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

Salt ion self-interception seawater desalination method based on continuous filtration method Download PDF

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CN112569805B
CN112569805B CN202011164746.8A CN202011164746A CN112569805B CN 112569805 B CN112569805 B CN 112569805B CN 202011164746 A CN202011164746 A CN 202011164746A CN 112569805 B CN112569805 B CN 112569805B
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CN112569805A (en
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石国升
陈俊杰
丁洲乐
刘星
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University of Shanghai for Science and Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
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    • C—CHEMISTRY; METALLURGY
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    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08—Seawater, e.g. for desalination
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F2301/066—Overpressure, high pressure
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    • Y02A20/131—Reverse-osmosis

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Abstract

The invention discloses a salt ion self-retention seawater desalination method based on a continuous filtration method, which comprises the steps of soaking a graphene oxide film in a saline water solution to a swelling state, carrying out forward pressure filtration, reducing the size of hydrated ions formed after salt in the film is dissolved by using film pressure, retaining the hydrated ions formed after the salt in the solution is dissolved, collecting an extraction solution, and repeating the steps until the extraction solution meeting the standard is obtained. The method disclosed by the invention can better realize seawater desalination under the filtering pressure of not more than 5 atmospheric pressures, greatly reduces the energy loss in the operation process, does not need special high-pressure-resistant materials, obviously reduces the operation cost, greatly reduces the high-pressure potential safety hazard in the traditional reverse osmosis process, is easy to operate, simple in operation condition and strong in universality of the operation environment, is suitable for large-scale seawater and brackish water desalination and industrial high-salt wastewater treatment, and has higher potential in the aspect of water treatment in the chemical industry, the medical industry and the electronic industry compared with the traditional reverse osmosis seawater desalination technology with more than 50 atmospheric pressures.

Description

Salt ion self-interception 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 salt ion self-interception seawater desalination and water treatment technology based on a continuous filtration method.
Background
The shortage problem of fresh water resources caused by human and natural reasons has seriously influenced the economic and sustainable development of society. One of the most ideal ways to solve the problem of shortage of fresh water resources is the seawater desalination and poor quality water treatment technologies, i.e. desalination of seawater or industrially produced high salinity wastewater to produce fresh water, increasing the total amount of fresh water, so as to meet the increasing demands of human beings on life, industry and agriculture. At present, the mature technology for desalinating seawater or brackish water or treating high-salinity wastewater mainly comprises a reverse osmosis method, a distillation method, an electrodialysis method and the like, wherein the reverse osmosis method is the most widely applied technology for desalinating seawater and treating brackish water by using a membrane at present.
However, the existing reverse osmosis technology has the advantages of high produced water quality, simple equipment, high automation degree and the like, and simultaneously has the following defects:
1. the ultrahigh pressure requirement is accompanied by higher energy consumption, the pressure is 55 bar-68 bar, and the high-pressure process causes higher requirements on membrane system components and operation equipment materials;
2. the working operation environment with ultrahigh service strength of the material brings huge potential safety hazards, particularly factors such as material aging and corrosion along with the increase of the operation time;
3. a complex pretreatment process flow is required to maintain the long-term stable operation;
4. the fouling of the membrane is severe and regular chemical cleaning requires a certain cost (Waterresearch,2014,66: 122).
Not only reverse osmosis techniques, but also traditional desalination techniques such as: the defects of high energy consumption, high cost, severe operating environment conditions and the like exist in different degrees of multi-stage flash evaporation, multi-effect evaporation, electrodialysis and the like, the defects are converted into high operating cost, part of non-renewable resources are consumed to a certain degree, and environmental pollution is caused. Therefore, it becomes important to further find a low-energy consumption, low-cost, simple-operation-condition and environment-friendly seawater desalination technology, which becomes a technical problem to be solved urgently.
