Photocatalytic activation of peroxymonosulfate (PMS) by CNN@NH₂-MIL-101(Fe) Z-scheme heterojunction for phthalates degradation under visible light irradiation

Phthalates (PAEs) are known to pose a serious threat to the environment and human health duo to their endocrine disrupting effects, thus a great deal of effort has been made to develop destruction technologies for PAEs treatment in the water environment, such as peroxymonosulfate (PMS)-based advanced oxidation technology. Here we prepared an environmentally friendly visible light catalyzer, a heterojunction of carbonitride nanosheets (CNN) doped with NH2-iron metal organic frameworks (NH2-MIL-101(Fe)), for the activation of PMS to efficaciously remove two representative PAEs-diisobutyl phthalate (DIBP) and diethyl phthalate (DEP)- from the aquatic environment. The CNN@NH2-MIL-101(Fe) photocatalyst possesses an excellent visible light harvesting performance with a narrow band gap (1.66 eV), low recombination ratio of photoinduced carriers, and long charge lifetime. The pore volume and surface area of the composite material was increased compared with any single component. The optimum CNN@NH2-MIL-101(Fe) catalyst manifested the high performance to activate PMS to degrade DIBP and DEP under visible irradiation with maximum removal of 94.5 +/- 2.2 % and 83.4 +/- 0.9 %, respectively. Four main active species (center dot OH, O-2(-)center dot, SO4- , and h+) were involved in PAEs photodegradation, with h+ and SO4- center dot playing a key role in the degradation of DIBP, and h+ in the degradation of DEP. The degradation mechanism of DIBP and DEP mainly involved the ester bond cleavage and oxidation by active species. Additionally, the CNN@NH2-MIL-101(Fe) heterojunction exhibited high and stable catalytic performance to activate PMS for PAEs destruction under pH 3 - 9. Therefore, this study provides a new strategy for designing and selecting environment-friendly treatment approach for the effective eradication of PAEs via a PMS-based advanced oxidation process.