阅读说明：本技术 一种新型g-C3N4衍生碳质吸附剂和光催化材料的制备方法 (Novel g-C3N4Method for preparing derived carbonaceous adsorbent and photocatalytic material ) 是由 王辉 王洋 王怀悦 王博 丁克强 于 2021-09-18 设计创作，主要内容包括：本发明涉及一种新型g-C3N4衍生碳质吸附剂和光催化材料的制备方法。具体而言,本发明首先采用热诱导前驱体发生一系列缩聚反应得到石墨相氮化碳g-C3N4,随后采用催化剂(高铁酸钾)一步法实现g-C3N4同步碳化和石墨化,将经高铁酸钾(K2FeO4)溶液完全浸渍后的g-C3N4置于管式炉中进行煅烧,通过调节催化剂的用量及碳化温度控制其微/介孔结构和石墨化程度。最终制得光催化剂材料的一种新型多孔g-C3N4衍生碳质材料。本发明的光催化剂材料吸附能力强,可快速吸附水中污染物,在光照条件下光催化剂可对污染物进行高速降解,表明它们的高活性、低成本双功能。(The invention relates to a preparation method of a novel g-C3N4 derived carbonaceous adsorbent and a photocatalytic material. Specifically, the method comprises the steps of firstly adopting a thermal induction precursor to carry out a series of polycondensation reactions to obtain graphite-phase carbon nitride g-C3N4, then adopting a catalyst (potassium ferrate) to realize synchronous carbonization and graphitization of g-C3N4 by a one-step method, placing g-C3N4 which is completely impregnated by a potassium ferrate (K2FeO4) solution in a tubular furnace to calcine, and controlling the micro/mesoporous structure and graphitization degree by adjusting the dosage of the catalyst and the carbonization temperature. Finally, a novel porous g-C3N4 derived carbonaceous material of the photocatalyst material is prepared. The photocatalyst material has strong adsorption capacity, can quickly adsorb pollutants in water, and can degrade the pollutants at high speed under the illumination condition, thereby showing the dual functions of high activity and low cost.)

1. A preparation method of a novel g-C3N4 derived carbonaceous adsorbent and a photocatalytic material is characterized by comprising the following steps: the preparation method of the g-C3N4 carbonized graphitized photocatalyst material comprises the following steps:

(1) and (3) carrying out thermal polymerization reaction on the precursor at normal pressure and high temperature by using a thermal polymerization method to generate g-C3N 4:

and (3) hermetically calcining the precursor in a muffle furnace, raising the temperature to a certain temperature at a certain speed, preserving the temperature for a certain time, and naturally cooling to room temperature. Grinding the obtained sample in an agate mortar to obtain powder A; dissolving the powder A in deionized water, carrying out ultrasonic treatment, and centrifuging to obtain a clear liquid B; the clear solution B was filtered with suction to obtain pure graphite-phase carbon nitride (g-C3N 4).

(2) Impregnation of catalyst solutions of different concentrations, and preparation of g-C3N 4-derived carbonaceous materials at different carbonization and graphitization temperatures:

soaking the pure graphite-phase carbon nitride (g-C3N4) obtained in the step 1) in catalyst solutions C with different concentrations, performing ultrasonic treatment and suction filtration, drying the sample, placing the sample in a tubular furnace, raising the temperature to a certain temperature in a gas atmosphere, preserving the temperature for a certain time, and naturally cooling to room temperature. And dissolving the sample in the solution D, stirring, performing ultrasonic treatment, performing suction filtration, and drying to obtain a g-C3N4 derived carbonaceous material sample.

2. The method for preparing the novel g-C3N4 derived carbonaceous adsorbent and photocatalytic material according to claim 1, wherein the method comprises the following steps: the precursor in the step 1) is one of urea, thiourea, melamine, dicyandiamide and cyanamide.

3. The method for preparing the novel g-C3N4 derived carbonaceous adsorbent and photocatalytic material according to claim 1, wherein the method comprises the following steps: in the step 1), the heating rate is 1-10 ℃/min, the heating temperature is 450 ℃ and 650 ℃, and the heat preservation time is 1-6 h.

4. The method for preparing the novel g-C3N4 derived carbonaceous adsorbent and photocatalytic material according to claim 1, wherein the method comprises the following steps: the solution C in the step 2) is potassium ferrate (K2FeO4) with the concentration of 0.0002-0.2 mol/L.

5. The method for preparing the novel g-C3N4 derived carbonaceous adsorbent and photocatalytic material according to claim 1, wherein the method comprises the following steps: in the step 2), the gas atmosphere is one of argon and nitrogen or a mixed gas.

