Sol-gel-based synthesis of metal oxide nanoparticles for air and water purification

According to the World Health Organization (WHO), water and air pollution constitutes about 23%-30% of the global burden of disease in the present-day society. It estimates that nearly 7 million people die due to outdoor air pollution every year, whereas indoor air pollution (owing to households cooking over coal, wood, and biomass stoves) can be linked to approximately 4.3 million deaths in 2012. Similarly, WHO estimates that polluted water accounts for almost 1.5 million deaths per year, including 0.36 million deaths of children below 5 years of age in the developing countries. Hence, there is an urgent need for developing 276techniques that could tone down the air and water pollution levels so as to improve the quality of life. In recent years, various metal oxide nanoparticles, attributed with unique physical and chemical properties, have emerged as a choice of technology to remove various types of pollutants from air and water. In this chapter, we will discuss the synthesis of various metal oxide nanoparticles using the sol-gel methodology and their application in the removal of various types of air and water pollutants.