System for loading nanoparticles on forward osmosis membrane

Abstract

The system comprises an anolyte storage tank, an anode reactor, a catholyte storage tank and a cathode reactor which are connected through a pipeline, the anode reactor is communicated with the cathode reactor through a reaction pipeline, and the forward osmosis membrane is installed in the reaction pipeline. Based on the characteristic that a forward osmosis system does not need to apply pressure to the system, solutions with different osmotic pressures are placed on the two sides of a membrane, the osmotic pressure difference of the solutions on the two sides of the membrane is used as driving force, water molecules spontaneously enter a draw liquid side through the forward osmosis membrane from a raw material liquid side, and meanwhile a nano material is loaded on the forward osmosis membrane; compared with a traditional gravity settling load and suction filtration mode, the method has better practicability and lower labor cost. In addition, when the forward osmosis membrane loaded with the material is put into a forward osmosis microbial fuel cell for use, membrane pollution can be reduced, so that the application of the system is enhanced to another extent.

Description

Technical Field

[0001] The present invention relates to the technical field of osmotic membrane modification, specifically to a system for loading nanoparticles on a forward osmosis membrane, and more specifically to a modification system that relies on the spontaneous process of forward osmosis to load nanoparticles on the forward osmosis membrane to reduce membrane fouling. Background Art

[0002] The forward osmosis (FO) system is a new type of membrane separation technology based on concentration driving force. Its core lies in using the osmotic pressure difference on both sides of the selective FO membrane as the driving force. Through the selective permeability of the FO membrane, water molecules are allowed to pass through while solutes are blocked. Two solutions with different osmotic pressures are placed on both sides of the membrane: one is the feed solution with a lower osmotic pressure, and the other is the draw solution with a higher osmotic pressure. Driven by the osmotic pressure difference, water molecules will spontaneously pass through the semipermeable membrane from the feed solution side to the draw solution side, realizing water transfer and concentration of the feed solution.

[0003] Since the development of FO technology, it has been widely applied in many fields, including but not limited to seawater desalination, food concentration, drug purification, etc., and has shown great potential. Although the FO system has many advantages, it still faces some technical challenges, such as the performance decline of the FO system caused by factors such as membrane material improvement and reverse solute diffusion. Among them, the improvement of membrane materials is one of the main improvement directions of the FO system. Existing FO also has the following problems: a. Serious membrane fouling. The fouled FO membrane will reduce the water flux, thus affecting the operation efficiency of the entire system; b. Concentration polarization phenomenon. Due to the accumulation of solutes on the membrane surface, a concentration polarization layer will be formed, further increasing the osmotic pressure difference on both sides of the membrane and reducing the water flux. In addition, concentration polarization may also cause solute reverse diffusion, that is, solutes diffuse from the high-concentration side to the low-concentration side, resulting in a decline in product quality. As mentioned above, the performance of membrane materials directly affects the separation efficiency and stability of the FO system. Existing FO membrane materials still need to be improved in terms of selectivity, flux, fouling resistance, mechanical strength, etc. These reasons have limited the application of the FO system to a certain extent. Therefore, loading certain nanoparticles on the FO membrane, changing the hydrophilicity and other characteristics of the membrane itself, and enhancing the application capabilities of FO and coupled systems are also one of the main future development directions.

[0004] When exploring methods for loading nanoparticles onto forward osmosis membranes, the suction filtration method is indeed a common technical means. The suction filtration method accelerates the filtration process by applying an external pressure (such as vacuum or compressed gas). Compared with natural gravity filtration, it can significantly improve the filtration efficiency and shorten the processing time. In addition, by adjusting the pressure and flow rate of the suction filtration device, the filtration process can be controlled to a certain extent. However, there are also corresponding drawbacks: the suction filtration method cannot precisely control the nanoparticle loading amount, and it requires complex equipment and operation processes, including adjusting the pressure and controlling the filtration speed, which increases the difficulty and cost of operation. Due to the relatively dense pore structure of the FO membrane, poor air permeability, and low water molecule permeation rate, the suction filtration process will be slow. However, excessive pressure may cause damage to the membrane pore structure, thereby affecting the separation performance and durability of the membrane; in addition, operational difficulties often lead to uneven distribution of nanoparticles on the membrane surface. Some areas may have a dense distribution of particles, while some areas may have a sparse distribution of particles. This uneven loading will affect the performance and stability of the membrane.

