CHAPTER 2: Photocatalytic Processes for the Removal of Toxic Metal Ions Check Access

Semiconductor photocatalytic processes have been studied extensively in recent years due to their considerable advantages in environmental remediation. In this chapter, we address the treatment of hazardous wastewater containing toxic heavy metals using photocatalysis. The chapter reviews the effects of various factors such as catalyst loading, initial concentration of metal ions, presence of electron or hole scavenger, solution pH and light intensity. We start with the appraisal of the fundamental principles and mechanisms of the photocatalytic degradation process, followed by thermodynamic analysis, reaction kinetics and mass transfer effects. In addition to this, the design features, challenges and efficiencies of various photoreactors along with their possible scaling-up options are discussed. Moreover, assessment of harvesting of the solar energy for photoreactions to make photocatalysis a cleaner and a cost-effective treatment method is analysed. Finally, the chapter concludes with the status, efficacy and challenges ahead for the treatment of drinking water and wastewater containing different heavy metals through heterogeneous photocatalysis.