WO2013053250A1

WO2013053250A1 - Method for using graphene sponge

Info

Publication number: WO2013053250A1
Application number: PCT/CN2012/078045
Authority: WO
Inventors: 孙立涛; 毕恒昌; 谢骁; 尹奎波; 周奕龙; 万树; 贺龙兵; 徐峰
Original assignee: 东南大学
Priority date: 2011-10-15
Filing date: 2012-07-02
Publication date: 2013-04-18
Also published as: CN102500133A

Abstract

Disclosed is a method for using a graphene sponge to absorb organic solvents or oils. The method for use is suitable for the fields of sewage treatment or liquid-liquid separation. After the graphene sponge has absorbed organic solvents or oils, a depollution treatment is carried out. The depollution treatment removes or recycles the organic solvents or oils from the graphene sponge, using methods such as distillation at a low pressure, extraction or distillation at a high temperature.

Description

Application method of graphene sponge

The invention relates to a method for applying a graphene sponge.

Background technique

Due to the leakage of crude oil and the pollution of industrial organic solvents, global water pollution problems are becoming more and more serious. In order to overcome environmental problems, it is extremely important to find an adsorbent that can effectively adsorb oils and organic pollutants and finally achieve separation from water (J. Yuan, X. Liu, 0. Akbulut, J. Hu, SL Suib, J. Kong and F. Stel lacci, Nat. Nanotechnol., 2008, 3, 332.; MA Shannon, PW Bohn, M. El imelech, JG Georgiadis, BJ Marinas and AM Mayes, Nature, 2008, 452, 301.). Conventional adsorbents such as activated carbon have a number of disadvantages, including long adsorption times, poor selectivity, and limited adsorption capacity (D. Cl ifford, S. Subranmonian and TJ Sorg, Environ. Sci. Technol., 1986, 20, 1072.; AB Fuertes, G. Marban and DM Nevskaia, Carbon, 2003, 41, 87.). Although expanded graphite has a strong adsorption capacity for oil, it does not work for toxic organic solvents. The recovery of expanded graphite is also very difficult. As for the polymer, although the range of adsorption has been greatly increased, on the one hand, its adsorption capacity is insufficient, on the other hand, high temperature is easily decomposed, and even secondary pollution is formed. Based on these shortcomings, porous materials with pore sizes of nanometers or micrometers (L. Feng, Z. Zhong, Z. Mai, B. Liu, L. Jiang and D. Zhu, Angew. Chem., Int. Ed., 2003, 42, 800.; Y. Zhang, S. Wei, F. Liu, Y. Du, S. Liu, Y. Ji, T. Ji, T. Yokoib, T. Tatsumib and FS Xiao, Nano Today, 2009 , 4, 135. ) or nanowire film (Α· Sayari, S. Hamoudi and Y. Yang, Chem. Mater., 2005, 17, 212.) has attracted people's attention. Because nano- and micro-scale porous materials and nanowire films have strong hydrophobic ability and superior lipophilic ability, the separation of organic pollutants and water, grease and water can be achieved well. At the same time, these materials have the characteristics of short adsorption time, high selectivity and high adsorption capacity. However, nano- and micro-scale porous materials and nanowire films have the disadvantages that the adsorption capacity is not strong enough, the cost is high, and it is not easy to mass-produce.

Summary of the invention

Technical Problem: The technical problem to be solved by the present invention is to provide a method for applying a graphene sponge which is used for absorbing organic solvents or fats and has the characteristics of strong adsorption capacity and fast adsorption speed.

Technical Solution: In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for applying a graphene sponge for absorbing an organic solvent or a grease. Further, after the graphene sponge absorbs the organic solvent or the grease, the decontamination treatment is performed: the decontamination treatment is a method of low-pressure distillation, extraction, or high-temperature distillation, and the organic solvent or grease is removed or recycled from the graphene sponge. .

