A Z-type carbon nitride heterojunction photocatalyst and its preparation method and antibacterial application

Abstract

The present invention discloses a Z-type carbon nitride heterojunction photocatalyst, a preparation method thereof, and antibacterial application, and belongs to the field of composite material technology. First, melamine and cyanuric acid in an appropriate molar ratio are fully ground and mixed in a mortar, a certain amount of the mixture is weighed in a crucible, and the mixture is placed in a muffle furnace for calcination and polymerization, and the carbon nitride powder is obtained by grinding, washing, and freeze-drying. Subsequently, the carbon nitride powder, urea, and sodium citrate are ground and mixed in a certain proportion and transferred to a crucible and heat-treated. Finally, the obtained yellow powder is fully washed and freeze-dried to obtain a Z-type heterojunction photocatalyst, which is further used for antibacterial applications. The present invention prepares a metal-free Z-type heterojunction photocatalyst by two-step calcination, which shows excellent disinfection performance against Staphylococcus aureus and Escherichia coli. As a metal-free composite photocatalyst with low preparation cost, no secondary pollution, and excellent bacterial disinfection performance, it shows good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and in particular relates to a Z-type carbon nitride heterojunction photocatalyst, a preparation method thereof, and antibacterial applications thereof. Background Art

[0002] Microbial contamination caused by industrial development and rapid population growth continues to threaten human health. In particular, the overuse of antibiotics has led to the emergence of drug-resistant bacteria, which has placed greater demands on the development of new bacterial disinfection strategies.

[0003] Photocatalytic disinfection technology is currently considered a promising disinfection strategy due to its high efficiency, energy conservation, and cost-effectiveness. While metal-based composite photocatalysts have demonstrated excellent photocatalytic disinfection performance, they inevitably cause secondary contamination during application. Therefore, the development of efficient, green, metal-free composite photocatalysts for bacterial disinfection in aquatic environments is crucial.

[0004] Since 2009, when Wang et al. pioneered the discovery that graphitic carbon nitride (GCN) can photocatalytically split water using visible light with the assistance of a co-catalyst, the development and application of GCN photocatalysts has attracted widespread interest. GCN can generate electron-hole pairs driven by visible light, which then undergo redox reactions with O₂ and H₂O molecules on its surface to generate a variety of reactive oxygen species (ROS). ROS are well-known strong oxidants with a broad range of microbial killing properties. Therefore, GCN is considered one of the most promising metal-free photocatalysts for photocatalytic bacterial disinfection. However, pure GCN as a photocatalytic disinfectant still suffers from limitations such as low visible light utilization, high recombination rates of photogenerated electrons and holes, small specific surface area, and low photocatalytic disinfection efficiency, making it unable to meet practical application requirements. Consequently, researchers at home and abroad have explored a number of modification strategies, such as morphology control, element doping, and heterostructure construction.

[0005] Among them, heterojunction construction is an effective strategy for preparing highly photocatalytically active graphite-phase carbon nitride-based composite photocatalysts. Existing heterojunction constructions often use metal compounds as ligands in combination with carbon nitride, such as the preparation of heterojunction composite photocatalysts with application numbers 202011151586.3, 202010938845.0, 202110668339.9, and 202210527800.3. Although their photocatalytic activity has been improved to a certain extent, their preparation cost is relatively high and they are prone to secondary pollution. In addition, some metal-free homogeneous heterojunction carbon nitride-based photocatalysts have been developed, such as the homogeneous heterojunction composite carbon nitride photocatalysts with patent application numbers 201810403004.2, 202111354174.4, and 202210445853.0, which are respectively used in waste gas catalytic treatment, photocatalytic hydrogen production, organic pollutant treatment, and hydrogen peroxide synthesis, etc., but are rarely used in photocatalytic bacterial disinfection. In addition, although the heterojunction promotes the separation and transport of photogenerated carriers, the carrier transport type of the heterojunction is not clear. At present, since the construction of the Z-type heterojunction has a significant effect on improving the photocatalytic activity, it is of great significance to develop a homogeneous heterojunction composite photocatalyst with a Z-type photogenerated carrier transport type and apply it to the field of photocatalytic bacterial disinfection. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a Z-type carbon nitride heterojunction photocatalyst that can be used for photocatalytic bacterial disinfection; another object of the present invention is to provide a method for preparing a Z-type carbon nitride heterojunction photocatalyst with a simple preparation process and low production cost; the Z-type carbon nitride heterojunction photocatalyst prepared by this method can be used for photocatalytic bacterial disinfection.

