Efficient organic pollutants conversion and electricity generation for carbonate-containing wastewater based on carbonate radical reactions initiated by BiVO4-Au/PVC system

In this paper, we propose an efficient simultaneous refractory organics degradation and electricity generation method for carbonate-containing wastewater based on carbonate radical reactions initiated by a BiVO4-Au/PVC (PVC: photovoltaic cell) system. In the system, nanoporous BiVO4 film and Au modified PVC were used as photoanode and photocathode, respectively. HCO3- was used as the electrolyte. Carbonate radicals, which have lower recombination rates than hydroxyl radicals and strong oxidation abilities, can be generated easily by the capture reaction of hydroxyl radicals with HCO3-, which is one of the most abundant anions in the aquatic environment. The results show that the removal ratios of rhodamine b, methyl orange and methylene blue in the system increased sharply to 77.98 %, 89.15 % and 93.2 % from 18.23 %, 21 % and 23.14 % (BiVO4-Pt/ SO42-), respectively, after 120 min. Meanwhile, the short-circuit current density is up to 2.19-2.41 times larger than the traditional system. Other common ions in natural water minimally affected the properties of the new system. The excellent performance could be ascribed to large amounts of carbonate radicals in the system, which have great potential for efficient carbonate-containing wastewater treatment and energy recovery.