Universal method for realizing seawater desalination based on carbon nanofiber / carbon fiber confinement material

Abstract

The invention discloses a universal method for realizing seawater desalination based on a carbon nanofiber / carbon fiber confinement material, and belongs to the technical field of water treatment.The universal method comprises the following steps that S1, the carbon nanofiber / carbon fiber confinement material is prepared; and S2, adjusting the pH value of a seawater sample, and pushing the seawater sample to pass through the carbon nanofiber / carbon fiber confinement material obtained in S1 at a constant speed by using an injection pump. According to the universal method for realizing seawater desalination based on the carbon nanofiber / carbon fiber confinement material, the carbon nanofiber / carbon fiber is used as a confinement fluid carrier, ultrapure water, methanol or n-hexane is used as an extraction agent, a chelating agent does not need to be introduced, and the method is green and environment-friendly; and moreover, the absorptivity of Na < + > and Cl <-> in seawater can reach up to 82% without consuming energy.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and particularly to a general method for seawater desalination based on a carbon nanofiber / carbon fiber confinement material. Background Art

[0002] In the past few decades, with the growth of the world's population, the expansion of agricultural irrigation areas, and the improvement of living standards, the shortage of fresh water resources has become a major challenge threatening the sustainable development of humanity. Currently, many countries and regions are facing the problem of fresh water resource shortage. Therefore, it is crucial to develop efficient seawater desalination technologies.

[0003] Traditional desalination methods are mainly divided into two categories: thermal methods and membrane methods. Compared with thermal methods, membrane methods have attracted much attention due to their advantages such as low energy consumption, low cost, and high water quality. The separation mechanism of membrane methods is mainly based on two principles: the molecular sieve effect of neutral solutes and the Donnan effect of charged solutes. As a typical porous membrane, carbon-based materials have advantages such as good electrical conductivity and suitable pore size distribution, so they are often used as electroadsorption electrodes. However, their complex operation process and time-consuming and laborious characteristics seriously restrict their wide application in the field of seawater desalination.

[0004] In recent years, the proposal of liquid-phase nanoextraction technology has provided a new research direction for seawater desalination. This technology is based on the size effect and interfacial effect of nano-confinement, and uses multi-dimensional pores as confinement fluid extraction units. Thermodynamic and kinetic studies have shown that this technology has advantages such as spontaneous process, fast mass transfer, and high throughput. Therefore, liquid-phase nanoextraction technology is expected to become an important breakthrough for developing low-energy-consuming and rapid desalination methods, providing new ideas for the development of seawater desalination technology. Summary of the Invention

[0005] The object of the present invention is to provide a general method for seawater desalination based on a carbon nanofiber / carbon fiber confinement material, using carbon nanofiber / carbon fiber as a confinement fluid carrier and ultrapure water, methanol or n-hexane as an extractant, without the need to introduce chelating agents, being green and environmentally friendly, and being able to achieve an absorption rate of up to 82% for Na + and Cl - in seawater without consuming energy.

[0006] To achieve the above object, the present invention provides a general method for seawater desalination based on a carbon nanofiber / carbon fiber confinement material, comprising the following steps:

[0007] S1. Prepare a carbon nanofiber / carbon fiber confinement material;

[0008] S2. Adjust the pH of the seawater sample, and use a syringe pump to uniformly push the seawater sample through the carbon nanofiber / carbon fiber confinement material obtained in S1.

[0009] Preferably, the specific steps of S1 are as follows: uniformly fill carbon nanofibers / carbon fibers into a polyethersulfone filter membrane, load the filled filter membrane onto a syringe, and use an injection pump to uniformly push the confinement solvent through the filter membrane to obtain a carbon nanofiber / carbon fiber confinement material.

[0010] Preferably, in S1, the confinement solvent is one of ultrapure water, methanol, and n-hexane.

[0011] Preferably, in S1, the passing speed of the confinement solvent through the membrane is 1-10 mL / min.

[0012] Preferably, in S1, the ratio of the confinement solvent to carbon nanofibers / carbon fibers in the carbon nanofiber / carbon fiber confinement material is: 1 mg of carbon nanofibers / carbon fibers corresponds to 1.43-5.72 μL of the confinement solvent.

[0013] Preferably, in S2, adjust the pH value of the seawater sample to 3-9.

[0014] Preferably, in S2, the passing speed of the seawater sample through the membrane is 1-10 mL / min.

[0015] Therefore, the present invention adopts the above-mentioned general method for seawater desalination based on a carbon nanofiber / carbon fiber confinement material, and has the following beneficial effects:

[0016] (1) Using carbon nanofibers / carbon fibers as the confinement fluid carrier and ultrapure water, methanol or n-hexane as the extractant, no chelating agent needs to be introduced, which is green and environmentally friendly;

[0017] (2) The carbon nanofiber / carbon fiber confined water not only affects the hydrogen bond configuration and diffusion mass transfer rate of water, but also accelerates the ion mass transfer rate;

[0018] (3) The carbon nanofiber / carbon fiber confined water absorbs Na + and Cl - in seawater, which is beneficial to the full interaction between the confined water and the target ions, and can efficiently remove Na + and Cl - in seawater without consuming energy.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the results of the absorption efficiency of different confinement fluid carriers and confinement solvents on Na + and Cl - in an embodiment of the general method for seawater desalination based on a carbon nanofiber / carbon fiber confinement material of the present invention. Detailed Embodiments

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention pertains.

