阅读说明：本技术 一种机械力化学法制备硫化膨胀石墨的方法及应用 (Method for preparing vulcanized expanded graphite by mechanochemical method and application ) 是由 张凌燕 杨珞 邱杨率 王靖 张臻 张旭东 于 2020-04-28 设计创作，主要内容包括：本发明涉及新材料领域,具体涉及一种机械力化学法制备硫化膨胀石墨的方法及应用,方法包括如下步骤：A、将三氧化硫吡啶复合物加入二甲基甲酰胺溶剂中搅拌均匀得到第一混合体系；B、用化学氧化法制备膨胀石墨；C、将膨胀石墨分散在第一混合体系中得到第二混合体系；D、将第二混合体系球磨改性一定时间；E、将球磨后的产品过滤并洗涤,干燥即可得到硫化膨胀石墨。本发明的方法所制备的硫化膨胀石墨与具有大粒径厚片层膨胀石墨相比,经过添加SO<Sub>3</Sub>-P和DMF研磨改性的硫化膨胀石墨的微观表面多孔性表现出显著的增加,以及粒径明显的减小。(The invention relates to the field of new materials, in particular to a method for preparing vulcanized expanded graphite by a mechanochemical method and application thereof, wherein the method comprises the following steps: A. adding the sulfur trioxide pyridine compound into a dimethylformamide solvent, and uniformly stirring to obtain a first mixed system; B. preparing expanded graphite by a chemical oxidation method; C. dispersing expanded graphite in the first mixed system to obtain a second mixed system; D. ball-milling and modifying the second mixed system for a certain time; E. and filtering, washing and drying the ball-milled product to obtain the vulcanized expanded graphite. Compared with the expanded graphite with large particle size and thick sheet layer, the vulcanized expanded graphite prepared by the method of the invention is added with SO 3 Grinding of-P and DMFThe microscopic surface porosity of the modified vulcanized expanded graphite shows a significant increase, as well as a significant decrease in particle size.)

1. A method for preparing vulcanized expanded graphite by a mechanochemical method is characterized by comprising the following steps:

A. adding the sulfur trioxide pyridine compound into a dimethylformamide solvent, and uniformly stirring to obtain a first mixed system;

B. preparing expanded graphite by a chemical oxidation method;

C. dispersing expanded graphite in the first mixed system to obtain a second mixed system;

D. ball-milling and modifying the second mixed system for a certain time;

E. and filtering, washing and drying the ball-milled product to obtain the vulcanized expanded graphite.

2. The mechanochemical process for preparing vulcanized expanded graphite according to claim 1, wherein: in the step A, the amount of the sulfur trioxide pyridine compound is 0.5 mmol-1.5 mmol, and the volume of the dimethylformamide is 100-200 mL.

3. The mechanochemical process for preparing vulcanized expanded graphite according to claim 1, wherein: and in the step B, mixing nitric acid and acetic acid according to the volume ratio of (12-20) to (5-9) to obtain mixed acid, adding natural crystalline flake graphite into the mixed acid, carrying out acid leaching at the temperature of 50-60 ℃, carrying out oxidation intercalation reaction, washing the natural crystalline flake graphite to be neutral after the reaction is finished, drying, and heating at the temperature of 800-900 ℃ to obtain the expanded graphite.

4. The mechanochemical process for preparing vulcanized expanded graphite according to claim 3, wherein: the solid-liquid ratio of the natural crystalline flake graphite to the mixed acid is (1: 29) - (3: 17).

5. The mechanochemical process for preparing vulcanized expanded graphite according to claim 3, wherein: the drying condition is drying at 60-65 ℃.

6. The mechanochemical process for preparing vulcanized expanded graphite according to claim 1, wherein: in the step C, the solid-to-liquid ratio of the expanded graphite to the first mixed system is 1: (47-95).

7. The mechanochemical process for preparing vulcanized expanded graphite according to claim 1, wherein: and D, modifying by using a planetary mill with a steel ball as a medium, wherein the diameter of the steel ball is 20-25 mm, the rotating speed of the planetary mill is 300-350 rmp, and the modification time is 2.5-3 h.

8. The mechanochemical process for preparing vulcanized expanded graphite according to claim 1, wherein: and in the step E, washing the ball-milled product with absolute ethyl alcohol for 5-8 times, and drying in a vacuum drying oven at 60-65 ℃ for 4-5 hours to obtain the vulcanized expanded graphite.

9. Use of the expanded graphite sulphide obtained by the mechanochemical process for the preparation of expanded graphite sulphide according to any one of claims 1 to 8 in the field of adsorption of heavy metal ions.

Technical Field

The invention relates to the field of new materials, in particular to a method for preparing vulcanized expanded graphite by a mechanochemical method and application thereof.

