阅读说明：本技术 高效、抗污羧基化氧化石墨烯纳滤膜、制备方法及其应用 (Efficient and anti-pollution carboxylated graphene oxide nanofiltration membrane, and preparation method and application thereof ) 是由 何毅 余昊 李虹杰 周良 范毅 马静 钟菲 殷祥英 王宇琪 于 2019-11-08 设计创作，主要内容包括：本申请实施例提供一种高效、抗污羧基化氧化石墨烯纳滤膜的制备方法,包括以下步骤：S1：将氧化石墨烯用纯水配置成氧化石墨烯分散液；S2：向氧化石墨烯分散液中加入HBr,搅拌反应10～15h；S3：步骤S2反应后,向其反应体系中加入草酸继续搅拌反应2～6h,取反应产物；S4：对步骤S3得到的反应产物进行离心提纯,得到羧基化氧化石墨烯；S5：将步骤S4得到的羧基化氧化石墨烯配置成羧基化氧化石墨烯分散液,并将羧基化石墨烯分散液抽滤在聚偏氟乙烯支撑膜上,得到羧基化氧化石墨烯纳滤膜。本发明所提供的制备羧基化氧化石墨烯纳滤膜的方法简单、操作容易,且不添加较多的化学试剂,更加环保以及节约成本、同时有机废水处理能力和抗污能力强。(The embodiment of the application provides a preparation method of a high-efficiency and anti-pollution carboxylated graphene oxide nanofiltration membrane, which comprises the following steps: s1: preparing graphene oxide into a graphene oxide dispersion liquid by using pure water; s2: adding HBr into the graphene oxide dispersion liquid, and stirring and reacting for 10-15 h; s3: after the reaction of the step S2, adding oxalic acid into the reaction system, continuously stirring and reacting for 2-6 h, and taking a reaction product; s4: carrying out centrifugal purification on the reaction product obtained in the step S3 to obtain carboxylated graphene oxide; s5: and (4) preparing the carboxylated graphene oxide obtained in the step (S4) into a carboxylated graphene oxide dispersion liquid, and performing suction filtration on the carboxylated graphene oxide dispersion liquid on a polyvinylidene fluoride support membrane to obtain the carboxylated graphene oxide nanofiltration membrane. The method for preparing the carboxylated graphene oxide nanofiltration membrane is simple, easy to operate, free of more chemical reagents, more environment-friendly, cost-saving, and strong in organic wastewater treatment capacity and anti-fouling capacity.)

1. A preparation method of an efficient and anti-pollution carboxylated graphene oxide nanofiltration membrane is characterized by comprising the following steps:

s1: preparing graphene oxide into a graphene oxide dispersion liquid by using pure water;

s2: adding HBr into the graphene oxide dispersion liquid, and stirring and reacting for 10-15 h;

s3: after the reaction of the step S2, adding oxalic acid into the reaction system, continuously stirring and reacting for 2-6 h, and taking a reaction product;

s4: carrying out centrifugal purification on the reaction product obtained in the step S3 to obtain carboxylated graphene oxide;

s5: and (4) preparing the carboxylated graphene oxide obtained in the step (S4) into a carboxylated graphene oxide dispersion liquid, and performing suction filtration on the carboxylated graphene oxide dispersion liquid on a polyvinylidene fluoride support membrane to obtain the carboxylated graphene oxide nanofiltration membrane.

2. The method according to claim 1, wherein the centrifugation purification in S4 is performed as follows:

s41, centrifuging the reaction product obtained in the step S3 at 10000 rpm, taking the precipitate, and cleaning the precipitate by pure water;

s42, centrifuging the sediment cleaned in the step S41 at 10000 r/min, taking the sediment, and cleaning the sediment by pure water;

and S43, centrifuging the precipitate cleaned in the step S42 at 10000 rpm, taking the precipitate, and cleaning the precipitate with pure water to obtain the carboxylated graphene oxide.

3. The method according to claim 1, wherein the ratio of S5: and preparing the carboxylated graphene oxide obtained in the step S4 into a carboxylated graphene oxide dispersion liquid, wherein the concentration of the carboxylated graphene oxide dispersion liquid is 0.05 mg/mL.

4. The preparation method according to claim 1, wherein the carboxylated graphene oxide dispersion liquid in S5 further comprises diluting the carboxylated graphene oxide dispersion liquid with pure water, stirring and ultrasonically dispersing the diluted carboxylated graphene oxide dispersion liquid before suction filtration.

5. The method according to claim 1, wherein in step S3, oxalic acid is added to the reaction system and the reaction is continued for 4 hours with stirring to obtain the reaction product.

6. The method according to claim 1, wherein in step S2, HBr is added to the graphene oxide dispersion, and the mixture is stirred at 1000 rpm at room temperature for 12 hours.

7. The preparation method according to claim 1, wherein the graphene oxide in the step S1 has a monolayer size of 15 μm or less.

8. The efficient and anti-fouling carboxylated graphene oxide nanofiltration membrane prepared by the preparation method according to claim 1.

9. The use of a high efficiency, anti-fouling carboxylated graphene oxide nanofiltration membrane according to claim 8 in organic wastewater treatment.