Disclosure of Invention
In order to solve the problems of the prior art, the invention aims to overcome the defects of high energy consumption, high cost, harsh operating conditions and the like in the seawater desalination and high-salinity wastewater treatment processes in the prior art, and provides a salt ion self-interception seawater desalination method based on a continuous filtration method, which can better realize seawater desalination under the filtration pressure of not more than 5 atmospheres compared with the traditional reverse osmosis seawater desalination technology exceeding 50 atmospheres, does not need special high-pressure-resistant materials, and greatly reduces the energy loss in the operating process. Meanwhile, the operation cost is obviously reduced, the high-pressure potential safety hazard in the traditional reverse osmosis technical process is greatly reduced, the method is easy to operate, simple in operation condition and strong in universality of operation environment, is suitable for large-scale seawater and brackish water desalination and industrial high-salinity wastewater treatment, and has high potential in the aspect of water treatment in the industries such as chemical industry, medicine, electronics and the like.
In order to achieve the purpose of the invention, the invention adopts the following technical scheme:
a salt ion self-interception seawater desalination method based on a continuous filtration method comprises 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 aqueous solution to a swelling state, then carrying out forward pressure filtration on the graphene oxide film, extruding hydrated ions formed after salt A in the graphene oxide film is dissolved by using the added pressure, and enabling the hydrated ions to deform, so that the size of the hydrated ions entering the graphene oxide film is reduced, the distance between the laminated layers in the membrane is reduced, the hydrated ions with larger sizes formed after the salt A in the solution is dissolved are intercepted, and collecting a drawing liquid penetrating through the graphene oxide film; and then taking the drawing liquid as a saline solution to be treated for the next filtration treatment process, repeating the steps, and continuously filtering until the drawing liquid meeting the standard is obtained, thereby completing the desalination process of the saline solution.
Preferably, the concentration of cations in the salt A-containing aqueous solution is 0.015-0.6 mol/L.
Preferably, a water system microporous filter membrane with the pore diameter not greater than 0.45 μm is used as a support base membrane of the graphene oxide film, a filter membrane suction filtration method is adopted to suction-filter the graphene oxide solution, and the graphene oxide is deposited and retained on the water system microporous filter membrane used as the support base membrane, so that the graphene oxide film with the composite lamellar structure and the thickness of 100-2500nm is prepared. The graphene oxide film has a smooth surface without obvious defects, and the thickness of the graphene oxide film is preferably 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; the concentration of the graphene oxide solution is more preferably 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%. The oxidation degree of the graphene oxide solution is preferably 30 to 55%, and more preferably 50 to 55%.
Preferably, in order to ensure that the graphene oxide film is fully swelled to ensure that a better self-interception effect is achieved, in the infiltration process, the temperature of the saline A-containing aqueous solution to be treated is controlled to be 15-25 ℃. More preferably, the temperature of the salt A-containing aqueous solution is 18-22 ℃, and even more preferably, the temperature of the salt A-containing aqueous solution is 20 ℃.
Preferably, in order to ensure that the graphene oxide film is completely swelled so as to ensure that a better self-interception effect is achieved, the soaking time is controlled to be 0.2-1h in the soaking process.
Preferably, in order to ensure that the filtration and desalination efficiency reaches the effect of forming hydrated ions after the salt a in the extrusion membrane is dissolved, so that the hydrated ions deform, and reduce energy consumption, in the pressure filtration process, the pressure applied to the salt-containing a aqueous solution is 0.05-0.5 MPa.
Preferably, the ions in the aqueous solution containing salt a comprise any one or any plurality of ions of inorganic cations and inorganic anions.
Preferably, the inorganic cation is Mg2+、Zn2+、Ca2+、Li+、K+、Na+、NH4 +Any one or any plurality of ions in (b).
Preferably, the inorganic anion is F-、Cl-、Br-、I-、PO4 3-、SO4 2-、CO3 2-、NO3 -Any one or any plurality of ions in (b).
Preferably, the pH value of the salt A-containing aqueous solution is 6-13; the preferable pH value is 5-8; the optimum pH is 7.
Preferably, the salt A of the salt-containing A aqueous solution is NaCl, KCl, LiCl or MgCl2And CaCl2Any one or any plurality of salts of (a).
Preferably, the repeated interception is carried out for a number of times depending on the salt concentration in the draw solution after each pressure filtration until the obtained draw solution meets the required salt concentration standard, thereby completing the desalination process of the saline solution.
Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:
1. according to the method, under the filtering pressure of not more than 5 atmospheres, the salt ions in the saline solution are used for improving the interception effect of the graphene oxide film, so that seawater desalination and high-salt industrial wastewater treatment are realized;
2. compared with the traditional reverse osmosis seawater desalination technology with the atmospheric pressure of more than 50, the method greatly reduces the energy loss in the operation process; meanwhile, due to the obvious reduction of the operation pressure, the selectivity of system component materials is wider, special high-pressure-resistant materials are not needed any more, the operation cost is obviously reduced, and the high-pressure potential safety hazard in the traditional reverse osmosis technical process is greatly reduced;
3. the method disclosed by the invention is easy to operate, simple in operation condition and strong in universality of operation environment, is suitable for large-scale seawater and brackish water desalination and industrial high-salinity wastewater treatment, has higher potential in the aspect of water treatment in the industries such as chemical industry, medicine and electronics, and is suitable for popularization and application.
Drawings
FIG. 1 shows the retention rate of each time NaCl-containing aqueous solution having a concentration of 0.6mol/L is retained to a fresh water standard in example 1 of the present invention
FIG. 2 shows the concentration of the draw solution after each interception of the aqueous solution containing NaCl with a concentration of 0.6mol/L according to the invention in example 1, which is intercepted to the fresh water standard.
FIG. 3 shows the water flux per filtration using an aqueous solution containing NaCl at a concentration of 0.6mol/L in example 1 of the present invention.
FIG. 4 shows the retention rate of KCl-containing aqueous solution with concentration of 0.1mol/L to a lower concentration standard in example 2 of the present invention.
FIG. 5 shows the concentration of the draw solution after each interception when the KCl-containing aqueous solution with the concentration of 0.1mol/L is intercepted to a lower concentration standard in example 2 of the invention.
FIG. 6 shows the water flux per filtration using an aqueous solution containing KCl at a concentration of 0.1mol/L in example 2 of the present invention.
FIG. 7 shows the rejection of an aqueous solution containing LiCl at a concentration of 0.1mol/L to a lower concentration standard per rejection rate in example 3 of the present invention.
FIG. 8 shows the concentration of the draw solution after each interception when an aqueous solution containing LiCl with a concentration of 0.1mol/L is intercepted to a lower concentration standard in example 3 of the present invention.
FIG. 9 shows the water flux per filtration using an aqueous solution containing LiCl at a concentration of 0.1mol/L in example 3 of the present invention.
FIG. 10 shows MgCl content with a concentration of 0.1mol/L used in example 4 of the present invention2Is trapped to a lower concentration standard per trapping rate
FIG. 11 shows MgCl content with a concentration of 0.1mol/L used in example 4 of the present invention2The aqueous solution is intercepted to the lower concentration standard, and the concentration of the drawing liquid after each interception is the same.
FIG. 12 shows the use of MgCl-containing solution at a concentration of 0.1mol/L in example 4 of the present invention2Per filtered water flux case.
FIG. 13 shows the use of CaCl-containing solution at a concentration of 0.1mol/L according to the invention in example 52Is trapped to a lower concentration standard per trapping rate
FIG. 14 shows the use of CaCl-containing solution at a concentration of 0.1mol/L in example 5 according to the invention2The aqueous solution is intercepted to the condition of the concentration of the drawing liquid after each interception of the lower concentration standard.
FIG. 15 shows the use of CaCl-containing solution at a concentration of 0.1mol/L in example 5 according to the invention2Per filtered water flux case.
FIG. 16 is a schematic view of a continuous filtration apparatus used in the process of the present invention.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.
In the following examples, the graphene oxide solution used was purchased from Jiangsu Wuxi Xinxin detection technology, Inc. The concentration of each ion in the extract was measured using an ICP spectrometer from Leeman, usa.