[0005] As described above, the traditional suction filtration method has many drawbacks when loading nanoparticles onto forward osmosis membranes. Therefore, it is necessary to explore a more efficient, uniform, and controllable loading method to improve the performance and stability of forward osmosis membranes. Summary of the Invention

[0006] In view of this, the present invention provides a system for loading nanoparticles onto a forward osmosis membrane. Based on the characteristic that the forward osmosis system does not require an external pressure to be applied to the system, by placing solutions with different osmotic pressures on both sides of the membrane, using the osmotic pressure difference between the solutions on both sides of the membrane as the driving force, water molecules spontaneously pass through the forward osmosis membrane from the feed solution side with a lower osmotic pressure into the draw solution side with a higher osmotic pressure while loading the nanomaterials onto the forward osmosis membrane.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A system for loading nanoparticles onto a forward osmosis membrane, comprising: an anolyte storage tank, an anodic reactor, a catholyte storage tank, and a cathodic reactor;

[0009] The anolyte storage tank is connected to the anodic reactor through an anolyte pipeline;

[0010] The catholyte storage tank is connected to the cathodic reactor through a catholyte pipeline;

[0011] The anodic reactor and the cathodic reactor are connected through a reaction pipeline;

[0012] A forward osmosis membrane is installed in the reaction pipeline.

[0013] Preferably, the anolyte pipeline includes an anolyte inlet pipeline and an anolyte return pipeline, and an anolyte pump is provided on the anolyte inlet pipeline.

[0014] Preferably, the cathode pipeline includes a cathode liquid inlet pipeline and a cathode liquid return pipeline, and a cathode pump is arranged on the cathode liquid inlet pipeline.

[0015] Preferably, the liquid in the anode liquid storage tank is a homogeneous aqueous solution containing nanoparticles to be loaded (where 0.02 g of nanoparticles are uniformly distributed in each portion of the anode liquid), and the liquid in the cathode liquid storage tank is a 0.5 mol / L NaCl solution.

[0016] Preferably, a magnetic rotor stirrer is arranged in the anode liquid storage tank.

[0017] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a system for loading nanoparticles on a forward osmosis membrane, which has the following beneficial effects:

[0018] Based on the characteristic that the forward osmosis system does not require an external pressure to be applied to the system, the present invention places solutions with different osmotic pressures on both sides of the membrane, uses the osmotic pressure difference between the solutions on both sides of the membrane as the driving force, and when water molecules spontaneously pass from the feed liquid side with a lower osmotic pressure through the forward osmosis membrane into the draw solution side with a higher osmotic pressure, the nanomaterials are intercepted by the FO membrane, thereby loading the nanomaterials onto the forward osmosis membrane. At the same time, a magnetic stir bar is added to prevent the loaded particles from sinking to the bottom. Compared with the traditional gravity sedimentation loading and suction filtration methods, it has better feasibility and lower labor costs. In addition, when the FO membrane loaded with this material is used in a forward osmosis microbial fuel cell, it can reduce membrane fouling, thereby enhancing the application of the system to another extent. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0020] Figure 1 It is a schematic diagram of the overall structure of the system of the present invention;

[0021] Figure 2 It is a scanning electron microscope image of the forward osmosis membrane loaded by the traditional technical solution;

[0022] Figure 3 It is a scanning electron microscope image of the forward osmosis membrane loaded by the technical solution of the present invention;

[0023] Figure 4 It is the change in the content of four membrane fouling components after running for 10 days;

[0024] In the figure: 1 - anolyte storage tank, 2 - anodic reactor, 3 - catholyte storage tank, 4 - cathodic reactor, 5 - anolyte inlet pipeline, 6 - anolyte return pipeline, 7 - catholyte inlet pipeline, 8 - catholyte return pipeline, 9 - anolyte pump, 10 - catholyte pump, 11 - reaction pipeline, 12 - forward osmosis membrane, 13 - magnetic rotor. Detailed implementation manners

[0025] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] As attached Figure 1 As described, the system for loading nanoparticles on the forward osmosis membrane includes: anolyte storage tank 1, anodic reactor 2, catholyte storage tank 3, cathodic reactor 4;

[0027] The anolyte storage tank 1 is connected to the anodic reactor 2 through an anolyte pipeline;

[0028] The catholyte storage tank 3 is connected to the cathodic reactor 4 through a catholyte pipeline;

[0029] The anodic reactor 2 is connected to the cathodic reactor 4 through a reaction pipeline 11;

[0030] A forward osmosis membrane 12 is installed in the reaction pipeline 11.

