CN112569805B - Salt ion self-interception seawater desalination method based on continuous filtration method - Google Patents

Abstract

The invention discloses a salt ion self-retaining sea water desalination method based on a continuous filtration method. The size of the hydrated ions formed, the hydrated ions formed after dissolving the salt in the solution are retained, the extraction solution is collected, and the above steps are repeated until the extraction solution that meets the standard is obtained. The method of the invention can better realize seawater desalination under the filtration pressure of no more than 5 atmospheres. Compared with the traditional reverse osmosis seawater desalination technology with more than 50 atmospheres, the energy loss in the operation process is greatly reduced, and special high-pressure-resistant materials are not required. Significantly reduces operating costs, greatly reduces high-pressure safety hazards in the traditional reverse osmosis process, easy operation, simple operating conditions, and strong operating environment universality, suitable for large-scale seawater, brackish water desalination and industrial high-salt wastewater treatment, and in the chemical industry. , medicine, electronics industry water treatment has high potential.

Description

Salt ion self-retention seawater desalination method based on continuous filtration method

technical field

The invention relates to the technical field of seawater desalination and water treatment, in particular to a seawater desalination and water treatment technology based on a continuous filtration method for self-retention of salt ions.

Background technique

The shortage of freshwater resources caused by man-made and natural reasons has been seriously affecting the economic and sustainable development of society. One of the most ideal ways to solve the shortage of freshwater resources is desalination and poor-quality water treatment technology, that is, desalination of seawater or high-salinity wastewater produced by industry, production of fresh water, and increase of the total amount of fresh water to meet the ever-increasing life and work of human beings. agricultural needs. At present, the more mature seawater or brackish water desalination or high-salt wastewater treatment technologies are mainly reverse osmosis, distillation and electrodialysis, among which reverse osmosis is the most widely used seawater desalination and brackish water membrane treatment technology.

However, while the existing reverse osmosis technology has the advantages of high output water quality, simple equipment and high degree of automation, the following defects generally exist:

1. The ultra-high pressure demand is accompanied by high energy consumption, which requires a pressure of 55bar to 68bar, and the high-pressure process leads to higher requirements on the material of membrane system components and operating equipment;

2. The working and operating environment of ultra-high material service strength brings huge potential safety hazards, especially factors such as material aging and corrosion with the increase of operating time;

3. It requires cumbersome pretreatment process to maintain its long-term stable operation;

4. The pollution of the membrane is serious, and regular chemical cleaning requires a certain cost (Water Research, 2014, 66: 122).

Not only reverse osmosis technology, but traditional seawater desalination technologies, such as multi-stage flash evaporation, multi-effect evaporation and electrodialysis, all have disadvantages such as high energy consumption, high cost and harsh operating conditions to varying degrees. All of them have been transformed into high operating costs, and to a certain extent, some non-renewable resources have been consumed, resulting in environmental pollution. Therefore, it is particularly important to further search for a seawater desalination technology with low energy consumption, low cost, simple operation conditions and environmental protection, which has become an urgent technical problem to be solved.

SUMMARY OF THE INVENTION

In order to solve the problems of the prior art, the object of the present invention is to overcome the defects such as high energy consumption, high cost and harsh operating conditions in the process of seawater desalination and high-salt wastewater treatment in the prior art, and a kind of salt ion self-retention based on continuous filtration method is provided. Compared with the traditional reverse osmosis seawater desalination technology with a pressure of more than 50 atmospheres, the seawater desalination method can better achieve seawater desalination under the filtration pressure of no more than 5 atmospheres, and no special high-pressure materials are required, which greatly reduces the Loss of energy during operation. At the same time, the operation cost is significantly reduced, and the hidden danger of high pressure in the process of traditional reverse osmosis technology is greatly reduced, and the method is easy to operate, with simple operating conditions and strong operating environment. It is suitable for large-scale seawater, brackish water desalination and industrial high Salt wastewater treatment, and has high potential in water treatment in chemical, pharmaceutical, electronics and other industries.

