The advent of nanotechnology has revolutionized the major sectors of science and technology. However, synthesis methodology plays a prime role in deciding the size, shape, and purity of nanoparticles. The sol-gel method of synthesis can control the size and morphology of nanoparticles. It is one of the simplest ways to produce nanoparticles in pure form from the bottom-up approach. In this study, silica nanoparticles were produced through the sol-gel method. Sodium silicate was used as precursor material, with ethanol as solvent. CTAB and Ammonia were used as catalyst and reducing agents respectively. The synthesis process was followed by 4 hours of calcination. The obtained nanoparticles were subjected to FESEM, EDAX, XRD, and PSD analysis. From the results, it is observed that the synthesized nanoparticles had an average diameter of 26nm.

Oxides of nitrogen (NOx) are highly reactive and major air pollutants generated from the vehicular emission and burning of fossil fuels in industries. These pollutants will create tropospheric ozone, formation of urban smog and occurrence of acid rain, etc. A potential solution for this would be heterogeneous photocatalysis. Using photocatalysts such as titanium dioxide (TiO2) inorganic and organic matter present in the air, such as NOx and VOCs can be adsorbed and oxidized by the action of ultraviolet (UV) light (sunlight). This technology is promising for cities with highly congested areas having high ground-level pollutant concentrations. Self-cleaning and air-purification coating with a super-hydrophilic photocatalyst (TiO2) coated on buildings can bring down the NOx concentration in the air. In addition, the incorporation of TiO2 in the form of nano-particles into cementitious materials will enhance their mechanical properties. This study evaluates and highlights the applications of nano titanium dioxide and its effects on the fresh and hardened characteristics of the cementitious composites.