The effect and mechanism of organic pollutants oxidation and chemical energy conversion for neutral wastewater via strengthening reactive oxygen species

Abstract

Toxic and refractory organic pollutants are continually discharged into the water environment, which has become the crisis for the human living and sustainable development. However, organic pollutants also contain large amounts of chemical energy. In this paper, we studied the effect and mechanism of organic pollutants oxidation and chemical energy conversion for neutral wastewater via strengthening reactive oxygen species (ROS) of HO and O2− in a photocatalytic fuel cell (PFC) system, since ROS has the power to oxidize or even mineralize the organics and is environment-friendly to treat refractory organic pollutants. In our PFC system, the HO was enhanced by the cyclic radical chain reaction via the addition of Fe2+ and tetrapolyphosphate (TPP), while O2− was enhanced by setting an additional bias voltage at the anode which was favorable to O2 production. The results show that the HO and O2− concentration are highly enhanced, showing 8.28 and 8.99 times those of traditional PFC, respectively. Meanwhile, the degradation rate constant is remarkably increased by 6.52 times when methylene blue is used as a model pollutant. Furthermore, the performance of wastewater PFC is so improved that the short-circuit current density (Jsc) and maximum power density (JVmax) have been increased by a factor of 9.05 and 12.67 times in the same experiment, respectively.