Heterogeneous photocatalysis has proven its value towards meeting the challenges posed by cost-effective treatments of wastewater. In spite of the enormous number of pollutants that have been the subject of photocatalytic treatment studies, knowledge on the photoinitiated advanced oxidation processes for the conversion of hazardous emerging chemical substrates introduced to the water ecosystem remains incomplete. Many questions concerning the complex and interrelated chemical and photochemical mechanisms of conversion still need to be answered, limiting the effectiveness

of the process. A nanotechnological approach can be used to harness the photocatalytic capabilities of titanium dioxide (TiO2), the most used catalyst in this type of applications, generating nanoarchitectures with extremely high surface area and remarkable redox properties, much more eficient than the ordinary grades of the oxide. In this chapter, we will describe some of our recent results on the degradation of critical and emerging pollutants present in wastewater, such as diphenhydramine and phenolic compounds, by using TiO2 alone or loaded with gold nanoparticles.