Visible light absorption by perylene diimide for synergistic persulfate activation towards efficient photodegradation of bisphenol A

A novel PDI/PS/Vis system was constructed and the photocatalytic activity of PDI with various degrees of self-assembly was explored. Perylene diimide (PDI) as photocatalysts possesses excellent charge separation efficiency and the electron injection from the PDI to persulfate (PS) can produce active species more efficiently. With the PDI/PS/Vis system, 5 mg/L bisphenol A (BPA, 50 mL) could be completely removed in 15 min with 0.5 g/L photocatalyst and 1.5 mM PS under visible light (lambda > 420 nm). Nearly 71.1 % of BPA was mineralized after 1 h degradation. Radical quenching tests and electron paramagnetic resonance (EPR) spectra revealed that h(+), O-2(-), OH and SO>4- all contributed to organics elimination with radical process. Based on the results of theoretical calculations and toxicity assessment, BPA will eventually be converted into non-toxic ring-opening products. Therefore, the highly efficient PDI/PS/Vis system has great potential for application in water environment remediation.