Preparation and application of cationic modified bacterial cellulose photocatalytic membrane

Abstract

The application discloses a preparation and application of a cation-modified bacterial cellulose photocatalytic membrane, the prepared cation-modified bacterial cellulose photocatalytic membrane is a floating photocatalyst, and visible light-driven hydrogen peroxide is generated directly from raw seawater with air as an O2 source, and the application of the cation-modified bacterial cellulose photocatalytic membrane to an in-situ photocatalytic inhibition method of a red tide algae Karenia mikimotoi is disclosed.The method directly starts from raw seawater, air is used as an O2 source, and no additional hydrogen peroxide is needed, so that the sunlight-driven hydrogen peroxide generation and the in-situ photocatalytic inhibition of the red tide algae Karenia mikimotoi can be realized.The photocatalytic membrane preparation method is simple and convenient, raw materials are easy to obtain, the photocatalytic membrane is biocompatible and environment-friendly, the photocatalytic activity is high, and the algae inhibition effect is good.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of new materials and its preparation technology and marine environment management, and particularly relates to preparation of cationic modified bacterial cellulose photocatalytic membrane; the synthesized cationic modified bacterial cellulose photocatalytic membrane is used as a floating visible light catalyst, air is used as an O2 source, and seawater photocatalysis occurs under room temperature, normal pressure and neutral reaction conditions, and hydrogen peroxide, and a new method for photocatalytic inhibition of in-situ Karenia mikimotoi algal bloom is applied. BACKGROUND

[0002] The problem of water bloom caused by abnormal proliferation and aggregation of algae on the water surface in water bodies can be traced back to the 19th century, but until the end of the 20th century, water bloom has attracted widespread attention. High-density algae can reduce water transparency, accelerate the consumption of dissolved oxygen in the aquatic ecosystem, cause the death of aquatic organisms, affect water environmental quality, and destroy the balance of the aquatic ecosystem. In addition, the algal toxins released by algae also pose an increasing threat to the ecosystem and human health [Chen Shuiyong, Wu Zhenming, et al. Formation, hazards and prevention of water eutrophication [J]. Environmental Science and Technology, 1999, 2, 12-16.]. In recent years, harmful red tide disasters caused by Karenia mikimotoi have occurred almost every year in China's coastal waters. Karenia mikimotoi is a typical representative of fish-toxic red tide in China's coastal waters. In 2012, there were 10 Karenia mikimotoi algal blooms in the coastal waters of Fujian Province, with a total area of 323km 2It has caused great harm to aquaculture, especially abalone culture, with direct economic losses of 2.31 billion yuan [X. Li, J. Lin, et al. Detrimental impacts of the dinoflagellate Karenia mikimotoi in Fujian coastal waters on typical marine organisms[J]. Harmful Algae, 2017, 61, 1-12.]. Currently, the main methods to control algae and water bloom outbreaks are chemical, physical and biological methods, which have many shortcomings such as secondary pollution, high cost, and inability to solve the root problem, unstable effect, slow effect, and inability to be widely applied [Li Dongpeng, Yang Lan, Zhao Xiaoxiang, et al. Research progress of photocatalytic algae inhibition materials[J]. Environmental Chemistry, 2023, 42(11): 3951-3964.]. Photocatalytic technology can directly utilize solar energy to excite materials to generate highly active free radicals, which can inactivate algae and simultaneously degrade algal toxins generated during the death process of algae. Therefore, it has become a research hotspot. Fan et al. [G. Fan, J. Zhang, et al. Recyclable self-foating A-GUN-coated foam as effective visible-light-driven photocatalyst for inactivation of Microcystis aeruginosa[J]. J. Hazard Mater., 2023, 442, 130059] used melamine foam as a solid support and loaded Ag / AgCl@g-C3N4@UIO-66(NH2) nanoparticles to construct a self-floating photocatalyst, which was applied to photocatalytic inhibition of Microcystis aeruginosa. The inactivation rate was 98% after 3 h of visible light irradiation, and the inactivation rate was still 92% after 5 cycles of catalyst recycling. The algae inhibition mechanism is that the photo-generated electrons of g-C3N4 are generated by light excitation, and the photo-generated electrons are transferred to the Ag / AgCl site through the UIO-66(NH2) unit, and superoxide free radicals are generated with the molecular oxygen adsorbed on the site.Hu et al. [L. Hu, J. Chen, R. Wang, et al. Photocatalytic degradation effect and mechanism of Karenia mikimotoi by non-noble metal modified TiO2 loading onto copper metal organic framework (SNP-TiO2@Cu-MOF) under visible light [J]. J. Hazard Mater., 2021, 419, 126407] combined TiO2 with MOF, designed and synthesized SNP-TiO2@Cu-MOF composite nanoparticle photocatalyst, and applied it to the photocatalytic inhibition of Karenia mikimotoi. When the amount of SNP-TiO2@Cu-MOF added was 100 mg / L, the inhibition rate was 93.75% after 6 h of reaction. Wang et al. [D. Wang, J. Chen, X. Gao, P. Wang, et al. Maximizing the utilization of photo-generated electrons and holes of g-C3N4 photocatalyst for harmful algae inactivation [J] Chem. Eng. J. 2022, 431, 134105.] proposed a method of hydrogen peroxide-assisted photocatalytic inhibition of Microcystis aeruginosa. Compared with the photocatalyst of g-C3N4 nanoparticles stripped by sulfuric acid alone, the reaction time was greatly reduced for the same algae inhibition rate. This shows that hydrogen peroxide not only has better algae removal ability, but also can produce a synergistic effect with the photocatalytic process.

