CN115364679B

CN115364679B - Potassium ion selective film and preparation method thereof

Info

Publication number: CN115364679B
Application number: CN202210891819.6A
Authority: CN
Inventors: 高鹏程; 吴晓庆; 陈雅捷
Original assignee: China University of Geosciences
Current assignee: China University of Geosciences
Priority date: 2022-07-27
Filing date: 2022-07-27
Publication date: 2023-06-27
Anticipated expiration: 2042-07-27
Also published as: CN115364679A

Abstract

The invention discloses a potassium ion selective film and a preparation method thereof. The preparation method comprises the following steps: adding graphene oxide powder and dimethyl dimethoxy silane liquid into deionized water, heating and stirring until the graphene oxide powder and the dimethyl dimethoxy silane liquid are completely dispersed, stopping stirring, cooling the solution to room temperature to form a colloid solution, dripping a certain amount of colloid solution on a porous substrate polyethylene terephthalate film, and naturally air-drying to obtain a functional graphene oxide film; and (3) placing the dried functionalized graphene oxide film into 0.1-0.5M KCl solution, adsorbing for 10-24 hours at room temperature, taking out, flushing with ionized water, and then drying with nitrogen. The invention uses graphene oxide film as ion transmission channel and dimethyl dimethoxy silane functional molecule as K ⁺ Is combined with the solution soaking method to soak K ⁺ Loaded on the functionalized graphene oxide film material to obtain a potassium ion selective film, thereby realizing K ⁺ Is selectively passed through.

Description

Potassium ion selective film and preparation method thereof

Technical Field

The invention relates to the technical field of selective films, in particular to a potassium ion selective film and a preparation method thereof.

Background

Since the discovery of biological channels and their importance in physiological processes, artificial biomimetics has been developed in research fields such as synthesizing a series of solid nano-channels to simulate the transmission characteristics of biological channels. For example, potassiumIon biological channel is responsible for K ⁺ Is the physiological process of transmembrane transport, K ⁺ The selectivity of (1) depends on four closely spaced groups of K in the pore channel ⁺ Binding sites, giving it a high K ⁺ And (5) selective transmission. If their absence or dysfunction may lead to serious diseases such as hyperkalemia. Thus, K is synthesized artificially ⁺ The development of channels provides a possibility to remedy the functional drawbacks. For K ⁺ Development of channels, only nanopores with similar size to potassium ion biological channels are synthesized at present, but K ⁺ Is not high and the throughput is low. Therefore, from the bionic point of view, the method for preparing the film which has similar size and consistent working mechanism with the potassium ion biological channel and has high flux and high selectivity is an important problem at present.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provide a K ⁺ A potassium ion selective membrane with high selectivity and higher flux and a preparation method thereof.

The preparation method of the potassium ion selective film comprises the following steps:

s1: preparation of functionalized graphene oxide thin films

Adding graphene oxide powder and dimethyl dimethoxy silane liquid into deionized water, heating and stirring until the graphene oxide powder and the dimethyl dimethoxy silane liquid are completely dispersed, stopping stirring, cooling the solution to room temperature to form a colloid solution, dripping a certain amount of colloid solution on a porous substrate polyethylene terephthalate film, and naturally air-drying to obtain a functional graphene oxide film;

s2: preparation of the load K ⁺ Functionalized graphene oxide thin film

Placing the dried functionalized graphene oxide film into 0.1-0.5M KCl solution, adsorbing for 10-24 hours at room temperature, taking out, flushing redundant ion solution on the surface of the functionalized graphene oxide film with ionized water, and then drying with nitrogen to prepare a load K ⁺ A functionalized graphene oxide film, i.e., a potassium ion selective film.

Further, in step S1, the following raw materials are adopted in mass ratio: graphene oxide, dimethyl dimethoxy silane, deionized water=7:250-350:2000.

Further, in the step S1, the heating temperature is 100-110 ℃, and the rotating speed is 350-500 r/min; and magnetically stirring and reacting for 5-7 h.

Further, the pore size of the porous base polyethylene terephthalate film was 30nm.

A potassium ion selective membrane prepared by the preparation method.

According to the invention, through the structural characteristics of a bionic potassium ion biological channel, the graphene oxide film is used as an ion transmission channel and a dimethyl dimethoxy silane functional molecule is used as K ⁺ Is combined with the solution soaking method to soak K ⁺ Loading on the functionalized graphene oxide film material to obtain a load K ⁺ Is a functional graphene oxide selective film, thereby realizing K ⁺ Is selectively passed through.