6. The method for preparing the novel g-C3N4 derived carbonaceous adsorbent and photocatalytic material according to claim 1, wherein the method comprises the following steps: the certain temperature in the step 2) is 600-900 ℃.

7. The method for preparing the novel g-C3N4 derived carbonaceous adsorbent and photocatalytic material according to claim 1, wherein the method comprises the following steps: the solution D in the step 2) is dilute hydrochloric acid or dilute nitric acid, and the concentration of the solution D is 0.5-3 mol/L.

8. Use of the g-C3N4 carbonized graphitized photocatalyst material of claim 1 in adsorbing and degrading contaminants in a liquid phase.

9. Use according to claim 6, characterized in that: the contaminant is a metal ion or an organic substance.

Technical Field

The invention relates to a catalyst, in particular to a novel g-C3N4 derived carbonaceous adsorbent and a photocatalytic material.

Background

With the development of modern industry, the ecological environment is continuously deteriorated. Most of water bodies in China are polluted to different degrees, however, the traditional sewage treatment technology has the defects of low treatment efficiency, high cost, narrow application range and the like, and a plurality of scientific researchers are dedicated to researching high-stability, high-activity, environment-friendly and economic semiconductor photocatalysts to treat environmental pollution. The g-C3N4 material is considered as a potential material for replacing Pt, reducing cost and improving the performance of the photocatalyst. The carbon combined material of the N element endows the carbon combined material with unique electronic structure irregular hexagonal carbon ring property, and nitrogen is doped with crystal lattices between carbon atoms and a pi system, so that active sites are increased, and the photocatalytic activity is obviously improved. In recent years, g-C3N4 and derivative materials are also widely used as potential transition metal catalysts to replace noble metals, further indicating their potential as high-activity, low-cost bifunctional catalysts.

The photoelectrocatalysis system relates to various interactions among light, a catalyst and a substrate, and is a relatively complex chemical reaction system, and the photoelectrocatalysis reaction principle mainly refers to the catalytic reaction principle of the catalyst and the action of each main step and the like.

The synchronous carbonization-graphitization of the g-C3N4 is realized by adopting a catalyst one-step method, the reaction active sites are effectively increased by high specific surface area and porosity, and the conductivity is improved by high graphitization degree. The novel one-step catalytic-graphitization process effectively realizes the synchronous graphitization and carbonization treatment of g-C3N4 at a lower temperature (900 ℃). The high-temperature treatment (2500 ℃) or stress graphitization process of the carbon-rich precursor for realizing the high graphitization degree of the nano porous carbon material in the traditional process is avoided. The potassium ferrate catalyst is used to effectively reduce energy consumption, and a two-step preparation strategy that hydroxide or ZnCl2 is used as a pore-forming agent and transition metal nitrate or chloride is used as a graphitization catalyst in the traditional graphitization process is avoided. Compared with the traditional graphitization process, the process is simple, safe and pollution-free, and meets the requirements of green chemistry principle.

The interconnected porous network formed by catalytic graphitization is favorable for promoting separation of photo-generated electrons from holes, reducing the transmission distance of carriers, promoting the photo-generated electrons to be rapidly transferred to the surface for chemical reaction, and enhancing the photocatalytic performance of the photo-generated electrons.

Disclosure of Invention

In view of the above circumstances, an object of the present invention is to provide a novel g-C3N 4-derived carbonaceous adsorbent and a photocatalytic material, and use of the photocatalytic material for removing organic contaminants in water.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a novel g-C3N4 derived carbonaceous adsorbent and a photocatalytic material comprises the following steps:

(1) and (3) carrying out thermal polymerization reaction on the precursor at normal pressure and high temperature by using a thermal polymerization method to generate g-C3N 4:

and placing the precursor into a round aluminum box, calcining the precursor in a muffle furnace at a certain heating rate to a certain temperature, preserving heat for a certain time, and naturally cooling to room temperature. Grinding the obtained sample in an agate mortar to obtain powder A; dissolving the powder A in deionized water, carrying out ultrasonic treatment, and centrifuging to obtain a clear liquid B; the clear solution B was filtered with suction to obtain pure graphite-phase carbon nitride (g-C3N 4).

