A collagen fiber-based interfacial photo-thermal evaporator for purifying oil-containing seawater and a preparation method thereof

Abstract

The present application relates to the technical field of seawater desalination, and particularly relates to a collagen fiber-based interfacial photothermal evaporator for purifying oil-containing seawater and a preparation method thereof.The collagen fiber-based interfacial photothermal evaporator takes a porous substrate constructed by hydroxypropyl methyl cellulose bonding collagen fibers as a carrier, and takes a plant polyphenol-trivalent iron ion coordination system as a modified load.The present application uses collagen fibers with a multi-level structure as raw materials, and prepares the collagen fiber-based interfacial photothermal evaporator with good mechanical properties through a green and non-toxic process.The obtained collagen fiber-based interfacial photothermal evaporator shows super-wettability to both water and oil phases and has underwater super-oleophobicity, and exhibits excellent oil-in-water emulsion separation performance, thereby overcoming the technical problem of poor performance effect of the solar-driven interfacial photothermal evaporator in treating oil-containing seawater in the prior art, and realizing integrated purification of the oil-containing seawater.

Description

Technical Field

[0001] This invention relates to the field of seawater desalination technology, and in particular to a collagen fiber-based interfacial photothermal evaporator for purifying oily seawater and its preparation method. Background Technology

[0002] Seawater desalination is an important and effective strategy for alleviating freshwater shortages, and it has gradually become a research hotspot for many scholars both domestically and internationally in recent years. Solar energy is an inexhaustible and environmentally friendly energy source. Using interfacial photothermal evaporators, solar energy can be converted into heat energy in a green way to achieve seawater evaporation. Therefore, solar-driven interfacial evaporation has significant advantages in the field of seawater desalination and may become the preferred method for seawater desalination in the coming years.

[0003] Oily seawater is generated by leaks or discharges during oil extraction and transportation. It not only damages the ecological environment but also poses a serious threat to biological health, making its purification a major focus of research. When using solar-driven interfacial photothermal evaporators to treat oily seawater, oil pollutants can enter the evaporator during the photothermal evaporation process, occupying the seawater transport channels and significantly reducing evaporation performance. Therefore, although solar-driven seawater desalination has made significant progress, the challenges posed by oily seawater, particularly the treatment of oil-water emulsions, still need to be addressed. Thus, there is an urgent need to develop photothermal evaporation materials that can effectively purify oily seawater to achieve integrated purification.

[0004] Based on this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a collagen fiber-based interfacial photothermal evaporator for oily seawater purification and its preparation method, so as to solve the technical problem of poor performance of the existing solar-driven interfacial photothermal evaporator in treating oily seawater, and to achieve integrated purification of oily seawater.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] One of the technical solutions of the present invention is to provide a collagen fiber-based interfacial photothermal evaporator, wherein the collagen fiber-based interfacial photothermal evaporator uses a porous substrate constructed by bonding collagen fibers with hydroxypropyl methylcellulose as a carrier and a plant polyphenol-trivalent iron ion coordination system as a modified loading material.

[0008] This invention utilizes hydroxypropyl methylcellulose to bond collagen fibers to construct a porous substrate, which is then further modified using a plant polyphenol-ferric ion coordination system to prepare a collagen fiber-based interfacial photothermal evaporator with superwetting properties and excellent photothermal conversion performance. In this invention, the collagen fiber-based interfacial photothermal evaporator exhibits superwetting properties towards both aqueous and oil phases and underwater superoleophobicity due to its multi-level structure (a multi-scale structure from nanofibers to microfibers to collagen fiber bundles providing capillary effects for liquid transport) and amphiphilicity. Furthermore, the presence of the multi-level structure increases the diffuse reflection of sunlight within the evaporator, further enhancing its photothermal conversion performance. The plant polyphenol-ferric ion coordination system binds to collagen molecules through hydrogen bonds and coordination bonds, enabling cross-linking of collagen fibers. This cross-linking, when used to modify collagen fibers, improves the product's compressive strength and stability in water (see...). Figure 15 Therefore, the collagen fiber-based interfacial photothermal evaporator prepared by this invention can prevent oil pollutants from entering the solar-driven interfacial photothermal evaporator and occupying the seawater transport channel, thereby improving the seawater evaporation performance.

[0009] Preferably, the method for preparing the porous substrate includes the following steps:

[0010] Hydroxypropyl methylcellulose was dissolved in water, then collagen fibers were added, and after stirring and reaction, the porous substrate was obtained by freeze drying.

[0011] Hydroxypropyl methylcellulose (HMC) offers advantages such as being environmentally friendly and cost-effective as an adhesive. The abundant hydroxyl groups in the HMC molecular chain provide a favorable chemical structure for constructing superphilic porous substrates. Collagen fibers possess a multi-level structure of nanofibers-microfibers-fiber bundles, providing excellent liquid transport effects for subsequent applications in water treatment. Furthermore, the abundant carboxyl, amino, and hydroxyl groups on collagen fibers facilitate the subsequent loading of plant polyphenols with ferric ion coordination compounds.