In order to achieve the above-mentioned purpose of invention and creation, the present invention adopts the following technical solutions:

A salt ion self-retaining seawater desalination method based on a continuous filtration method, the steps are as follows:

A graphene oxide film is used as the filter membrane, and the graphene oxide film has a lamellar structure of a composite material. The graphene oxide film is infiltrated into a swollen state in an aqueous solution containing salt A, and then the graphene oxide film is subjected to positive addition. Pressure filtration, using the applied pressure to squeeze the hydrated ions formed after the dissolution of the salt A in the graphene oxide film, so that the hydrated ions are deformed, thereby reducing the size of the hydrated ions entering the graphene oxide film, reducing the inner lamellae The distance between, thereby the larger hydrated ion formed after the salt A dissolves in the interception solution, collects the drawing liquid that penetrates the graphene oxide film; Then the drawing liquid is used as the salt solution to be treated for carrying out the next filtration process, The above steps are repeated, and continuous filtration is performed until a drawing solution that meets the standard is obtained, thereby completing the desalination process of the salt-containing aqueous solution.

Preferably, in the aqueous solution containing the salt A, the cation concentration is 0.015-0.6 mol/L.

Preferably, an aqueous microporous filter membrane with a pore size of not more than 0.45 μm is used as the supporting base membrane of the graphene oxide film, and a filter membrane suction filtration method is used to filter the graphene oxide solution, and the graphene oxide deposition is trapped as a support. A graphene oxide film with a thickness of 100-2500 nm with a composite sheet structure is prepared. The graphene oxide film should have a smooth surface and no obvious defects, and the preferred thickness of the graphene oxide film is 100-250 μm.

Preferably, in the preparation process of the graphene oxide film, the concentration of the graphene oxide solution is 1-15 mg/mL; a better concentration of the graphene oxide solution is 3-5 mg/mL.

Preferably, in the preparation process of the graphene oxide film, the oxidation degree of graphene oxide in the graphene oxide solution is 20-55%. More preferably, the oxidation degree of the graphene oxide solution is 30-55%, and even more preferably, the oxidation degree of the graphene oxide solution is 50-55%.

Preferably, in order to ensure that the graphene oxide film is fully swollen to ensure a better self-retention effect, during the infiltration process, the temperature of the aqueous solution containing the salt A to be treated is controlled to be 15-25°C. The more preferable temperature of the aqueous solution containing salt A is 18-22°C, and the especially preferable temperature of the aqueous solution containing salt A is 20°C.

Preferably, in order to ensure that the graphene oxide film is completely swollen to ensure a better self-interception effect, in the infiltration process, the immersion time is controlled to be 0.2-1 h.

Preferably, in order to ensure that the filtration desalination efficiency reaches the hydrated ions formed after the dissolution of the salt A in the extrusion membrane, the hydrated ions are deformed, and the energy consumption is reduced at the same time, during the pressure filtration process, the salt A-containing aqueous solution is The applied pressure is 0.05 to 0.5 MPa.

Preferably, the ions in the aqueous solution containing the salt A comprise any one or any plurality of ions among inorganic cations and inorganic anions.

Preferably, the inorganic cation is any one or any multiple ions of Mg ²⁺ , Zn ²⁺ , Ca ²⁺ , Li ⁺ , K ⁺ , Na ⁺ , and NH ₄ ⁺ .

Preferably, the inorganic anion is any one or any multiple ions of F ^- , Cl ^- , Br ^- , I ^- , PO ₄ ^3- , SO ₄ ^2- , CO ₃ ^2- , NO ₃ ^- .

Preferably, the pH in the aqueous solution containing the salt A is 6-13; the preferred pH is 5-8; the optimum pH is 7.

Preferably, the salt A of the salt A-containing aqueous solution is any one or any multiple salts of NaCl, KCl, LiCl, MgCl ₂ and CaCl ₂ .

Preferably, the number of times of repeated interception depends on the salt concentration in the drawing solution after each pressure filtration, until the obtained drawing solution meets the required salt concentration standard, thereby completing the desalination process of the saline solution.

Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant advantages:

1. the inventive method, under the filtration pressure of no more than 5 atmospheres, uses the salt ion itself in the saline solution to improve the retention effect of the graphene oxide film, and realizes the treatment of seawater desalination and high-salt industrial waste water;

2. Compared with the traditional reverse osmosis seawater desalination technology with a pressure of more than 50 atmospheres, the method of the present invention greatly reduces the energy loss during operation; at the same time, due to the significant drop in the operating pressure, the selectivity of the system component materials is more extensive, no longer necessary. Special high-pressure-resistant materials are required, which significantly reduces operating costs and greatly reduces the hidden dangers of high-pressure safety in the process of traditional reverse osmosis technology;

3. The method of the present invention is easy to operate, has simple operating conditions, and has strong operating environment universality, is suitable for large-scale seawater, brackish water desalination and industrial high-salt wastewater treatment, and has relatively high performance in water treatment in chemical, pharmaceutical, electronic and other industries. High potential, suitable for promotion and use.

