Preparation method and application of graphite phase carbon nitride loaded manganese phthalocyanine heterogeneous catalyst

Abstract

The invention discloses a preparation method and application of a graphite phase carbon nitride loaded manganese phthalocyanine heterogeneous catalyst, according to the method, manganese phthalocyanine is loaded on graphite phase carbon nitride by adopting a chemical deposition / loading method to obtain a MnPc / CN heterogeneous catalyst, under the room temperature condition, compared with unloaded manganese phthalocyanine, the catalytic activity of the catalyst is effectively improved, and the performance of the catalyst is improved. Finally, the catalyst which is efficient and has a very good application effect in an actual complex water environment is obtained. The graphite-phase carbon nitride loaded manganese phthalocyanine heterogeneous catalyst prepared by the invention can activate peroxymonosulfate to degrade levofloxacin in a water environment, can significantly improve the degradation rate of levofloxacin, and has good resistance to an actual complex water matrix.

Description

Technical Field

[0001] The invention belongs to the technical field of supported manganese phthalocyanine catalysts for degrading water environmental pollutants, and specifically relates to a preparation method and application of a graphite phase carbon nitride supported manganese phthalocyanine heterogeneous catalyst. Background Art

[0002] Antibiotics are widely used in the fields of human and animal disease prevention and control, aquaculture, agriculture and animal husbandry. They have complex structures, are difficult to biodegrade, and persist in the environment, posing a serious threat to human life and health and ecological and environmental safety. Persulfate-based advanced oxidation technology (AOPs) has received increasing attention. The AOPs system dominated by free radical oxidation is easily affected by inorganic anions and natural organic matter in the water matrix. How to selectively remove certain types of antibiotics in a complex water environment is a challenge. High-valent metal oxygen species have the characteristics of high spin state, high reduction potential, long life, and oxidation and degradation of organic pollutants in a wide pH range. Advanced oxidation technology based on the production of high-valent metal oxygen species is a very promising technology.

[0003] Manganese phthalocyanine (MnPc) is used as a catalytic material due to its low cost and chemical stability, but the strong association between each other causes MnPc molecules to tend to form dimers or polymers. Therefore, loading it on a suitable carrier material can effectively avoid the formation of dimers and polymers to improve its catalytic activity. It is a simple and efficient technical means and has good prospects in practical applications. The patent document with publication number CN105478169A discloses a preparation method of a sepiolite-supported metal phthalocyanine catalyst, taking pretreated sepiolite, metal phthalocyanine, water or DMF or chloroform or dichloromethane, mixing, stirring reaction, filtering, washing, and drying to obtain sepiolite-supported metal phthalocyanine; the metal phthalocyanine is selected from sulfonated iron phthalocyanine, sulfonated cobalt phthalocyanine, sulfonated manganese phthalocyanine, nitro phthalocyanine iron, nitro cobalt phthalocyanine, nitro manganese phthalocyanine, alkoxy-substituted iron phthalocyanine, alkoxy-substituted cobalt phthalocyanine or alkoxy-substituted manganese phthalocyanine. The sepiolite loaded metal phthalocyanine prepared by the method is used for catalytic oxidation of weathered coal to prepare humic acid, with a small amount of catalyst used, a short reaction time, and a high content of humic acid in the obtained product, which has great application value in industrial production. However, the carrier used in the patent technology is pretreated sepiolite, and the dispersion effect of the loaded metal phthalocyanine in water is still not ideal, with certain polymerization and agglomeration phenomena, and the patent document does not have any relevant records on the use of the loaded manganese phthalocyanine catalyst for activating peroxymonosulfate to degrade organic pollutants in the water environment.

