Black-TiO2 based photoelectrochemical oxidation of flue-gas desulfurization wastewater for effective reuse in flow-electrode CDI

This study proposes two integrated electrochemical methods for the reuse of flue-gas desulfurization wastewater (FGDW): photoelectrochemical oxidation (PECO) using a self-doped black TiO2 nanotube array (Black-TNA) catalyst and flow-electrode capacitive deionization (FCDI). The electrocatalytic activity and oxidative performance of the Black-TNA annealed at 600 degrees C were superior to those of the conventional Blue-TNA, as determined via Mott-Schottky and cyclic voltammetry plots. Furthermore, the removal of organic pollutants via PECO under sulfate-based conditions using the Black-TNA showed exceptional degradative results. Subsequently, FGDW was introduced to the FCDI system to evaluate its feasibility as a flow-electrode electrolytic solution in comparison with other synthetic electrolytes (NaCl, Na2SO4, and NaCl/Na2SO4 composite), and was confirmed for its feasibility. Thus, the integrated PECO-FCDI system was demonstrated to be an effective means of removing organic pollutants and salts without the use of additional chemicals.

Automated summary

This study proposes two integrated electrochemical methods for the reuse of flue-gas desulfurization wastewater (FGDW): photoelectrochemical oxidation (PECO) using a self-doped black TiO2 nanotube array (Black-TNA) catalyst and flow-electrode capacitive deionization (FCDI). The study found that the electrocatalytic activity and oxidative performance of the Black-TNA annealed at 600 degrees C were superior to those of the conventional Blue-TNA. Furthermore, the use of Black-TNA in PECO under sulfate-based conditions showed exceptional degradative results for the removal of organic pollutants. The study also confirmed the feasibility of using FGDW as a flow-electrode electrolytic solution in the FCDI system, and demonstrated that the integrated PECO-FCDI system can effectively remove organic pollutants and salts without the use of additional chemicals.