Advantageous Effects: Compared with the prior art, the technical solution has the following beneficial effects:

1. The application method is simple in operation and low in cost, and can be applied to industrial production. Because graphene sponge has excellent water repellency and has strong adsorption capacity and fast adsorption speed for organic solvents and oils, graphene sponge has the advantage of being used for adsorbing organic solvents and greases. In particular, graphene sponges are used in liquid-liquid separation and sewage treatment, and graphene sponges are used to adsorb organic solvents and greases.

2. The graphene sponge can be reused, and the organic solvent and grease can be recycled. In the present technical solution, the organic solvent and grease adsorbed by the graphene sponge are separated from the graphene sponge by low-pressure distillation, extraction or high-temperature evaporation, and the graphene sponge from which the organic solvent and the grease are removed can be reused. The separated organic solvents and greases can be recycled. The graphene sponge has wide application potential for various separations between different liquids and sewage treatment. DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph showing the adsorption ratio of a graphene sponge to an organic solvent and a fat or oil in the present invention.

Fig. 2 is a thermogravimetric analysis chart of the graphene sponge of the present invention.

Fig. 3 is a view showing the experiment of adsorbing and desorbing toluene using a graphene sponge in Example 1 of the present invention. Fig. 4 is a view showing an experiment of adsorption and desorption of dodecane by a graphene sponge in Example 2 of the present invention. Fig. 5 is a graph showing the adsorption ratio of a porous polymer obtained by polymerizing 1, 3, 5-triethylbenzene benzene, and a porous polymer obtained by polymerizing 1, 4-diethylbenzene to an organic solvent and a fat.

detailed description

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

In the method for applying a graphene sponge of the present invention, the graphene sponge is used for absorbing an organic solvent or a grease.

The preparation method of the graphene sponge in the present invention is as follows:

In the first step, 35 ml of a graphene oxide dispersion having a concentration of 2 mg/ml is weighed, and 1 ml of ammonia water is added to form a mixed solution; the concentration of the ammonia water is 30%, which means that 30 g of hydrogen peroxide is contained per 100 g of ammonia water.

In the second step, the mixture is poured into a reaction kettle at a high temperature of 180 ° C for 24 hours, then naturally cooled, and the reaction vessel can be unscrewed. A graphene gel was obtained.

In the third step, the obtained graphene gel is freeze-dried at a low pressure to obtain a porous graphene sponge.

The organic solvent or fat includes vegetable oil, crude oil, pump oil, dodecane, n-decane, octane, hexane, phenol, nitrobenzene, chloroform, dichlorobenzene, ethylbenzene, toluene, benzene, Dimethyl sulfoxide, tetrahydrofuran, dimethylformamide, acetone, ethanol, methanol, kerosene, castor oil, heptane, diesel, gasoline, carbon tetrachloride.

In this application method, a graphene sponge is used as an adsorbent. Graphene sponge can be used in the field of liquid-liquid separation or sewage separation. The graphene sponge is used as an adsorbent to absorb organic solvents or grease. The test method for the adsorption rate of graphene sponge is: cut the prepared graphene sponge into small pieces, and weigh each piece of mass, denoted as w, and then put each graphene sponge into the solvent to be adsorbed, graphene sponge Adequate adsorption of the test solution, and finally weigh the weight of each graphene sponge, denoted as w _fi , then the adsorption rate of the graphene sponge is calculated by the following formula: adsorption rate = ^ wet _ ^ dry >< 100% Test method for testing graphene sponge as methanol, ethanol, acetone, tetrahydrofuran, dimethyl sulfoxide, toluene, ethylbenzene, dichlorobenzene, chloroform, nitrobenzene, hexane, heptane, octane as the solvent Adsorption rates of n-decane, dodecane, pump oil, kerosene, castor oil and soybean oil. The test results are shown in Fig. 1. The abscissa indicates the adsorption rate of the graphene sponge, and the ordinate indicates the organic solvent or grease to be adsorbed. For example, the adsorption rate of graphene sponge to pump oil is 6854%, the adsorption rate of graphene sponge to dodecane is 5050%, the adsorption rate of graphene sponge to nitrobenzene is 6382%, and the adsorption of graphene sponge on chloroform. The rate is 8612%.