Description of drawings

Fig. 1 is the interception rate situation of each time when the aqueous solution containing NaCl with a concentration of 0.6 mol/L is intercepted to the fresh water standard in Example 1 of the present invention

Fig. 2 is the concentration situation of drawing liquid after each interception of using the NaCl-containing aqueous solution of concentration 0.6mol/L to be intercepted to the fresh water standard in Example 1 of the present invention.

Fig. 3 is the water flux of each filtration using an aqueous solution containing NaCl with a concentration of 0.6 mol/L in Example 1 of the present invention.

Fig. 4 is the interception rate situation of using the KCl-containing aqueous solution with a concentration of 0.1 mol/L in Example 2 of the present invention to be intercepted to a lower concentration standard each time.

Fig. 5 is in the embodiment of the present invention 2 using the KCl-containing aqueous solution with a concentration of 0.1 mol/L to be intercepted to a lower concentration standard after each interception of the concentration of the drawn liquid.

FIG. 6 is the water flux of each filtration using an aqueous solution containing KCl with a concentration of 0.1 mol/L in Example 2 of the present invention.

FIG. 7 shows the situation of each time the interception rate of using the LiCl-containing aqueous solution with a concentration of 0.1 mol/L is intercepted to a lower concentration standard in Example 3 of the present invention.

FIG. 8 shows the concentration of the extracted solution after each interception of an aqueous solution containing LiCl with a concentration of 0.1 mol/L that is trapped to a lower concentration standard in Example 3 of the present invention.

FIG. 9 shows the water flux of each filtration using an aqueous solution containing LiCl with a concentration of 0.1 mol/L in Example 3 of the present invention.

Fig. 10 is the situation that the aqueous solution containing MgCl ₂ with a concentration of 0.1 mol/L is intercepted to a lower concentration standard in Example 4 of the present invention.

Fig. 11 is the concentration situation of the drawing liquid after each interception of the aqueous solution containing MgCl with a concentration of 0.1 mol/L being trapped to a lower concentration standard in Example ₄ of the present invention.

Figure 12 shows the water flux of each filtration using an aqueous solution containing MgCl ₂ with a concentration of 0.1 mol/L in Example 4 of the present invention.

Fig. 13 shows the situation of the interception rate of each time when the aqueous solution containing CaCl ₂ with a concentration of 0.1 mol/L is intercepted to a lower concentration standard in Example 5 of the present invention

FIG. 14 is the concentration situation of the drawn liquid after each interception of the aqueous solution containing CaCl ₂ with a concentration of 0.1 mol/L being trapped to a lower concentration standard in Example 5 of the present invention.

Figure 15 shows the water flux of each filtration using an aqueous solution containing CaCl ₂ with a concentration of 0.1 mol/L in Example 5 of the present invention.

Figure 16 is a schematic structural diagram of the continuous filtering device used in the method of the present invention.

Detailed ways

The present invention is further described below by way of examples, but the present invention is not limited to the scope of the described examples. In the following examples, the experimental methods without specific conditions are selected according to conventional methods and conditions, or according to the product description.

In the following examples, the graphene oxide solution used was purchased from Jiangsu Wuxi Huaxin Detection Technology Co., Ltd. The concentration of each ion in the extraction solution was measured using an ICP spectrometer of Leeman Company in the United States.

The above scheme will be further described below in conjunction with specific embodiments, and preferred embodiments of the present invention are described in detail as follows:

Example 1

In the present embodiment, referring to Fig. 1, Fig. 2 and Fig. 3, a salt ion self-retaining seawater desalination method based on a continuous filtration method, the steps are as follows:

a. Preparation of graphene oxide films:

An aqueous microporous membrane with a pore size of 0.45 μm was used as the supporting base membrane, and the membrane suction filtration method was used to filter a graphene oxide solution with a concentration of 5 mg/mL and a degree of oxidation of 55%, and the graphene oxide deposits were trapped in On the water-based microporous filter membrane as a supporting substrate, a graphene oxide film with a thickness of 2500 nm having a composite lamella structure is prepared for use;

b. Desalination process of brine solution:

The solution to be treated is a NaCl solution with a concentration of 0.6 mol/L, the pH of the NaCl solution is adjusted to 7, the graphene oxide film is soaked in the NaCl solution for 0.5 h, and the temperature of the NaCl solution is controlled to 20 °C, so that the graphene oxide film is fully Swelling, then the graphene oxide film is subjected to positive pressure filtration, and under the pressure of 0.1MPa, the hydrated ions formed after the dissolution of NaCl in the graphene oxide film is extruded, so that the hydrated ions are deformed, thereby reducing the amount of entering The size of the hydrated ions in the graphene oxide film reduces the distance between the sheets in the film, thereby retaining the larger size hydrated ions formed after the dissolution of NaCl in the solution, collecting the extraction liquid passing through the graphene oxide film and measuring the ions in it Concentration, record the water flux and the salt retention rate of this filtration; then draw the liquid as the salt solution to be treated for carrying out the next filtration process, repeat the above steps, carry out continuous filtration, until the ^Na concentration in the draw liquid is lower than 0.017 M, thereby completing the desalination process of the brine solution.

Experimental test analysis:

It can be seen from Figure 1, Figure 2 and Figure 3 that this example maintains a relatively high retention rate for each filtration, and the water flux shows an overall upward trend with the decrease in the concentration of the added salt solution. The number of times of repeated interception depends on the salt concentration in the drawing solution after each pressure filtration, until the obtained drawing solution meets the required salt concentration standard, thereby completing the desalination process of the saline solution. Compared with the traditional reverse osmosis seawater desalination technology with a pressure of more than 50 atmospheres, the method of this embodiment can better achieve seawater desalination under the filtration pressure of no more than 5 atmospheres, and no special high-pressure materials are needed, which greatly reduces the operation time. energy loss in the process. The operation cost is significantly reduced, the hidden danger of high pressure in the process of the traditional reverse osmosis technology is greatly reduced, and the method is easy to operate, the operation conditions are simple, and the operation environment is widely applicable.

Example 2

This embodiment is basically the same as Embodiment 1, and the special features are:

In this embodiment, referring to Fig. 4, Fig. 5 and Fig. 6, a salt ion self-retaining seawater desalination method based on a continuous filtration method, the steps are as follows:

a. Preparation of graphene oxide films:

An aqueous microporous membrane with a pore size of 0.45 μm was used as the supporting base membrane, and the membrane suction filtration method was used to filter a graphene oxide solution with a concentration of 5 mg/mL and a degree of oxidation of 55%, and the graphene oxide deposits were trapped in On the water-based microporous filter membrane as a supporting substrate, a graphene oxide film with a thickness of 2500 nm having a composite lamella structure is prepared for use;

b. Desalination process of brine solution:

The solution to be treated is a KCl solution with a concentration of 0.1 mol/L, the pH of the KCl solution is adjusted to 7, the graphene oxide film is soaked in the KCl solution for 0.5 h, and the temperature of the KCl solution is controlled to be 20 °C, so that the graphene oxide film is fully Swell, and then filter the graphene oxide film under positive pressure. Under the pressure of 0.1MPa, squeeze the hydrated ions formed after the KCl in the graphene oxide film is dissolved, so that the hydrated ions are deformed, thereby reducing the entry of the hydrated ions. The size of the hydrated ions in the graphene oxide film reduces the distance between the sheets in the film, thereby retaining the larger size hydrated ions formed after KCl is dissolved in the solution, collecting the drawing liquid passing through the graphene oxide film and measuring the ions in it Concentration, record the water flux and the salt retention rate of this filtration; then draw the liquid as the salt solution to be treated to carry out the next filtration process, repeat the above steps, carry out continuous filtration, until the ^K concentration in the draw liquid is lower than 0.017 M, thereby completing the desalination process of the brine solution.

Experimental test analysis:

It can be seen from Figure 4, Figure 5 and Figure 6 that the retention rate of K ⁺ in this example fluctuates around 25%, the retention rate is relatively stable, and the water flux shows an overall upward trend with the decrease of the added salt solution concentration. The number of times of repeated interception depends on the salt concentration in the drawing solution after each pressure filtration, until the obtained drawing solution meets the required salt concentration standard, thereby completing the desalination process of the saline solution. Compared with the traditional reverse osmosis seawater desalination technology with a pressure of more than 50 atmospheres, the method of this embodiment can better achieve seawater desalination under the filtration pressure of no more than 5 atmospheres, and no special high-pressure materials are needed, which greatly reduces the operation time. energy loss in the process. The operation cost is significantly reduced, the hidden danger of high pressure in the process of the traditional reverse osmosis technology is greatly reduced, and the method is easy to operate, the operation conditions are simple, and the operation environment is widely applicable.

