Abstract
Photocatalytic fuel cell (PFC) has been verified to be a promising technique to treat organic matter and recover energy synchronously. Sulfate radicals (SO4·−), as a strong oxidant, have obvious advantages in the degradation of refractory pollutants compared with hydroxyl radicals (·OH), which is the dominant radical in PFC. This study reports a coupling method of PFC and persulfate (PS) activation to promote the degradation of antibiotic norfloxacin (NOR) and simultaneous electricity generation. The added PS as an electron acceptor could be activated by photoelectric effects to produce SO4·− at the electrodes-electrolyte interface. In the solution, PS as supporting electrolyte could accelerate the electron transfer and also be activated by ultraviolet (UV) light irradiation, which could extend the radical oxidation reaction to the whole solution and improve the PFC performance. The performance comparison among different systems indicated the excellent synergistic effect of PFC and PS activation for improving NOR degradation and electricity generation. The effects of influencing factors including initial pH, PS concentration, and initial NOR concentration on the degradation of NOR were investigated extensively to find out the optimal conditions. Moreover, according to the results of radical capture experiments, the significantly contribution of both SO4·− and ·OH to the degradation of NOR was demonstrated and a tentative function mechanism for the NOR degradation in the proposed system was provided. Finally, total organic carbon and real wastewater treatment confirmed the high mineralization and practical applicability of the proposed PFC/PS system.
Highlights
With the massive consumption of fossil fuels including coal, petroleum, and natural gas, conventional energy is facing a dry up
Attributed to the synergy of Photocatalytic fuel cell (PFC) and. These results reveal the efficient electricity output of PFC/PS system and such a high performance is attributed to the synergy of PFC and PS
scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses confirmed that the prepared photoanode contained TiO2 nanorods with a 3 μm length and a 200 nm edge length of square top facets
Summary
With the massive consumption of fossil fuels including coal, petroleum, and natural gas, conventional energy is facing a dry up. Zhao et al [17] established a novel Fenton-PFC system using TiO2 nanotube arrays as a photoanode and adding ferrous ions to induce photoelectric Fenton reaction and expand the radical reaction for organic pollutants degradation from the surface of electrodes to the whole solution system. The decomposition of PS via thermal, photochemical, or metal ions activation can form reactive radical intermediates, namely sulfate free radical (SO4 ·− ), with a E0 value varied between +2.5 and +3.1 V versus NHE which is higher than hydroxyl radicals (·OH) (E0 varied between +1.8 and +2.7V versus NHE) [19] Such a high E0 suggests SO4 ·− can oxidize almost all organic compounds non-selectively and efficiently. In order to make full use of every space of PFC system to expand photocatalytic redox reactions and further improve the performance of PFC, PFC was combined with PS to develop PFC/PS system for simultaneous organic pollutants degradation and electricity production in this work. The total organic carbon (TOC) removal and real wastewater treatment experiments were conducted to study the NOR mineralization and potential practical applicability of the proposed PFC/PS system
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