[0003] Bacterial cellulose (BC) is the finest nanoscale fiber formed naturally, with a diameter of 20-60 nm, and does not cause light scattering, with excellent optical properties. The sub-fiber crystals of BC form fibrils, which aggregate into bundles to form a ribbon structure, and then form a rich and uniform three-dimensional network of nanoscale porous structure. At the same time, the BC surface has a large number of hydroxyl functional groups, which are easy to modify and surface modify.

[0004] Based on this, the application ① directly starts from raw seawater, air is a source of molecular oxygen, and ion-doped functionalized g-C3N4 with high selectivity and high activity of a two-electron oxygen reduction (2e-ORR) path is constructed by ionothermal synthesis by means of crystal engineering, doping engineering and surface functionalization. ② The cationic etherifying agent is introduced to modify the positive electric property of BC, and a cationic modified bacterial cellulose nanomembrane with rich hydroxyl functional groups and positive electric property is obtained. The synthesized ion-doped functionalized g-C3N4 is stably immobilized and confined in the rich nanopore channels in the BC nanomembrane structure by electrostatic force interaction and hydrogen bond, and a porous cationic modified BC photocatalytic membrane with fully and uniformly dispersed g-C3N4 is obtained. ③ The porous cationic modified BC photocatalytic membrane is used as a floating visible light catalyst, and the photogenerated holes generated in situ during the hydrogen peroxide generation and photocatalytic process are used as active oxygen substances, so that the sunlight-driven efficient and green photocatalytic inhibition of red tide algae Karenia mikimotoi is realized. SUMMARY

[0005] One of the purposes of the application is to use ion-doped functionalized g-C3N4 as a guest molecule, cationic modified bacterial cellulose with rich and regular nanoscale channels as a host molecule, and through molecular self-assembly and film forming processing, ion-doped functionalized g-C3N4 is stably immobilized and confined in the nanopore channels in the BC nanomembrane structure, and a porous structure floating photocatalytic membrane with fully and uniformly dispersed g-C3N4 is obtained. In addition, the rich hydroxyl functional groups in the BC membrane structure can further amplify the “electron trap effect” and reduce the influence of cations in seawater on the reduction of molecular oxygen to generate hydrogen peroxide.