Example 3

This embodiment is basically the same as the previous embodiment, and the special features are:

In this embodiment, referring to Fig. 7, Fig. 8 and Fig. 9, a salt ion self-retaining seawater desalination method based on a continuous filtration method, the steps are as follows:

a. Preparation of graphene oxide film:

An aqueous microporous membrane with a pore size of 0.45 μm was used as the supporting base membrane, and the membrane suction filtration method was used to filter a graphene oxide solution with a concentration of 5 mg/mL and a degree of oxidation of 55%, and the graphene oxide deposits were trapped in On the water-based microporous filter membrane as a supporting substrate, a graphene oxide film with a thickness of 2500 nm having a composite lamella structure is prepared for use;

b. Desalination process of brine solution:

The solution to be treated is a LiCl solution with a concentration of 0.1 mol/L, the pH of the LiCl solution is adjusted to 7, the graphene oxide film is soaked in the LiCl solution for 0.5 h, and the temperature of the LiCl solution is controlled to 20 ° C, so that the graphene oxide film is fully Swell, and then filter the graphene oxide film under positive pressure. Under the pressure of 0.1MPa, squeeze the hydrated ions formed after the dissolution of LiCl in the graphene oxide film, so that the hydrated ions are deformed, thereby reducing the amount of entering The size of the hydrated ions in the graphene oxide film reduces the distance between the sheets in the film, thereby retaining the larger size hydrated ions formed after the dissolution of LiCl in the solution, collecting the extraction liquid passing through the graphene oxide film and measuring the ions in it Concentration, record the water flux and salt retention rate of this filtration; then draw the liquid as the to-be ^- treated salt solution for the next filtration process, repeat the above steps, carry out continuous filtration, until the Li concentration in the drawn liquid is lower than 0.017 M, thereby completing the desalination process of the brine solution.

Experimental test analysis:

It can be seen from Figure 7, Figure 8 and Figure 9 that the retention rate of this example increases with the increase of the number of filtrations, and the water flux shows an overall upward trend with the decrease of the added salt solution concentration. The number of times of repeated interception depends on the salt concentration in the drawing solution after each pressure filtration, until the obtained drawing solution meets the required salt concentration standard, thereby completing the desalination process of the saline solution. Compared with the traditional reverse osmosis seawater desalination technology with a pressure of more than 50 atmospheres, the method of this embodiment can better achieve seawater desalination under the filtration pressure of no more than 5 atmospheres, and no special high-pressure materials are needed, which greatly reduces the operation time. energy loss in the process. The operation cost is significantly reduced, the hidden danger of high pressure in the process of the traditional reverse osmosis technology is greatly reduced, and the method is easy to operate, the operation conditions are simple, and the operation environment is widely applicable.

Example 4

This embodiment is basically the same as the previous embodiment, and the special features are:

In this embodiment, referring to Fig. 10, Fig. 11 and Fig. 12, a salt ion self-retaining seawater desalination method based on a continuous filtration method, the steps are as follows:

a. Preparation of graphene oxide film:

An aqueous microporous membrane with a pore size of 0.45 μm was used as the supporting base membrane, and the membrane suction filtration method was used to filter a graphene oxide solution with a concentration of 5 mg/mL and a degree of oxidation of 55%, and the graphene oxide deposits were trapped in On the water-based microporous filter membrane as a supporting substrate, a graphene oxide film with a thickness of 2500 nm having a composite lamella structure is prepared for use;

b. Desalination process of brine solution:

The solution to be treated is a MgCl _{2 solution with a concentration of 0.1 mol/L, the pH of the MgCl 2 solution} is adjusted to 6, the graphene oxide film is soaked in the MgCl ₂ solution for 0.5h, and the temperature of the MgCl ₂ solution is controlled to 20 ° C to make the oxidation The graphene film is fully swollen, and then the graphene oxide film is subjected to positive pressure filtration. Under the pressure of 0.1 MPa, the hydrated ions formed after the dissolution of MgCl in the graphene _oxide film is extruded to deform the hydrated ions. , thereby reducing the size of the hydrated ions entering the graphene oxide film, reducing the distance between the sheets in the film, thereby intercepting the larger hydrated _ions formed after the dissolution of MgCl in the solution, and collecting the hydrated ions that pass through the graphene oxide film. Draw the liquid and measure the ion concentration therein, record the water flux and salt retention rate of this filtration; then use the drawn liquid as the salt solution to be treated for carrying out the next filtration process, repeat the above steps, and carry out continuous filtration until the liquid is drawn. The Mg ²⁺ concentration is lower than 0.017M, thus completing the desalination process of the brine solution.

