Photoelectrocatalytic Oxidation of Textile Industry Wastewater by RuO2/IrO2/TaO2 Coated Titanium Electrodes

Photoelectrocatalytic Oxidation (PECO) system prominently increases the migration of photoexcited charges, hinders the fast recombination of electron-hole, and increases the period of photogenerated holes. In this article, we constructed a novel PECO system to degrade textile industry wastewater by RuO2/IrO2/TaO2 coated titanium electrodes. The result shows that PECO treatment can effectively reduce the color and true color of the secondary pollutants present in the wastewater. It is confirmed that a synergistic effect exists between photocatalysis (PC) and electrocatalysis (EC). Moreover, we discussed the influence of pH, current density, electrolyte concentration, and stirring speed. The maximum decolorization efficiency of textile industry wastewater with a pH of 8.2 was found to be 96% under the optimum condition stirrer speed of 200 rpm, an electrolyte concentration of 0.05M, a current density of 15 mA.cm-2, and at a treatment time of 30 mins. The UV-Visible spectra confirm the degradation of textile industry wastewater.

Effect of Potential and Chlorides on Photoelectrochemical Removal of Diethyl Phthalate from Water

Removal of persistent pollutants from water by photoelectrocatalysis has emerged as a promising powerful process. Applied potential plays a key role in the photocatalytic activity of the semi-conductor as well as the possible presence of chloride ions in the solution. This work aims to investigate these effects on the photoelectrocatalytic oxidation of diethyl phthalate (DEP) by using TiO2 nanotubular anodes under solar light irradiation. PEC tests were performed at constant potentials under different concentration of NaCl. The process is able to remove DEP following a pseudo-first order kinetics: values of kapp of 1.25 × 10−3 min−1 and 1.56 × 10−4 min−1 have been obtained at applied potentials of 1.8 and 0.2 V, respectively. Results showed that, depending on the applied potential, the presence of chloride ions in the solution affects the degradation rate resulting in a negative effect: the presence of 500 mM of Cl− reduces the value of kapp by 50 and 80% at 0.2 and 1.8 V respectively.

Research Progress on Photocatalytic/Photoelectrocatalytic Oxidation of Nitrogen Oxides

The emission of nitrogen oxides (NOx) increases year by year, causing serious problems to our livelihoods. The photocatalytic oxidation of NOx has attracted more attention recently because of its efficient removal of NOx, especially for low concentrations of NOx. In this review, the mechanism of the photocatalytic oxidation of NOx is described. Then, the recent progress on the development of photocatalysts is reviewed according to the categories of inorganic semiconductors, bismuth-based compounds, nitrogen carbide polymer, and metal organic frameworks (MOFs). In addition, the photoelectrocatalytic oxidation of NOx, a method involving the application of an external voltage on the photocatalytic system to further increase the removal efficiency of NOx, and its progress are summarized. Finally, we outline the remaining challenges and provide our perspectives on the future directions for the photocatalytic oxidation of NOx.