CN112340820A - Preparation and application of composite material for capacitive deionization technology electrode - Google Patents

Preparation and application of composite material for capacitive deionization technology electrode Download PDF

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Publication number
CN112340820A
CN112340820A CN202011269215.5A CN202011269215A CN112340820A CN 112340820 A CN112340820 A CN 112340820A CN 202011269215 A CN202011269215 A CN 202011269215A CN 112340820 A CN112340820 A CN 112340820A
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composite material
electrode
graphene oxide
preparation
capacitive deionization
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王黎
郑鹏坤
余杨
张嘉方
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Wuhan University of Science and Engineering WUSE
Wuhan University of Science and Technology WHUST
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Wuhan University of Science and Engineering WUSE
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4691—Capacitive deionisation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08—Seawater, e.g. for desalination

Abstract

The invention discloses an electrode composite material for capacitive deionization technology and application thereof, wherein the composite electrode material is prepared by preparing Graphene Oxide (GO) by adopting an improved Hummers method and modifying the graphene oxide (MnO) by using manganese dioxide2/GO) is used as a main adsorption material of the electrode composite material, and acetylene black is used as a conductive agent. And taking graphite paper as a collector, and taking polyvinylidene fluoride (PVDF) as a binder to obtain the manganese dioxide/graphene oxide composite electrode. The graphene oxide has a large specific surface area and more oxygen-containing functional groups, so that the hydrophilicity of the electrode material is increased. Introduction of MnO between graphene sheets2Form one-dimensional MnO2The nanowire effectively weakens the stacking effect of the lamella, improves the electrochemical performance of the composite material and increases the desalination amount. The method has the advantages of simple process, convenient operation, rich raw material resources, low production cost, good application prospect and good economic benefit.