Experimental test analysis:

It can be seen from Figure 10, Figure 11 and Figure 12 that the retention rate of Mg ²⁺ in this example fluctuated around 25%, the retention rate was relatively stable, and the water flux showed an overall upward trend as the concentration of the added salt solution decreased. The number of times of repeated interception depends on the salt concentration in the drawing solution after each pressure filtration, until the obtained drawing solution meets the required salt concentration standard, thereby completing the desalination process of the saline solution. Compared with the traditional reverse osmosis seawater desalination technology with a pressure of more than 50 atmospheres, the method of this embodiment can better achieve seawater desalination under the filtration pressure of no more than 5 atmospheres, and no special high-pressure materials are needed, which greatly reduces the operation time. energy loss in the process. The operation cost is significantly reduced, the hidden danger of high pressure in the process of the traditional reverse osmosis technology is greatly reduced, and the method is easy to operate, the operation conditions are simple, and the operation environment is widely applicable.

Example 5

In this embodiment, referring to Fig. 13, Fig. 14 and Fig. 15, a salt ion self-retaining seawater desalination method based on a continuous filtration method, the steps are as follows:

a. Preparation of graphene oxide film:

An aqueous microporous membrane with a pore size of 0.45 μm was used as the supporting base membrane, and the membrane suction filtration method was used to filter a graphene oxide solution with a concentration of 5 mg/mL and a degree of oxidation of 55%, and the graphene oxide deposits were trapped in On the water-based microporous filter membrane as a supporting substrate, a graphene oxide film with a thickness of 2500 nm having a composite lamella structure is prepared for use;

b. Desalination process of brine solution:

The solution to be treated is a CaCl _{2 solution with a concentration of 0.1 mol/L, the pH of the CaCl 2 solution} is adjusted to 6, the graphene oxide film is soaked in the CaCl ₂ solution for 0.5h, and the temperature of the CaCl ₂ solution is controlled to be 20 ° C to make the oxidation The graphene film is fully swollen, and then the graphene oxide film is subjected to positive pressure filtration. Under the pressure of 0.1MPa, the hydrated ions formed after the dissolution of _CaCl2 in the graphene oxide film is extruded, so that the hydrated ions are deformed. , thereby reducing the size of the hydrated ions entering the graphene oxide film and reducing the distance between the sheets in the film, thereby intercepting the larger hydrated _ions formed after the dissolution of CaCl in the solution, and collecting the hydrated ions that pass through the graphene oxide film. Draw the liquid and measure the ion concentration therein, record the water flux and salt retention rate of this filtration; then use the drawn liquid as the salt solution to be treated for carrying out the next filtration process, repeat the above steps, and carry out continuous filtration until the liquid is drawn. The Ca ²⁺ concentration is lower than 0.017M, thus completing the desalination process of the brine solution.

Experimental test analysis:

It can be seen from Figure 13, Figure 14 and Figure 15 that the retention rate of Ca ²⁺ in this example fluctuates around 20%, and the retention rate is relatively stable. Case. The number of times of repeated interception depends on the salt concentration in the drawing solution after each pressure filtration, until the obtained drawing solution meets the required salt concentration standard, thereby completing the desalination process of the saline solution. Compared with the traditional reverse osmosis seawater desalination technology with a pressure of more than 50 atmospheres, the method of this embodiment can better achieve seawater desalination under the filtration pressure of no more than 5 atmospheres, and no special high-pressure materials are needed, which greatly reduces the operation time. energy loss in the process. The operation cost is significantly reduced, the hidden danger of high pressure in the process of the traditional reverse osmosis technology is greatly reduced, and the method is easy to operate, the operation conditions are simple, and the operation environment is widely applicable.