[0007] The present invention adopts the following specific technical solutions:

[0008] A Z-type carbon nitride heterojunction photocatalyst is composed of carbon nitride nanosheets and carbon nitride quantum dots. The carbon nitride quantum dots can be dispersedly loaded on the surface of the carbon nitride nanosheets, and a Z-type heterojunction is formed between the two components.

[0009] The above-mentioned Z-type carbon nitride heterojunction photocatalyst comprises carbon nitride nanosheets prepared by calcination polymerization using melamine and cyanuric acid as raw materials; the carbon nitride nanosheets are calcined with a mixture of urea / sodium citrate so that carbon nitride quantum dots are dispersed on the carbon nitride nanosheets to obtain a Z-type carbon nitride heterojunction photocatalyst.

[0010] To achieve the above objectives, the present invention provides a carbon nitride heterojunction photocatalyst, which is prepared by the following method:

[0011] (1) mixing melamine and cyanuric acid, and calcining to obtain a crude product of carbon nitride nanosheets;

[0012] (2) washing the crude product of carbon nitride nanosheets with water and ethanol, and freeze-drying the product to obtain carbon nitride nanosheets;

[0013] (3) mixing urea and sodium citrate to obtain a mixture, mixing the mixture with carbon nitride nanosheets, and calcining to obtain a crude product of a Z-type carbon nitride heterojunction photocatalyst;

[0014] (4) Washing the crude product of the Z-type carbon nitride heterojunction photocatalyst, freeze-drying, and obtaining the Z-type carbon nitride heterojunction photocatalyst.

[0015] Furthermore, in step (1), the molar ratio of melamine to cyanuric acid is (0.5-2):1, specifically 1:1.

[0016] Furthermore, the calcination temperature in step (1) is 450-650°C, and specifically can be 550°C.

[0017] Furthermore, the calcination time in step (1) is 3 to 5 hours, and specifically can be 4 hours.

[0018] Furthermore, in step (3), the molar ratio of urea to sodium citrate is (2-4):1, specifically 3-1.

[0019] Furthermore, in step (3), the mass ratio of the mixture to the carbon nitride nanosheets is (0.05-1):0.5.

[0020] Preferably, the mass ratio of the mixture to the carbon nitride nanosheets in step (3) is (0.3-0.8):0.5.

[0021] Specifically, optionally, in step (3), the mass ratio of the mixture to the carbon nitride nanosheets is 0.474:0.5.

[0022] Furthermore, the calcination temperature in step (3) is 150-250°C, and specifically can be 180°C.

[0023] Furthermore, the calcination time in step (3) is 1 to 5 hours, specifically 2 hours.

[0024] The present invention further proposes the application of the above-mentioned Z-type carbon nitride heterojunction photocatalyst in the field of bacterial disinfection in non-human environments, and the specific steps are as follows:

[0025] The Z-type carbon nitride heterojunction photocatalyst is dispersed in water and mixed with the bacterial suspension, and then irradiated under a light source to carry out a photocatalytic reaction and photocatalytically inactivate the bacteria.

[0026] Furthermore, the additive dosage of the Z-type carbon nitride heterojunction photocatalyst is 0.05 mg / mL to 0.4 mg / mL.

[0027] Furthermore, the light source is a 350W xenon lamp (λ>420nm).

[0028] Furthermore, the bacteria in the bacterial suspension are one or more of Staphylococcus aureus or Escherichia coli.

[0029] Furthermore, the bacterial solution concentration was 1×10 2 ~9×10 8 CFU / mL.

[0030] Preferably, the bacterial solution concentration is 3×10 5 ~3×10 8 CFU / mL.

[0031] Furthermore, the stirring speed of the photocatalytic reaction is 300 rpm to 600 rpm, and the time of the photocatalytic reaction is 0.5 h to 6 h.

[0032] A method for inactivating Staphylococcus aureus in a non-human environment using a Z-type carbon nitride heterojunction photocatalyst comprises the following steps:

[0033] The Z-type carbon nitride heterojunction photocatalyst prepared above is dispersed in water and mixed with a Staphylococcus aureus suspension, and then irradiated under a light source to carry out a photocatalytic reaction, thereby photocatalytically inactivating the Staphylococcus aureus.