Description

Preparation and application of composite material for capacitive deionization technology electrode
Technical Field
The invention relates to the field of material preparation, in particular to preparation and application of a composite material for a capacitive deionization technology electrode
Background
Water is the source of lifeWater is required for both growth and activity, and is said to be the most valuable resource for humans. However, with the development of modern industry and the acceleration of urbanization, water pollution is more and more serious, and fresh water resources which can be directly utilized are increasingly deficient. Fresh water is an indispensable precious resource for human life, so people look at the sea water desalination to solve the problem of continuously providing available fresh water[1～3]. As the fresh water resource is not closely related to the operation of human life, scientists are engaged in desalination and desalination of sea water and salt water.
The Capacitive Deionization (CDI) technology has the advantages of simple operation, high efficiency, low energy consumption, no secondary pollution, easy regeneration, low cost, etc., so the Capacitive Deionization technology is considered as one of the technologies with great development prospects. Carbon-based materials are generally the best choice for CDI electrode coating materials. The carbon material has good hydrophilicity and conductivity, can keep good chemical stability in strong brine under the electrified condition, has higher specific surface area and reasonable micro and mesoporous structures, and can ensure better adsorption and desorption performances. Therefore, in recent years, most of domestic and foreign research focuses on the aspects of selection and treatment of the capacitive deionization electrode material, process parameters in the operation process and the like. However, most of the electrode materials are used singly, but researches show that the electrode made of the composite material has better effect in the adsorption process of capacitive deionization. The selection of proper electrode materials and the adjustment of the most proper process parameters are important rings for improving the capacitive deionization adsorption efficiency.
The invention content is as follows:
the invention aims to enable the composite material to have the advantages of a plurality of single materials simultaneously by preparing the composite material on the basis of the existing carbon material. The manganese dioxide/graphene oxide composite material is prepared, the specific surface area of the material is improved, the pore size distribution is rich, the surface functional groups, the conductivity and the hydrophilicity are enhanced, the electrode is protected, and the like.
The inventionThe technical principle of (1): the graphene oxide is prepared by adopting an improved Hummers method, and after graphite is oxidized and stripped into few layers of graphene oxide, a large number of oxygen-containing functional groups are introduced into the structure, so that the internal atomic arrangement mode is changed. Introduction of MnO between graphene sheets2Form one-dimensional MnO2The nanowire effectively weakens the stacking effect of the lamella, improves the electrochemical performance of the composite material and increases the desalination amount. The manganese dioxide/graphene oxide composite material electrode is generated, and the one-dimensional MnO2 nano structure is introduced into the middle of the graphene sheet layer, so that the stacking effect between the graphene sheet layers is effectively weakened, the material capacitance is improved, the effective contact area of the material and ions in a solution is increased, and the desalting performance is improved.
The technical scheme of the invention is as follows: the method comprises the following steps of preparing graphene oxide by an improved Hummers method in three temperature stages of low temperature, medium temperature and high temperature, and mixing the graphene oxide and manganese dioxide to prepare a composite material:
adding graphite powder into concentrated sulfuric acid to perform first-stage low-temperature stirring;
the mass of graphite powder is 10g and concentrated sulfuric acid (230ml, 98%);
the system temperature of the first stage is 5 ℃, and the stirring time is 2.5 h;
step (2) adding KMnO4Slowly adding the mixture for multiple times to carry out medium-temperature stirring in the second stage;
KMnO4has a mass of 30 g;
the system temperature of the second stage is 20-35 ℃, and the stirring time is 2.5 h;
step (3) carrying out high-temperature stirring in the third stage, and continuing to oxidize the graphite powder;
the temperature of the system in the third stage is 98 ℃, the stirring time is 15-20 min, a large amount of deionized water is slowly added to terminate the reaction, and meanwhile, hydrogen peroxide (30% H) is added2O225ml) the solution changed from brown-black to bright yellow. Washing the product to neutrality by using dilute hydrochloric acid;
the volume ratio of the dilute hydrochloric acid is 1:5, 1L;
step (4) 1.133g of graphene oxide and 0.27g of MnCl2·4H2Adding O into 50mL of isopropanol, and dispersing by ultrasonic;
performing ultrasonic treatment for 0.5 h;
step (5) heating the dispersed mixed solution to 855 ℃ in water bath, condensing and refluxing the mixed solution, and adding KMnO4Dissolving into deionized water, adding into the mixed solution, and reacting for 0.5h to obtain a mixed solution;
0.15g KMnO45mL of deionized water;
and (6) filtering the mixed solution, and washing a filter cake obtained by filtering with deionized water for a plurality of times until the pH value of the filtrate is neutral. Vacuum drying to obtain black powder, and generating MnO with 15% of loading capacity2the/GO loading material and other loading amounts are adjusted by changing the addition amount of graphene;
vacuum drying at 50 deg.C for 12 hr;
mixing the carbon material, the acetylene black and the adhesive (PVDF) according to a mass ratio, adding a proper amount of NMP, grinding uniformly, preparing electrode material coating slurry, uniformly coating the electrode material coating slurry on graphite paper, drying the electrode material coating slurry in an oven, and drying the electrode material coating slurry in a vacuum drying oven in vacuum;