[0004] Graphite phase carbon nitride is a two-dimensional layered structure material with advantages such as environmental friendliness, chemical stability and cost-effectiveness. Loading manganese phthalocyanine on graphite phase carbon nitride can improve dispersibility, avoid the formation of dimers, and thus improve catalytic activity. Based on the above analysis, the present invention adopts a chemical deposition / loading method to load manganese phthalocyanine on graphite phase carbon nitride to obtain MnPc / CN catalyst, which effectively improves its catalytic activity compared to unloaded manganese phthalocyanine at room temperature, and finally obtains a highly efficient catalyst with good applicability in actual complex water environments. There is currently no relevant report in this regard. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method for preparing a graphite phase carbon nitride-supported manganese phthalocyanine heterogeneous catalyst which is simple to operate, low in cost, high in efficiency and good in application effect. The graphite phase carbon nitride-supported manganese phthalocyanine heterogeneous catalyst can be used to activate peroxymonosulfate to degrade levofloxacin (LVF) pollutants and has a good degradation effect.

[0006] The present invention adopts the following technical scheme to solve the above technical problems. A method for preparing a graphite phase carbon nitride supported manganese phthalocyanine heterogeneous catalyst is characterized in that the specific steps are: placing urea in a ceramic crucible wrapped with aluminum foil and annealing at 500-700°C for 1-3h in an air atmosphere to obtain a light yellow powder sample, i.e., gC 3 N 4 Powder, take 1g of prepared gC 3 N 4 The powder is ultrasonically dispersed in 100 mL of anhydrous ethanol, and then continuously stirred and mixed at 60-70° C. to obtain a suspension; 25-100 mg of manganese phthalocyanine is ultrasonically dispersed in 200 mL of anhydrous ethanol and added to the suspension, and then continuously stirred and mixed at 60-70° C. to obtain a graphite-phase carbon nitride-supported manganese phthalocyanine heterogeneous catalyst after natural cooling. The carrier graphite-phase carbon nitride in the prepared graphite-phase carbon nitride-supported manganese phthalocyanine heterogeneous catalyst can improve the dispersibility of manganese phthalocyanine in aqueous solution, thereby improving its catalytic activity and generating more active sites. The graphite-phase carbon nitride-supported manganese phthalocyanine heterogeneous catalyst can be used to activate peroxymonosulfate to degrade levofloxacin pollutants.

[0007] The invention discloses an application of the graphite phase carbon nitride supported manganese phthalocyanine heterogeneous catalyst in activating peroxymonosulfate to degrade levofloxacin pollutants, characterized in that the specific process comprises: adding 50 mL of a 20 mg / L levofloxacin pollutant solution and the graphite phase carbon nitride supported manganese phthalocyanine heterogeneous catalyst into a reaction container, wherein the addition amount of the graphite phase carbon nitride supported manganese phthalocyanine heterogeneous catalyst is 1.0 g / L, controlling the pH of the reaction system to 8 with a phosphate buffer solution, and then adding peroxymonosulfate (PMS) to start the reaction, wherein the addition amount of the peroxymonosulfate is 1 mM, and the degradation rate of the levofloxacin pollutant reaches 99% within 5 minutes.

[0008] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention prepares graphite phase carbon nitride as a carrier, and loads manganese phthalocyanine on the surface of the carrier; 2. The graphite-phase carbon nitride-supported manganese phthalocyanine heterogeneous catalyst prepared by the present invention can activate peroxymonosulfate to degrade levofloxacin in water environment, can significantly increase the degradation rate of levofloxacin, and has good resistance to actual complex water matrix; 3. The MnPc / CN heterogeneous catalyst prepared by the present invention degrades levofloxacin mainly by generating high-valent metal oxygen species and singlet oxygen, and the high-valent metal oxygen species plays a leading role in the degradation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is the X-ray diffraction pattern of catalysts with different loading amounts of manganese phthalocyanine; Figure 2 This is a graph showing the degradation rate of LVF by catalysts with different manganese phthalocyanine loadings. DETAILED DESCRIPTION

