Preparation method of phosphorus modified biochar / graphitic carbon nitride material

Abstract

The application discloses a preparation method of phosphorus modified biochar / graphitic carbon nitride material. First, a sugarcane bagasse biomass precursor is prepared by using a physical impregnation method, then a phosphorus modified biochar is prepared through pyrolysis, and then the phosphorus modified biochar is combined with graphitic carbon nitride through a mechanical chemical method to obtain the phosphorus modified biochar / graphitic carbon nitride material. The application utilizes a phosphoric acid activation method to make the sugarcane bagasse biochar form more active end faces and contain rich phosphorus oxygen functional groups; then the mechanical chemical method is used to combine the biochar with the graphitic carbon nitride to form a composite material containing active P-N bonds; and the prepared composite material has excellent degradation performance on indigo under ultraviolet visible light irradiation. The preparation method disclosed by the application is easy to control, raw materials are low in price, and is suitable for large-scale production, and has a good application prospect in the field of indigo organic pollution treatment.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photocatalytic materials, and particularly relates to a preparation method of phosphorus-modified biochar / graphitic carbon nitride material. BACKGROUND

[0002] In recent years, with the development of the textile industry, the problem of organic dye wastewater pollution is also becoming increasingly serious. Organic dye wastewater has attracted widespread attention due to its long-term threat to the ecological environment and human health. Compared with traditional adsorption methods, photodegradation is considered as a green and efficient method for degrading organic dyes in wastewater. So far, a large number of inorganic non-metallic materials have been proved to be used as photocatalysts for degrading pollutants. Among them, graphitic carbon nitride (g-C3N4) as a non-toxic, environmentally friendly inorganic non-metallic material, has become a promising material due to its excellent chemical stability and high visible light response, but g-C3N4 has problems such as fast recombination speed of photo-carriers and slow charge migration. Biochar as a new photocatalyst has attracted much attention due to its advantages such as rich oxygen-containing functional groups on the surface and strong ion exchange capacity, but the biochar formed by low-temperature pyrolysis is a dense block, which greatly limits its photocatalytic performance due to low specific surface area and few active sites. In order to solve these problems, physical and chemical modification and synthesis of composite materials are currently used to improve the catalytic activity.

[0003] Chinese patent "Cellulose biochar supported graphitic carbon nitride catalytic material and its preparation method and application" (authorized announcement number: CN117019196A) mixes cellulose with urea and pyrolyzes them in a muffle furnace at 500-600 ℃. In this method, biochar is used as a support material, and graphitic carbon nitride is loaded on it, thereby exposing more active sites. Chinese patent "Preparation method and application of biochar supported graphitic carbon nitride composite photocatalyst for degrading petroleum hydrocarbons" (authorized announcement number: CN109304203A) calcines soybean straw to form biochar, which is treated with 1 mol / L hydrochloric acid and then dried for standby; then the biochar is mixed with melamine and ground, and then high-temperature calcination is carried out, and after cooling to room temperature, the biochar supported graphitic carbon nitride material is obtained. In this method, the biochar is modified by hydrochloric acid, which is more conducive to the compounding of biochar and graphitic carbon nitride, and to some extent, the photocatalytic performance is improved. In the above-mentioned methods, high-temperature pyrolysis is used to successfully compound biochar and graphitic carbon nitride, but high-temperature pyrolysis increases the operation risk and energy consumption to some extent, and does not form a special structure between biochar and graphitic carbon nitride, so the photocatalytic performance is not ideal. Therefore, it is of great significance to prepare biochar at low temperature and compound it with graphitic carbon nitride, especially to form a special structure of photocatalytic material. SUMMARY

[0004] The present application aims to provide a preparation method of phosphorus modified biochar / graphitic carbon nitride material.

[0005] The specific steps are as follows:

[0006] (1) The bagasse powder is immersed in a 1 mol / L H3PO4 solution according to the mass ratio of bagasse powder to phosphoric acid of 1:3-8, and is left for 2 h to obtain a phosphoric acid bagasse biomass precursor.

