Sulfidation enhanced reduction of polybrominated diphenyl ether and Pb(II) combined pollutants by nanoscale zerovalent iron: Competitive reaction between pollutants and electronic transmission mechanism

•S-nZVI can quickly remove BDE-209 and Pb(II) composite pollutants.•Compared with BDE-209, Pb(II) can preferentially react with S-nZVI.•Pb0 enhances the electron transfer rate from S-nZVI to BDE-209.•Pb(II) adversely affects the longevity of S-nZVI.