Technical Field

The application relates to the technical field of nanofiltration membranes, in particular to a high-efficiency and anti-pollution carboxylated graphene oxide nanofiltration membrane, a preparation method and application thereof.

Background

In the water treatment separation membrane, a nanofiltration membrane is used as a new membrane technology, the separation efficiency of the nanofiltration membrane is higher than that of an ultrafiltration membrane, organic micromolecules and multivalent salts can be effectively intercepted, and purified water can meet most purposes, such as: food, medical treatment, scientific research, pharmacy and the like. In addition, on the premise that the filtration effect is close to that of the reverse osmosis technology, the applied pressure required by the reverse osmosis membrane technology is much smaller than that of the reverse osmosis membrane technology, so that the nanofiltration membrane technology attracts attention as a membrane separation technology with high efficiency and low energy consumption.

In the practical application of the nanofiltration membrane, the traditional polymeric nanofiltration membrane is limited due to the low water treatment efficiency, the complex process and the environmental protection of raw materials. Compared with the traditional nanofiltration membrane material, the graphene oxide nanofiltration membrane becomes a natural nanofiltration membrane material due to the strong mechanical stability and controllable interlayer spacing of the graphene oxide nanofiltration membrane. In recent years, the research report of the graphene oxide nanofiltration membrane is frequent, and the prior art well solves the problem of low water flux of the traditional nanofiltration membrane technology. However, under the condition of an applied pressure, the graphene oxide nanofiltration membrane has two major challenges in treating organic wastewater, namely: high water treatment efficiency and long-term stability.

Disclosure of Invention

An object of the embodiment of the application is to provide a preparation method of a high-efficiency anti-pollution carboxylated graphene oxide nanofiltration membrane, so as to achieve the technical effects of improving the anti-pollution performance of the nanofiltration membrane, treating the organic wastewater and prolonging the service life of the membrane.

The application is realized by the following technical scheme:

the method comprises the following steps:

s1: preparing graphene oxide into a graphene oxide dispersion liquid by using pure water;

s2: adding HBr into the graphene oxide dispersion liquid, and stirring and reacting for 10-15 h;

s3: after the reaction of the step S2, adding oxalic acid into the reaction system, continuously stirring and reacting for 2-6 h, and taking a reaction product;

s4: carrying out centrifugal purification on the reaction product obtained in the step S3 to obtain carboxylated graphene oxide;

s5: and (4) preparing the carboxylated graphene oxide obtained in the step (S4) into a carboxylated graphene oxide dispersion liquid, and performing suction filtration on the carboxylated graphene oxide dispersion liquid on a polyvinylidene fluoride support membrane to obtain the carboxylated graphene oxide nanofiltration membrane.

In order to better implement the present application, further, the specific operation of centrifugal purification in S4 is as follows:

s41, centrifuging the reaction product obtained in the step S3 at 10000 rpm, taking the precipitate, and cleaning the precipitate by pure water;

s42, centrifuging the sediment cleaned in the step S41 at 10000 r/min, taking the sediment, and cleaning the sediment by pure water;

and S43, centrifuging the precipitate cleaned in the step S42 at 10000 rpm, taking the precipitate, and cleaning the precipitate with pure water to obtain the carboxylated graphene oxide. .

To better implement the present application, further, the S5: and preparing the carboxylated graphene oxide obtained in the step S4 into a carboxylated graphene oxide dispersion liquid, wherein the concentration of the carboxylated graphene oxide dispersion liquid is 0.05 mg/mL.

In order to better implement the present application, the carboxylated graphene oxide dispersion in S5 further includes diluting the carboxylated graphene oxide dispersion with pure water, stirring, and performing ultrasonic dispersion before suction filtration.

In order to better implement the present application, further, in the step S3, oxalic acid is added into the reaction system, and the reaction is continued to be stirred for 4 hours, and the reaction product is taken out.

In order to better implement the present application, in step S2, HBr is added to the graphene oxide dispersion, and the mixture is stirred at 1000 rpm at normal temperature for 12 hours. .

In order to better realize the application, further, the monolayer size of the graphene oxide in the step S1 is less than or equal to 15 μm.

The second purpose of the embodiment of the application is to provide a high-efficient, anti-soil carboxylation oxidation graphite alkene nanofiltration membrane.

The third purpose of the embodiment of the application is to provide an application of the efficient and anti-pollution carboxylated graphene oxide nanofiltration membrane in organic wastewater treatment.

The action mechanism is as follows: the invention provides a high-efficiency anti-fouling carboxylated graphene oxide nanofiltration membrane, HBr and oxalic acid are added into a graphene oxide dispersion liquid for biochemical reaction to obtain carboxylated graphene oxide, after carboxylation, a large number of negative charge carboxyl groups are arranged on the surface of the membrane, electrostatic repulsion is increased, and the inter-lamellar spacing of the nanofiltration membrane is further increased, so that the water flux is increased, the filtration efficiency is improved, and the working efficiency is further improved in the subsequent use process; the removal rate of the carboxylated nanofiltration membrane can reach more than 99.10 percent in the organic wastewater treatment process by taking a Trimeryl blue solution as an example, and compared with the existing graphene oxide nanofiltration membrane, the prepared carboxylated graphene oxide has better anti-fouling and easy-cleaning performances, mainly because the electrostatic action formed after carboxylation has the effect of repelling anionic dye, the service life of the membrane is prolonged, and the removal rate of the dye is increased.