Example 6

This embodiment is basically the same as the previous embodiment, and the special features are:

In the present embodiment, a salt ion self-retaining seawater desalination method based on a continuous filtration method, the steps are as follows:

a. Preparation of graphene oxide film:

An aqueous microporous filter membrane with a pore size of 0.45 μm was used as the supporting base membrane, and the membrane suction filtration method was used to filter a graphene oxide solution with a concentration of 3 mg/mL and a degree of oxidation of 30%, and the graphene oxide deposition was trapped in On the water-based microporous filter membrane as the supporting substrate, a graphene oxide film with a thickness of 100 nm having a composite lamella structure is prepared, for use;

b. Desalination process of brine solution:

The solution to be treated is a NaCl solution with a concentration of 0.1 mol/L, the pH of the NaCl solution is adjusted to 6, the graphene oxide film is immersed in the NaCl solution for 1 h, and the temperature of the NaCl solution is controlled to 22 °C, so that the graphene oxide film is fully swollen Then, the graphene oxide film is subjected to positive pressure filtration. Under the pressure of 0.5MPa, the hydrated ions formed after the dissolution of NaCl in the graphene oxide film is extruded, so that the hydrated ions are deformed, thereby reducing the amount of water entering the oxide film. The size of the hydrated ions in the graphene film reduces the distance between the sheets in the film, thereby retaining the larger hydrated ions formed after the NaCl dissolves in the solution, collects the extraction solution that passes through the graphene oxide film and measures the ion concentration. , record the water flux and the salt retention rate of this filtration; then draw the liquid as the salt solution to be treated for the next filtration process, repeat the above steps, carry out continuous filtration, until the Na concentration in the drawn liquid is lower than ^0.017M , so as to complete the desalination process of the brine solution.

Experimental test analysis:

In this example, a relatively high retention rate was maintained for each filtration, and the water flux showed an overall upward trend as the concentration of the added salt solution decreased. The number of times of repeated interception depends on the salt concentration in the drawing solution after each pressure filtration, until the obtained drawing solution meets the required salt concentration standard, thereby completing the desalination process of the saline solution. Compared with the traditional reverse osmosis seawater desalination technology with a pressure of more than 50 atmospheres, the method of this embodiment can better achieve seawater desalination under the filtration pressure of no more than 5 atmospheres, and no special high-pressure materials are needed, which greatly reduces the operation time. energy loss in the process. The operation cost is significantly reduced, the hidden danger of high pressure in the process of the traditional reverse osmosis technology is greatly reduced, and the method is easy to operate, the operation conditions are simple, and the operation environment is widely applicable.

Example 7

This embodiment is basically the same as the previous embodiment, and the special features are:

In the present embodiment, referring to FIG. 11 , a salt ion self-retaining seawater desalination method based on a continuous filtration method adopts a graphene oxide film as a filter film, and the graphene oxide film is respectively installed in each of the continuous filtration devices of FIG. 11 . In the first-stage filtration device, the brine-containing water to be treated enters from the water inlet of the first-stage filtration unit, and is filtered through the first-stage graphene oxide film, and the first-stage drawing liquid continues to enter the second-stage filtration unit, and continues to filter. Collect the drawing liquid of each grade of filtration unit through the graphene oxide film and measure the ion concentration, record the water flux and salt rejection rate of this filtration, and the number of times of repeated interception or the number of stages of the filtration unit depends on each time. After the pressure filtration, the salt concentration in the liquid is drawn, until the obtained drawn liquid meets the required salt concentration standard, thereby completing the desalination process of the salt-containing aqueous solution.

The present embodiment is a salt ion self-retaining seawater desalination method based on a continuous filtration method. The graphene oxide film has a lamellar structure of a composite material. The graphene oxide film is infiltrated in an aqueous solution containing salt A to a swollen state, and then The graphene oxide film is subjected to positive pressure filtration, and the hydrated ions formed after dissolving the salt A in the graphene oxide film are extruded by the applied pressure, so that the hydrated ions are deformed, thereby reducing the amount of water entering the graphene oxide film. The size of the hydrated ions reduces the distance between the sheets in the membrane, thereby retaining the larger hydrated ions formed after dissolving the salt A in the solution, and collecting the drawing solution that penetrates the graphene oxide film; then the drawing solution is used as the next time The salt solution to be treated in the treatment process is filtered, the above steps are repeated, and continuous filtration is performed until a drawing solution that meets the standard is obtained, thereby completing the desalination process of the salt-containing aqueous solution.