The above-described scheme is further illustrated below with reference to specific embodiments, which are detailed below:
example 1
In this embodiment, referring to fig. 1, fig. 2 and fig. 3, a method for desalinating seawater by self-interception of salt ions based on a continuous filtration method comprises the following steps:
a. preparing a graphene oxide film:
adopting a water system microporous filter membrane with the aperture of 0.45 mu m as a supporting base membrane, adopting a filter membrane suction filtration method to carry out suction filtration on a graphene oxide solution with the oxidation degree of 55% and the concentration of 5mg/mL, and depositing and retaining graphene oxide on the water system microporous filter membrane as the supporting base, thereby preparing the graphene oxide film with the composite lamellar structure and the thickness of 2500nm for later use;
b. desalting process of saline solution:
the method comprises the steps of adjusting the pH value of a NaCl solution to be treated to be 0.6mol/L, soaking a graphene oxide film in the NaCl solution for 0.5h, controlling the temperature of the NaCl solution to be 20 ℃, enabling the graphene oxide film to fully swell, then carrying out forward pressure filtration on the graphene oxide film, driving under the pressure of 0.1MPa, extruding hydrated ions formed after NaCl in the graphene oxide film is dissolved, enabling the hydrated ions to deform, reducing the size of the hydrated ions entering the graphene oxide film, reducing the distance between film layers, intercepting the hydrated ions with larger size formed after NaCl in the solution is dissolved, collecting an absorption liquid penetrating through the graphene oxide film, determining the ion concentration in the absorption liquid, and recording the water flux and the salt interception rate of the current filtration; then taking the draw solution as a salt solution to be treated for the next filtration treatment process, repeating the steps, and continuously filtering until Na in the draw solution+The concentration is lower than 0.017M, thereby completing the desalting process of the saline solution.
Experimental test analysis:
as can be seen from fig. 1, 2 and 3, the retention rate of each filtration of the present example is relatively high, and the water flux increases as the concentration of the added salt solution decreases. The repeated interception is carried out for times depending on the salt concentration in the drawing liquid after each pressure filtration until the obtained drawing liquid 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 the atmospheric pressure of more than 50, the method of the embodiment can better realize seawater desalination under the filtering pressure of not more than 5 atmospheric pressures, does not need special high-pressure-resistant materials any more, and greatly reduces the energy loss in the operation process. The method has the advantages of obviously reducing the operation cost, greatly reducing the high-pressure potential safety hazard in the traditional reverse osmosis technical process, along with easy operation, simple operation condition and strong universality of the operation environment.
Example 2
This embodiment is substantially the same as embodiment 1, and is characterized in that:
in this embodiment, referring to fig. 4, 5 and 6, a method for desalinating seawater by self-interception of salt ions based on a continuous filtration method comprises the following steps:
a. preparing a graphene oxide film:
adopting a water system microporous filter membrane with the aperture of 0.45 mu m as a supporting base membrane, adopting a filter membrane suction filtration method to carry out suction filtration on a graphene oxide solution with the oxidation degree of 55% and the concentration of 5mg/mL, and depositing and retaining graphene oxide on the water system microporous filter membrane as the supporting base, thereby preparing the graphene oxide film with the composite lamellar structure and the thickness of 2500nm for later use;
b. desalting process of saline solution:
the solution to be treated is a KCl solution with the concentration of 0.1mol/L, the pH value of the KCl solution is adjusted to be 7, the graphene oxide film is soaked in the KCl solution for 0.5h, the temperature of the KCl solution is controlled to be 20 ℃, the graphene oxide film is fully swelled, and then the graphene oxide film is subjected to forward pressure filtrationUnder the drive of the pressure of 0.1MPa, pressing hydrated ions formed after KCl in the graphene oxide film is dissolved, enabling the hydrated ions to deform, so that the sizes of the hydrated ions entering the graphene oxide film are reduced, the distance between film layers in the film is reduced, the hydrated ions with larger sizes formed after KCl in the solution is dissolved are intercepted, the absorption liquid penetrating through the graphene oxide film is collected, the ion concentration in the absorption liquid is measured, and the water flux and the salt interception rate of the current filtration are recorded; then taking the draw solution as a salt solution to be treated for the next filtration treatment process, repeating the steps, and continuously filtering until K in the draw solution+The concentration is lower than 0.017M, thereby completing the desalting process of the saline solution.
Experimental test analysis:
as seen in FIGS. 4, 5 and 6, example K+The retention rate fluctuates around 25 percent, the retention rate is relatively stable, and the water flux is in an overall rising trend along with the reduction of the concentration of the added salt solution. The repeated interception is carried out for times depending on the salt concentration in the drawing liquid after each pressure filtration until the obtained drawing liquid 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 the atmospheric pressure of more than 50, the method of the embodiment can better realize seawater desalination under the filtering pressure of not more than 5 atmospheric pressures, does not need special high-pressure-resistant materials any more, and greatly reduces the energy loss in the operation process. The method has the advantages of obviously reducing the operation cost, greatly reducing the high-pressure potential safety hazard in the traditional reverse osmosis technical process, along with easy operation, simple operation condition and strong universality of the operation environment.
