科研之友
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摘要
A new TiO2-coated stirred glass reactor was designed, comprising a film of fluorine-doped tin oxide (FTO) coated on a transparent glass anode. The potential of FTO for the O-2 evolution reaction - determined by linear scan voltammetry - was equal to 2.1 V vs. the SHE, high enough to form hydroxyl radicals ((OH)-O-center dot) through anodic oxidation (AO). By letting UVA light shine through the glass reactor coated with an optimal TiO2 loading of 0.311 mg cm(-2), heterogeneous photocatalysis occurred, which led to a second source of cOH. Coupled with a three-dimensional (3D) carbonaceous cathode and with the addition of a catalytic amount of Fe2+, four more sources of cOH could be implemented through H2O2 electroactivation, the Fenton reaction, H2O2 photolysis and Fe(III)-hydroxy complex photolysis. This combined photoelectrocatalytic Fenton process allowed reaching a phenol (chosen as a model pollutant to allow for easy comparison with other processes) degradation rate of 0.0168 min(-1) and a mineralization yield of 97% after 8 h of treatment, far better than those of each individual process. Notably, the phenol degradation rate of the combined process was 37% higher than that of electro-Fenton (EF) alone and 42% higher than that of AO alone. A synergy was observed (with a photocatalytic synergy value of SPC = 1.26) in the presence of TiO2, which improved on UV photolysis alone (UV synergy value, SUV = 0.97) and could be further augmented in a novel 3D-printed flow-cell reactor, designed to maximize the distance of electrode separation and the contact between gaseous O-2 and the carbon cathode. Indeed, UVA radiation shining through the FTO anode - with a transmissivity of 65% - improved the kinetics of photolytic reactions as compared to dark processes, with a synergy value (SUV) as high as 1.87. Thanks to these enhancements, the overall phenol degradation rate could be further increased to 0.0175 min(-1), 14% higher than that within the stirred glass reactor (0.0153 min(-1)). Following optimization of the current density and Fe2+ concentration, a kinetic rate of degradation of 0.0214 min(-1) was attained, an all-time high showcasing the promise of the novel photoelectrocatalytic reactor.
- 出版日期2017-12-21
