High-effective degradation of thiamphenicol with ferrous/ polyaniline encapsulated in molybdenum disulfide activate peroxymonosulfate: Synergism of iron and molybdenum

Fe(II) displayed a great potential in peroxymonosulfate (PMS) activation to remove pollutants but was limited by the cycle of Fe(III)/Fe(II) in the process. To solve this problem, different percentages of flower-like MoS 2 nanosheets were successfully coated on the surface of polyaniline (PANI) nanotubes named as MoS 2 @PANI-X(1, 2, 3) activating PMS efficiently with trace Fe(II) to remove thiamphenicol (TAP), in which MoS 2 @PANI-2 with 92.6% of MoS 2 was the best by removing 99% TAP within 15 min. Notably, the used trace Fe(II) concentration (2 μM) was environmentally friendly because it was far lower than the allowable limit (0.3 mg/L) in standard for drinking water by WHO. With the increase of PMS concentration (0.1–2.0 mM), k PMS increased from 0.083 to 0.118 min −1 and then decreased to 0.098 min −1 .When MoS 2 @PANI-2 dosage increased from 10 to 50 mg/L, k M o S 2 @ P A N I - 2 increased from 0.068 to 0.558 min −1 . However, N O 3 - , C l - , H P O 4 2 - , H C O 3 - , H 2 P O 4 - and natural organic matter inhibited the degradation of TAP in varying degrees. The special structure of MoS 2 @PANI increased many activity sites of Mo(IV) to promote the cycle of Fe(III)/Fe(II) for sustainable and effective activating PMS which generated SO 4 · - , H O · , O 2 · - and 1 O 2 to achieve high removal rate of TAP in a wide range of pH (3–9) (>93%). Twenty-two degradation intermediates were identified and three possible degradation paths of TAP were proposed. Overall, this study provided a novel strategy to remove antibiotics by overcoming the limiting cycle of Fe(III)/Fe(II) in the peroxymonosulfate activation process, which had a great application in water treatment.