[0010] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention. Example 1

[0011] (1) Preparation of graphite carbon nitride: Urea was placed in a ceramic crucible wrapped with aluminum foil and annealed at 600 °C for 2 h in air to obtain a light yellow powder sample, namely gC 3 N 4 powder; (2) Preparation of graphite carbon nitride supported manganese phthalocyanine catalyst: Take 1g of prepared gC 3 N 4The powder is ultrasonically dispersed in 100 mL of anhydrous ethanol, and then continuously stirred and mixed at 60° C. to obtain a suspension; 25 mg, 50 mg, 75 mg, and 100 mg of manganese phthalocyanine are ultrasonically dispersed in 200 mL of anhydrous ethanol and added to the suspension, and continuously stirred and mixed at 60° C. to obtain a graphite phase carbon nitride supported manganese phthalocyanine heterogeneous catalyst after natural cooling and repeated filtering and washing with deionized water and anhydrous ethanol, and then dried to obtain the surface morphology of the catalyst using a scanning electron microscope; (3) Add 50 mL of 20 mg / L levofloxacin pollutant solution and graphite carbon nitride-supported manganese phthalocyanine heterogeneous catalyst to a beaker, wherein the dosage of graphite carbon nitride-supported manganese phthalocyanine heterogeneous catalyst is 1.0 g / L, and use phosphate buffer solution to control the pH of the reaction system to 8. Then add PMS to start the reaction, wherein the dosage of PMS is 1 mM. Take a certain amount of solution at regular intervals, filter it through a 0.22 μm polyethersulfone membrane, and immediately mix 900 μL of the filtrate with 100 μL of Na 2 S 2 O 3 (0.1 M) was mixed to terminate the reaction, and the degradation rate of levofloxacin pollutant reached 99% within 5 min. Example 2

[0012] As described in Example 1, except that the quencher in step (3) is 100 mM methanol, steps (1) and (2) are the same as in Example 1, and the degradation rate of LVF is 99%.

[0013] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a graphite phase carbon nitride supported manganese phthalocyanine heterogeneous catalyst, characterized in that The specific steps are as follows: urea is placed in a ceramic crucible wrapped with aluminum foil and annealed at 500-700° C. for 1-3 hours in an air atmosphere to obtain a light yellow powder sample, namely g-C3N4 powder; 1 g of the prepared g-C3N4 powder is ultrasonically dispersed in 100 mL of anhydrous ethanol, and then continuously stirred and mixed at 60-70° C. to obtain a suspension; 25-100 mg of manganese phthalocyanine is ultrasonically dispersed in 200 mL of anhydrous ethanol and added to the suspension, and continuously stirred and mixed at 60-70° C. to obtain a suspension; after natural cooling, it is washed and filtered multiple times with deionized water and anhydrous ethanol, and then dried to obtain a graphite-phase carbon nitride-supported manganese phthalocyanine heterogeneous catalyst; the carrier graphite-phase carbon nitride in the prepared graphite-phase carbon nitride-supported manganese phthalocyanine heterogeneous catalyst can improve the dispersibility of manganese phthalocyanine in aqueous solution, thereby improving its catalytic activity and generating more active sites; the graphite-phase carbon nitride-supported manganese phthalocyanine heterogeneous catalyst can be used to activate peroxymonosulfate to degrade levofloxacin pollutants.

2. Use of the graphite phase carbon nitride supported manganese phthalocyanine heterogeneous catalyst prepared according to the method of claim 1 in activating peroxymonosulfate to degrade levofloxacin pollutants.

3. The use according to claim 2, characterized in that The specific process is: add 50mL of 20mg / L levofloxacin pollutant solution and graphite phase carbon nitride-loaded manganese phthalocyanine heterogeneous catalyst into the reaction container, wherein the addition amount of graphite phase carbon nitride-loaded manganese phthalocyanine heterogeneous catalyst is 1.0g / L, use phosphate buffer solution to control the pH of the reaction system to 8, then add permonosulfate to start the reaction, wherein the addition amount of permonosulfate is 1mM, and the degradation rate of levofloxacin pollutant reaches 99% within 5 minutes.

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