[0012] Preferably, the mass ratio of hydroxypropyl methylcellulose to collagen fiber is 1:5 to 1:15.

[0013] The amount of collagen fibers added affects the porous structure. When too much collagen is added, the porosity of the prepared porous substrate is low, which seriously reduces the separation flux and evaporation efficiency during emulsion separation; when too little collagen is added, the prepared porous substrate is prone to collapse and cannot support its shape.

[0014] Preferably, the plant polyphenol-ferric ion coordination system is ferric tannate. The dark-colored ferric tannate loaded on the porous substrate increases the absorption of sunlight.

[0015] The second technical solution of the present invention, the preparation method of the above-mentioned collagen fiber-based interfacial photothermal evaporator, includes the following steps:

[0016] Hydroxypropyl methylcellulose was dissolved in water, then collagen fibers were added, and after stirring and reaction, the mixture was freeze-dried to obtain a porous substrate.

[0017] The porous substrate is subjected to a first reaction in a plant polyphenol solution, followed by a second reaction in an iron salt solution to obtain the collagen fiber-based interfacial photothermal evaporator.

[0018] Preferably, the reaction temperature is 40-60℃ and the reaction time is 2-4h.

[0019] Preferably, the freeze-drying temperature is -70 to -50°C and the time is 48-72 hours.

[0020] Preferably, the molar ratio of the plant polyphenol to the iron salt is 1:1 to 1:3.

[0021] Preferably, the plant polyphenol is tannic acid, and the iron salt is ferric chloride.

[0022] Preferably, the step of performing a first reaction in a plant polyphenol solution followed by adding an iron salt solution for a second reaction to obtain the collagen fiber-based interfacial photothermal evaporator specifically includes:

[0023] The porous substrate was placed in a plant polyphenol ethanol solution with a concentration of 40-240 mmol / L and subjected to a first reaction at 40-60°C for 1-2 hours. An equal volume of ferric salt ethanol solution with a concentration of 40-240 mmol / L was added and subjected to a second reaction at 40-60°C for 1-2 hours. The substrate was then vacuum dried to obtain the collagen fiber-based interfacial photothermal evaporator.

[0024] The third technical solution of the present invention is the application of the above-mentioned collagen fiber-based interfacial photothermal evaporator in seawater purification.

[0025] Optionally, the seawater is oil-containing seawater.

[0026] The fourth technical solution of the present invention is an integrated purification system for oily seawater, comprising an emulsion separation device and the aforementioned collagen fiber-based interfacial photothermal evaporator connected in series; the emulsion separation device includes a separation column filled with the aforementioned collagen fiber-based interfacial photothermal evaporator.

[0027] The fifth technical solution of the present invention is an integrated purification method for oily seawater, comprising passing the oily seawater sequentially through an emulsion separation device and a collagen fiber-based interfacial photothermal evaporator of the aforementioned integrated purification system for oily seawater, thereby purifying the oily seawater.

[0028] The present invention discloses the following technical effects:

[0029] This invention uses collagen fibers with a multi-level structure as raw materials and prepares a collagen fiber-based interfacial photothermal evaporator with excellent mechanical properties through a green and non-toxic process. The resulting collagen fiber-based interfacial photothermal evaporator exhibits superwetting properties to both aqueous and oil phases and underwater superoleophobicity, demonstrating excellent performance in separating oil-in-water emulsions.

[0030] The collagen fiber-based interfacial photothermal evaporator porous material prepared by this invention exhibits a black appearance and excellent photothermal conversion performance, making it effective for seawater desalination as an interfacial photothermal evaporator. Based on these characteristics, the collagen fiber-based interfacial photothermal evaporator prepared by this invention can complete the integrated purification of oily seawater, that is, directly obtain freshwater resources that meet the standards of the World Health Organization from oily seawater.

[0031] The collagen fiber-based interfacial photothermal evaporator prepared by this invention uses natural polymers as materials and primarily employs green materials in its preparation process. On one hand, the collagen fiber-based interfacial photothermal evaporator prepared by this invention is more environmentally friendly, safer, and easier to recycle than other interfacial photothermal evaporator substrates (melamine foam, polyamide membranes, etc.). On the other hand, this invention does not require traditional solution foaming processes; instead, it directly constructs an irregular porous structure through the bonding of collagen fibers. After modification, the resulting collagen fiber-based interfacial photothermal evaporator exhibits a porous structure with high porosity and good mechanical properties, providing an excellent physical structural basis for its application in emulsion separation and seawater photothermal evaporation.

