Enhanced MnO2/peroxymonosulfate activation for phthalic acid esters degradation: Regulation of oxygen vacancy

The α-, β-, γ-, and δ-MnO2 were fabricated to activate peroxymonosulfate (PMS) for phthalic acid esters (PAEs) degradation, and the oxygen vacancies (OVs) were proved to be a key role in PMS activation. The α-MnO2 showed high catalytic activity due to its rich OVs (18.4%), whereas no OVs were detected on the β-, γ-, and δ-MnO2. The α-MnO2 OVs ratio decreased to ∼3.1% after 180 min reaction, and the activated ability could be revived by OVs regeneration procedure. The β-, γ-, and δ-MnO2 activated abilities also could be awakened by the same procedure. The formation energy (Ef) of OVs and the adsorption energy (Eab) of PMS were calculated by density functional theory method. The calculation results showed that the OVs-rich α-MnO2 has the highest PMS adsorption ability. This work presents direct evidence for the OVs in enhancing PMS activated ability for PAEs degradation.