[0034] Furthermore, the additive dosage of the Z-type carbon nitride heterojunction photocatalyst is 0.05 mg / mL to 0.4 mg / mL.

[0035] Furthermore, the light source is a 350W xenon lamp (λ>420nm).

[0036] Furthermore, the concentration of the Staphylococcus aureus suspension was 3×10 5 ~3×10 8 CFU / mL.

[0037] Furthermore, the stirring speed of the photocatalytic reaction is 300 rpm to 600 rpm, and the time of the photocatalytic reaction is 0.5 h to 6 h.

[0038] The beneficial effects of the present invention are:

[0039] 1. The present invention adopts a two-step calcination method to prepare a metal-free Z-type carbon nitride heterojunction photocatalyst. The raw materials used for the synthesis are easily obtained and low in cost, and can be applied to large-scale production; and no secondary pollution is caused.

[0040] 2. A Z-type heterojunction with carrier transport type is formed between the two components of the composite photocatalyst obtained by this method. The photogenerated electrons and holes generated by this type of heterojunction have stronger redox ability.

[0041] 3. The Z-type carbon nitride heterojunction photocatalyst obtained by this method has excellent bacterial disinfection performance, and can inactivate about 5 orders of magnitude of Staphylococcus aureus within 2 hours and 3 orders of magnitude of Escherichia coli within 4 hours.

[0042] 4. The Z-type carbon nitride heterojunction photocatalyst obtained by this method can effectively adsorb Staphylococcus aureus and promote the inactivation effect of active species generated by photocatalysis on Staphylococcus aureus. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a transmission electron microscope image of the Z-type carbon nitride heterojunction photocatalyst obtained by implementing the present invention.

[0044] Figure 2 The X-ray diffraction spectra of the carbon nitride nanosheets and Z-type carbon nitride heterojunction photocatalyst obtained by the implementation of the present invention are shown.

[0045] Figure 3 This is an infrared spectrum of the carbon nitride nanosheets and Z-type carbon nitride heterojunction photocatalyst obtained by the implementation of the present invention.

[0046] Figure 4 X-ray photoelectron spectra (a), C1s spectra (b), and N1s spectra (c) of carbon nitride nanosheets and Z-type carbon nitride heterojunction photocatalysts obtained by the present invention.

[0047] Figure 5 The transient photocurrent density of the carbon nitride nanosheets and Z-type carbon nitride heterojunction photocatalyst obtained by the implementation of the present invention.

[0048] Figure 6 The fluorescence spectra of the carbon nitride nanosheets and Z-type carbon nitride heterojunction photocatalyst obtained by the implementation of the present invention are shown.

[0049] Figure 7 UV-visible diffuse reflectance absorption spectra (a) of carbon nitride nanosheets, carbon nitride quantum dots, and Z-type carbon nitride heterojunction photocatalysts obtained by the present invention, energy band gaps (b), XPS valence band spectra (c) of carbon nitride nanosheets and carbon nitride quantum dots, and carrier transport schematic diagram of the Z-type carbon nitride heterojunction photocatalyst (d).

[0050] Figure 8The inactivation efficiency of the carbon nitride nanosheets and Z-type carbon nitride heterojunction photocatalyst obtained by the present invention on Staphylococcus aureus (a) and Escherichia coli (b) under visible light irradiation.

[0051] Figure 9 The inactivation efficiency of Z-type carbon nitride heterojunction photocatalysts with different carbon nitride quantum dot loadings obtained in the present invention on Staphylococcus aureus (a) and Escherichia coli (b). DETAILED DESCRIPTION

[0052] Source of raw materials:

[0053] Melamine (C3H6N6, 99%), cyanuric acid (C3H3N3O3, 98%), urea (CH4N2O, 99%), and trisodium citrate dihydrate (C6H5Na3O7.2H2O, 99%) were purchased from Beijing Inokai Chemical Technology Co., Ltd. Staphylococcus aureus (ATCC 43300) and Escherichia coli (ATCC 25922) were from strains frozen in our laboratory. Both strains were incubated overnight in LB medium at 37°C and 220 rpm. The bacterial suspension was then centrifuged at 5000 rpm for 10 min to enrich the bacteria. The suspension was then resuspended in physiological saline and the optical density (OD) of the bacterial suspension was adjusted. 600 ) is 1.0, for standby use.

