Carbon-based heterogeneous photocatalysts for water cleaning technologies: a review

摘要

Clean and accessible water for all has been defined by the United Nations as a major goal to promote sustainability in a planet with improved life quality. However, the growth of population and global industry processes are having a massive impact on the water quality. The presence of organic pollutants in water and wastewater, such as pharmaceuticals, organic dyes and by-products of industrial processes, is a major issue. Conventional wastewater treatments are still limited, and, consequently, it is crucial to design innovative cleaning technologies such as heterogeneous photocatalysis with nanomaterials. Here we review mechanisms and applications of carbon-based nanostructures for heterogeneous photocatalysis applied to water purification. In particular, we present recent developments in synthetic routes and surface modification of carbon nanostructures aiming at their use under visible light irradiation. As such, carbon-based nanostructures decorated with distinct phases have been investigated, such as semiconductor compounds and polyoxometalates. The photocatalytic efficiency of hybrid nanocomposite materials is attributed to improved light harvesting and reduced recombination of photo-generated charge carriers. Furthermore, the recovery of photocatalysts by using assisted magnetic separation is presented as a promising strategy of reusability.