Application of α-naphthoflavone in photocatalytic degradation of DOPO and its derivatives

Abstract

The application discloses application of alpha-naphthoflavone in photocatalytic degradation of DOPO and derivatives thereof. In the application, the alpha-naphthoflavone is used as a photosensitizer under an oxygen-free condition, active species such as carbon-centered free radicals are generated under irradiation, and pollutants are degraded, so that the micro-pollutants in water can be efficiently removed while cost is saved, and effective removal of the micro-pollutants is realized.

Description

Technical Field

[0001] The invention belongs to the field of photocatalytic degradation of organic micropollutants, and specifically relates to the application of α-naphthoflavone in the efficient photocatalytic degradation of an organophosphorus flame retardant precursor (DOPO) and its derivatives. Background Art

[0002] As traditional halogenated flame retardants are gradually phased out, organophosphorus flame retardants (OPFRs) are increasingly being used as flame retardants, plasticizers, stabilizers, and more in various consumer and industrial material-related products due to their advantages such as high stability and good antioxidant properties. The extensive use of OPFRs has also led to high concentrations of OPFRs being detected in various countries and regions. DOPO is one of the six subgroups of OPFR monomers and can be used to construct a multifunctional platform for flame retardants with the characteristics of simple operation and low cost. Although DOPO is not used directly as a flame retardant, DOPO derivatives will decompose into DOPO during use and enter the environment, and the biological toxicity of DOPO will threaten the health of aquatic ecosystems. Therefore, there is an urgent need for a simple and efficient method to efficiently degrade DOPO in water. Summary of the Invention

[0003] The purpose of the present invention is to provide an application of α-naphthoflavone in the efficient photocatalytic degradation of DOPO and its derivatives, which provides a good idea for the photocatalytic degradation of micropollutants.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The purpose of the present invention is to protect the use of α-naphthoflavone in the photocatalytic degradation of DOPO and its derivatives. Specifically, under anaerobic conditions, α-naphthoflavone is activated by sunlight to generate carbon-centered free radicals, thereby efficiently degrading DOPO and its derivatives.

[0006] Furthermore, DOPO derivatives are produced by reacting DOPO with various organic compounds. For example, DOPO can react with benzoquinone and naphthoquinone to form products with two phenolic hydroxyl groups, such as DHP-DOPO (10-(2',5'-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide); ODOPM (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-hydroxymethyl-10-oxide) synthesized by reacting DOPO with formaldehyde oligomers, and then reacting it with polyphthalonitrile resin (PN) or phenolic resin (MPN) to form ODOPM-PN and ODOPM-MPN; and [(6-oxo-(6H)-dibenzo-(CE)(1,2)-oxaphosphahexane-6-one)methyl]-succinic acid (DOPO-DDP).

[0007] To achieve the above objectives, the present invention also provides a reaction device for photocatalytic degradation of DOPO and its derivatives by α-naphthoflavone, which includes a reactor, a xenon lamp light source, a circulating condensed water device, a magnetic stirrer, and a nitrogen supply device.

[0008] The top of the reactor is covered with a quartz glass slide to prevent chemicals from evaporating from the solution.

[0009] A xenon lamp light source simulates sunlight to provide a collimated beam to the reactor.

[0010] A magnetic stirrer is provided at the bottom of the reactor to mix the reaction solution uniformly.

[0011] The circulating water condensation device was connected to the reactor through a rubber tube to keep the system at 25 °C.

[0012] The nitrogen supply device is connected to the reactor through a rubber tube to blow out the dissolved oxygen in the system.

[0013] When in use, wastewater containing target pollutants, phosphate buffer solution with pH=7 and α-naphthoflavone solution are added to the reactor, then the valves at both ends of the reactor are opened, the nitrogen flow device is turned on, and the solution in the reactor is purged for 30 minutes. After purging, the valves on both sides of the reactor are closed to prevent oxygen from entering the reaction system; then the magnetic stirrer is turned on to mix it evenly, and the circulating water condensation device is turned on to ensure the temperature of the reaction system is stable, and then the xenon lamp light source is turned on for irradiation to carry out the reaction.

[0014] The present invention has the following remarkable effects:

[0015] The present invention provides a new use of α-naphthoflavone. The method only requires adding α-naphthoflavone to wastewater under anaerobic conditions, and utilizing the catalytic effect of sunlight to cause the α-naphthoflavone in the water to generate carbon-centered free radicals, thereby degrading and mineralizing target pollutants in the system into small molecular substances that are harmless to the environment. The operation process is simple, the treated water is colorless, odorless, clear and transparent, and the pollutant removal rate can reach 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the pseudo-first-order kinetics of the DOPO degradation effect of different reaction systems.

