Polypyrrole, polyethylene glycol and sodium alginate composite gel as well as preparation method and application thereof
By preparing a composite gel of polypyrrole, polyethylene glycol and sodium alginate, the influence of salt crystallization on solar evaporators was solved, the evaporation efficiency and salt resistance were improved, and high-efficiency photothermal evaporation performance was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-13
- Publication Date
- 2026-04-07
AI Technical Summary
Existing solar evaporators suffer from reduced sunlight absorption, decreased steam production, and shortened lifespan when salt crystals accumulate, making it difficult to design a multi-functional integrated evaporator.
A porous structure was prepared by using a composite gel of polypyrrole, polyethylene glycol and sodium alginate through freeze drying and ionic crosslinking reaction, combined with in-situ polymerization of polypyrrole, to form a material with high intermediate water content and salt resistance.
It achieves efficient solar absorption and environmental heat capture, increases the evaporation rate to 4.3 kg m⁻²h⁻¹, and achieves a water collection rate of 37.09 kg m⁻², while maintaining stable performance in salt water.
Smart Images
Figure CN121801154A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of functional materials technology, specifically relating to a polypyrrole, polyethylene glycol and sodium alginate composite gel, its preparation method and application. Background Technology
[0002] Inspired by the natural water cycle, solar evaporation technology accelerates the cycle using photothermal evaporators, offering advantages such as low cost, safety, environmental friendliness, and high solar energy conversion efficiency. However, salt accumulation on the surface of the equipment during evaporation is a technical problem that needs to be solved. On the one hand, crystallized salt hinders sunlight absorption and reduces evaporation performance; on the other hand, salt can clog the internal water supply pathways, leading to a sharp drop in steam production and a shortened evaporator lifespan. Therefore, rationally designing evaporation devices to suppress salt crystallization is crucial but challenging. In the past two years, significant progress has been made in the structural design of polypyrrole-based photothermal evaporators, including adjustable water supply design, hydrophilic-hydrophobic adjustment, and porous structure design. Among these, the porous structure design has been extensively studied due to the following advantages: 1) 3D porous evaporators promote multidirectional diffusion, helping to reduce salt deposition on the evaporator surface; 2) Another significant advantage is that 3D porous evaporators can increase specific surface area and reduce heat loss through radiative cooling. Hydrogels are ideal carriers for 3D porous evaporators and have been extensively studied, including polyvinyl alcohol, cellulose, chitosan, and sodium alginate. However, given the practical applications of hydrogel evaporators, the design of a multifunctional integrated evaporator remains an important but challenging problem, including simple preparation methods, excellent energy capture, and salt resistance. Summary of the Invention
[0003] To address the shortcomings of existing technologies, this invention provides a polypyrrole, polyethylene glycol, and sodium alginate composite gel, its preparation method, and its applications. The polypyrrole-polyethylene glycol-sodium alginate composite gel prepared by this invention exhibits excellent solar light absorption (light absorptivity greater than 92%) and environmental heat capture performance (side surface temperature < ambient temperature). This polypyrrole-polyethylene glycol-sodium alginate composite gel possesses a high intermediate water content, multiple energy harvesting mechanisms, and salt tolerance, providing an effective method for high-performance solar-driven wastewater treatment.
[0004] The technical solution provided by this invention is as follows: A method for preparing a composite gel of polypyrrole, polyethylene glycol, and sodium alginate includes the following steps: 1) First, polyethylene glycol and sodium alginate are magnetically dispersed in pure water to obtain a mixture of polyethylene glycol and sodium alginate. Then, the mixture is freeze-dried (preferably at a temperature of -40 to -60°C for 40 to 50 hours). Next, the dried gel is immersed in an ionic solution to carry out a cross-linking reaction. Finally, it is freeze-dried again (preferably at a temperature of -40 to -60°C for 20 to 24 hours) to obtain a composite gel of polyethylene glycol and sodium alginate. 2) Polypyrrole was polymerized in situ at the top of the polyethylene glycol and sodium alginate composite gel material to obtain a polypyrrole, polyethylene glycol and sodium alginate composite gel.