[0006] The synthesis of ion-doped functionalized g-C3N4 uses dicyandiamide (abbreviated as D), melamine (abbreviated as M), melamine cyanuric acid complex (abbreviated as R), urea (abbreviated as U), and urea and thiourea (abbreviated as UT) as precursors, sodium chloride / potassium chloride as a eutectic salt, and ionothermal polycondensation reaction to synthesize a series of ion-doped functionalized g-C3N4 with high crystallinity and relatively regular morphology of sodium / potassium-doped hydroxyl / cyan functional groups. The high crystallinity and regular morphology improve the light absorption of g-C3N4, and the introduced sodium and potassium ions construct electron channels on the surface and between the layers of the g-C3N4 bulk phase, respectively, to realize the full separation and rapid transmission of the photo-generated e - , photo-generated h + The cyan functional groups introduced in the molecular structure act as a photo-generated electron reservoir, which on the one hand makes up for the spatial and temporal mismatch between the photo-generation process and the catalytic process, and on the other hand reduces the recombination of photo-generated e - , photo-generated h +The composite of the g-C3N4 and the BC nanomembrane, on the one hand, the strong dipole effect enhances the adsorption of molecular oxygen in the active center of the triazine, prevents the generation of superoxide free radicals, and improves the selectivity of the two-electron reduction path of molecular oxygen to generate hydrogen peroxide; on the other hand, the introduction of the hydroxyl functional group endows the surface of the g-C3N4 with amphiphilic activity, which is beneficial to promote the reaction between the molecular oxygen and the water molecules at the interface of the active site and the generated hydrogen peroxide is removed in time, thereby reducing the occurrence of the oxidative decomposition side reaction.

[0007] To achieve the above object, the application adopts the following technical scheme:

[0008] The ion-doped functionalized g-C3N4 takes dicyandiamide (abbreviated as D) or melamine (abbreviated as M) or cyanuric acid melamine (abbreviated as R), or urea (abbreviated as U), or urea / thiourea (abbreviated as UT) as a precursor, sodium chloride / potassium chloride as a eutectic salt, and is synthesized through an ionothermal polycondensation reaction under a nitrogen atmosphere. Further, the chemical formula of the ion-doped functionalized g-C3N4 is PCN-D, PCN-M, PCN-R, PCN-U, and PCN-UT. The structure of the ion-doped functionalized g-C3N4 is shown in the figure. Figure 1

[0009] Further, the synthesis of the ion-doped functionalized g-C3N4 includes the following steps:

[0010] Step S101: After dicyandiamide or melamine or cyanuric acid melamine or urea or urea / thiourea and sodium chloride / potassium chloride of different masses are fully mixed and ground, they are placed in a box-type muffle furnace, nitrogen is continuously introduced (5-15 ml / min), the heating rate is controlled to be 1.2-2.5 ℃ / min, heating is performed to 500-620 ℃, and reaction is performed for 3-5 h. The crude product is fully ground, washed with ion-free water and ethanol, and vacuum dried to constant weight to obtain the target product.

[0011] The second object of the application is to use the synthesized series of ion-doped functionalized g-C3N4 as a guest molecule and a cation-modified BC nanomembrane as a host molecule, to construct a floating cation-modified BC photocatalytic membrane through molecular self-assembly and substrate compounding and vacuum drying. Specifically, the following steps are included:

[0012] ​Step S201: BC nanometer film is cut into 10*10 cm size, placed in 0.1 mol / L sodium hydroxide aqueous solution, stirred at 60-90 DEG C for 3 h, rinsed with ion-free water until neutral, so as to remove the bacterial cells and residual culture medium on the film surface. The purified BC nanometer film is added into 20-60 wt% cationic etherification agent (3-chloro-2-hydroxypropyl trimethyl ammonium chloride) aqueous solution and stirred overnight, then rinsed with ion-free water until neutral and freeze-dried. Different amounts of ion-doped functionalized g-C3N4 are ultrasonically dispersed in 100 mL ion-free water until the Tyndall phenomenon appears, 10 mL of the suspension is vacuum filtered onto the cationic modified bacterial cellulose nanometer film to obtain porous g-C3N4@ cationic modified BC photocatalytic film with different loadings, and the photocatalytic film is vacuum dried after being combined with a floating substrate (melamine foam) to serve as a floating photocatalyst.

[0013] The third object of the present application is to provide a method for using the cationic modified BC photocatalytic film as a floating visible light catalyst to directly use air as an O2 source to photocatalyze hydrogen peroxide in seawater in situ under environmental conditions and for photocatalytic inhibition of Karenia mikimotoi.

[0014] S300: In a quartz photo-reaction bottle equipped with magnetic stirring and circulating cooling water, cationic modified BC photocatalytic film with g-C3N4 loading of 3 mg or 5 mg, 50 ml of original seawater (taken from Mawei), and 3 ml of ethanol are sequentially added, stirring is started, and air is bubbled for dark reaction for 0.5 h. A 300 W xenon lamp light source (with 1.5G filter) is turned on, the air input speed is controlled at 1-2 ml / min, and the reaction is carried out for 4 h. The hydrogen peroxide yield is 704-1430 μmol / g.h.