[0054] Example 1

[0055] The preparation method of the Z-type carbon nitride heterojunction photocatalyst is as follows:

[0056] (1) Melamine and cyanuric acid were accurately weighed in a molar ratio of 1:1 and thoroughly ground in a mortar. The ground powder was placed in a muffle furnace, heated to 550°C at a heating rate of 2.5°C / min, and maintained at 550°C for 4 h to obtain a light yellow solid, which was then ground to obtain a light yellow powder.

[0057] (2) The light yellow powder obtained in step (1) was washed alternately with ultrapure water and ethanol for 5 times, and then the washed light yellow powder was freeze-dried for 12 h to obtain carbon nitride nanosheets, which were labeled as g-CN.

[0058] (3) Urea and sodium citrate were weighed in a molar ratio of 3:1 and thoroughly ground in a mortar to obtain a mixture. 0.119 g of this mixture was weighed and thoroughly mixed with 0.5 g of g-CN and placed in a crucible. The crucible was then transferred to a muffle furnace and heated to 180°C at a rate of 2.5°C / min and held for 2 h to obtain a yellow powder.

[0059] (4) The yellow powder obtained in step (3) was thoroughly washed alternately with ultrapure water and anhydrous ethanol, and the washed precipitate was freeze-dried for 12 h to obtain a Z-type carbon nitride heterojunction photocatalyst, which was labeled as HJ-CN1.

[0060] Example 2

[0061] The carbon nitride nanosheets prepared in step (2) of Example 1 were thoroughly mixed with 0.237 g of a urea / sodium citrate mixture and placed in a crucible. The crucible was then transferred to a muffle furnace and heated to 180°C at a heating rate of 2.5°C / min and maintained for 2 h. The resulting yellow powder was washed alternately with ultrapure water and anhydrous ethanol. The washed precipitate was freeze-dried for 12 h to obtain a Z-type carbon nitride heterojunction photocatalyst, labeled HJ-CN2.

[0062] Example 3

[0063] The carbon nitride nanosheets prepared in step (2) of Example 1 were thoroughly mixed with 0.474 g of a urea / sodium citrate mixture and placed in a crucible. The crucible was then transferred to a muffle furnace and heated to 180°C at a heating rate of 2.5°C / min and maintained for 2 h. The resulting yellow powder was washed alternately with ultrapure water and anhydrous ethanol. The washed precipitate was freeze-dried for 12 h to obtain a Z-type carbon nitride heterojunction photocatalyst, labeled HJ-CN3.

[0064] Example 4

[0065] The carbon nitride nanosheets prepared in step (2) of Example 1 were thoroughly mixed with 0.711 g of a urea / sodium citrate mixture and placed in a crucible. The crucible was then transferred to a muffle furnace and heated to 180°C at a heating rate of 2.5°C / min and maintained at that temperature for 2 h. The resulting yellow powder was washed alternately with ultrapure water and anhydrous ethanol. The washed precipitate was freeze-dried for 12 h to obtain a Z-type carbon nitride heterojunction photocatalyst, labeled HJ-CN4.

[0066] Example 5

[0067] Without adding g-CN powder, carbon nitride quantum dots were obtained using the same strategy, labeled as g-CNQDs, with the following steps:

[0068] (1) Urea and sodium citrate were weighed in a molar ratio of 3:1 and thoroughly ground in a mortar to obtain a mixture. 0.119 g of the mixture was weighed and placed in a crucible. The mixture was then transferred to a muffle furnace and heated to 180°C at a heating rate of 2.5°C / min and maintained for 2 h to obtain a yellow powder.

[0069] (2) The yellow powder obtained in step (1) was thoroughly washed alternately with ultrapure water and anhydrous ethanol, and the washed precipitate was freeze-dried for 12 h to obtain carbon nitride quantum dots, which were labeled as g-CNQDs.

[0070] Example 6

[0071] This example is for performance characterization.

[0072] The Z-type carbon nitride heterojunction photocatalyst prepared in Example 3 was characterized by transmission electron microscopy. Figure 1 We can find that HJ-CN3 maintains the sheet structure of g-CN, and the presence of carbon nitride quantum dots is clearly observed in the magnified image of the yellow box area in the figure, which fully confirms the feasibility of synthesizing Z-type carbon nitride heterojunction photocatalysts by the two-step calcination strategy.