[0005] Compared with polypyrrole-sodium alginate gel, the introduction of polyethylene glycol in the above composite gel increases the intermediate water content by 6.8%. Combined with the three-dimensional skeleton structure of the material, the polypyrrole, polyethylene glycol and sodium alginate composite gel has high intermediate water content, high energy acquisition and salt resistance.
[0006] Specifically: In step 1), the mass ratio of polyethylene glycol, sodium alginate, and pure water is (0.12~0.75):1:(20~50).
[0007] Based on the above technical solution, sufficient hydroxyl groups can still be present after crosslinking of polyethylene glycol and sodium alginate, thus enabling the material to achieve a high intermediate water content.
[0008] Specifically, the molecular weight of polyethylene glycol is 900-1100.
[0009] Specifically: In step 1), the ionic solution includes Ca... 2+ and / or Fe 3+ Ions, Ca 2+ and / or Fe 3+ The ion weight percentage concentration is 3-8 wt%; the mass ratio of the ion solution to sodium alginate is 40-100:1.
[0010] Specifically: In step 1), the cross-linking reaction time is 2-10 h and the reaction temperature is 20-30℃.
[0011] Specifically, step 2) includes the following steps: mixing the polyethylene glycol and sodium alginate composite gel obtained in step 1) with a pyrrole solution, then adding an oxidant and allowing it to react fully, and finally freeze-drying (preferably at a temperature of -40 to -60°C for 20-50 hours) to obtain the polypyrrole, polyethylene glycol and sodium alginate composite gel.
[0012] In-situ polymerization can strongly polymerize polypyrrole onto the composite gel framework of polyethylene glycol and sodium alginate, thereby improving the photothermal evaporation performance of the polypyrrole, polyethylene glycol and sodium alginate composite gel material.
[0013] Specifically: The pyrrole solution uses pure water as the solvent, and the volume ratio of pyrrole to water is 1:(15~25). The volume ratio of the pyrrole solution to the polyethylene glycol and sodium alginate mixture in step 1) is (1.25~5):60; Add pyrrole solution dropwise to the surface of the polyethylene glycol and sodium alginate composite gel material in step 1) until it is completely absorbed, to obtain a mixture of polyethylene glycol and sodium alginate composite gel and pyrrole solution.
[0014] Specifically, in step 2): The oxidant is an aqueous solution of ammonium persulfate or ferric chloride, with a concentration of 0.01~0.05 g / mL. -1 ; The volume ratio of the added oxidant to the pyrrole solution is 1:(1~1.5), the reaction time is 1-2 minutes, and the color changes from white to black.
[0015] The present invention also provides a composite gel of polypyrrole, polyethylene glycol and sodium alginate, which is prepared according to the preparation method described above.
[0016] The composite gel of polypyrrole, polyethylene glycol, and sodium alginate can evaporate at a rate as high as 4.3 kg m³ under solar irradiation. - 2 h -1 This is 1.46 times that of polypyrrole-sodium alginate gel. Simultaneously, the polypyrrole-polyethylene glycol-sodium alginate composite gel maintains a stable evaporation rate during continuous operation in brine. The polypyrrole-polyethylene glycol-sodium alginate composite gel can achieve ~37.09 kg m³ in 8 hours of operation. -2 High water collection rate.
[0017] This invention also provides the application of a composite gel of polypyrrole, polyethylene glycol and sodium alginate as a photothermal evaporation material.
[0018] Specifically, it serves as a photothermal evaporation material that absorbs sunlight and / or ambient heat.