Background

The Expanded Graphite (EG) does not destroy the hexagonal network structure of natural graphite, so the excellent physical and chemical properties of graphite are maintained, and the graphite intercalation compound shows new performance due to the insertion of other non-carbonaceous reactants. The expanded graphite not only has the characteristics of heat resistance, corrosion resistance, radiation resistance, electric conduction, self lubrication and the like, but also has the properties of light weight, softness, porosity, compressibility, resilience and the like. The expanded graphite has a large amount of reticular pore structures inside, so that the expanded graphite has a large specific surface area, high surface activity and strong adsorption performance.

Heavy metal lead has good chemical stability, is one of five toxins in heavy metals, especially Pb²⁺It is easy to be enriched in organism, and it can be absorbed by plant and enter human body along food chain, and can seriously damage the operation of normal tissue system in human body. It can not only inhibit enzymes by binding to-SH in enzymes or proteins, but also destroy the function of bone cells by changing the circulating level of hormones, thereby damaging the central nervous system. When lead is excessive, liver and kidney damage and cerebral reaction delay can be caused; the excessive lead in the pregnant woman can cause the congenital mental retardation of the infant. Thus, Pb in the wastewater is reduced²⁺The content is necessary to make the standard concentration of the sodium alginate to be 0.05-0.1 mg/L. At present, Pb in sewage is removed²⁺The commonly used treatment methods are: physical methods such as precipitation, flotation, filtration, etc.; the chemical methods include neutralization, oxidation-reduction, adsorption, and the like. The biological method is a method for removing heavy metal ions by utilizing the functions of enrichment, absorption, adsorption, flocculation and the like of plants and microorganisms, and comprises a plant restoration method, a biological flocculation method, a biological adsorption method, a genetic engineering technology and the like. Wherein, the adsorption method has low cost, high adsorption rate, good adsorption effect, no sludge generation and even regeneration of the adsorbentAnd (4) recycling. Although a large number of adsorbing materials for treating heavy metal wastewater are emerging at present, the preparation of an adsorbent with high adsorption efficiency, no secondary pollution and good recycling performance is still a challenge.

Disclosure of Invention

One of the purposes of the invention is to provide a method for preparing vulcanized expanded graphite by a mechanochemical method, which increases the specific surface area of the expanded graphite, reduces the granularity and improves the adsorption capacity of the expanded graphite.

The invention also aims to provide application of the vulcanized expanded graphite prepared by the method for preparing the vulcanized expanded graphite by the mechanochemical method.

The scheme adopted by the invention for realizing one of the purposes is as follows: a method for preparing vulcanized expanded graphite by a mechanochemical method comprises the following steps:

A. adding the sulfur trioxide pyridine compound into a dimethylformamide solvent, and uniformly stirring to obtain a first mixed system;

B. preparing expanded graphite by a chemical oxidation method;

C. dispersing expanded graphite in the first mixed system to obtain a second mixed system;

D. ball-milling and modifying the second mixed system for a certain time;

E. and filtering, washing and drying the ball-milled product to obtain the vulcanized expanded graphite.

The vulcanized expanded graphite (SEG) prepared by mechanochemical method is compared with Expanded Graphite (EG) with large particle size and thick lamella by adding SO₃The microscopic surface porosity of the P and DMF mill-modified vulcanized expanded graphite showed a significant increase, as well as a significant decrease in particle size. The surface of the vulcanized expanded graphite modified by the vulcanized functional group has a porous structure, so that the diffusion speed of heavy metal ions in the SEG is accelerated, and the adsorption capacity of the expanded graphite is improved. The ball milling is adopted to modify the expanded graphite, more fresh surfaces of the expanded graphite are exposed in the ball milling process, more channels are formed inside the expanded graphite, the granularity of the modified vulcanized expanded graphite is obviously reduced, so that the comparative area of the vulcanized expanded graphite is much larger,the preparation of the vulcanized expanded graphite by a mechanochemical method has important significance for improving the comparative area and the adsorption performance of the expanded graphite.

In the analysis of the surface element composition of the expanded graphite and the vulcanized expanded graphite, after the expanded graphite is subjected to mechanochemical modification, the surface sulfur element content is obviously increased, and the carbon element content is obviously reduced, which indicates that the vulcanization functional group is effectively introduced into the vulcanization modification of the expanded graphite. XPS hologra scanning and C1s peak-splitting narrow spectrum of vulcanized expanded graphite can prove SO₃The combination of-Py and expanded graphite is SO₃The sulfur element in the Py and the C element on the surface of the expanded graphite are bonded through oxygen atoms, and the oxygen atoms are introduced in the mechanical mechanochemical modification process. The prepared vulcanized expanded graphite is D₂₅＝19.70，D₅₀＝25.64，D₇₅38.44, i.e. 25% of the particles have a size of less than 19.70 μm, 50% of the particles have a size of less than 25.64 μm and 75% of the particles have a size of less than 38.44 μm.