[0073] The g-CN and HJ-CN3 described in Examples 1 and 3 were characterized by XRD. Figure 2 The characteristic diffraction peaks of 27.3° and 13.0° correspond to the (002) and (100) planes of hexagonal graphitic carbon nitride, respectively. Since HJ-CN3 is composed of two carbon nitrides with different morphologies, its diffraction peaks have only slightly changed compared with g-CN. FT-IR spectroscopy reveals the molecular structure of the photocatalyst ( Figure 3 ), g-CN at 808cm -1 The characteristic peak at 1100-1700 cm corresponds to the typical out-of-plane bending vibration mode of the tris-s-triazine ring. -1 The characteristic peaks in the range of 3000-3400cm correspond to the stretching vibration modes of aromatic C–N heterocycles. -1 The broad peak between the two is due to the NH stretching vibration mode. HJ-CN3 as a whole shows a characteristic peak distribution similar to that of g-CN, in which the characteristic peak corresponding to N–C–N is weakened, which may be caused by the scission of g-CN bonds under the calcination composite conditions.

[0074] The g-CN and HJ-CN3 described in Examples 1 and 3 were further characterized by XPS. Figure 4 a), g-CN and HJ-CN3 are both composed of C, N, and O, but the proportions of the elements are slightly different. The proportions of N and O in HJ-CN3 are higher than those in g-CN, which is mainly attributed to the successful loading of carbon nitride quantum dots. Then, the peak fitting deconvolution was performed on the refined spectra of the three elements. C1s spectrum ( Figure 4There are four convolution peaks centered at 284.8, 286.3, 288.3, ​​and 289.3 eV in (b), which correspond to C–C / C=C, C–O, N–C=N, and O–C=O bonds, respectively. With the introduction of g-CNQDs, the ratio of N–C=N bonds in HJ-CN3 increases significantly, while the characteristic peak corresponding to C–C / C=C decreases. N1s spectrum ( Figure 4 Figure c) also shows four deconvoluted peaks at 398.6 eV (C–N=C), 399.6 eV (N–(C)3 or H–N–(C)2), 401.2 eV (N–Hx), and 404.8 eV (π-π* excitation of the C–N conjugated structure). Notably, the increased intensities of N–(C)3 and N–Hx in the HJ-CN3 spectrum are consistent with the FT-IR results. These results fully confirm the successful preparation of HJ-CN.

[0075] The photoelectric conversion performance of g-CN and HJ-CN3 described in Examples 1 and 3 was characterized. The photocatalytic performance of a photocatalyst is closely related to its photoelectric properties, which in turn depend on the separation / migration efficiency of photogenerated carriers. Figure 5 The periodic on-off photocurrent response curve of the prepared material in the electrolyte is shown. The photocurrent density of HJ-CN3 is significantly higher than that of g-CN, indicating that the loading of carbon nitride quantum dots promotes the separation and transport of photogenerated carriers. In addition, Figure 6 As shown in the figure, under 375nm excitation light, g-CN and HJ-CN3 exhibited fluorescence emission peaks with similar shapes. However, the fluorescence intensity of the HJ-CN3 emission peak was significantly lower than that of g-CN, indicating that the introduction of carbon nitride quantum dots significantly reduced the recombination probability of photogenerated holes and electrons. The above results confirm that the composite strategy can significantly promote the separation of photogenerated carriers, thereby improving the photocatalytic performance of the composite photocatalyst.