[0015] S301: A conical flask is sequentially added with 40 ml of seawater, 10 ml of algal liquid with a density of 5*10 5 cells / ml, an appropriate amount of f / 2 medium, cationic modified BC photocatalytic film, and placed in a light incubator for 24 h (culturing conditions: light power 18 W, light intensity 5000 Lux, temperature 23 DEG C, humidity 65%). The cationic modified BC photocatalytic film is kept floating on the liquid surface during the process. The Karenia mikimotoi inhibition rate is 35%-81% after 12 h, and the Karenia mikimotoi inhibition rate is 43%-88% after 24 h.

[0016] S302: After the cationic modified BC photocatalytic film is separated, it can be directly recycled, and the hydrogen peroxide yield and the Karenia mikimotoi inhibition rate remain basically unchanged after three cycles. The cationic modified BC photocatalytic film can be regenerated by ion-free water washing and vacuum drying.

[0017] The present application has the following beneficial effects:

[0018] 1. In the ion-doped functionalized g-C3N4 structure, the hydroxyl functional group and the cyano functional group are combined with the N atom of the amino functional group in the g-C3N4 structure in the form of a covalent bond. The cyano functional group acts as a light-generated electron reservoir, which on the one hand makes up for the mismatch in time and space between the light generation process and the catalytic process, reduces the recombination probability of the light-generated e - + , and on the other hand, as the adsorption of molecular oxygen at the triazine active center, prevents the generation of superoxide free radicals, and improves the selectivity of the reaction; the hydroxyl functional group endows the g-C3N4 surface with amphiphilic activity, promotes the reaction between molecular oxygen and water molecules at the active site surface interface, and generates hydrogen peroxide and removes it in time, thereby reducing the occurrence of oxidative decomposition side reactions; sodium and potassium ions are inserted into the g-C3N4 bulk phase by coordination, and construct an "ion bridge", which promotes the transport of photo-generated carriers and the separation of photo-generated electrons and photo-generated holes.

[0019] 2. In the cation-modified BC photocatalytic membrane structure, the ion-doped functionalized g-C3N4 nanoparticles are stably immobilized and confined in the nanoscale pores in the BC nanomembrane structure by electrostatic force and hydrogen bond, and are uniformly dispersed and closely combined, showing a multi-level pore structure with micropores, mesopores and macropores coexisting. The hydroxyl functional group in the BC membrane structure is rich, which on the one hand is beneficial to the adsorption of molecular oxygen and water molecules, and on the other hand, the hydroxyl group can be ionized with the cations in seawater to produce an "electron trap" effect, and the number of hydroxyl groups amplifies the "electron trap" effect, greatly reducing the influence of ions in seawater on the photocatalytic process. In addition, the BC membrane is environmentally friendly and biocompatible, and algal cells are easy to adsorb and enrich on it.

[0020] 3. The cation-modified BC photocatalytic membrane is a floating visible light catalyst, and air is the O2 source. Under environmental reaction conditions (room temperature, normal pressure and neutral reaction conditions), solar light-driven in-situ generation of hydrogen peroxide in seawater and its application in photocatalytic inhibition of the red tide algal bloom of Karenia mikimotoi are realized.

[0021] 4. The cation-modified BC photocatalytic membrane can be directly recycled after separation, and the catalytic activity remains basically unchanged after 3 cycles. The cation-modified BC photocatalytic membrane can be regenerated by washing with ion-free water and vacuum drying. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the synthesis route and structure of the ion-doped functionalized g-C3N4 described in the present application;

[0023] Figure 2 is the FT-IR and XRD spectra of the ion-doped functionalized g-C3N4 described in the present application;

[0024] Figure 3 ​The scanning electron microscope (SEM) spectrum of the cationic modified BC photocatalytic membrane BC@PCN-R described in the application; (a) photocatalytic membrane BC@PCN-R (flat); (b) photocatalytic membrane BC@PCN-R (elevation), (PCN-R solid loading 3 mg);

[0025] Figure 4 (a) transient photocurrent response, (b) EIS impedance and (c) Mott-Schottky plot of the cationic modified BC photocatalytic membrane BC@PCN-R (PCN-R solid loading 3 mg);

[0026] Figure 5 The optical microscope, scanning electron microscope of BC@PCN-R photocatalytic membrane (PCN-R solid loading 3 mg) inhibits karenia brevis, a-b control group; c-d photocatalytic inhibition test group; e-h scanning electron microscope of the control group; i-l scanning electron microscope of the test group. DETAILED DESCRIPTION

[0027] The application will be further described in conjunction with specific embodiments, but the application is not limited to only these embodiments.