carbon material, acetylene black and a binder (PVDF) in a mass ratio of 8: 1: 1;
drying in an oven at 80 ℃ for 1h, and drying in a vacuum drying oven at 80 ℃ for 24 h.
The invention has the beneficial effects that: the inherent structure of graphite is changed, so that graphene oxide of a single atomic layer or few layers is stripped, and the specific surface area and adsorption sites of the material are increased. The surface of the graphene oxide contains oxygen-containing groups such as hydroxyl, carboxyl and the like, so that the graphene oxide has better hydrophilicity. The oxidized graphene has a large number of oxidized functional groups, occupies graphene pores, and reduces the available specific surface area of the graphene. And the graphene oxide is dispersed into the solution in the process of loading Mn02, and the stacked graphene sheets are re-dispersed; meanwhile, oxygen-containing functional groups on the surface of the graphene oxide are reduced, and the pore structure of the graphene is exposed again; in addition, MnO2Can open up the graphene lamellar spacing, and the processes all result in the specific surface area of the material along with MnO2Increases in load.
Drawings
Fig. 1 is an XRD pattern for preparing graphene oxide;
FIG. 2 is an XRD contrast diagram of graphene oxide and manganese dioxide/graphene oxide;
fig. 3 is an SEM image of graphene oxide (a) manganese dioxide/graphene oxide composite (B).
Detailed Description
Detailed description of the preferred embodimentsthe present invention will now be further analyzed in connection with the following examples
Preparing graphene oxide: in the experiment, an improved Hummers method is adopted to prepare Graphene Oxide (GO). The graphite powder was sieved with a 500-mesh sieve to obtain 10g of a graphite powder having a uniform particle size and a small particle size. Adding concentrated H into dried 2L beaker2SO4(230ml, 98%) and moderator NaNO3(5g) In that respect When the temperature of the system is lower than 10 ℃, adding the graphite into a beaker, and stirring for 2.5 h. KMnO is slowly added in multiple times4(30g) And controlling the temperature not to exceed 20 ℃. KMnO4Stirring for 90min after all the addition. The beaker is put in a constant temperature oil bath at about 35 ℃ and is evenly stirred. Adding deionized water (460ml) after the temperature of the mixed solution rises to 35 ℃ for reaction for 2H, controlling the reaction temperature to be about 98 ℃, continuously stirring for 15-20 min, slowly adding a large amount of deionized water to terminate the reaction, and simultaneously adding hydrogen peroxide (30% H)2O225ml) the solution changed from brown-black to bright yellow. Filtering while hot, washing the product with dilute hydrochloric acid (volume ratio of 1:5,1L) to near neutral, and washing with deionized water until no SO is in the filtrate4 2-Finally, the mixture is placed in a culture dish, dried in a vacuum drying oven to constant weight, and sealed and stored in a small beaker.
Preparing a manganese dioxide/graphene oxide composite material: 1.133g of graphene oxide and 0.27g of MnCl2·4H2Adding O into 50mL of isopropanol, and dispersing by ultrasonic treatment for 0.5 h; heating the dispersed mixture in water bath to 85 deg.C, condensing and refluxing, and adding 0.15g KMnO4Dissolving the mixed solution into 5mL of deionized water, adding the mixed solution, and reacting for 0.5h to obtain a mixed solution; filtering the mixed solution to obtainThe filter cake is washed for several times by deionized water until the pH value of the filtrate is neutral. Vacuum drying at 50 deg.C for 12h to obtain black powder, and generating 15% MnO2the/GO loading material and other loading amounts are adjusted by changing the addition amount of graphene. Carbon material, acetylene black and a binder (PVDF) in a mass ratio of 8: 1: 1, adding a proper amount of N-methyl pyrrolidone (NMP), grinding uniformly, preparing electrode material coating slurry, uniformly coating the electrode material coating slurry on graphite paper, wherein the electrode area is 4cm multiplied by 4cm, drying in an oven at 80 ℃ for 1h, and drying in a vacuum drying oven at 80 ℃ for 24 h.
FIG. 1 is an X-ray diffraction (XRD) pattern of graphite and Graphene Oxide (GO) prepared by a modified Hummers method. The peak position of the GO diffraction peak is 10.9 ° at 2 θ, and the interplanar spacing d is 0.811nm, and the analysis of the results shows that: this value is significantly greater than the conventional graphite interlayer spacing (0.34nm) due to the large number of oxidative functional groups inserted between the graphite platelets, enlarging the interlayer spacing. As can be seen in FIG. 2, MnO is compared to the XRD profile of graphene oxide2The crystal face of the XRD curve of/GO disappears, and the nano rod-shaped MnO on the surface of the graphene oxide is uniformly distributed2A molecule. The absorption peak in the curve at 2 θ ═ 10.9 ° is the crystal plane of the reduced graphene oxide sheet layer.
Fig. 3(a) shows that the graphene oxide has a gauze-like structure, which has an uneven surface and many folds and stacked parts, due to the effect of the oxidant on the graphite sheet during the strong oxidation of graphite. FIG. 3(B) shows MnO2SEM image of/GO shows that the fold structure of the graphene oxide surface is not obviously changed: MnO2The molecular shape is in a shape of a nanorod and is distributed on the surface of the graphene oxide nanosheet. Notably, MnO2The nanorods are generally distributed on the edge of the graphene oxide, because the graphene oxide edge contains a large amount of oxidation functional groups, which easily react with MnO2Combined, to MnO2The molecules are firmly bound to the surface.
TABLE 1 comparative area BET parameter for composite electrodes
Figure BDA0002777172260000041
Load MnO2In the process (2), graphene oxide is dispersed into the solution, and the stacked graphene sheets are re-dispersed; meanwhile, oxygen-containing functional groups on the surface of the graphene oxide are reduced, and the pore structure of the graphene is exposed again; in addition, MnO2Can open up the graphene lamellar spacing, and the processes all result in the specific surface area of the material along with MnO2Increases in load.

