N-doped carbon intercalated Fe-doped MoS2 nanosheets with widened interlayer spacing: An efficient peroxymonosulfate activator for high-salinity organic wastewater treatment

Peroxymonosulfate (PMS) heterogeneous catalysis dominated by nonradical pathway showed excellent adaptability for pollutant removal in complex water matrixes. Herein, ultra-small Fe-doped MoS2 nanosheets with N-doped carbon intercalation (CF-MoS2) were synthesized via a one-step hydrothermal method to treat high salinity organic wastewater. CF-MoS2 exhibited an expanded interlayer spacing by 1.63 times and the specific surface area by 9 times compared with Fe-doped MoS2 (F-MoS2), substantially increasing the active sites. Homogeneous Fe2+ catalytic experiments confirmed that the promotion of car-bon intercalated MoS2 (C-MoS2) on Fe3+/Fe2+ redox cycle was much higher than pure MoS2. Besides, the considerable removal of tetracycline (TC) under high salinity conditions (0-7.1%) was attributed to the dominant role of PMS nonradical oxidation pathways, including 1O2 and surface-bound radicals. The cat-alytic sites included Fe3+/Fe2+, Mo4+/Mo5+/Mo6+, C=O, pyridine N, pyrrolic N and hydroxyl groups. Finally, density functional theory (DFT) was employed to get the radical electrophilic attack sites and nucleophile attack sites of TC, and the results were consistent with the TC degradation products determined by HPLC-MS. This work would broaden the application of MoS2-based catalysts, especially for PMS catalytic removal of organic pollutants from high salinity wastewater.(c) 2022 Published by Elsevier Inc.

Automated summary

This study synthesized ultra-small Fe-doped MoS2 nanosheets with N-doped carbon intercalation for the efficient removal of high salinity organic wastewater. The intercalation of N-doped carbon expanded the interlayer spacing and increased the specific surface area, leading to enhanced active sites. The promotion of the N-doped carbon intercalation on the Fe3+/Fe2+ redox cycle was confirmed to be higher than pure MoS2. The nonradical oxidation pathways, including 1O2 and surface-bound radicals, played a dominant role in the removal of tetracycline under high salinity conditions. The catalytic sites included Fe3+/Fe2+, Mo4+/Mo5+/Mo6+, C=O, pyridine N, pyrrolic N, and hydroxyl groups. Density functional theory calculations provided insights into the reactive sites of tetracycline, which were consistent with the degradation products determined by HPLC-MS.