A porous g-C3 N4 nanosheets containing nitrogen defects for enhanced photocatalytic removal meropenem: Mechanism, degradation pathway and DFT calculation

Environmental Research
Jin WangZhaokun Ma

Abstract

A porous g-C3N4 nanosheet containing nitrogen defects (D-g-C3N4) was synthesized by using a one-step polymerization process in an atmosphere produced via the decomposition of ammonium persulfate. The photocatalytic removal rate of D3-g-C3N4 for meropenem (MER) is 7.45-fold higher than the one of a conventional g-C3N4 sample. The sample mineralization increases from 27% to 52% when the defects are generated. The position of the N defects was inferred via XPS, element analysis and ESR. The introduction of the N2C defects leads to the formation of a midgap state that suppresses the photoexcited carrier recombination. In addition, several environmental factors were simulated during the MER degradation including the initial concentration of MER, of humic acid (HA), and of the common anions and cations. The analysis of the Fukui function combined with LC-Q-TOF-MS predicted the probable degradation path of MER. Its main channel includes the breaking of the β-lactam ring and of the C-S bond, and the shedding of the carboxyl group and the amino group. Moreover, the toxicity of the intermediates was acquired via USEPA.

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