[0007] (2) The bagasse biomass precursor obtained in step (1) is moved into a covered crucible, and is then placed in a muffle furnace for pyrolysis at 250-400 DEG C for 3-4 h, and is cooled to room temperature to obtain a phosphorus modified biochar.

[0008] (3) An appropriate amount of melamine is moved into a covered crucible, and is then placed in a muffle furnace for pyrolysis at 550 DEG C for 4 h, and is cooled to room temperature to obtain a graphitic carbon nitride.

[0009] (4) The phosphorus modified biochar and the graphitic carbon nitride obtained in steps (2) and (3) are respectively weighed according to the mass ratio of 1:2, and are then mixed and moved into a ball mill jar, and are ball milled at a rotation speed of 300 rpm for 4-6 h with the rotation direction changed every 0.5 h using a planetary ball mill. After the ball milling, the product is separated from the medium balls to obtain a phosphorus modified biochar / graphitic carbon nitride material.

[0010] The prepared phosphorus modified biochar / graphitic carbon nitride material contains active P-N chemical bonds, and has excellent light degradation ability for indigo organic pollutants under ultraviolet visible light irradiation. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 The figure is an ultraviolet absorption spectrum of the phosphorus modified biochar / graphitic carbon nitride material prepared in Example 1 for light degradation of indigo organic solution at different times.

[0012] Figure 2 The figure is a scanning electron micrograph of the phosphorus modified biochar / graphitic carbon nitride material prepared in Example 3. DETAILED DESCRIPTION

[0013] The following examples will further illustrate the present application but do not limit the present application.

[0014] Example 1:

[0015] (1) Bagasse powder was prepared by drying, crushing and sieving the bagasse through a 60-mesh sieve, and then 3 g of the bagasse powder was weighed and mixed with 15 g of 1 mol / L H3PO4 solution and left to stand for 2 h to obtain a bagasse biomass precursor of phosphoric acid.

[0016] (2) The bagasse biomass precursor obtained in step (1) was moved into a covered crucible, which was then placed in a muffle furnace for pyrolysis treatment at 300 °C for 3 h. After the reaction was completed, the product was cooled to room temperature to obtain a phosphorus-modified biochar.

[0017] (3) 5 g of melamine was weighed and moved into a covered crucible, which was then placed in a muffle furnace for pyrolysis treatment at 550 °C for 4 h. After the reaction was completed, the product was cooled to room temperature to obtain a graphite phase carbon nitride.

[0018] (4) 0.3 g of the phosphorus-modified biochar and 0.6 g of the graphite phase carbon nitride prepared in steps (2) and (3), respectively, were weighed and mixed, and then moved into a ball mill jar. A planetary ball mill was used for ball milling at a speed of 300 rpm, with the rotation direction changed every 0.5 h, for 6 h. After the ball milling was completed, the product was separated from the medium balls to obtain a phosphorus-modified biochar / graphite phase carbon nitride material.

[0019] 20 mg of the above phosphorus-modified biochar / graphite phase carbon nitride material was weighed and added to 100 mL of an indigo organic solution with a concentration of 50 mg / L. After magnetic stirring in the dark for 30 min to reach dynamic equilibrium, the solution was subjected to light irradiation under a 300 W xenon lamp for 4 h. The results showed that the removal rate of indigo reached 95%.

[0020] Example 2:

[0021] (1) Bagasse powder was prepared by drying, crushing and sieving the bagasse through a 60-mesh sieve, and then 3 g of the bagasse powder was weighed and mixed with 15 g of 1 mol / L H3PO4 solution and left to stand for 2 h to obtain a bagasse biomass precursor of phosphoric acid.

[0022] (2) The bagasse biomass precursor obtained in step (1) was moved into a covered crucible, which was then placed in a muffle furnace for pyrolysis treatment at 300 °C for 3 h. After the reaction was completed, the product was cooled to room temperature to obtain a phosphorus-modified biochar.