The adsorption rate of a porous polymer obtained by polymerizing 1, 3, 5-triethylbenzene and 1, 4-diethylbenzene to a grease or an organic solvent, and an adsorption rate of a graphene sponge For comparison. As shown in FIG. 5, the abscissa indicates the adsorption ratio of the porous polymer obtained by polymerizing 1, 3, 5-triethylbenzene and the adsorption ratio of the porous polymer obtained by polymerizing 1, 4-diethylbenzene. , gray indicates the adsorption rate of the porous polymer obtained by polymerizing 1, 3, 5-triethylbenzene, black indicates the adsorption rate of the porous polymer obtained by polymerizing 1, 4-diethylbenzene; the ordinate indicates the adsorption to be adsorbed Organic solvent or fat, of which vegetable-oi l : vegetable oil; pump-oi l : pump oil; dodecane: 12th house; decane: nunnery; octane: 辛院; hexane : 院院; phenol : 苯西分; Nitrobenzene: chloroform: chloroform; 1, 2_dichlorobenzene: dichlorobenzene; ethylbenzene: ethylbenzene; toluene: toluene; benzene: benzene; DMS0: dimethyl sulfoxide; THF: tetrahydrofuran; DMF: dimethylformamide; Acetone : acetone; ethanol : ethanol; methanol : methanol; weight gain: adsorption rate; CMP-1 : 1, 3, 5 - triethyl benzene polymerized porous polymer; CMP-2: 1, 4- 2 A porous polymer obtained by polymerizing benzene. 1, 3, 5-triethylbenzene benzene polymerization of porous polymer adsorption rate test method, and 1, 4-diethyl benzene polymerization of porous polymer adsorption rate test method, both with graphene sponge The test method for the adsorption rate is the same. In the present comparative example, a porous polymer obtained by polymerizing 1,3,5-triethylbenzene, and a porous polymer obtained by polymerizing 1, 4-diethylbenzene are respectively applied to vegetable oil, pump oil, dodecane, and cesium. Adsorption rates of alkane, octane, hexane, phenol, nitrobenzene, chloroform, dichlorobenzene, ethylbenzene, toluene, benzene, dimethyl sulfoxide, tetrahydrofuran, dimethylformamide, acetone, ethanol, methanol test. For example, the adsorption rate of porous polymer obtained by polymerizing 1,3,5-triethylbenzene to vegetable oil is 950-1000%, and the adsorption rate of porous polymer obtained by polymerizing 1, 4-diethylbenzene to vegetable oil is 1000-1100%; 1, 3, 5-triethylbenzene benzene polymerized porous polymer adsorption rate of ethanol is about 1000%, 1, 4-diethylbenzene benzene polymerized porous polymer to ethanol The adsorption rate is 575-625%.

By comparing Tables 1 and 5, it can be seen that for the same grease or organic solvent to be adsorbed, the adsorption rate of the graphene sponge is much larger than that of the porous polymer obtained by polymerizing 1,3,5-triethylbenzene. Or the adsorption rate of a porous polymer obtained by polymerizing 1, 4-diethylbenzene. For example, for pump oil, the adsorption rate of porous polymer obtained by polymerizing 1, 3, 5-triethylbenzene is about 800%, and the adsorption rate of porous polymer obtained by polymerizing 1, 4-diethylbenzene is 725%. Left and right, and the adsorption rate of graphene sponge is 5050%; for nitrobenzene, the adsorption rate of porous polymer obtained by polymerizing 1, 3, 5-triethylbenzene is about 1600%, 1, 4-diethylbenzene The adsorption rate of the polymerized porous polymer is about 1650%, and the adsorption rate of the graphene sponge is 6382%. For the ethanol, the adsorption rate of the porous polymer obtained by polymerizing 1, 3, 5-triethylbenzene is 1000%. The adsorption rate of the porous polymer obtained by polymerizing 1, 4-diethylbenzene is about 575-625%, and the adsorption rate of graphene sponge is 5103%.