(2) Impregnation of catalyst solutions of different concentrations, and preparation of g-C3N 4-derived carbonaceous materials at different carbonization and graphitization temperatures:

soaking the pure graphite-phase carbon nitride (g-C3N4) obtained in the step 1) in catalyst solutions C with different concentrations, performing ultrasonic treatment and suction filtration, drying the sample, placing the sample in a tubular furnace, raising the temperature to a certain temperature in a gas atmosphere, preserving the temperature for a certain time, and naturally cooling to room temperature. And dissolving the sample in the solution D, stirring, performing ultrasonic treatment, performing suction filtration, and drying to obtain a g-C3N4 derived carbonaceous material sample.

Preferably, in the above preparation method, the solution A in the step 2) is potassium ferrate (K2FeO4) with a concentration of 0.001 mol/L.

Preferably, in the above production method, the gas atmosphere in step 2) is nitrogen.

Preferably, in the above production method, the temperature in step 2) is 700 ℃.

Preferably, in the above preparation method, the solution B in the step 2) is diluted hydrochloric acid, and the concentration thereof is 1 mol/L.

g-C3N 4-derived carbonaceous material obtained by the above preparation method.

The g-C3N4 derivative carbonaceous adsorbent and the application of the photocatalytic material in adsorbing and degrading organic pollutants in water.

Compared with the prior art, the invention adopting the technical scheme has the following advantages:

(1) the g-C3N4 is used as the only steady-state structural unit in five crystal phases of C3N4 and extends infinitely from triazine rings to form a network structure. Because the cost is low, the environment is protected, no pollution is caused, the stability is good, and the product is a non-metal element;

(2) the graphite-phase carbon nitride (g-C3N4) is a promising high-activity photocatalyst with high nitrogen content, a unique electronic structure similar to a graphene sp2 bonding structure, abundant lamellar planes and defects, low cost, environmental protection, high thermochemical stability and the like, and has the advantages of simplicity and large-scale preparation. Therefore, the method can effectively improve the specific surface area and porosity of the material by etching the g-C3N4 with the potassium ferrate and carrying out high-temperature catalytic graphitization, thereby increasing the active sites to improve the catalytic performance.

(3) The novel catalytic graphitization process effectively realizes the synchronous graphitization and carbonization treatment of the biomass at lower temperature (800 ℃). The high-temperature treatment (2500 ℃) or stress graphitization process of the carbon-rich precursor for realizing the high graphitization degree of the nano porous carbon material in the traditional process is avoided. The interconnected porous network not only reduces the transport and diffusion resistance of ions, but also provides a larger accessible surface area. The graphitized carbon has good conductivity, and g-C3N4 derived carbonaceous materials with multi-channel and porous structures can promote ion transportation and electrolyte diffusion and transmission, and improve the reaction kinetic rate. The graphitization temperature is greatly reduced (lower than 800 ℃), and the energy consumption is effectively reduced. Compared with the two-step strategy of most porous graphite biomass carbon preparation methods, the method has the advantages of simple process and low experimental condition requirement, so the method has the advantage of low cost.

Drawings

FIG. 1 is an SEM image of g-C3N 4.

Figure 2 is an XRD pattern of g-C3N4 and its catalytically graphitized derivatized carbonaceous material.

FIG. 3 is an SEM image of g-C3N4 derivatized carbonaceous material.

FIG. 4 is a graph of N2 adsorption and desorption curves and a pore size distribution plot for g-C3N4 derivatized carbonaceous materials.

FIG. 5 is a graph of adsorption and photocatalytic degradation of methyl orange for g-C3N4 derivatized carbonaceous material (dark adsorption for the first 45 min).

Detailed Description

The technical solutions of the present invention will be further described with reference to the accompanying drawings and specific embodiments. Unless otherwise specifically stated, reagents, materials, instruments and the like used in the following examples are commercially available.

Example 1: the precursor is thermally polymerized at normal pressure and high temperature by a thermal polymerization method to generate g-C3N 4.

At room temperature, 0.3g of dicyandiamide is placed in a round aluminum box, the temperature is raised to 550 ℃ in a muffle furnace at the speed of 2.3 ℃/min for calcination, and after 2 hours of heat preservation, the round aluminum box is naturally cooled to the room temperature. And (3) putting the obtained sample into an agate mortar, grinding the sample into powder, dissolving the powder in deionized water, carrying out ultrasonic treatment, and centrifuging for multiple times to obtain clear liquid.

From this, it can be seen that g-C3N4 is composed of a large number of three-dimensional ultrathin mesoporous nano-sheets connected with each other. The continuously interconnected network structure may provide a large number of holes and potential active sites.

Example 2: the porous g-C3N4 derived carbonaceous material prepared by catalytic graphitization at 620 ℃.

