Portable wastewater treatment system based on synergistic photocatalytic and persulphate degradation under visible light

Abstract

Highly efficient, low-cost, and portable wastewater treatment and purification solutions are urgently needed for aqueous pollution removal, especially at remote sites. Synergistic photocatalytic (PC) and persulphate (PS) degradation under visible light offers an exceptional alternative for this purpose. In this work, we coupled a TiO 2-based PC system with a PS oxidation system into a portable advanced oxidation device for rapid and deep degradation of organic contaminants in wastewater. Using hydrogenation, we fabricated hydrogenated anatase branched-rutile TiO 2 nanorod (H-AB@RTNR) photocatalysts which enable the PC degradation to occur under visible light and improve the utilization of solar energy. We also discovered that the addition of PS resulted in the synergistic degradation of tenacious and persistent organics, dramatically improving the extent and kinetics of the degradation. A degradation rate of 100% and a reaction rate constant of 0.0221 min −1 for degrading 1 L rhodamine B (20 mg L −1) were achieved in 120 min in a specially designed thin-layer cell under visible light irradiation. The superior performance of the synergistic PC and PS degradation system was also demonstrated in the degradation of real industrial wastewater. Both remarkable performances can be attributed to the heterophase junction and oxygen vacancies in the photocatalyst that facilitate the catalytic conversion of PS anions into highly active radicals (•SO 4 − and •OH). This work suggests that the as-proposed synergistic degradation design is a promising solution for building a portable wastewater treatment system.

Au/g-C3N4 heterostructure sensitized by black phosphorus for full solar spectrum waste-to-hydrogen conversion

“…8c indicated that the current of the BP/Au/CN composite was higher than that of pure CN and BP/CN in the dark condition, indicating that BP/ Au/CN had the highest charge separation rate. The timeresolved PL decay curves were measured to further investigate the charge transfer dynamics, and the corresponding average lifetimes were calculated according to Equation (2) [46][47][48]:…”

Degradation of Water Pollutants by Biochar Combined with Advanced Oxidation: A Systematic Review

“…SO 4 − • has the capability to convert OH − to •OH and 1 O 2 (Equations ( 18) and ( 19)) [12,13]. In aqueous solutions, ozone reacts with various components in two ways: through the direct oxidation of molecular ozone, which involves a selective reaction; or an indirect mechanism by which •OH radicals are produced through ozonolysis (Equation (20)), which are non-selective and highly reactive [14]. Ozone and •OH free radicals are powerful chemical oxidants involved in the disinfection and oxidation of pollutants.…”

“…Usually, activation is required to break the -o-o-bond and produce SO 4 − •. In the presence of light, the persulfate system uses energy from ultraviolet or visible light to break the peroxygen bond in the persulfate ion, resulting in the creation of sulfate radicals (Equations ( 1)-( 3), (28), and ( 29)) [20]. The same principle applies to the thermal activation of PS (Equations ( 30)-( 32)) [21].…”