiO2 coated on glass showed a higher photocatalytic activity and self cleaning effect that can effectively be used in building envelop