Adding potassium ferrate into the clear liquid to make the concentration be 0.0002mol/L, carrying out ultrasonic treatment for 2h, carrying out suction filtration, and then freezing and drying the sample. And putting the freeze-dried powdery sample into a tube furnace, heating to 620 ℃ at a speed of 3 ℃/min in an argon atmosphere, preserving the temperature for 2h, and naturally cooling to room temperature. Dissolving the sample in 1 mol. L-1 dilute hydrochloric acid, stirring for 2h, performing ultrasonic treatment for 2h, performing suction filtration, and freeze-drying to obtain the sample of 620-p-g-C3N 4.

Example 3: a porous g-C3N4 derived carbonaceous material prepared by catalytic graphitization at 700 ℃.

Adding potassium ferrate into the clear liquid to make the concentration be 0.0002mol/L, carrying out ultrasonic treatment for 2h, carrying out suction filtration, and then freezing and drying the sample. And putting the freeze-dried powdery sample into a tube furnace, heating to 700 ℃ at a speed of 3 ℃/min in an argon atmosphere, preserving the temperature for 2h, and naturally cooling to room temperature. Dissolving the sample in 1 mol. L-1 dilute hydrochloric acid, stirring for 2h, performing ultrasonic treatment for 2h, performing suction filtration, and freeze-drying to obtain the sample of 700 ℃ -p-g-C3N 4.

Example 4: porous g-C3N4 derived carbonaceous materials prepared by catalytic graphitization at 800 ℃.

Adding potassium ferrate into the clear liquid to make the concentration be 0.0002mol/L, carrying out ultrasonic treatment for 2h, carrying out suction filtration, and then freezing and drying the sample. And putting the freeze-dried powdery sample into a tube furnace, heating to 800 ℃ at a speed of 3 ℃/min in an argon atmosphere, preserving the temperature for 2h, and naturally cooling to room temperature. Dissolving the sample in 1 mol. L-1 dilute hydrochloric acid, stirring for 2h, performing ultrasonic treatment for 2h, performing suction filtration, and freeze-drying to obtain a sample of 800-p-g-C3N 4.

As can be seen from the X-ray diffraction (XRD) analysis pattern of the final product, the powder XRD pattern of g-C3N4 shows two diffraction peaks at positions 2 θ ═ 13.30 ° and 27.43 °, respectively, which correspond to the (100) and (002) crystal planes of g-C3N4, respectively. A3-s-triazine ring structure exists in g-C3N4, wherein the (100) crystal face of g-C3N4 is formed by regularly distributing and arranging basic unit triazine rings in the plane, the strong diffraction peak corresponding to the (002) crystal face is caused by the stacking reflection of the laminated material, the p-g-C3N4 diffraction peak position after high-temperature carbonization-graphitization obviously shifts to a high-angle region, the interlayer spacing is increased, and the graphitization degree is enhanced. In conclusion, the distance between the layers of the g-C3N4 structure after high-temperature carbonization-graphitization is increased, and the specific surface area is increased.

Example 5: and (3) testing the adsorption of the g-C3N4 carbonized graphitized photocatalyst material on methyl orange.

0.02g of the sample was dispersed in 50ml of deionized water and sonicated for 30min, then 50ml of 20mg L-1 methyl orange aqueous solution was added. And (3) placing the mixed solution in the dark, continuously stirring, extracting 5ml of supernate by using a filter at 0min, 15 min, 30min and 45min respectively, and measuring the absorbance at the maximum absorption wavelength by using an ultraviolet spectrophotometer to obtain the concentration of the residual impurities.

Example 6: and g-C3N4 carbonized graphitized photocatalyst material is used for carrying out photocatalytic degradation experiments on methyl orange.

The intensity of the incident light was adjusted to 1 solar light intensity using a 300W xenon lamp as a light source. Dispersing 0.02g of a photocatalytic sample in 50ml of deionized water, carrying out ultrasonic treatment for 1h, and then adding 50ml of 20mg of L-1 methyl orange aqueous solution; stirring the mixed solution in the dark for 45min, and then extracting 5ml of supernatant liquid by using a filter, and marking the supernatant liquid as 0; irradiating the suspension with visible light while stirring, and extracting 5ml of supernatant with a filter every 5min, wherein the supernatant is marked with 1, 2, 3, 4 and 5; and testing the absorbance of the ultraviolet-visible spectrophotometer, and processing the collected data.

It can be seen that Methyl Orange (MO) is used as a standard model pollutant under the irradiation of simulated sunlight, and the adsorption/desorption balance is achieved after stirring for 45min, so that the adsorption performance is greatly increased, which indicates that the porosity is increased and the specific surface area is increased.