[0028] Example 1: Synthesis of PCN-D, PCN-M, PCN-R, PCN-U and PCN-UT

[0029] Step S101: 3g of dicyandiamide, or 5g of melamine, or 5g of MCR, or 5g of urea, or 10g of a mixture of 5g of urea / 5g of thiourea, was added to a mortar, and was mixed with 15g of a sodium chloride / potassium chloride mixture (sodium chloride / potassium chloride = 1:1.25 (molar ratio)) respectively, and was ground thoroughly. The mixture was placed in a nitrogen atmosphere muffle furnace, and the heating rate was controlled at 2.0℃ / min, and was heated to 550℃ for 4h, and was naturally cooled to room temperature. The crude product was thoroughly ground, washed with deionized water and ethanol, and was vacuum dried to constant weight to obtain the target product.

[0030] Example 2: Synthesis of cationic modified BC photocatalytic membrane

[0031] Step S201: The BC membrane was cut into a size of 10×10cm, and was placed in a 0.1mol / L sodium hydroxide aqueous solution, and was stirred at 90℃ for 4h. After being rinsed with deionized water to neutral, 30% (mass percentage) 3-chloro-2-hydroxypropyl trimethylammonium chloride aqueous solution was added, and was stirred overnight. The BC membrane was taken out, rinsed with deionized water to neutral, and was freeze-dried for standby use.

[0032] Step S202: 30 mg or 50 mg of functionalized g-C3N4 was dispersed in 100 mL of ion-free water, respectively, and ultrasonicated until the Tyndall phenomenon appeared. 10 mL of the suspension was vacuum filtered onto the cationic modified bacterial cellulose nanomembrane to obtain a porous g-C3N4@ cationic modified BC photocatalytic original membrane with a loading of 3 mg or 5 mg, respectively. The original membrane was vacuum dried after being compounded and pressed with a melamine foam substrate to obtain a floating catalyst.

[0033] Application Example 1: Photocatalytic hydrogen peroxide in situ generated by cationic modified BC photocatalytic membrane in seawater

[0034] In a quartz photo-reactor bottle equipped with magnetic stirring and circulating cooling water, 50 ml of original seawater, 3 ml of ethanol, and cationic modified BC photocatalytic membrane were sequentially added. The mixture was irradiated under a 300 W xenon lamp light source (with a 420 nm filter) with continuous air bubbling for 4 h. The results are shown in Table-1.

[0035] Table-1 Results of photocatalytic hydrogen peroxide in situ generated by cationic modified BC photocatalytic membrane in seawater

[0036]

[0037]

[0038] Application Example 2: Recycling use of cationic modified BC photocatalytic membrane for photocatalytic synthesis of hydrogen peroxide

[0039] The photocatalytic membrane separated in Application Example 1 can be directly recycled for use, and the operating conditions are the same as in Application Example 1. The hydrogen peroxide yield of the 5 mg porous g-C3N4 loaded BC@PCN-R photocatalytic membrane was 1417 μmol / g.h in the first cycle, 1420 μmol / g.h in the second cycle, and 1414 μmol / g.h in the third cycle.

[0040] Application Example 3: Photocatalytic algal inhibition by cationic modified BC photocatalytic membrane

[0041] A conical flask was sequentially added with 40 ml of seawater, 10 ml of algal solution with an algal density of 5 x 10 5 cells / ml, 12 g of appropriate f / 2 medium, and BC photocatalytic membrane. The BC photocatalytic membrane was kept floating on the liquid surface during the process in a light incubator (cultivation conditions: light power 18 W, light intensity 5000 Lux, temperature 23℃, humidity 65%). The sample was taken every 12 h, and the number of algal cells was counted under a microscope by hemocytometer counting to calculate the algal inhibition rate. The results are shown in Table-2.