[0023] Main instruments and reagents used: The PXSJ-226T ion selective electrode (ISE, Leici, China) was used to detect the concentration of Na + and Cl - ; The XFP01-B injection pump (Suzhou Xunfei Co., Ltd., China) was used; Chromatographic grade methanol (MeOH) and n-hexane (HEX) (Sigma Aldrich).

[0024] Example 1

[0025] A general method for seawater desalination based on carbon nanofiber / carbon fiber confinement materials, comprising the following steps:

[0026] S1. Prepare carbon nanofiber / carbon fiber confined water: 0.35 g of carbon nanofiber / carbon fiber was uniformly filled into a polyethersulfone membrane filter with a pore size of 0.22 μm. The filled membrane filter was loaded onto a syringe, and ultrapure water was uniformly pushed through the membrane filter at a speed of 3 mL / min using an injection pump to obtain carbon nanofiber / carbon fiber confined water. The ratio of ultrapure water to carbon nanofiber / carbon fiber in the carbon nanofiber / carbon fiber confined water is: 1 mg of carbon nanofiber / carbon fiber corresponds to 4.29 μL of ultrapure water.

[0027] S2. The original pH value of the seawater sample is 8, and 5 mL of the seawater sample is uniformly pushed through the carbon nanofiber / carbon fiber confined water obtained in S1 at a speed of 3 mL / min using an injection pump.

[0028] Example 2

[0029] A general method for seawater desalination based on carbon nanofiber / carbon fiber confinement materials, comprising the following steps:

[0030] S1. Prepare carbon nanofiber / carbon fiber confined methanol: 0.35 g of carbon nanofiber / carbon fiber was uniformly filled into a polyethersulfone membrane filter with a pore size of 0.22 μm. The filled membrane filter was loaded onto a syringe, and methanol was uniformly pushed through the membrane filter at a speed of 3 mL / min using an injection pump to obtain carbon nanofiber / carbon fiber confined methanol. The ratio of methanol to carbon nanofiber / carbon fiber in the carbon nanofiber / carbon fiber confined methanol is: 1 mg of carbon nanofiber / carbon fiber corresponds to 4.29 μL of methanol.

[0031] S2. The original pH value of the seawater sample is 8. Using a syringe pump, 5 mL of the seawater sample is evenly pushed through the carbon nanofiber / carbon fiber-confined methanol obtained in S1 at a speed of 3 mL / min.

[0032] Example 3

[0033] A general method for seawater desalination based on carbon nanofiber / carbon fiber-confined materials, comprising the following steps:

[0034] S1. Prepare carbon nanofiber / carbon fiber-confined n-hexane: Evenly fill 0.35 g of carbon nanofiber / carbon fiber into a polyethersulfone membrane filter with a pore size of 0.22 μm. Load the filled membrane filter onto a syringe, and use a syringe pump to evenly push n-hexane through the membrane filter at a speed of 3 mL / min to obtain carbon nanofiber / carbon fiber-confined n-hexane. The ratio of n-hexane to carbon nanofiber / carbon fiber in the carbon nanofiber / carbon fiber-confined n-hexane is: 1 mg of carbon nanofiber / carbon fiber corresponds to 4.29 μL of n-hexane.

[0035] S2. The original pH value of the seawater sample is 8. Using a syringe pump, 5 mL of the seawater sample is evenly pushed through the carbon nanofiber / carbon fiber-confined n-hexane obtained in S1 at a speed of 3 mL / min.

[0036] Comparative Example 1

[0037] A general method for seawater desalination based on carbon fiber-confined materials, comprising the following steps:

[0038] S1. Prepare carbon fiber-confined water: Evenly fill 0.35 g of carbon fiber into a polyethersulfone membrane filter with a pore size of 0.22 μm. Load the filled membrane filter onto a syringe, and use a syringe pump to evenly push ultrapure water through the membrane filter at a speed of 3 mL / min to obtain carbon fiber-confined water. The ratio of ultrapure water to carbon fiber in the carbon fiber-confined water is: 1 mg of carbon fiber corresponds to 4.29 μL of ultrapure water.

[0039] S2. The original pH value of the seawater sample is 8. Using a syringe pump, 5 mL of the seawater sample is evenly pushed through the carbon fiber-confined water obtained in S1 at a speed of 3 mL / min.

