CHAPTER 4: Solar Photocatalysis: Fundamentals, Reactors and Applications

The use of solar light to drive photocatalytic processes has huge potential from the environmental and the economic viewpoints. However, the size and therefore the cost of solar collectors are strongly dependent on the availability of solar resources. This chapter describes the main aspects to be considered in the design of solar photocatalytic reactors. Compound parabolic collectors (CPCs) tilted towards the equator at an angle equivalent to the local latitude are considered nowadays the state of the art for solar photocatalytic applications, as they maximize the use of the available ultraviolet radiation, both direct and diffuse. Regarding the photocatalytic materials, most large-scale solar photocatalytic applications reported in the literature have been based on the use of titanium dioxide slurries. However, many efforts have been devoted to the modification of TiO₂ by doping, coupling with another semiconductor or dye sensitization with the aim of enhancing absorption of the visible light to improve the use of the photons available in solar light. Applications of solar photocatalysis have been reviewed, especially focusing on water decontamination and disinfection. Finally, synergistic effects of the combination of photocatalytic processes with biological treatments or membrane processes have been also evaluated.