The salt ion self-retention seawater desalination technology based on the continuous filtration method in this embodiment can better achieve seawater desalination under the filtration pressure of not more than 5 atmospheres. Compared with the traditional reverse osmosis seawater desalination technology with a pressure of more than 50 atmospheres, It greatly reduces the energy loss during operation, does not require special high-pressure-resistant materials, significantly reduces operating costs, and greatly reduces the high-pressure safety hazards in the process of traditional reverse osmosis technology. The method is easy to operate, with simple operating conditions and a universal operating environment. It has strong properties and is suitable for large-scale seawater, brackish water desalination and industrial high-salt wastewater treatment, and has high potential for water treatment in chemical, pharmaceutical, electronic and other industries.

The embodiments of the present invention have been described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and various changes can also be made according to the purpose of the invention and creation of the present invention. Changes, modifications, substitutions, combinations or simplifications should be equivalent substitution methods, as long as they meet the purpose of the present invention, as long as they do not deviate from the technical principles and inventive concepts of the present invention, all belong to the protection scope of the present invention.

Claims (8)

1. A salt ion self-interception seawater desalination method based on a continuous filtration method is characterized by comprising the following steps:

the method comprises the steps of taking a graphene oxide film as a filter membrane, wherein the graphene oxide film has a laminated structure made of composite materials, soaking the graphene oxide film in a saline A water solution to a swelling state, then carrying out forward pressure filtration on the graphene oxide film, wherein in the pressure filtration process, the pressure applied to the saline A water solution is 0.05-0.5 MPa, and extruding hydrated ions formed after the saline A in the graphene oxide film is dissolved by utilizing the applied pressure to deform the hydrated ions, so that the size of the hydrated ions entering the graphene oxide film is reduced, the distance between laminated layers in the film is reduced, the hydrated ions with larger size formed after the saline A in the solution is dissolved are intercepted, and a drawing liquid penetrating through the graphene oxide film is collected; and then, taking the drawing liquid as a saline solution to be treated in the next filtering treatment process, repeating the steps, and continuously filtering until the drawing liquid meeting the standard is obtained, thereby completing the desalting process of the saline solution.

2. The method for desalinating seawater by self-interception of salt ions according to claim 1, wherein the concentration of cations in the aqueous solution containing salt A is 0.015-0.6 mol/L.

3. The salt ion self-interception seawater desalination method based on the continuous filtration method as claimed in claim 1, wherein a water system microporous filter membrane with pore size not greater than 0.45 μm is used as a support base membrane of the graphene oxide film, the graphene oxide solution is subjected to suction filtration by a membrane suction filtration method, and the graphene oxide is deposited and intercepted on the water system microporous filter membrane used as the support base membrane, so as to prepare the graphene oxide film with composite lamellar structure and thickness of 100-2500 nm.

4. The salt ion self-interception seawater desalination method based on the continuous filtration method according to claim 3, wherein the concentration of the graphene oxide solution is 1-15 mg/mL in the preparation process of the graphene oxide film;

or in the preparation process of the graphene oxide film, the oxidation degree of graphene oxide in the graphene oxide solution is 20-55%.

5. The method for desalinating the seawater by self-interception of salt ions based on the continuous filtration method according to claim 1, wherein in the infiltration process, the temperature of the aqueous solution containing salt A to be treated is controlled to be 15-25 ℃;

or, in the soaking process, the soaking time is controlled to be 0.2-1 h.

6. The method for desalinating seawater by self-interception of salt ions according to claim 1, wherein said ions in said aqueous solution containing salt a comprise any one or more ions selected from the group consisting of inorganic cations and inorganic anions.

7. The method for desalinating seawater by self-interception of salt ions according to claim 6, wherein said inorganic cation is Mg²⁺、Zn²⁺、Ca²⁺、Li⁺、K⁺、Na⁺、NH₄ ⁺Any one or any plurality of ions of (a);

alternatively, the inorganic anion is F^-、Cl^-、Br^-、I^-、PO₄ ^3-、SO₄ ^2-、CO₃ ^2-、NO₃ ^-Any one or any plurality of ions of (a);

or the pH value of the salt A-containing aqueous solution is 6-13.

8. The method for desalinating seawater by self-interception of salt ions based on a continuous filtration process according to claim 6, wherein said salt A comprising an aqueous salt A solution is a salt A comprising NaCl, KCl, LiCl, MgCl₂And CaCl₂Any one or any plurality of salts of (a).

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