In addition, for expanded graphite, expanded graphite only absorbs oil and does not absorb toxic substances such as toluene, in order to enable it to adsorb toluene, Shande Li (SD Li, SH Tian, CM Du, C. He, CP Cen, Y. Xiong. Chemical Engineering Journal, 2010, 162, 546.), modified expanded graphite with petrolatum. The adsorption rate of adsorbed toluene was 21.3%, which was much lower than that of graphene sponge of 5477. 4%.

Figure 1 shows the adsorption rates of graphene sponges for organic solvents and greases. As can be seen from Fig. 1, the graphene sponge not only has a strong adsorption force for organic solvents, but also has a strong adsorption force for oils and fats. However, graphene sponges have different adsorption capacities for different organic solvents or greases. This is the embodiment of graphene sponges with selective adsorption. In addition, the graphene sponge is hydrophobic, so that effective removal of organic pollutants can be achieved.

Further, after the graphene sponge absorbs the organic solvent or the grease, the decontamination treatment is performed: the decontamination treatment is a method of low-pressure distillation, extraction, or high-temperature distillation, and the organic solvent or grease is removed or recycled from the graphene sponge. . The method of low-pressure distillation is to reduce the boiling point of the adsorbed substance by reducing the gas pressure of the closed container in which the graphene sponge is located, so that the adsorbed substance can be desorbed from the graphene sponge by evaporation. For example, the boiling point of octane is 125. 8 ° C at a pressure of 101. 325 kPa. The octane-absorbing graphene sponge was placed in a flask, and the gas was evacuated by a mechanical pump to reduce the gas pressure in the flask, until the gas pressure was 10.13 kPa, at which point the boiling point of the octane was lowered. The octane is evaporated in a low pressure environment of 10.13 kPa to obtain a clean octane. Low pressure distillation includes vacuum distillation, vacuum distillation, high vacuum distillation, excimer distillation or molecular distillation. The vacuum distillation uses the boiling point of the liquid to change with the external pressure. If the pressure in the system is lowered by means of a vacuum pump, the boiling point of the liquid can be lowered, which is the theoretical basis for the vacuum distillation operation, so it is particularly suitable for Those substances which have been decomposed, oxidized or polymerized by thermal decomposition at atmospheric boiling. Vacuum distillation is carried out under reduced pressure, and is generally used to separate substances which are easily decomposed when heated to a boiling point under normal pressure, or in combination with other distillation methods such as steam distillation to lower the distillation temperature and improve the separation efficiency. High vacuum distillation is for compounds with high boiling points or is easily oxidized by atmospheric distillation. Generally, the vacuum is first applied, and the vacuum is stabilized and then heated. When the temperature approaches the boiling point at this vacuum, the heating rate is slowed down. Excimer or molecular distillation is a distillation process that operates under high vacuum, where the mean free path of the vapor molecules is greater than the distance between the evaporation surface and the condensation surface, thereby allowing the difference in evaporation rates of the components in the feed liquid to be utilized. The liquid mixture is separated.

The extraction is mainly for substances that are not easily volatilized, such as pump oil. The specific process is to place the graphene sponge with non-volatile substances in another organic solvent with a lower boiling point, and the non-volatile substance is easy to dissolve. In a lower boiling organic solvent, the organic solvent is then used to displace the non-volatile material, and finally the graphene sponge is subjected to low pressure or high temperature distillation. For example, a graphene sponge with dodecane is placed in a beaker containing 250 ml of ethanol, and the dodecane in the graphene sponge is fully dissolved in ethanol, which is equivalent to replacing the graphene sponge with ethanol. The dodecane, at this time, the graphene sponge is heated to 80 ° C, the ethanol can be completely evaporated, thereby obtaining a clean graphene sponge, which can be reused.

The high-temperature distillation method is to evaporate an organic solvent or fat by a high temperature, and then recover the organic solvent or fat by condensation. For example, a graphene sponge with dodecane is placed in an Erlenmeyer flask, the Erlenmeyer flask is connected to a condensing device, and then the Erlenmeyer flask is heated to 220 ° C, and the generated dodecane vapor enters the condensing device and becomes Liquid dodecane.