Claims (8)

1. The preparation method and the application of the composite material for the capacitive deionization technology electrode are characterized in that manganese dioxide/graphene oxide is used as an adsorption material, acetylene black is used as a conductive agent, and polyvinyl alcohol is used as a binder. Mixing to prepare the composite electrode material, and sequentially carrying out the following steps:
(1) adding graphite powder into concentrated sulfuric acid to perform first-stage low-temperature stirring;
(2) mixing KMnO4Slowly adding the mixture for multiple times to carry out medium-temperature stirring in the second stage;
(3) high-temperature stirring is carried out in the third stage, and the graphite powder is continuously oxidized;
(4) mixing graphene oxide and MnCl2·4H2Adding O into isopropanol, and dispersing by ultrasonic;
(5) heating the dispersed mixture in water bath, condensing and refluxing, and adding KMnO4Dissolving the mixture into deionized water, adding the deionized water into the mixed solution, and reacting to obtain a mixed solution;
(6) and filtering the mixed solution, and washing a filter cake obtained by filtering with deionized water for several times until the pH value of filtrate is neutral. Drying in vacuum to obtain black powder, and generating MnO with 15 percent of loading2the/GO loading material and other loading amounts are adjusted by changing the addition amount of graphene;
(7) mixing a carbon material, acetylene black and a binder (PVDF) according to a mass ratio, adding a proper amount of N-methyl pyrrolidone (NMP), uniformly grinding, preparing electrode material coating slurry, uniformly coating the electrode material coating slurry on graphite paper, drying the electrode material coating slurry in an oven, and then drying the electrode material coating slurry in vacuum.
2. The preparation of a composite material for electrodes in capacitive deionization technology and its use according to claim 1, wherein the mass of graphite powder is 10g, concentrated sulfuric acid (230ml, 98%).
3. The preparation and application of the composite material for the capacitive deionization technology electrode according to claim 1, wherein the system temperature in the first stage is 5 ℃, and the stirring time is 2.5 h; KMnO4The mass of (3) was 30 g.
4. The preparation method and the application of the composite material for the capacitive deionization technology electrode according to claim 1, wherein the system temperature in the second stage is 20-35 ℃, and the stirring time is 2.5 h.
5. The preparation method and the application of the composite material for the capacitive deionization technology electrode according to claim 1, wherein the temperature of the system in the third stage is 98 ℃, the stirring time is 15-20 min, a large amount of deionized water is slowly added to terminate the reaction, and meanwhile, hydrogen peroxide (30% H) is added2O225ml) the solution changed from brown-black to bright yellow. Washing the product to neutrality by using dilute hydrochloric acid; the volume ratio of the dilute hydrochloric acid is 1:5, 1L; the oven temperature was controlled at 80 ℃.
6. Preparation of a composite material for electrodes in capacitive deionization technology as claimed in claim 1 and its use, characterized in that the composite material is heated in a water bath to 85 ℃ and KMnO40.15g and 5mL of deionized water, and the reaction is carried out for 0.5 h.
7. Preparation of a composite material for electrodes in capacitive deionization technology as claimed in claim 1 and its use, characterized in that graphene oxide 1.133g, MnCl2·4H20.27g of O and 50mL of isopropanol, carrying out ultrasonic treatment for 0.5h, and drying in a vacuum drying oven at 50 ℃ for 12 h.
8. Preparation of a composite material for electrodes of capacitive deionization technology and its use according to claim 1, characterized in that the carbon material, acetylene black and binder (PVDF) are mixed in a mass ratio of 8: 1: 1. taking a proper amount of NMP; drying in an oven at 80 ℃ for 1h, and controlling the vacuum drying temperature to be 85 ℃; the drying time is 24 h.
CN202011269215.5A 2020-11-13 2020-11-13 Preparation and application of composite material for capacitive deionization technology electrode Pending CN112340820A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114380337A (en) * 2021-12-31 2022-04-22 山东利特纳米技术有限公司 Preparation of MnO from waste liquid of graphene oxide production2Method for producing/GO composite materials

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114380337A (en) * 2021-12-31 2022-04-22 山东利特纳米技术有限公司 Preparation of MnO from waste liquid of graphene oxide production2Method for producing/GO composite materials

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