The invention starts from a bionic potassium ion biological channel and firstly proposes the utilization of K ⁺ Film-loaded manner to reduce K ⁺ By potential barrier, overcome artificial K ⁺ The problems of low channel selectivity and low flux are that K ⁺ /Na ⁺ The selectivity was increased to 46 and the flux was increased by an order of magnitude.

The preparation method is simple in technical operation, the functionalized graphene oxide film prepared by the blending method and the potassium ion selective film prepared by the solution soaking method are adopted, and the synthesis method is simple and convenient and has good performance.

The invention loads K on the functionalized graphene oxide film by a solution soaking method ⁺ The potassium ion selective film is prepared by the method, and the film has the adsorption time of 10 to 24 hours and K adsorption ⁺ K with a concentration of 0.1-0.5M ⁺ The selective passing effect is optimal, and too short adsorption time or too high concentration of adsorption solution can inhibit K ⁺ Selectively through the membrane.

Drawings

FIG. 1 is a SEM image of the cross-section of the films of example 1, example 2, example 3 and comparative example 1;

FIG. 2 is XRD patterns of the films of example 1, example 2, example 3 and comparative example 1;

FIG. 3 shows Zeta potential diagrams for films of example 1, example 2, example 3 and comparative example 1 at different pH values;

FIG. 4 shows the ionic transmembrane conductance and K at various concentrations for example 1 ⁺ With Na and Na ⁺ Selecting a ratio graph;

FIG. 5 shows the ionic transmembrane conductance and K at various concentrations for example 2 ⁺ With Na and Na ⁺ Selecting a ratio graph;

FIG. 6 shows the ionic transmembrane conductance and K at various concentrations for example 3 ⁺ With Na and Na ⁺ Selecting a ratio graph;

FIG. 7 shows ionic transmembrane conductance and K at various concentrations for comparative example 1 ⁺ With Na and Na ⁺ Selecting a ratio graph;

FIG. 8 shows the ionic transmembrane conductance and K at various concentrations for comparative example 2 ⁺ With Na and Na ⁺ Selecting a ratio graph;

FIG. 9 shows the ionic transmembrane conductance and K at various concentrations for comparative example 3 ⁺ With Na and Na ⁺ A ratio map is selected.

Detailed Description

The following are specific embodiments of the present invention and the technical solutions of the present invention will be further described with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

Example 1

The experimental procedure was as follows:

the raw materials with the following mass ratio are adopted: graphene oxide, dimethyl dimethoxy silane and deionized water=7:250-350:2000;

adding graphene oxide powder and dimethyl dimethoxy silane liquid into deionized water, heating and stirring until the graphene oxide powder and the dimethyl dimethoxy silane liquid are completely dispersed to form a colloid solution, wherein the heating temperature is 100-110 ℃, and the rotating speed is 350-500 r/min; after magnetically stirring and reacting for 5-7 h, stopping stirring and cooling the solution to room temperature;

and (3) dripping 10 mu L of the cooled colloid solution on a porous substrate polyethylene terephthalate (polyethylene terephthalate, PET) film with the area of 5 multiplied by 5mm, wherein the pore diameter of the porous substrate PET is 30nm, and naturally air-drying at room temperature to obtain the functionalized graphene oxide film.

The dried functionalized graphene oxide film is put into 1mL of 0.1M KCl solution, and K is adsorbed at room temperature ⁺ 10h, washing the superfluous ion solution on the surface with deionized water for 1-3 min, and then drying with nitrogen to prepare the load K ⁺ A functionalized graphene oxide film.

Example 2

The procedure is as in example 1, except that K ⁺ The adsorption time was 15h.

Example 3

The procedure is as in example 1, except that K ⁺ The adsorption time was 24h.

Comparative example 1

The procedure is as in example 1, except that K is not adsorbed ⁺ 。

Comparative example 2

The procedure is as in example 1, except that K ⁺ The adsorption time was 1h.

Comparative example 3

The procedure was as in example 1, except that the concentration of the ion-adsorbed solution was 1M.

The ions pass through a potassium ion selective film test, comprising the steps of:

a self-made symmetrical electrolytic tank is adopted, a potassium ion selective film is clamped between the two electrolytic tanks, about 0.5mL of ion solution is added into each electrolytic tank at two sides, then two self-made Ag/AgCl electrodes are respectively placed in the two electrolytic tanks and connected with an electrochemical workstation, and I-V curve test is carried out. And (3) performing linear fitting on the tested I-V curve to obtain a slope, namely the transmembrane conductance. By calculating K ⁺ With Na and Na ⁺ The selection ratio of the potassium ion selective membrane can be calculated by the ratio of the transmembrane conductance of the film:

the ionic solution is one of KCl and NaCl.