As shown in Figure 2, the abscissa represents temperature, in units. C, the ordinate represents the weight percentage of the graphene sponge. As can be seen from Figure 3: When the temperature rises to 70 CTC, the graphene sponge does not undergo significant chemical and physical damage, and the weight of the graphene sponge is only reduced by about 17%. The graphene sponge has very good thermal stability. Sex. The The characteristics also make it possible to adsorb grease or organic contaminants from high temperature separation graphene sponges (generally the boiling point of organic matter is not high). That is to say, the material adsorbed by the graphene sponge can be desorbed from the graphene sponge by high temperature without affecting the structure of the graphene sponge. Since graphene sponges are resistant to high temperatures, that is, have high thermal stability, high temperature distillation can be used. Example 1

The graphene sponge to which toluene was adsorbed was subjected to an adsorption and desorption cycle experiment by a method of low-pressure distillation. That is, the same piece of graphene sponge was tested. The specific process is as follows: The graphene sponge to which toluene is adsorbed is placed in a closed container, and then the gas in the container is withdrawn by a mechanical pump to reduce the gas pressure inside the container, and then the toluene is evaporated by means of a graphene sponge. The escape escapes, and after the distillation is completed, the graphene sponge is placed in toluene, reabsorbed, and thus circulated. As shown in Figure 3, the experiment was performed ten times in total. Figure 3 shows the amount of adsorption and desorption of graphene sponge in each experiment. In Fig. 3, the abscissa indicates the number of cycles of the experiment, a total of ten times; the ordinate indicates the weight of toluene adsorbed by the graphene sponge, the unit is m _{g ;} the curve at the top indicates the weight of the adsorbed toluene, and the curve at the lower indicates the graphite The weight of toluene remaining in the olefin sponge.

It can be seen from Fig. 3 that the desorption rate of toluene adsorbed by the graphene sponge can reach 99% or more, and the adsorption capacity of the desorbed graphene sponge is basically unchanged, and can be reused. Example 2

The adsorption and desorption cycle experiments of the graphene sponge adsorbed with dodecane were carried out using ethanol as an extractant. That is, the same piece of graphene sponge was tested. The specific process is as follows: The graphene sponge adsorbed with dodecane is immersed in enough ethanol. After the dodecane is substantially dissolved in ethanol, the graphene sponge is taken out and placed in a thermostat at 60 ° C. After 2 hours, then take out and adsorb dodecane, and cycle 10 times. Figure 4 shows the amount of adsorption and residual amount of graphene sponge in each experiment. In Fig. 4, the abscissa indicates the number of cycles of the experiment, ten times in total; the ordinate indicates the weight of dodecane adsorbed by the graphene sponge in units of mg. The upper curve shows the weight of the adsorbed dodecane, and the lower curve shows the weight of the graphene sponge after the low pressure distillation of dodecane in the graphene sponge.

It can be seen from Fig. 4 that the desorption rate of dodecane adsorbed by the graphene sponge can reach 99% or more, and the adsorption capacity of the desorbed graphene sponge is basically unchanged, and can be reused.

Claims

Claim

A method of applying a graphene sponge, characterized in that the graphene sponge is used for absorbing an organic solvent or a grease.

The method for applying a graphene sponge according to claim 1, wherein the organic solvent or fat comprises vegetable oil, crude oil, pump oil, dodecane, n-decane, octane, hexane, phenol, Nitrobenzene, chloroform, dichlorobenzene, ethylbenzene, toluene, benzene, dimethyl sulfoxide, tetrahydrofuran, dimethylformamide, acetone, ethanol, methanol, kerosene, castor oil, heptane, diesel, Gasoline, carbon tetrachloride.

The method for applying a graphene sponge according to claim 1, wherein: the graphene sponge absorbs an organic solvent or a grease, and then performs a decontamination treatment: the decontamination treatment is a low pressure distillation, extraction, or high temperature. The method of distillation removes or recycles the organic solvent or grease from the graphene sponge.

The method for applying a graphene sponge according to claim 3, wherein the low pressure distillation comprises vacuum distillation, vacuum distillation, high vacuum distillation, excimer distillation or molecular distillation.