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The immobilization of catalysts hinders the application of nanosized photocatalysts in wastewater treatment. In this study, a simple method for the preparation of flexible composite non-woven catalysts with a good spectral response is presented. Firstly, the porous g-C3N4 nanosheets containing nitrogen defects (DCN) and sodium alginate (SA) were blended to prepare the casting solution and then coated on the surface of polyester and viscose blend non-woven fabric (NW). Finally, the robust three-dimensional composite non-woven catalyst (DCN@SA/NW) was constructed by cross-linking with CaCl2. The as-prepared samples were characterized by different physicochemical techniques including SEM, EDS, FTIR, Raman, XRD, XPS, and TGA. The photocatalytic degradation of dyes and antibiotics and self-cleaning and antibacterial properties of the catalyst were investigated. The optimal DCN@SA/NW formulation was 2.0 wt.% DCN and 2.0 wt.% SA. The DCN@SA/NW composite efficiently degraded rhodamine (RhB) and tetracycline hydrochloride (TC). Moreover, the synthesized non-woven composite catalyst was easily recycled and remained stable, indicating its promising potential in wastewater treatment. The DCN@SA/NW also exhibited outstanding self-cleaning and antibacterial performance. This study provides an interesting idea for the research and development of immobilized photocatalysts and has great potential in future practical photocatalytic applications. [ABSTRACT FROM AUTHOR]

The environmental hazards of antibiotics and the resulting antibiotic-resistant bacteria (ARB) have attracted more and more attention. In this study, an efficient synergistic system constructed by vacancy g-C 3 N 4 (CN V0.8 ) and persulfate (PS) showed excellent oxidation performance to degrade aztreonam (AZT) and Escherichia coli (E. coli) screened from wastewater treatment plant (WWTP), as the typical β-lactam antibiotic and ARB. As the recombination of electron and hole was effectively inhibited and the interaction with PS was enhanced after the introduction of defects, CN V0.8 showed superior PS activation ability compared with bulk-g-C 3 N 4 (BCN). The synergistic mechanism was systematically analyzed at three levels step by step. Firstly, the conversion of reactive oxygen radicals (ROSs) was studied using electron spin resonance (ESR) and quenching experiments. Then based on the DFT simulation, the enhancement of adsorption energy between catalysts and PS from -8.924 eV (BCN) to -11.190 eV (CN V0.8 ) and the elongation of O-O bond in PS (from 1.496 Å to 1.505 Å) indicated CN V0.8 had better activation performance for PS compared with BCN. The electron transfer results observed by deformation charge density showed that more electrons could be transferred from the CN V0.8 layer to the surrounding of PS for its own activation in the synergistic mechanism. Thirdly, the noncovalent interaction of PS/CN V0.8 belonged to the region of van der Waals force which was defined by the reduced density gradient (RDG) analysis. The intermediate products in the degradation of AZT were first studied in detail using Fukui function calculations and HPLC-QTOF-MS analysis. Subsequently, the environmental practicability of the oxidation system was investigated through wastewater simulation. This research provides a possible strategy for the effective removal of micropollutants and promotes the development of the sulfate radical-advanced oxidation processes (SR-AOPs) in the field of wastewater treatment., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A porous g-C 3 N 4 nanosheet containing nitrogen defects (D-g-C 3 N 4 ) 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-C 3 N 4 for meropenem (MER) is 7.45-fold higher than the one of a conventional g-C 3 N 4 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 N 2C 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., Competing Interests: Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)