[0076] The energy band alignment of g-CN, HJ-CN3 and g-CNQDs prepared in Examples 1, 3 and 5 was analyzed. First, the light absorption properties of the prepared materials were evaluated using UV-visible diffuse reflectance spectroscopy. Figure 7 As shown in a, g-CNQDs has strong absorption in the entire visible light region and extends to the near-infrared region. The light absorption curve of HJ-CN3 is between that of g-CNQDs and g-CN, and its absorption edge has undergone a significant red shift, indicating that coupling with g-CNQDs significantly improves the light absorption capacity and light response range of g-CN. Subsequently, according to the converted Tauc curve, it can be determined that the energy band gaps of g-CN, g-CNQDs and HJ-CN3 are 2.83eV, 2.05eV and 2.70eV respectively ( Figure 7b) The reduced energy band gap indicates that the composite photocatalyst has a more ideal visible light capture ability and can generate more photogenerated carriers. Subsequently, XPS-VB was used to characterize g-CNQDs and g-CN, and their valence band positions were determined. Figure 7 As shown in c, the energies corresponding to the valence band positions of g-CNQDs and g-CN are 2.25 and 2.93 eV, respectively, which correspond to the contact potential difference between the sample and the test instrument at pH = 7. According to the formula E NHE =φ+E VB-XPS -4.44(E NHE represents the standard hydrogen electrode potential; φ represents the electron work function of the test instrument; E VB-XPS = indicates the VB value determined by XPS-VB), we can directly calculate that the VB values ​​of g-CNQDs and g-CN are 2.69 and 2.01 eV (relative to NHE), respectively. Furthermore, the conduction band potentials of g-CNQDs and g-CN are calculated to be 0.82 eV and 0.64 eV, respectively. Given the calculated band gap value of a single component and the measured VB energy (relative to the reversible hydrogen electrode, RHE), Figure 7 d summarizes the energy band positions of g-CNQDs and g-CN and the redox potentials of the main active species generated. Under visible light irradiation, both single-component g-CNQDs and g-CN can be excited to produce e - and h + If the composite photocatalyst follows a conventional type-II heterojunction, the photogenerated e- in g-CN with a higher CB position would tend to migrate to the CB position of g-CNQDs. The CB potential of g-CNQDs is more positive than the reduction potential for generating ·O2- (E(O2 / ·O2-) = -0.33 V), making it impossible to oxidize dissolved O2 in water to ·O2-. This conclusion clearly contradicts actual active species capture experiments. Therefore, a direct Z-type heterojunction charge transfer process is proposed here.

[0077] Example 7

[0078] The photocatalytic bacterial disinfection performance of g-CN and HJ-CN3 samples described in Examples 1 and 3 was tested. 6 mg of HJ-CN3 was dispersed in 27 mL of normal saline by ultrasonication for 20 min and then mixed with 3 mL of bacterial solution at a concentration of about 3×10 5 ~3×10 8 The CFU / mL suspensions of Staphylococcus aureus and Escherichia coli were thoroughly mixed, and then the reaction system was exposed to a 350W xenon lamp (λ>420nm) for photocatalytic reaction. The stirring speed was set to 500 rpm to complete the photocatalytic inactivation of bacteria.

[0079] The experimental results are as follows Figure 8As shown in Figures 8a and 8b, control experiments in darkness (no visible light photocatalyst) and visible light (visible light irradiation without photocatalyst) showed that visible light irradiation and the photocatalyst samples had no toxic effects on either strain. Under visible light irradiation, the number of viable Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) in the photocatalyst-treated groups gradually decreased with the extension of irradiation time. Furthermore, the bactericidal efficiency gradually increased with the extension of photocatalytic treatment time, which may be due to the continuous accumulation of active species in the reaction system. After 2 hours of visible light irradiation, the log (C / C0) inactivation efficiency of g-CN and HJ-CN3 against MRSA was 1.4 log and 5.3 log, respectively. After 4 hours of visible light irradiation, the photocatalytic inactivation efficiency of g-CN and HJ-CN3 against E. coli was 0.96 log and 3.1 log, respectively. Based on the above results, we found that for the bacterial models MRSA and E. coli, the photocatalytic bactericidal activity of the composite photocatalyst HJ-CN was significantly higher than that of g-CN, which fully confirmed that the formation of the Z-type heterojunction significantly enhanced the photocatalytic activity.

[0080] Comparative Example 1

[0081] The samples in Examples 1 to 4 were tested for their photocatalytic bacterial disinfection performance. 6 mg of the catalysts prepared in Examples 1 to 4 were dispersed in 27 mL of normal saline solution by ultrasonication for 20 min, and then mixed with 3 mL of bacterial solution with a concentration of 3×10 5 ~3×10 8 The CFU / mL suspensions of Staphylococcus aureus and Escherichia coli were thoroughly mixed, and then the reaction system was exposed to a 350W xenon lamp (λ>420nm) for photocatalytic reaction. The stirring speed was set to 500rpm to complete the photocatalytic inactivation of bacteria.