[0019] As described above, the polypyrrole, polyethylene glycol, and sodium alginate composite gel provided by this invention exhibits excellent evaporation rate and high water collection rate. Furthermore, during operation, its side surface temperature can be as low as 10°C lower than the ambient temperature, thereby absorbing ambient heat for photothermal evaporation.
[0020] Specifically, it can be applied to the photothermal evaporation of salt water, such as water bodies containing salts like sodium chloride. Compared with the prior art, the beneficial effects of the present invention are: 1. This invention selects polypyrrole as the photothermal conversion material. The synthesis method of polypyrrole is simple, clean and pollution-free, and low in cost, which is beneficial to practical applications; 2. This invention uses polyethylene glycol-sodium alginate as a porous framework to polymerize photothermal materials into a porous system to form an integrated structure, demonstrating good solar light absorption (light absorption rate greater than 92%) and environmental heat capture (side surface temperature < ambient temperature); 3. This invention introduces polyethylene glycol, increasing the intermediate water content by 6.8%, and achieving an evaporation rate as high as 4.3 kg m³ under solar irradiation. -2 h -1 It is 1.46 times that of polypyrrole-sodium alginate gel; 4. The polypyrrole-polyethylene glycol-sodium alginate composite gel prepared by this invention maintains a stable evaporation rate during continuous operation in brine; practical application shows that the polypyrrole-polyethylene glycol-sodium alginate composite gel can achieve an evaporation rate of ~37.09 kg m³ during 8 hours of operation. -2 Its high water catchment rate provides a sustainable green strategy for alleviating water shortages. Attached Figure Description
[0021] Figure 1 This is a SEM image of the polypyrrole-polyethylene glycol-sodium alginate composite gel of Example 1 of the present invention; Figure 2 This is an XPS image of the polypyrrole-polyethylene glycol-sodium alginate composite gel of Example 1 of the present invention; Figure 3 This is a light absorption characteristic diagram of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of the present invention; Figure 4 The Raman spectrum of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of this invention; Figure 5 This is a graph showing the evaporation performance of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of the present invention. Figure 6 This is a surface temperature diagram of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of the present invention; Figure 7 The diagram shows the evaporation performance of the polypyrrole-polyethylene glycol-sodium alginate composite gel in saline solutions of different concentrations in Example 1 of this invention. Figure 8 This is a graph showing the long-term evaporation performance of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of the present invention. Figure 9 This is an outdoor test performance diagram of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of the present invention; Figure 10The diagram shows the brine purification performance of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of this invention. Detailed Implementation
[0022] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.
[0023] Unless otherwise specified, the test methods used in the embodiments are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.
[0024] The brand name and model of the polyethylene glycol is Sinopharm CP.
[0025] Example 1 (1) Preparation of polyethylene glycol-sodium alginate composite gel: 0.08 g of polyethylene glycol and 0.33 g of sodium alginate were magnetically stirred and dispersed in 10 mL of pure water to obtain a polyethylene glycol-sodium alginate mixture. The mixture was then poured into a 10 mL centrifuge tube and freeze-dried for 48 h. The dried gel was then immersed in 20 mL of 5 wt% calcium chloride solution for cross-linking reaction for 8 h. Finally, it was freeze-dried again for 48 h to obtain the polyethylene glycol-sodium alginate composite gel.
[0026] (2) Preparation of polypyrrole-polyethylene glycol-sodium alginate composite gel: Add 0.5 mL of pyrrole solution (0.05 mL) dropwise from one end. -1 Apply the solution to the surface of the polyethylene glycol-sodium alginate composite gel from step 1), and then drop in 0.5 mL of ammonium persulfate solution (0.025 g / mL). -1 The polypyrrole-polyethylene glycol-sodium alginate composite gel is prepared by reacting it with a pyrrole solution until the top turns black, and then freeze-drying it for 12 hours to obtain the polypyrrole-polyethylene glycol-sodium alginate composite gel.