[0031] Among them, the anolyte pipeline includes an anolyte inlet pipeline 5 and an anolyte return pipeline 6, an anolyte pump 9 is provided on the anolyte inlet pipeline 5, the catholyte pipeline includes a catholyte inlet pipeline 7 and a catholyte return pipeline 8, and a catholyte pump 10 is provided on the catholyte inlet pipeline 7.

[0032] The liquid in the anolyte storage tank 1 is a uniform aqueous solution containing nanoparticles to be loaded, the liquid in the catholyte storage tank 2 is a 0.5 mol / L NaCl solution, and a magnetic rotor stirrer 13 can be provided in both the anolyte storage tank 1 and the anodic reactor 2.

[0033] The specific application principle is as follows:

[0034] Liquid circulation is carried out in the anodic reactor 2 through the anolyte pipeline and the anolyte pump 9, and liquid circulation is carried out in the cathodic reactor 4 through the catholyte pipeline and the catholyte pump 10. The nanoparticles in the uniform aqueous solution with nanoparticles flowing through in the anodic reactor 2 are loaded on the forward osmosis membrane 12 by using the concentration difference on both sides.

[0035] Experimental examples

[0036] In this experimental example, MIL-101(Fe) / β-PDI nanoparticles were used as the loading host, and the loading amount was 0.02 g. Group 1 was the blank control group without loading, Group 2 was the forward osmosis membrane loaded by the traditional method, and Group 3 was the forward osmosis membrane loaded by the proposed method of the present invention. The blank forward osmosis membrane without loading and the membranes loaded with nanoparticles by the traditional method and the proposed method of the present invention were respectively put into three forward osmosis microbial fuel cell reactors. Other operating conditions were the same. The condition of the loaded particles on the membrane surface after loading was investigated; the differences in membrane fouling of the membrane loaded by the proposed method of the present invention, the blank control group without loading, and the forward osmosis membrane loaded by the traditional method after 10 days of operation were investigated to verify the feasibility of the device of the present invention.

[0037] The test results are as Figure 2 shown. The image of the material loaded by the traditional method under the SEM (scanning electron microscope) shows that although the nanomaterial can be loaded on the FO membrane, the nanomaterial shows an agglomeration phenomenon, and the uneven loading will affect the effect of inhibiting membrane fouling. As Figure 3 shown, the image of the material loaded by the proposed method of the present invention under the scanning electron microscope shows that after being loaded by FO, the material can be more evenly loaded on the FO membrane. After 10 days of operation of the system, a laser confocal microscope was used to quantitatively analyze the concentration of each component of the membrane fouling. The results are as Figure 4 shown. It can be seen that generally, the membrane fouling of the FO membrane loaded with nanoparticles is lower than that of the blank control group, and the novel loading method of this patent is superior to the traditional loading method. It is proved that this loading method is more stable.

[0038] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0039] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A system for loading nanoparticles on a forward osmosis membrane, characterized in that: include: Anolyte storage tank, anode reactor, catholyte storage tank, cathode reactor; The anolyte storage tank is in communication with the anode reactor via an anode pipeline; The cathode liquid storage tank is connected to the cathode reactor through a cathode pipeline; The anode reactor and the cathode reactor are connected via a reaction pipeline; A forward osmosis membrane is installed in the reaction pipeline.

2. A system for loading nanoparticles on a forward osmosis membrane according to claim 1, characterized in that: The anode pipeline comprises an anode liquid inlet pipeline and an anode liquid return pipeline, and an anode pump is arranged on the anode liquid inlet pipeline.

3. A system for loading nanoparticles on a forward osmosis membrane according to claim 1, characterized in that: The cathode pipeline comprises a cathode liquid inlet pipeline and a cathode liquid return pipeline, and a cathode pump is arranged on the cathode liquid inlet pipeline.

4. A system for loading nanoparticles on a forward osmosis membrane according to claim 1, characterized in that: The liquid in the anode liquid storage tank is a uniform aqueous solution containing nanoparticles to be loaded, and the liquid in the cathode liquid storage tank is a 0.5 mol / L NaCl solution.

5. The system for loading nanoparticles on a forward osmosis membrane according to claim 1, characterized in that: A magnetic rotor is arranged in the anolyte storage tank for stirring.

Images