Example 3
This embodiment is substantially the same as the previous embodiment, and is characterized in that:
in this embodiment, referring to fig. 7, 8 and 9, a method for desalinating seawater by self-interception of salt ions based on a continuous filtration method comprises the following steps:
a. preparing a graphene oxide film:
adopting a water system microporous filter membrane with the aperture of 0.45 mu m as a supporting base membrane, adopting a filter membrane suction filtration method to carry out suction filtration on a graphene oxide solution with the oxidation degree of 55% and the concentration of 5mg/mL, and depositing and retaining graphene oxide on the water system microporous filter membrane as the supporting base, thereby preparing the graphene oxide film with the composite lamellar structure and the thickness of 2500nm for later use;
b. desalting process of saline solution:
the method comprises the steps of adjusting the pH value of a LiCl solution to be treated to be 7, soaking a graphene oxide film in the LiCl solution for 0.5h, controlling the temperature of the LiCl solution to be 20 ℃, fully swelling the graphene oxide film, then carrying out forward pressure filtration on the graphene oxide film, extruding hydrated ions formed after LiCl in the graphene oxide film is dissolved under the driving of 0.1MPa, deforming the hydrated ions, reducing the sizes of the hydrated ions entering the graphene oxide film, reducing the distance between film layers in the film, intercepting hydrated ions with larger sizes formed after LiCl in the solution is dissolved, collecting a suction liquid penetrating through the graphene oxide film, measuring the ion concentration in the suction liquid, and recording the water flux and the salt rate of the filtration; then taking the draw solution as a salt solution to be treated for the next filtration treatment process, repeating the steps, and continuously filtering until Li in the draw solution+The concentration is lower than 0.017M, thereby completing the desalting process of the saline solution.
Experimental test analysis:
as seen from fig. 7, 8 and 9, the rejection rate of the present example increases with the number of filtrations, and the water flux generally increases with the decrease in the concentration of the added salt solution. The repeated interception is carried out for times depending on the salt concentration in the drawing liquid after each pressure filtration until the obtained drawing liquid 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 the atmospheric pressure of more than 50, the method of the embodiment can better realize seawater desalination under the filtering pressure of not more than 5 atmospheric pressures, does not need special high-pressure-resistant materials any more, and greatly reduces the energy loss in the operation process. The method has the advantages of obviously reducing the operation cost, greatly reducing the high-pressure potential safety hazard in the traditional reverse osmosis technical process, along with easy operation, simple operation condition and strong universality of the operation environment.
Example 4
This embodiment is substantially the same as the previous embodiment, and is characterized in that:
in this embodiment, referring to fig. 10, fig. 11 and fig. 12, a method for desalinating seawater by self-interception of salt ions based on a continuous filtration method comprises the following steps:
a. preparing a graphene oxide film:
adopting a water system microporous filter membrane with the aperture of 0.45 mu m as a supporting base membrane, adopting a filter membrane suction filtration method to carry out suction filtration on a graphene oxide solution with the oxidation degree of 55% and the concentration of 5mg/mL, and depositing and retaining graphene oxide on the water system microporous filter membrane as the supporting base, thereby preparing the graphene oxide film with the composite lamellar structure and the thickness of 2500nm for later use;
b. desalting process of salt-containing aqueous solution:
the solution to be treated is MgCl with the concentration of 0.1mol/L2Solution, conditioning of MgCl2The pH of the solution is 6, and the graphene oxide film is placed on MgCl2Soaking in the solution for 0.5h, and controlling MgCl2The solution temperature is 20 ℃, so that the graphene oxide film is fully swelled, then the graphene oxide film is subjected to forward pressure filtration, and MgCl in the graphene oxide film is extruded under the drive of the pressure of 0.1MPa2Hydrated ions formed after dissolution deform the hydrated ions, so that the sizes of the hydrated ions entering the graphene oxide film are reduced, the distance between film layers in the film is reduced, and MgCl in the solution is trapped2Collecting the drawing liquid penetrating through the graphene oxide film, measuring the ion concentration of the drawing liquid, and recording the water flux and the salt rejection rate of the current filtration; then, the draw solution is used as a salt solution to be treated for the next filtration treatment process, the steps are repeated, and continuous filtration is carried out until Mg in the draw solution2+The concentration is lower than 0.017M, thereby completing the desalting process of the saline solution.