[0082] like Figure 9As shown in (a) and (b), under visible light irradiation, the number of viable MRSA and E. coli in the photocatalyst-treated groups gradually decreased with the extension of irradiation time. After 2 hours of visible light irradiation, the log(C / C0) inactivation efficiency of HJ-CN1 against MRSA was only 2.64-log. After 4 hours of visible light irradiation, the photocatalytic inactivation efficiency of HJ-CN1 against E. coli was only 1.13-log. After 2 hours of visible light irradiation, the log(C / C0) inactivation efficiency of HJ-CN2 against MRSA was only 3.16-log. After 4 hours of visible light irradiation, the photocatalytic inactivation efficiency of HJ-CN2 against E. coli was only 2.26-log. After 2 hours of visible light irradiation, the log(C / C0) inactivation efficiency of HJ-CN4 against MRSA was only 4.90-log. After 4 hours of visible light irradiation, the photocatalytic inactivation efficiency of HJ-CN4 against E. coli was only 2.95-log. Therefore, the photocatalytic inactivation efficiencies of HJ-CN1, 2, and 4 against MRSA and E. coli were much lower than those of HJ-CN3, which had the highest carbon nitride quantum dot loading. Specific photocatalytic inactivation efficiency data are shown in Tables 1 and 2 below.

[0083] HJ-CN1 HJ-CN2 HJ-CN3 HJ-CN4 0min 0.01024 0.00336 -0.03374 0.01179 30min -0.43429 -0.46356 -0.93777 -0.81505 60min -1.01462 -1.18174 -2.02509 -1.98494 90 minutes -1.87306 -2.26219 -3.49657 -3.2637 120 minutes -2.63848 -3.16164 -5.13411 -4.89863

[0084] Table 1 Inactivation efficiency of Z-type carbon nitride heterojunction photocatalyst on Staphylococcus aureus log (C / C0).

[0085] HJ-CN1 HJ-CN2 HJ-CN3 HJ-CN4 0min -0.02785 -0.0128 -0.03651 -0.03529 60min -0.1633 -0.23951 -0.31788 -0.32517 120 minutes -0.38632 -0.62542 -1.01618 -0.99614 180 minutes -0.68115 -1.33845 -1.95963 -1.92562 240 minutes -1.1346 -2.25949 -3.10431 -2.94738

[0086] Table 2 Inactivation efficiency of Z-type carbon nitride heterojunction photocatalyst for Escherichia coli log (C / C0).

[0087] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. Application of Z-type carbon nitride heterojunction photocatalyst in the field of bacterial disinfection in non-human environment, characterized in that: The application steps are as follows: The Z-shaped carbon nitride heterojunction photocatalyst is dispersed in water and mixed with the bacterial solution, and then irradiated under a light source to carry out a photocatalytic reaction to photocatalytically inactivate the bacteria. The preparation process of the Z-type carbon nitride heterojunction photocatalyst is as follows: (1) Mixing melamine and cyanuric acid, calcining, and preparing a crude product of carbon nitride nanosheets; the molar ratio of melamine to cyanuric acid is 0.5 to 1:1; (2) washing the crude carbon nitride nanosheets with water and ethanol, and freeze-drying to obtain carbon nitride nanosheets; (3) Mixing urea and sodium citrate to prepare a mixture, mixing the mixture with carbon nitride nanosheets, and calcining to prepare a crude product of a Z-type carbon nitride heterojunction photocatalyst; the molar ratio of urea to sodium citrate is 3-4:1; and the mass ratio of the mixture to the carbon nitride nanosheets is 0.3-0.474:0.5; (4) Washing the crude product of the Z-type carbon nitride heterojunction photocatalyst, freeze-drying, and obtaining the Z-type carbon nitride heterojunction photocatalyst.

2. The use according to claim 1, characterized in that In step (1), the calcination temperature is 450-650° C., and the calcination time is 3-5 h.

3. The use according to claim 1, characterized in that In step (3), the calcination temperature is 150-250° C., and the calcination time is 1-5 h.

4. The use according to claim 1, characterized in that The additive dosage of the Z-type carbon nitride heterojunction photocatalyst is 0.05 mg / mL to 0.4 mg / mL.

5. The use according to claim 1, characterized in that The bacterial concentration in the bacterial solution is 1×10 2 ~9×10 8 CFU / mL.

Images