[0023] (3) 5 g of melamine was weighed and moved into a covered crucible, which was then placed in a muffle furnace for pyrolysis treatment at 550 °C for 4 h. After the reaction was completed, the product was cooled to room temperature to obtain a graphite phase carbon nitride.

[0024] (4) 0.3 g of the phosphorus-modified biochar prepared in step (2) and 0.6 g of the graphite-like carbon nitride prepared in step (3) were weighed out respectively and mixed, and then transferred into a ball mill jar. A planetary ball mill was used to mill the mixture at a rotation speed of 300 rpm for 4 h, with the rotation direction being changed every 0.5 h. After the ball milling was completed, the product was separated from the medium balls to obtain the phosphorus-modified biochar / graphite-like carbon nitride material.

[0025] 20 mg of the phosphorus-modified biochar / graphite-like carbon nitride material was weighed out, and the photodegradation of indigo blue experiment was performed according to Example 1. The results showed that the removal rate of indigo blue reached 92%.

[0026] Example 3:

[0027] (1) Bagasse was dried, crushed and sieved through a 60-mesh sieve to obtain bagasse powder. Then, 3 g of the bagasse powder was weighed out and mixed with 24 g of 1 mol / L H3PO4 solution and allowed to stand for 2 h to obtain a bagasse biomass precursor of phosphoric acid.

[0028] (2) The bagasse biomass precursor of phosphoric acid obtained in step (1) was transferred into a covered crucible, which was then placed in a muffle furnace for pyrolysis treatment at 400 °C for 4 h. After the reaction was completed, the product was cooled to room temperature to obtain the phosphorus-modified biochar.

[0029] (3) 5 g of melamine was weighed out and transferred into a covered crucible, which was then placed in a muffle furnace for pyrolysis treatment at 550 °C for 4 h. After the reaction was completed, the product was cooled to room temperature to obtain the graphite-like carbon nitride.

[0030] (4) 0.3 g of the phosphorus-modified biochar prepared in step (2) and 0.6 g of the graphite-like carbon nitride prepared in step (3) were weighed out respectively and mixed, and then transferred into a ball mill jar. A planetary ball mill was used to mill the mixture at a rotation speed of 300 rpm for 6 h, with the rotation direction being changed every 0.5 h. After the ball milling was completed, the product was separated from the medium balls to obtain the phosphorus-modified biochar / graphite-like carbon nitride material.

[0031] 20 mg of the phosphorus-modified biochar / graphite-like carbon nitride material was weighed out, and the photodegradation of indigo blue experiment was performed according to Example 1. The results showed that the removal rate of indigo blue reached 94%.

Claims

1. A method for preparing a phosphorus-modified biochar / graphitic carbon nitride material, characterized in that, The specific steps are as follows: (1) according to the mass ratio of bagasse powder to phosphoric acid solution 1:3~8, the bagasse powder is immersed in 1 mol / L H3PO4 solution, and is placed for 2 h to obtain a phosphoric acid bagasse biomass precursor; (2) the bagasse biomass precursor obtained in step (1) is moved into a covered crucible, and is placed in a muffle furnace for pyrolysis at 250~400 ℃ for 3~4 h, and is cooled to room temperature to obtain a phosphorus modified biochar; (3) an appropriate amount of melamine is taken and moved into a covered crucible, and is placed in a muffle furnace for pyrolysis at 550 ℃ for 4 h, and is cooled to room temperature to obtain graphite phase carbon nitride; (4) according to the mass ratio of 1:2, the phosphorus modified biochar and graphite phase carbon nitride prepared in steps (2) and (3) are respectively weighed, and are mixed and moved into a ball mill pot, and are ball milled using a planetary ball mill at a rotating speed of 300 rpm, and the rotating direction is changed every 0.5 h for 4~6 h; after ball milling, the product is separated from the medium balls to obtain a phosphorus modified biochar / graphite phase carbon nitride material.

2. The phosphorus-modified biochar / graphitic carbon nitride material prepared according to the method of claim 1, characterized in that: The material contains active P-N chemical bonds, and has a photo-degradation capacity for indigo organic pollutants under ultraviolet visible light irradiation.

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