Experimental test analysis:
from FIGS. 10, 11 and 12Example Mg2+The retention rate fluctuates around 25 percent, the retention rate is relatively stable, and the water flux is in an overall rising trend along with the reduction of the concentration of the added salt solution. The repeated interception is carried out for times depending on the salt concentration in the drawing liquid after each pressure filtration until the obtained drawing liquid 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 the atmospheric pressure of more than 50, the method of the embodiment can better realize seawater desalination under the filtering pressure of not more than 5 atmospheric pressures, does not need special high-pressure-resistant materials any more, and greatly reduces the energy loss in the operation process. The method has the advantages of obviously reducing the operation cost, greatly reducing the high-pressure potential safety hazard in the traditional reverse osmosis technical process, along with easy operation, simple operation condition and strong universality of the operation environment.
Example 5
In this embodiment, referring to fig. 13, 14 and 15, a method for desalinating seawater by self-interception of salt ions based on a continuous filtration method comprises the following steps:
a. preparing a graphene oxide film:
adopting a water system microporous filter membrane with the aperture of 0.45 mu m as a supporting base membrane, adopting a filter membrane suction filtration method to carry out suction filtration on a graphene oxide solution with the oxidation degree of 55% and the concentration of 5mg/mL, and depositing and retaining graphene oxide on the water system microporous filter membrane as the supporting base, thereby preparing the graphene oxide film with the composite lamellar structure and the thickness of 2500nm for later use;
b. desalting process of saline solution:
the solution to be treated is CaCl with the concentration of 0.1mol/L2Solution, adjusting CaCl2The pH value of the solution is 6, and the graphene oxide film is placed in CaCl2Soaking in the solution for 0.5h, and controlling CaCl2The solution temperature is 20 ℃, so that the graphene oxide film is fully swelled, then the graphene oxide film is subjected to forward pressure filtration, and CaCl in the graphene oxide film is extruded under the drive of the pressure of 0.1MPa2The hydrated ions formed after dissolution deform the hydrated ions, thereby reducing the size of the hydrated ions entering the graphene oxide filmReducing the distance between the inner film layers so as to trap CaCl in the solution2Collecting the drawing liquid penetrating through the graphene oxide film, measuring the ion concentration of the drawing liquid, and recording the water flux and the salt rejection rate of the current filtration; then taking the draw solution as a salt solution to be treated for the next filtration treatment process, repeating the steps, and continuously filtering until Ca in the draw solution2+The concentration is lower than 0.017M, thereby completing the desalting process of the saline solution.
Experimental test analysis:
as seen from FIGS. 13, 14 and 15, example Ca2+The retention rate of the water treatment agent fluctuates around 20 percent, the retention rate is relatively stable, the water flux is not greatly changed along with the reduction of the concentration of the added salt solution, and the water treatment agent is in a fluctuating condition. The repeated interception is carried out for times depending on the salt concentration in the drawing liquid after each pressure filtration until the obtained drawing liquid 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 the atmospheric pressure of more than 50, the method of the embodiment can better realize seawater desalination under the filtering pressure of not more than 5 atmospheric pressures, does not need special high-pressure-resistant materials any more, and greatly reduces the energy loss in the operation process. The method has the advantages of obviously reducing the operation cost, greatly reducing the high-pressure potential safety hazard in the traditional reverse osmosis technical process, along with easy operation, simple operation condition and strong universality of the operation environment.
