Water Reclamation by Heterogeneous Photocatalysis over Titanium Dioxide

Ultrasound-Assisted Synthesis of Nonmetal-Doped Titanium Dioxide Photocatalysts for Simultaneous H2 Production and Chemical Oxygen Demand Removal from Industrial Wastewater

“…Prior to the photocatalytic reaction, they must be properly adsorbed onto the photocatalyst surface under a dark condition. Thus, the appropriate pollutant loading should be determined to get an effective operating condition since a too low pollutant loading would give ineffective e – –h + separation, while a too high pollutant loading may saturate the surface of the photocatalyst and become a shading barrier to absorb the photon energy from irradiated light leading to a low photocatalytic efficiency …”

“…It is well-known that the dark adsorption of active substances proceeds with the photocatalytic reaction. The quality and quantity of absorbed molecules depend upon the relationship between the PZC of the photocatalytic materials and the pH of the aqueous medium . Due to electrostatic interactions, when the solution pH is higher than the PZC value, the photocatalyst exhibits negative charges, which strongly prefer to adsorb cationic molecules.…”

“…Thus, the appropriate pollutant loading should be determined to get an effective operating condition since a too low pollutant loading would give ineffective e − −h + separation, while a too high pollutant loading may saturate the surface of the photocatalyst and become a shading barrier to absorb the photon energy from irradiated light leading to a low photocatalytic efficiency. 46 In this study, the pollutant loading was designed as a function of the COD level as a high COD level (∼7322 ± 736 mg/L, obtained from pretreated wastewater) and a low COD level (∼1574 ± 275 mg/L obtained from a dilution of the pretreated wastewater). As shown in Figure 1, the wastewater with a high COD level provided a higher quantity of H 2 production and COD removal for all selected photocatalysts.…”

“…The quality and quantity of absorbed molecules depend upon the relationship between the PZC of the photocatalytic materials and the pH of the aqueous medium. 46 Due to electrostatic interactions, when the solution pH is higher than the PZC value, the photocatalyst exhibits negative charges, which strongly prefer to adsorb cationic molecules. However, when the solution pH is lower than the PZC value, the photocatalyst is positively charged and readily adsorbs anionic molecules.…”

Ozone and Photocatalytic Processes for Pathogens Removal from Water: A Review

“…However, new findings proved that not only H 2 O 2 but also singlet oxygen ( 1 O 2 ) may play an important role in the photocatalytic disinfection mechanism [35,74]. However, before ROS can act, the adhesion of bacteria to the photocatalyst as well as ROS generation onto the surface has to take place [125]. During photocatalytic disinfection, the attack of ROS on microorganisms firstly occurs at the outside of the organism, and next inside, this action permits destroying the genetic material and inhibiting the metabolic processes [37].…”