[0040] Comparative Example 2

[0041] A general method for seawater desalination based on carbon fiber-confined materials, comprising the following steps:

[0042] S1. Preparation of carbon fiber-confined methanol: 0.35 g of carbon fiber was evenly filled into a polyethersulfone filter membrane with a pore size of 0.22 μm. The filled filter membrane was loaded onto a syringe, and methanol was uniformly pushed through the filter membrane at a speed of 3 mL / min using a syringe pump to obtain carbon fiber-confined methanol. The ratio of methanol to carbon fiber in the carbon fiber-confined methanol was: 4.29 μL of methanol corresponded to 1 mg of carbon fiber.

[0043] S2. The original pH value of the seawater sample was 8. 5 mL of the seawater sample was uniformly pushed through the carbon fiber-confined methanol obtained in S1 at a speed of 3 mL / min using a syringe pump.

[0044] Comparative Example 3

[0045] A general method for seawater desalination based on carbon fiber-confined materials, comprising the following steps:

[0046] S1. Preparation of carbon fiber-confined n-hexane: 0.35 g of carbon fiber was evenly filled into a polyethersulfone filter membrane with a pore size of 0.22 μm. The filled filter membrane was loaded onto a syringe, and n-hexane was uniformly pushed through the filter membrane at a speed of 3 mL / min using a syringe pump to obtain carbon fiber-confined n-hexane. The ratio of n-hexane to carbon fiber in the carbon fiber-confined n-hexane was: 4.29 μL of n-hexane corresponded to 1 mg of carbon fiber.

[0047] S2. The original pH value of the seawater sample was 8. 5 mL of the seawater sample was uniformly pushed through the carbon fiber-confined n-hexane obtained in S1 at a speed of 3 mL / min using a syringe pump.

[0048] Collect the filtrates of the seawater samples after filtration in Examples 1-3 and Comparative Examples 1-3, and measure the Na + and Cl - concentrations. Calculate the absorption rates of carbon nanofibers / carbon fiber-confined water and carbon fiber for Na + and Cl - in the seawater sample according to the following formula.

[0049]

[0050] In the formula, η is the absorption rate, %; C is the concentration of Na + and Cl - in the filtrate, mol / L; C 0 is the concentration of Na + and Cl - in the seawater sample, mol / L.

[0051] Figure 1 are the schematic diagrams of the results of the absorption efficiencies of different confined fluid carriers and confined solvents for Na + and Cl - , respectively.Figure 1 It can be seen that the absorption rates of carbon nanofiber / carbon fiber confined materials for Na + and Cl - are both higher than those of carbon fiber confined materials. According to the "nano-confinement effect" and the "like dissolves like principle", when carbon nanofiber / carbon fiber is used as the confined fluid carrier and ultrapure water is used as the confined solvent, the absorption rates for Na + and Cl - are the highest, about 82%.

[0052] Therefore, the present invention adopts the above general method for seawater desalination based on carbon nanofiber / carbon fiber confined materials, uses carbon nanofiber / carbon fiber as the confined fluid carrier, and uses ultrapure water, methanol or n-hexane as the extractant. It does not need to introduce chelating agents, is green and environmentally friendly, and can achieve an absorption rate of up to 82% for Na + and Cl - in seawater without consuming energy.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A general method for achieving seawater desalination based on carbon nanofiber / carbon fiber confined materials, characterized in that: The following steps are involved: S1. Preparation of carbon nanofiber / carbon fiber confined materials; S2. Adjust the pH of the seawater sample, and use a syringe pump to push the seawater sample at a uniform speed through the carbon nanofiber / carbon fiber confinement material obtained in S1.

2. A general method for achieving seawater desalination based on carbon nanofiber / carbon fiber confined materials according to claim 1, characterized in that: The specific steps of S1 are: filling the carbon nanofiber / carbon fiber evenly into the polyethersulfone filter membrane, loading the filled filter membrane onto a syringe, and using a syringe pump to push the confined solvent through the filter membrane at a uniform speed to obtain a carbon nanofiber / carbon fiber confined material.

3. A general method for achieving seawater desalination based on carbon nanofiber / carbon fiber confined materials according to claim 2, characterized in that: In S1, the confined solvent is one of ultrapure water, methanol, and n-hexane.

4. A general method for achieving seawater desalination based on carbon nanofiber / carbon fiber confined materials according to claim 2, characterized in that: In S1, the confined solvent passes through the membrane at a rate of 1-10 mL / min.

5. A general method for achieving seawater desalination based on carbon nanofiber / carbon fiber confined materials according to claim 2, characterized in that: In S1, the ratio of the confined solvent to the carbon nanofiber / carbon fiber in the carbon nanofiber / carbon fiber confined material is: 1 mg of carbon nanofiber / carbon fiber corresponds to 1.43-5.72 μL of confined solvent.

6. A general method for achieving seawater desalination based on carbon nanofiber / carbon fiber confined materials according to claim 1, characterized in that: In S2, the pH value of the seawater sample is adjusted to 3-9.

7. A general method for achieving seawater desalination based on carbon nanofiber / carbon fiber confined materials according to claim 1, characterized in that: In S2, the seawater sample passes through the membrane at a rate of 1-10 mL / min.

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