Through carrying out cycle test to the blue solution of tritolyl blue with the carboxylation oxidation graphite alkene nanofiltration membrane that this application provided, though there is certain decline in throughput after the circulation many times, remain throughout more than 92%, further prove that carboxylation oxidation graphite alkene nanofiltration membrane antipollution ability is stronger, and is more durable, and economic benefits is higher.

In the process of preparing the carboxylated graphene oxide nanofiltration membrane, the size of a single layer of graphene oxide is preferably less than or equal to 15 microns, because the smaller the size, the more favorable the subsequent dispersion and the more favorable the subsequent carboxylation reaction.

In order to enhance the effect of dispersion centrifugation, it is preferable that the reaction product obtained in step S4 is centrifuged and purified three times to obtain carboxylated graphene oxide having a smaller size.

When the carboxylated graphene oxide dispersion liquid is prepared, no precipitation occurs in the subsequent film making process, so that the concentration of the carboxylated graphene oxide dispersion liquid is further limited to be 0.05mg/mL, and the carboxylated graphene oxide dispersion liquid is diluted before suction filtration, so that the film making effect is ensured.

The beneficial effects of the embodiment of the application are that:

(1) the method for preparing the carboxylated graphene oxide nanofiltration membrane is simple, easy to operate, free of more chemical reagents, more environment-friendly and cost-saving; meanwhile, the prepared nanofiltration membrane has a large number of negatively charged carboxyl groups, and the lamella spacing is increased under the action of electrostatic repulsion, so that the water flux is increased, the filtration speed is increased, and the service life of the nanofiltration membrane is prolonged and the removal rate of dye is increased because the electrostatic interaction has the effects of resisting and repelling anionic dye.

(2) According to the invention, a method of modifying the surface functional groups of the graphene oxide by oxalic acid is adopted, a large amount of charges are enriched, and the hydrophilicity and the electrostatic repulsion of the membrane are enhanced while the interlayer spacing of the graphene oxide membrane is increased, so that the effects of increasing the water flux and improving the fuel repulsion are achieved; greatly prolongs the service life of the membrane and the capability of treating organic wastewater, thereby increasing the economic benefit of enterprises.

(3) The carboxylated graphene oxide prepared by the invention keeps better treatment capacity in the organic wastewater treatment process.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.

FIG. 1 is a schematic representation of the preparative carboxylation reaction of the present application;

fig. 2 is a schematic view of the preparation of the carboxylated graphene oxide nanofiltration membrane according to the present application;

FIG. 3 is a graphical representation of XPS characterization of the relative content of oxygen-containing functional groups of graphene oxide and carboxylated graphene oxide, respectively, according to the present application;

FIG. 4 is a schematic thermogravimetric analysis of graphene oxide and carboxylated graphene oxide according to the present application;

FIG. 5 is an infrared spectrum of graphene oxide and carboxylated graphene oxide of the present application;

fig. 6 is a raman spectrum of graphene oxide and carboxylated graphene oxide according to the present application;

FIG. 7 is a schematic representation of water contact angles of graphene oxide and carboxylated graphene oxide according to the present application;

FIG. 8 is a zete potential diagram of graphene oxide dispersions and carboxylated graphene oxide dispersions of the present application;

fig. 9 is an XRD spectrogram of the graphene oxide nanofiltration membrane and the carboxylated graphene oxide nanofiltration membrane both in a dry state;

fig. 10 is an XRD spectrum of the graphene oxide nanofiltration membrane and the carboxylated graphene oxide nanofiltration membrane in a wet state;

fig. 11 is an XPD spectrum of the carboxylated graphene oxide nanofiltration membrane according to the present application at different PH values;

figure 12 is an SEM image of the graphene oxide nanofiltration membrane and carboxylated graphene oxide nanofiltration membrane of the present application;

figure 13 is a schematic water flux diagram of graphene oxide nanofiltration membranes and carboxylated graphene oxide nanofiltration membranes according to the present application;

fig. 14 is a schematic diagram of a curve showing the removal rate of the dye, namely, tricresyl blue, by the graphene oxide nanofiltration membrane and the carboxylated graphene oxide nanofiltration membrane according to the present application, as a function of the volume of the filtrate;

fig. 15 is a line graph of the removal rate of the graphene oxide nanofiltration membrane and the carboxylated graphene oxide nanofiltration membrane for 5 cycles of tritolyl blue;

figure 16 is a schematic diagram of the final flux of the present disclosure after cycling of the graphene oxide nanofiltration membrane and the carboxylated graphene oxide nanofiltration membrane;

fig. 17 is a comparison graph of the graphene oxide nanofiltration membrane and the carboxylated graphene oxide nanofiltration membrane before and after surface filtration and after cleaning.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.