[0027] The preparation method of the polyethylene glycol-sodium alginate material used for comparison is as follows: refer to the preparation method of Example 1, except that step (2) is not performed after step (1), and the polyethylene glycol-sodium alginate composite gel is obtained.
[0028] The preparation method of the polypyrrole-sodium alginate material used for comparison is as follows: polyethylene glycol is not added in step (1).
[0029] Figure 1 This is a SEM image of the polypyrrole-polyethylene glycol-sodium alginate composite gel from Example 1 of the present invention. The synthesized sample exhibits an interconnected porous network structure. In addition to the microporous structure, the surface of the framework also has numerous interconnected small pores, presenting a dual network structure with different pore sizes, and spherical particles distributed on its surface.
[0030] Figure 2 The C 1s peak fractionation results of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 were disclosed, showing four peaks (C=C, CC, CO, and C=O) at 283.8, 284.8, 286.4, and 288.4 eV. The N 1s peak fractionation results showed two peaks at 399.6 and 401.1 eV, corresponding to pyrrole N and CN, respectively. + .
[0031] Figure 3 This is a light absorption characteristic diagram of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of the present invention. The polypyrrole-polyethylene glycol-sodium alginate composite gel exhibits satisfactory broadband light absorption capability across the entire wavelength range of 300-2500 nm, with a light absorption rate greater than 92%.
[0032] Figure 4 This is a comparative Raman spectrum of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of the present invention. The peaks at 3260 and 3372 cm⁻¹ are related to the in-phase and out-of-phase –OH stretching vibrations of the two typical hydrogen bonds of free water, while the peaks at 3473 and 3611 cm⁻¹ correspond to the weak hydrogen bonds of intermediate water. Obviously, the stronger the peak intensity of intermediate water in water molecules, the higher its proportion relative to free water. Calculations show that the proportions of intermediate water to free water in the polypyrrole-sodium alginate composite gel and the polypyrrole-polyethylene glycol-sodium alginate composite gel are 1.33 and 1.72, respectively. The experiment was conducted by wetting the polypyrrole-polyethylene glycol-sodium alginate composite gel and the polypyrrole-sodium alginate with water, respectively.
[0033] Figure 5 This is a graph showing the evaporation performance of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of the present invention; it can be clearly seen that when the exposure height is 3 cm, at 1 kW m -2 Under simulated solar radiation, the polypyrrole-polyethylene glycol-sodium alginate gel exhibited the highest evaporation performance, with a weight change of 2.15 kg m³ after 30 minutes of irradiation. -2 The evaporation rate is 4.30 kgm³. -2 h -1 The value was higher than that of polypyrrole-sodium alginate composite gel. Other comparative materials were also exposed at a height of 3 cm at 1 kW m. -2 The test was conducted under simulated solar radiation.
[0034] Figure 6This is a surface temperature diagram of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of the present invention. The side surface temperature of the polypyrrole-polyethylene glycol-sodium alginate composite gel is lower than that of the surrounding environment. The specific test method involves an exposure height of 3 cm at a 1 kW m³ / h ohm. -2 Measured by infrared thermal imaging under simulated solar radiation.
[0035] Figure 7 This diagram shows the evaporation performance of the polypyrrole-polyethylene glycol-sodium alginate composite gel in saline solutions of different concentrations in Example 1 of this invention. As the saline solution concentration increases, the evaporation rate of the polypyrrole-polyethylene glycol-sodium alginate composite gel decreases slightly, mainly due to the high surface tension of the saline solution. However, it can be clearly seen that in a high-concentration saline solution of 20 wt%, the polypyrrole-polyethylene glycol-sodium alginate composite gel still maintains high evaporation performance, with an evaporation rate of 3.72 kg m³. -2 h -1 The specific test method involves an exposure height of 3 cm at a 1 kW m³ temperature. -2 Measured under simulated solar radiation.
