Solar-driven on-site H2O2 generation and tandem photo-Fenton reaction on a triphase interface for rapid organic pollutant degradation

Abstract

• An air–liquid-solid triphase photocatalytic system was designed. • O 2 in air phase could rapidly diffuse to the photocatalysts (hydrophilic interface). • The photo generation rate of H 2 O 2 from O 2 and H 2 O is reached 4370 μmol h −1 . • The on-site generation of H 2 O 2 was decomposed to reactive oxygen species (ROS) by photo-Fenton. • Degradation efficiency for organic pollutants is higher than 99% in 130 min. Organic pollutants in wastewater have raised great concerns because of their considerable risk to human health and the ecosystem. Although Fenton reaction of advanced oxidation process represents a promising water treatment strategy. However, continuous consumption and low utilization efficiency of H 2 O 2 limit its practical application. Herein, we propose photocatalytic in-situ production and activation H 2 O 2 at triphase interface to reach excellent removal efficiency for contaminants. The triphase interface configuration allows oxygen rapid diffusion from the air to the surface of photocatalyst and avoids the problem of poor mass transfer of oxygen in solution. Meanwhile, using the Z-type heterojunction MIL-101(Fe)/g−C 3 N 4 as model photocatalysts could largely promote the photo-induced electrons and holes separation efficiency to further improve reaction efficiency. As a result, the triphase photocatalytic system achieved an in-situ H 2 O 2 production rate of 4370 μmol h −1 (greater than5 times higher than the diphase control) and a superior degradation efficiency for organic pollutants (model pollutant: methyl orange, concentration: 10 ppm, 99% removal rate in 130 min, while only 21% in diphase control) with a 17.5 times higher reaction rate constant. Therefore, the triphase photocatalytic system realized the highly efficient degradation of organic pollutants in wastewater by solar-driven, in-situ generation and activation of H 2 O 2 with high catalytic activity and minimized oxygen transport limitation, thus providing a green and sustainable strategy for wastewater treatment and broadly environmental remediation.