The concentration of the ionic solution is one of 0.01M, 0.1M and 1M.

Analysis of experimental results

Fig. 1 is a SEM image of the cross-sections of the films of example 1, example 2, example 3 and comparative example 1. From the figure, graphene oxide nano sheets are stacked flatly and orderly in structure, which indicates that the potassium ion selective film is successfully prepared. SEM images of comparative example 1, example 2, example 3 and comparative example 1, the morphology structures were found to be similar, indicating that the film morphology was not changed by soaking.

Fig. 2 is the XRD patterns of the films of example 1, example 2, example 3 and comparative example 1. As can be seen from the figure, the film of comparative example 1 has a diffraction characteristic peak at 11.1 °; the example 1 film had a diffraction peak at 11.0 °; example 2 film had a diffraction peak at 11.0 °; example 3 film has a diffraction peak at 10.9℃corresponding to (d ₀₀₁ ) The diffraction peaks of the crystal faces are calculated to be the layer spacing respectively through a Bragg equation

And->

XRD results show that when the functionalized graphene oxide film is loaded with K ⁺ Thereafter, the interlayer spacing of the film increases, indicating K ⁺ Intercalation into functionalized graphene oxide crystals was successful.

FIG. 3 shows the Zeta potential of the films of example 1, example 2, example 3 and comparative example 1 at different pH values. As seen from the figure, the Zeta potential of the film is more negative as the pH increases, indicating that the negative charge on the film surface increases with increasing pH. Load K compared to comparative example 1 ⁺ The films, examples 1, 2 and 3 are all positive for Zeta potential over the film of comparative example 1, illustrating the load K ⁺ After that, the negative charge on the surface of the functionalized graphene oxide is weakened, which indicates that the surface of the film is loaded with K ⁺ Successful. In addition, example 1 is thinThe Zeta potential of the films was slightly lower than that of the films of example 2 and 3, while the Zeta potentials of the films of example 2 and 3 were not much different, indicating that the functionalized graphene oxide film supported K with increasing adsorption time ⁺ The more, but after a certain time the load quantity is stable.

FIG. 4 is a graph showing the results of the calculation of the I-V test curve for the film of example 1. As seen from the figure, as the concentration of the ionic solution increases, the conductance of the transmembrane ions increases, K ⁺ /Na ⁺ The selection ratio increases accordingly. K at 0.1M concentration ⁺ /Na ⁺ The selection ratio is 3-20; at a high concentration of 1M, the selection ratio was 1 to 19, indicating the load K ⁺ The film is K under the voltage driving condition ⁺ Rate of passage of Na ⁺ The rate of passage is high. This phenomenon is mainly due to the film load K ⁺ Thereafter, when K is exotic ⁺ When entering the channel, K occupies the adsorption site ⁺ Will automatically move to the next adsorption site to adsorb extraneous K ⁺ This reduces K ⁺ Potential barrier moving in channel, K is raised ⁺ Is a movement rate of (a); while when external Na ⁺ When entering the channel, due to K ⁺ Ratio Na ⁺ Is easier to be adsorbed on the film, K ⁺ The occupied adsorption sites do not automatically move to the next adsorption site and positively charged K ⁺ Rejection of Na with the same charge ⁺ Na is reduced ⁺ The rate of movement in the channel, therefore, the film of example 1 has a higher K ⁺ /Na ⁺ The ratio is selected.

FIG. 5 is a graph showing the results of the calculation of the I-V test curve for the film of example 2. In agreement with the results of example 1 of FIG. 4, as the concentration of the ionic solution increases, the conductance of the transmembrane ions increases, K ⁺ /Na ⁺ The selection ratio increases accordingly. K at 0.1M concentration ⁺ /Na ⁺ The selection ratio is 9-21; at a high concentration of 1M, the selection ratio is 14 to 23. Comparative example 1 results, K of the film of example 2 ⁺ /Na ⁺ The selection ratio is slightly higher, which is attributed to K ⁺ Occupy more adsorption sites, K ⁺ Barrier drop for movement between filmsLow, the movement rate increases.