[0036] Figure 8 This is a graph showing the long-term evaporation performance of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of this invention. After a long-term brine evaporation test, the photothermal properties remained unchanged, and no salt crystals were found on the surface of the polypyrrole-polyethylene glycol-sodium alginate composite gel. The brine used in the experiment was a 3.5 wt% NaCl solution.
[0037] Figure 9 This is a graph showing the photothermal performance of the polypyrrole-polyethylene glycol-sodium alginate composite gel under natural sunlight in Example 1 of this invention. The polypyrrole-polyethylene glycol-sodium alginate composite gel achieved a yield of ~37.09 kg m³ after 8 hours of operation. -2 The test demonstrated a high water collection rate. The specific testing method involved placing a polypyrrole-polyethylene glycol-sodium alginate composite gel in a homemade water collection device under natural sunlight, with an exposure height of 3 cm. A 3.5 wt% NaCl solution was used, and the test was conducted on a building rooftop. During the test period from 9:30 AM to 5:30 PM, the solar irradiance ranged from 297.7 to 1090.2 W / m². -2 Fluctuations between.
[0038] Figure 10 This is a diagram illustrating the brine purification performance of the polypyrrole-polyethylene glycol-sodium alginate composite gel in Example 1 of this invention. The salinity of the desalinated water is very low, close to 0.00%, lower than that of tap water (0.08%). The specific testing method involves measuring the salinity of collected water, tap water, and brine using an electronic salinity meter.
[0039] Example 2 The preparation method of Example 1 was followed, except that the amount of polyethylene glycol was changed to 0.04 g. At 1 kW m -2 After half an hour of illumination, the change in photothermal evaporation was 1.71 kg m³. -2 .
[0040] Example 3 The preparation method of Example 1 was followed, except that the amount of polyethylene glycol was changed to 0.16 g. At 1 kW m -2 After half an hour of illumination, the change in photothermal evaporation was 1.75 kg m³. -2 .
[0041] Example 4 The preparation method of Example 1 was followed, except that the amount of polyethylene glycol was changed to 0.25 g. At 1 kW m -2 After half an hour of illumination, the change in photothermal evaporation was 1.28 kg m³. -2 .
[0042] Example 5 The preparation method of Example 1 was followed, except that the amounts of pyrrole and ammonium persulfate were changed to 0.25 mL. The result was as follows: Figure 1 The morphology. The test method was performed at 1 kW m -2 After half an hour of illumination, the change in photothermal evaporation was 1.24 kg m³. -2 .
[0043] Example 6 The preparation method of Example 1 was followed, except that the amounts of pyrrole and ammonium persulfate were changed to 0.75 mL. The result was as follows: Figure 1 The morphology. The test method was performed at 1 kW m -2 After half an hour of illumination, the change in photothermal evaporation was 1.98 kg m³. -2 .
[0044] Example 7 The preparation method of Example 1 was followed, except that the amounts of pyrrole and ammonium persulfate were changed to 1 mL. The result was as follows: Figure 1 The morphology. The test method was performed at 1 kW m -2 After half an hour of illumination, the change in photothermal evaporation was 1.56 kg m³. -2 .
[0045] Example 8 The preparation method of Example 1 was followed, except that the crosslinking reaction time was changed to 2 hours. The result was as follows: Figure 1 The morphology. At 1 kWm -1 After half an hour of illumination, the change in photothermal evaporation was 2.15 kg m³. -2 .
[0046] Example 9 The preparation method of Example 1 was followed, except that the crosslinking reaction time was changed to 4 hours. The result was as follows: Figure 1 The morphology. At 1 kWm -2 After half an hour of illumination, the change in photothermal evaporation was 2.15 kg m³. -2 .
[0047] Example 10 The preparation method of Example 1 was followed, except that the crosslinking reaction time was changed to 6 hours. The result was as follows: Figure 1 The morphology. At 1 kWm -2 After half an hour of illumination, the change in photothermal evaporation was 2.15 kg m³. -2 .