Example 6
This embodiment is substantially the same as the previous embodiment, and is characterized in that:
in this embodiment, a method for desalinating seawater by self-interception of salt ions based on a continuous filtration method includes the following steps:
a. preparing a graphene oxide film:
adopting a water system microporous filter membrane with the aperture of 0.45 mu m as a supporting base membrane, adopting a filter membrane suction filtration method to carry out suction filtration on graphene oxide solution with the oxidation degree of 30% and the concentration of 3mg/mL, and depositing and retaining graphene oxide on the water system microporous filter membrane as the supporting base membrane, thereby preparing the graphene oxide film with the composite lamellar structure and the thickness of 100nm for later use;
b. desalting process of saline solution:
the method comprises the steps of adjusting the pH value of a NaCl solution to be treated to 6, soaking a graphene oxide film in the NaCl solution for 1h, controlling the temperature of the NaCl solution to be 22 ℃, fully swelling the graphene oxide film, then carrying out forward pressure filtration on the graphene oxide film, extruding hydrated ions formed after NaCl in the graphene oxide film is dissolved under the drive of a pressure of 0.5MPa, enabling the hydrated ions to deform, so that the size of the hydrated ions entering the graphene oxide film is reduced, reducing the distance between film layers, intercepting the hydrated ions with larger sizes formed after NaCl in the solution is dissolved, collecting a drawing liquid penetrating through the graphene oxide film, measuring the ion concentration of the drawing liquid, and recording the filtered water flux and salt rejection rate; then the draw solution is used as the salt solution to be treated in the next filtration treatment process, the steps are repeated, and continuous filtration is carried out until Na in the draw solution+The concentration is lower than 0.017M, thereby completing the desalting process of the saline solution.
Experimental test analysis:
the present example maintained a relatively high rejection rate per filtration and the water flux generally increased as the concentration of the added salt solution decreased. The repeated interception is carried out for times depending on the salt concentration in the drawing liquid after each pressure filtration until the obtained drawing liquid 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 the atmospheric pressure of more than 50, the method of the embodiment can better realize seawater desalination under the filtering pressure of not more than 5 atmospheric pressures, does not need special high-pressure-resistant materials any more, and greatly reduces the energy loss in the operation process. The method has the advantages of obviously reducing the operation cost, greatly reducing the high-pressure potential safety hazard in the traditional reverse osmosis technical process, along with easy operation, simple operation condition and strong universality of the operation environment.
Example 7
This embodiment is substantially the same as the previous embodiment, and is characterized in that:
in this embodiment, referring to fig. 11, a method for desalinating seawater by self-interception of salt ions based on a continuous filtration method includes using a graphene oxide film as a filter membrane, installing the graphene oxide film in each stage of the continuous filtration device in fig. 11, respectively, allowing a saline water body to be treated to enter from a first stage of filtration unit after entering, filtering through the first stage of graphene oxide film, and allowing a first stage of drawn liquid to continue to enter a second stage of filtration unit for further filtration. Collecting the absorption liquid penetrating through the graphene oxide film of each stage of filtering unit, determining the ion concentration of the absorption liquid, recording the water flux and the salt rejection rate of the filtering, and repeatedly intercepting the absorption liquid for a plurality of times or determining the stage number of the filtering unit according to the salt concentration of the absorption liquid after each pressurizing and filtering until the obtained absorption liquid meets the required salt concentration standard, thereby completing the desalting process of the salt-containing water solution.
The embodiment provides a salt ion self-retention seawater desalination method based on a continuous filtration method, wherein a graphene oxide film has a laminated structure made of a composite material, the graphene oxide film is soaked in a saline A aqueous solution to a swelling state, then the graphene oxide film is subjected to forward pressure filtration, the added pressure is utilized to squeeze hydrated ions formed after the salt A in the graphene oxide film is dissolved, the hydrated ions are deformed, the size of the hydrated ions entering the graphene oxide film is reduced, the distance between the laminated layers in the film is reduced, the hydrated ions with larger sizes formed after the salt A in the solution is dissolved are retained, 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.
The salt ion self-interception seawater desalination technology based on the continuous filtration method can well realize seawater desalination under the filtration pressure of not more than 5 atmospheric pressure, compared with the traditional reverse osmosis seawater desalination technology with more than 50 atmospheric pressures, the method greatly reduces the energy loss in the operation process, does not need special high-pressure-resistant materials, obviously reduces the operation cost, and greatly reduces the high-pressure potential safety hazard in the traditional reverse osmosis technology process.
The embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the embodiments, and various changes and modifications can be made according to the purpose of the invention, and any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention shall be equivalent substitutions, as long as the purpose of the present invention is met, and the present invention shall fall within the protection scope of the present invention without departing from the technical principle and inventive concept 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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