Efficient removal of endocrine disruptors using nano zero-valent iron loaded organo-attapulgite: Mechanism and factors

Abstract

Endocrine-disrupting pollutants have become a major problem in aquatic environments. Advanced oxidation processes are recognized as promising technologies for treating endocrine disruptor-contaminated water. Herein, a novel nanoscale zero-valent iron loaded organo-attapulgite (NZVI@OATP) was employed as a catalyst to activate persulfate (PDS) for phenanthrene (PHE) and dibutyl phthalate (DBP) degradation. NZVI@OATP with a NZVI:OATP mole ratio of 1:1 (CTAB:ATP = 1:200) exhibited 100 % PHE and 84 % DBP degradation within 30 min, and chloride was found to have a positive effect on their degradation. Radical scavenger and electron paramagnetic resonance studies revealed that the contribution of the active species follows the order of O2- ≈ 1O2>SO4- ≫ OH. The optimal degradation pathways were proposed based on the liquid chromatography-mass spectrometry and density functional theory and the possible degradation paths of PHE and DBP, including the 9,10-phenanthraquinone and phthalic acid pathways, respectively, were proposed. The toxicity estimation software tool showed that the toxicities of PHE and DBP were reduced after degradation. Moreover, 50 % PHE degradation could be achieved after five cycles, demonstrating that NZVI@OATP is a promising catalyst for endocrine disruptor treatment with PDS.