[0048] Example 11 The preparation method of Example 1 was followed, except that the concentration of the calcium chloride solution was changed to 3 wt%. At 1 kW m -2 After half an hour of illumination, the change in photothermal evaporation was 2.15 kg m³. -2 .
[0049] Example 12 The preparation method of Example 1 was followed, except that the concentration of the calcium chloride solution was changed to 8 wt%. At 1 kW m -2 After half an hour of illumination, the change in photothermal evaporation was 2.15 kg m³. -2 .
[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a composite gel of polypyrrole, polyethylene glycol, and sodium alginate, characterized in that, Includes the following steps: 1) First, polyethylene glycol and sodium alginate are magnetically stirred and dispersed in pure water to obtain a mixture of polyethylene glycol and sodium alginate. Then, the mixture is freeze-dried and cross-linked in an ionic solution. Finally, it is freeze-dried again to obtain a composite gel of polyethylene glycol and sodium alginate. 2) Polypyrrole was polymerized in situ at the top of the polyethylene glycol and sodium alginate composite gel material to obtain a polypyrrole, polyethylene glycol and sodium alginate composite gel.
2. The method for preparing the polypyrrole, polyethylene glycol, and sodium alginate composite gel according to claim 1, characterized in that: In step 1), the mass ratio of polyethylene glycol, sodium alginate, and pure water is (0.12~0.75):1:(20~50).
3. The method for preparing the polypyrrole, polyethylene glycol, and sodium alginate composite gel according to claim 1, characterized in that: In step 1), the ionic solution includes Ca. 2+ and / or Fe 3+ Ions, Ca 2+ and / or Fe 3+ The ion weight percentage concentration is 3-8 wt%; the mass ratio of the ion solution to sodium alginate is (40~100):
1.
4. The method for preparing the polypyrrole, polyethylene glycol, and sodium alginate composite gel according to claim 1, characterized in that: In step 1), the cross-linking reaction time is 2-10 h and the reaction temperature is 20-30℃.
5. The method for preparing the polypyrrole, polyethylene glycol, and sodium alginate composite gel according to claim 1, characterized in that, Step 2) includes the following steps: mixing the polyethylene glycol and sodium alginate composite gel obtained in step 1) with a pyrrole solution, then adding an oxidant and allowing it to react fully, and finally freeze-drying to obtain the polypyrrole, polyethylene glycol and sodium alginate composite gel.
6. The method for preparing the polypyrrole, polyethylene glycol, and sodium alginate composite gel according to claim 5, characterized in that: The pyrrole solution uses pure water as the solvent, and the volume ratio of pyrrole to water is 1:(15~25). The volume ratio of the pyrrole solution to the polyethylene glycol and sodium alginate mixture in step 1) is (1.25~5):60; The specific operation of mixing the polyethylene glycol and sodium alginate composite gel obtained in step 1) with the pyrrole solution is to dropwise add the pyrrole solution onto the surface of the polyethylene glycol and sodium alginate composite gel material in step 1) until it is completely absorbed, thereby obtaining a mixture of polyethylene glycol and sodium alginate composite gel and pyrrole solution.
7. The method for preparing the polypyrrole, polyethylene glycol, and sodium alginate composite gel according to claim 5, characterized in that, In step 2): The oxidant is an aqueous solution of ammonium persulfate or ferric chloride, with a concentration of 0.01~0.05 g / mL. -1 ; The volume ratio of the added oxidant to the pyrrole solution is 1:(1~1.5).
8. A composite gel of polypyrrole, polyethylene glycol, and sodium alginate, characterized in that: It is prepared according to any one of claims 1 to 7.
9. An application of the polypyrrole, polyethylene glycol and sodium alginate composite gel according to claim 8, characterized in that: As a photothermal evaporation material.
10. The application according to claim 9, characterized in that: As a photothermal evaporation material that absorbs sunlight and / or absorbs ambient heat.