FIG. 6 is a graph showing the results of the calculation of the I-V test curve for the film of example 3. As can be seen from the figure, at a concentration of 0.01M, K ⁺ /Na ⁺ The selection ratio is 11-37; k at 0.1M concentration ⁺ /Na ⁺ The selection ratio is 6-13; at a concentration of 1M, the selection ratio is 28 to 46. The results of example 1 and example 2 are compared, K for the film of example 3 ⁺ /Na ⁺ The selection ratio is increased by a larger extent. From the results of example 1, example 2, and example 3, it was found that the potassium ion selective thin film was successfully produced. According to K ⁺ Different adsorption time, K ⁺ /Na ⁺ The selection ratio of (2) can reach 46 at the highest and is far higher than other K ⁺ A selective thin film; according to the data of transmembrane conductance, the transmembrane conductance of the potassium ion selective membrane of the invention can reach 10 mu S at most, which is about an order of magnitude higher than other membranes. This demonstrates the advantages of the potassium ion selective membranes of the present invention in terms of high selectivity and high flux.

FIG. 7 is a graph showing the results of the calculation of the I-V test curve for the film of comparative example 1. As seen from the figure, as the concentration of the ionic solution tested increases, the transmembrane ionic conductance increases. In addition, as the ion concentration increases, K ⁺ /Na ⁺ The selection ratio also increases, but the selection ratio is not more than 5 at the highest, which is far lower than in examples 1, 2 and 3. This phenomenon is mainly due to the fact that K is not loaded ⁺ Under the condition of voltage driving, the film can be preferentially intercalated between layers of the film and adsorbed on the functionalized graphene sheet, thereby reducing K ⁺ /Na ⁺ The ratio is selected.

FIG. 8 is the results of the film of comparative example 2 passing the I-V test curve and calculated. As seen from the figure, in accordance with comparative example 1 and example 1, as the concentration of the ionic solution increases, the transmembrane ionic conductance also increases. But unlike comparative example 1 and example 1, K was increased with the concentration of the ionic solution ⁺ /Na ⁺ The selection ratio decreases and the selection ratio does not exceed 3 at the highest. Mainly due to adsorption of K ⁺ Too little time, load K in channel ⁺ Is small in amount and is not effective in reducing K ⁺ Through thin-film channelsPotential barrier of (c), thus K ⁺ /Na ⁺ The selection ratio was similar to that in comparative example 1. Through K ⁺ The test of the loading time shows that the movement barrier of the cations in the channel can be reduced only when the cations are fully adsorbed on the film, so that the effect of 'passing through the same ions and rejecting the different ions' is achieved.

FIG. 9 is a graph showing the results of the calculation of the I-V test curve for the film of comparative example 3. Compared with the results of example 1, K ⁺ /Na ⁺ The selection ratio is much lower than in example 1. This phenomenon is mainly due to the fact that when high concentrations of 1M KCl are used as the load K ⁺ The adsorption sites in the film are almost filled up under the voltage driven condition, K ⁺ The potential barrier to move from the occupied adsorption site to the next empty adsorption site is high, at this time, the load K ⁺ Film for extraneous K ⁺ With Na and Na ⁺ Has the same rejection effect, thus, K ⁺ /Na ⁺ The selection ratio is close to 1.

The above is not relevant and is applicable to the prior art.

While certain specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the foregoing examples are provided for the purpose of illustration only and are not intended to limit the scope of the invention, and that various modifications or additions and substitutions to the described specific embodiments may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the invention as defined in the accompanying claims. It should be understood by those skilled in the art that any modification, equivalent substitution, improvement, etc. made to the above embodiments according to the technical substance of the present invention should be included in the scope of protection of the present invention.

Claims

1. A preparation method of a potassium ion selective film is characterized in that: the method comprises the following steps:

s1: preparation of functionalized graphene oxide thin films

s2: preparation of the load K ⁺ Functionalized graphene oxide thin film

2. The method for preparing a potassium ion selective membrane according to claim 1, wherein: in the step S1, the following raw materials in mass ratio are adopted: graphene oxide, dimethyl dimethoxy silane, deionized water=7:250-350:2000.

3. The method for preparing a potassium ion selective membrane according to claim 1, wherein: in the step S1, the heating temperature is 100-110 ℃, and the rotating speed is 350-500 r/min; and magnetically stirring and reacting for 5-7 h.

4. The method for preparing a potassium ion selective membrane according to claim 1, wherein: the pore size of the porous base polyethylene terephthalate membrane was 30nm.

5. A potassium ion selective membrane prepared by the method of any one of claims 1-4.