Photoelectrochemical sewage treatment by sulfite activation over an optimized BiVO4 photoanode to simultaneously promote PPCPs degradation, H2 evolution and E. coli disinfection

A new photoelectrochemical (PEC) system by means of adding sodium sulfite (Na 2 SO 3 ) was developed to treat sewage. The PEC system simultaneously promoted pharmaceuticals and personal care products (PPCPs) degradation, H 2 evolution and E. coli disinfection using an optimized, visible–light driven BiVO 4 photoanode. The PEC reactions were first carried out in 1.5 mM Na 2 SO 3 electrolyte. 92.3% of 2 ppm benzophenone-3 (BZP) was degraded, and 115.36 μmol of H 2 was produced in 90 min at 1.0 V vs. Ag/AgCl, which was a significant improvement over cases where the electrolyte was either Na 2 SO 4 or NaCl. The sulfite ions were first activated by holes and then converted into sulfate radicals, which played a dominant role in the degradation of BZP. As the holes were caught by the sulfite, charge separation was also enhanced, increasing H 2 evolution. The PEC reactions were also used to treat real sewage, in which case an 82% improvement in the rate constant of BZP degradation, 60% increase of H 2 evolution, and 0.78 log enhancement of E. coli disinfection were achieved by adding 1.5 mM Na 2 SO 3. The system was also feasible to degrade various PPCPs, and showed excellent reusability and stability, proving its great potential in sewage treatment.