Preferably, in the step A, the amount of the sulfur trioxide pyridine complex is 0.5 mmol-1.5 mmol, and the volume of the dimethylformamide is 100-200 mL.

Preferably, in the step B, nitric acid and acetic acid are mixed into mixed acid according to the volume ratio of (12-20): (5-9), natural crystalline flake graphite is added into the mixed acid, acid leaching is carried out at the temperature of 50-60 ℃, oxidation intercalation reaction is carried out, the natural crystalline flake graphite is washed to be neutral after the reaction is finished, and the expanded graphite is obtained by heating at the temperature of 800-900 ℃ after drying.

Preferably, the solid-liquid ratio of the natural crystalline flake graphite to the mixed acid is (1: 29) - (3: 17).

Preferably, the drying condition is drying at 60-65 ℃.

Preferably, in the step C, the solid-to-liquid ratio of the expanded graphite to the first mixed system is 1: (47-95).

Preferably, in the step D, a planetary mill with a steel ball as a medium is used for modification, the diameter of the steel ball is 20-25 mm, the rotating speed of the planetary mill is 300-350 rmp, and the modification time is 2.5-3 h.

When the reaction time is controlled in a proper range, the flocculation of the sample can be effectively reduced, so that the modification process is smoothly carried out. The expanded graphite is modified by adopting the planetary ball mill, more fresh surfaces of the expanded graphite are exposed in the ball milling process, more channels are formed inside the expanded graphite, and the granularity of the modified vulcanized expanded graphite is obviously reduced, so that the comparative area of the vulcanized expanded graphite is much larger. The preparation of the vulcanized expanded graphite by a mechanochemical method has important significance for improving the comparative area and the adsorption performance of the expanded graphite.

Preferably, in the step E, the product after ball milling is washed with absolute ethyl alcohol for 5-8 times, and dried in a vacuum drying oven at 60-65 ℃ for 4-5 hours, so as to obtain the vulcanized expanded graphite.

The second scheme adopted by the invention for achieving the purpose is as follows: the vulcanized expanded graphite prepared by the method for preparing the vulcanized expanded graphite by the mechanochemical method is applied to the field of heavy metal ion adsorption.

The invention has the following advantages and beneficial effects: compared with the expanded graphite with large particle size and thick sheet layer, the vulcanized expanded graphite prepared by the method of the invention is added with SO₃The microscopic surface porosity of the P and DMF mill-modified vulcanized expanded graphite showed a significant increase, as well as a significant decrease in particle size. The surface of the vulcanized expanded graphite modified by the vulcanized functional group has a porous structure, so that the diffusion speed of heavy metal ions in the SEG is accelerated, and the adsorption capacity of the expanded graphite is improved. The microcosmic surface porosity of the vulcanized expanded graphite after grinding modification is obviously increased compared with that of the common expanded graphite, and the particle size is also obviously reduced. More fresh surfaces of the modified expanded graphite subjected to ball milling are exposed, more channels are formed in the expanded graphite, and the particle size of the modified vulcanized expanded graphite is obviously reduced. The specific surface area, the average pore diameter and the average pore volume of the modified vulcanized expanded graphite are obviously improved.

The application of the invention shows that the diffusion speed of heavy metal ions on the surface of the vulcanized expanded graphite modified by the vulcanized functional groups is accelerated, and the vulcanized expanded graphite prepared by the method has better adsorption effect on the heavy metal ions than the common expanded graphite.

Drawings

FIG. 1 is an SEM photograph (a) of a vulcanized expanded graphite of example 1 of the present invention and a view showing a distribution (b) of elemental sulfur on the surface thereof;

FIG. 2 is an XPS survey of an expanded vulcanized graphite according to example 1 of the present invention;

FIG. 3 is a narrow spectrum of the C1s peak fraction of the vulcanized expanded graphite of example 1 of the present invention;

FIG. 4 is a particle size distribution curve of the vulcanized expanded graphite of example 1 of the present invention;

FIG. 5 is an infrared spectrum of EG, SEG, Pb (II) -adsorbed sulfurized expanded graphite of example 1 of the present invention;

FIG. 6 is a graph showing the results of a quantity test of vulcanized expanded graphite according to example 4 of the present invention;

FIG. 7 is a graph of initial concentration versus adsorption data for different Pb (II) for the sulfurized expanded graphite of example 5 of the present invention.

Detailed Description

The following examples are provided to further illustrate the present invention for better understanding, but the present invention is not limited to the following examples.