[0042] Table-2 Results of photocatalytic inhibition of Micractinium chui by cationic modified photocatalytic membrane

[0043]

[0044] Note: [1] D. salina; [2] I. galbana; [3] K. micura;

[0045] [4] Inhibition rate: IR (%) = (1 - N1 / N0) x 100 Wherein N1 is the number of algae cells in the experimental group;

[0046] N0 is the number of algae cells in the blank group

[0047] Embodiment 4: Cation-modified BC photocatalytic membrane photocatalytic algae inhibition recycling

[0048] The photocatalytic membrane separated in embodiment 3 can be directly recycled, and the operation conditions are the same as those in embodiment 3. The results are shown in Table 3.

[0049] Table 3: Cation-modified photocatalytic membrane photocatalytic inhibition of K. micura recycling results

[0050]

[0051] Note: [1] Loading 5 mg;

[0052] [2] Inhibition rate: IR (%) = (1 - N1 / N0) x 100 Wherein N1 is the number of algae cells in the experimental group; N0 is the number of algae cells in the blank group

[0053] Embodiment 6: Regeneration of cation-modified BC photocatalytic membrane

[0054] The photocatalytic membrane separated in embodiment 3 or embodiment 1 is washed with deionized water (3 x 60 ml) and dried to constant weight at 60°C under vacuum, which completes the regeneration.

[0055] The above is only the preferred embodiment of the present application, any equivalent changes and modifications made according to the scope of the present application patent application shall be included in the scope of the present application.

Claims

1. A cationically modified bacterial cellulose photocatalytic membrane, characterized by: The cationic etherifying agent 3-chloro-2-hydroxypropyl trimethyl ammonium chloride is used to modify the positive electric property of the bacterial cellulose nanomembrane, and a cationic modified bacterial cellulose nanomembrane with rich hydroxyl functional groups and positive electric property is obtained. The ion-doped functionalized g-C3N4 is stably immobilized and confined in the rich nanopore channels of the bacterial cellulose nanomembrane structure through electrostatic interaction and hydrogen bonding, and a multi-level pore g-C3N4@ cationic modified bacterial cellulose photocatalytic membrane with fully and uniformly dispersed ion-doped functionalized g-C3N4 is obtained. The ion-doped functionalized g-C3N4 takes one or more of dicyandiamide, melamine, cyanuric acid melamine, urea, and thiourea as a precursor, and KCl and NaCl eutectic salt as a hot melt salt, and through ionothermal polycondensation reaction, hydroxyl functional groups and cyano functional groups are introduced into the molecular structure of the functionalized g-C3N4 in the form of covalent bonds; potassium ions and sodium ions are introduced into the interlayer and surface of the g-C3N4 bulk phase, respectively, to obtain the ion-doped functionalized g-C3N4.

2. The method for preparing the cationic modified bacterial cellulose photocatalytic membrane according to claim 1, characterized in that: The method comprises the following steps: Step 1: The bacterial cellulose nanomembrane is cut into a size of 10×10 cm, placed in a 0.1 mol / L sodium hydroxide aqueous solution, stirred at 60-90°C for 3 h, rinsed with deionized water until neutral, and the bacterial cells and residual culture medium on the surface of the membrane are removed; the purified bacterial cellulose membrane is added into a 30-60 wt% cationic etherifying agent 3-chloro-2-hydroxypropyl trimethyl ammonium chloride aqueous solution and stirred overnight, taken out, rinsed with deionized water until neutral, and freeze-dried to obtain a cationic modified bacterial cellulose nanomembrane; Step 2: The ion-doped functionalized g-C3N4 is dispersed in 100 mL deionized water and ultrasonically treated until fully dispersed; 10 mL of the suspension is vacuum filtered onto the cationic modified bacterial cellulose nanomembrane to obtain a multi-level pore g-C3N4@ cationic modified bacterial cellulose photocatalytic membrane with a solid loading of 3 mg or 5 mg.

3. Use of the cationically modified bacterial cellulose photocatalytic membrane according to claim 1, characterized in that: The multi-level pore g-C3N4@ cationic modified bacterial cellulose photocatalytic membrane is combined with a floating substrate melamine foam as a floating photocatalyst, and air is used as a molecular oxygen source to generate hydrogen peroxide in seawater in situ under visible light at room temperature, normal pressure and neutral conditions, and is applied to in-situ photocatalytic inhibition of chlorella vulgaris.

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