[0017] Figure 2 This is the pseudo-first-order kinetics of the degradation effect of DOPO using α-naphthoflavone at different pH under anaerobic conditions.

[0018] Figure 3 This is the pseudo-first-order kinetics of the degradation of DOPO by α-naphthoflavone and β-naphthoflavone under anaerobic conditions. DETAILED DESCRIPTION

[0019] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0020] Example:

[0021] The sunlight / α-naphthoflavone process was used to treat DOPO-containing wastewater under laboratory conditions, and the degradation efficiency of DOPO in the wastewater was analyzed by liquid chromatography.

[0022] The reaction equipment used includes a reactor, a xenon lamp light source, a circulating condensed water device, a magnetic stirrer, and a nitrogen flow device. The specific operation steps include the preparation of the α-naphthoflavone solution, system preparation, nitrogen flow treatment, light treatment, and sampling and testing:

[0023] 1) Preparation of α-naphthoflavone solution: Weigh 0.0272 g of α-naphthoflavone and dilute to 100 mL with ultrapure water to prepare a 1 mM α-naphthoflavone solution.

[0024] 2) System preparation: Take 1 mL of the prepared α-naphthoflavone solution into the reactor, and then add the wastewater containing the target pollutant into the reactor to make the total volume 100 mL.

[0025] 3) Nitrogen treatment: Open the valves at both ends of the reactor, connect the nitrogen flow device, flow nitrogen for 30 minutes to remove dissolved oxygen in the wastewater, then close the valves at both ends, turn on the magnetic stirrer, and connect the circulating water condensation device to keep the temperature of the reactor at 25°C.

[0026] 4) Light treatment: Turn on the xenon lamp light source to irradiate and react.

[0027] 5) Sampling test: Sampling is performed through the sampling port provided on the reactor. The volume of each sample is 1 mL (it is necessary to ensure that the total volume of the sample does not exceed 20% of the volume of the solution in the reactor). The sampling time is 0, 1, 3, 5, and 10 min. The samples are tested by high performance liquid chromatography to obtain the degradation rate and efficiency of the target pollutant by the sunlight / α-naphthoflavone process.

[0028] HPLC conditions were as follows: an Agilent 1260 HPLC system equipped with an Agilent Zorbax SB-C18 column (150 mm × 4.6 mm, 5 μm i.d.) was used, with a photodiode array detector (λ = 245 nm). The HPLC mobile phase consisted of methanol / ammonium acetate (30:70). The injection volume was 50 μL, the flow rate was 1.0 mL / min, and the column temperature was 40°C. The sodium acetate solution used was prepared by weighing 0.7865 g of ammonium acetate and diluting the volume to 500 mL.

[0029] Figure 1 The pseudo-first-order kinetics of DOPO degradation by different reaction systems are shown in the figure. The results show that under anaerobic conditions, α-naphthoflavone can generate more active species under the stimulation of sunlight to promote DOPO degradation, with the apparent degradation rate being 24.4 times that under single sunlight conditions.

[0030] Figure 2 The pseudo-first-order kinetics of DOPO degradation by α-naphthoflavone at different pH values ​​under anaerobic conditions show that α-naphthoflavone maintains a good degradation effect on DOPO under weakly acidic and neutral conditions.

[0031] Figure 3 The results in the figure show that under the same conditions, the degradation efficiency of DOPO by α-naphthoflavone and β-naphthoflavone (K obs =0.00244 s -1 ) is β-naphthoflavone (K obs =0.00057 s -1 ) is 4.28 times.

[0032] It should be understood that the embodiments and examples discussed herein are for illustrative purposes only. Those skilled in the art may readily modify or alter the embodiments, such as the photosensitizer dosage, reaction system temperature, pH conditions, and the like, and all such modifications and alterations are intended to fall within the scope of the appended claims. As long as these combinations of reaction conditions do not affect the pollutant degradation and disinfection byproduct removal performance of the process of the present invention, they are intended to be considered within the scope of this specification.

[0033] The above examples merely represent implementation methods suitable for the description of this patent. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that researchers or technicians in this field can, without departing from the concept of the present invention, make variations and optimizations based on the actual conditions and properties of the water and pollutants being treated, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the appended claims.

Claims

1. Application of α-naphthoflavone in photocatalytic degradation of DOPO and its derivatives, characterized in that: Under anaerobic conditions, sunlight is used to activate α-naphthoflavone, thereby efficiently degrading DOPO and its derivatives.

2. The use according to claim 1, characterized in that DOPO derivatives include DHP-DOPO, ODOPM, ODOPM-PN, ODOPM-MPN, and DOPO-DDP.

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