| As a commonly used drug and refractory organic pollutant present in various aquatic environments,the environmental fate of antibiotics is of great concern.Antibiotics cause serious harm to human health by triggering bacterial resistance,and due to their high physicochemical stability,they are difficult to be degraded by conventional water treatment technologies such as adsorption,filtration,biodegradation,etc.Therefore,there is an urgent need to find a method that can effectively degrade antibiotics,among which photocatalysis is considered to be the most promising strategy to effectively degrade antibiotics and alleviate the energy crisis.g-C3N5,a new star in the graphitic carbon nitride family,has the advantage of additional physical and electrical properties,and its ability to have a wider absorption of visible light(narrow band gap of about 2.2 eV)with fast electron transfer makes it of great interest to researchers.However,like other single semiconductors,g-C3N5 has some drawbacks,such as small specific surface area,lightinduced charge recombination and too short light absorption range,which limit its further application in photocatalysis.Therefore,it is important to develop g-C3N5-based Zscheme heterojunction photocatalysts with efficient charge transfer rate and full-spectrum light absorption range.In this paper,a novel full-spectrum Z-scheme heterojunction photocatalyst was constructed by combining the reducing semiconductor g-C3N5 and the oxidizing semiconductor W18O49,and a series of studies were carried out by degrading tetracycline hydrochloride in water,with the following results:First of all,2Dg-C3N5 nanosheets were prepared by thermal polymerization,and then 1D nanowire W18O49 was loaded on the surface of g-C3N5 by solvothermal method,and 2Dg-C3N5/1DW18O49(g-C3N5/W18O49)Z-scheme heterojunction photocatalyst was successfully prepared.The prepared photocatalysts were subjected to a series of characterization by XRD,SEM and TEM,and the experimental results proved that gC3N5 and W18O49 were successfully bonded together.The UV diffuse mapping confirmed that the photoresponse range of g-C3N5/W18O49 Z-scheme heterojunction photocatalyst broadened to the near-infrared region,and the band gap structure analysis indicated that g-C3N5 and W18O49 had a suitable matching energy band,while the photoelectric performance analysis confirmed that the carrier transfer rate of g-C3N5/W118O49Z-scheme heterojunction photocatalyst was accelerated and the electron-hole recombination efficiency was reduced,which was beneficial to promote the photocatalytic performance.Favorable to promote photocatalytic performance.Secondly,the degradation efficiency of g-C3N5/W18O49 Z-scheme photocatalyst for tetracycline hydrochloride under the irradiation of xenon lamp(simulated sunlight)was 92.1%,and the degradation rate was 2.5 times that of pure g-C3N5 and 4.24 times that of W18O49.In addition,the TOC mineralization rate of g-C3N5/W18O49 was 47.85%.In addition,the effects of different g-C3N5 loadings,anions and cations,pH values,initial concentrations of tetracycline hydrochloride,photocatalyst additions and different water environments on the degradation of tetracycline hydrochloride were also investigated,and the experimental results confirmed that the g-C3N5/W18O49 Z-scheme photocatalyst had excellent degradation effects on tetracycline hydrochloride.Based on the results of the cycling experiments and the XRD diffractograms and FTIR maps of g-C3N5/W18O49 before and after,it illustrates that g-C3N5/W18O49 has a very stable structure.We explored the degradation mechanism of tetracycline hydrochloride,and combined with LC-MS spectroscopic analysis two pathways were postulated,pathway 1:formation of P7(m/z=437)by demethylation,followed by ring opening,deacylation and decarboxylation to give P8(m/z=274)and P9(m/z=246),pathway 2:conversion of tetracycline hydrochloride to P1(m/z=476),P2(m/z=393)and P6(m/z=283).We also investigated the degradation mechanism of g-C3N5/W18O49 Z-scheme heterojunction photocatalyst,and proposed the synergistic effect of dual-channel charge transfer in combination with radical capture experiments and relevant characterization data.In summary,the efficient photocatalytic effect of g-C3N5/W18O49 Z-scheme heterojunction photocatalyst mainly comes from;1D nano wire W18O49 is more favorable to couple with 2Dg-C3N5 to obtain a high-quality contact surface;the construction of Z-scheme heterostructure improves the separation of electron-hole pairs and electron transfer efficiency;the LSPR effect induced by W18O49 in the near-infrared region also improves the The LSPR effect induced by W18O49 in the near-infrared region also improves the light collection range:the "hot electron" injection process generated by LSPR also allows the photocatalytic material to exhibit high photodegradation efficiency.At last,A dynamic cyclic reactor with g-C3N5/W18O49 Z-scheme heterojunction photocatalyst for the degradation of tetracycline hydrochloride wastewater was constructed,and the experimental results showed that the degradation efficiency of the cyclic reactor still reached 86.4%for tetracycline hydrochloride after dynamic stabilization... |
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