[0032] This invention utilizes collagen fibers as raw materials and leverages the adhesive properties of hydroxypropyl methylcellulose and the modification effect of a plant polyphenol-ferric coordination system to prepare a collagen fiber-based interfacial photothermal evaporator with superamophilic properties. The collagen fiber-based interfacial photothermal evaporator prepared by this invention can stably separate oil-in-water emulsions over a long period and can also efficiently achieve photothermal evaporation of seawater. Based on these characteristics, the integrated oil-containing seawater purification process based on the collagen fiber-based interfacial photothermal evaporator prepared by this invention can directly obtain clean freshwater resources from oil-containing seawater. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 These are physical images of the collagen fiber-based interfacial photothermal evaporators prepared in Example 2 and Comparative Example 1 of the present invention.

[0035] Figure 2These are microscopic images of the products prepared in Example 2 and Comparative Example 1 of the present invention, wherein (a) is a scanning electron microscope image of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2, (b) is a scanning electron microscope image of the collagen fiber-based interfacial photothermal evaporator prepared in Comparative Example 1, (c) is a scanning electron microscope image of a single collagen fiber in the collagen fiber-based interfacial photothermal evaporator prepared in Example 2, (d) is a scanning electron microscope image of a single collagen fiber in the collagen fiber-based interfacial photothermal evaporator prepared in Comparative Example 1, and (e) is an elemental distribution diagram of the collagen fiber-based interface prepared in Example 2.

[0036] Figure 3 The absorption time of water droplets and n-dodecane droplets in air for the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention;

[0037] Figure 4 The contact angle of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of this invention with carbon trichloride underwater;

[0038] Figure 5 The diagram shows the compressive strength test results of the collagen fiber-based interfacial photothermal evaporators prepared in Example 2 and Comparative Example 1 of this invention under dry conditions.

[0039] Figure 6 The images show the effects of immersing the collagen fiber-based interfacial photothermal evaporators prepared in Example 2 and Comparative Example 1 in water.

[0040] Figure 7 The figure shows the performance test results of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention after immersion in water.

[0041] Figure 8 The graph shows the absorption rate of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 and Comparative Example 1 of this invention in the ultraviolet-near infrared spectrum range of 200-1000 nm.

[0042] Figure 9 The thermal imaging analysis results of the collagen fiber-based interfacial photothermal evaporators prepared in Example 2 and Comparative Example 1 of this invention are shown in the figure.

[0043] Figure 10 Digital and optical microscope images of the collagen fiber-based interfacial photothermal evaporator before and after separation of water-encapsulated n-dodecane emulsion (NE1) prepared in Example 2 of this invention;

[0044] Figure 11 The diagram shows the separation performance of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of this invention, which repeatedly separated water-in-n-dodecane emulsion (NE1) for 10 cycles.

[0045] Figure 12 This is an integrated purification device for oily seawater used in Example 2 of the present invention;

[0046] Figure 13 This is a diagram illustrating the emulsion separation capability of the integrated purification process for oily seawater in Example 2 of this invention.

[0047] Figure 14 The diagram shows the effect of inorganic salt ion separation capability of the integrated purification process for oily seawater in Example 2 of this invention.

[0048] Figure 15 This is a diagram illustrating the modification mechanism of collagen fibers by the tannic acid-iron coordination system in the technical solution of this invention. Detailed Implementation

[0049] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0050] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0051] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0052] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0053] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0054] An embodiment of the present invention provides a method for preparing a collagen fiber-based interfacial photothermal evaporator for oily seawater purification, comprising the following steps:

[0055] (1) Hydroxypropyl methylcellulose was dissolved in water, then collagen fibers were added, and after stirring and reacting, the mixture was introduced into a polytetrafluoroethylene mold and freeze-dried to obtain a collagen fiber-based porous substrate.

[0056] (2) The collagen fiber-based porous substrate was immersed in a tannic acid ethanol solution and subjected to a water bath shaking reaction; then an equal volume of ferric chloride ethanol solution was added, and the water bath shaking reaction was continued. Finally, the modified collagen fiber-based porous substrate was vacuum dried to obtain a collagen fiber-based interfacial photothermal evaporator.

[0057] In one specific implementation, in step (1), the mass ratio of hydroxypropyl methylcellulose to collagen fiber is 1:5 to 1:15.

[0058] In one specific implementation, the concentration of the tannic acid ethanol solution in step (2) is 40–240 mmol / L.

[0059] In one specific implementation, the concentration of the ferric chloride ethanol solution in step (2) is 40–240 mmol / L.

[0060] In one specific implementation, the molar ratio of tannic acid to ferric chloride in step (2) is 1:1 to 1:3.

[0061] The raw materials used in the following embodiments of the present invention are all commercially available products, and the source of the raw materials does not affect the technical effect of the present invention.

[0062] Example 1

[0063] (1) Dissolve 0.3g of hydroxypropyl methylcellulose in 100mL of water, then add 1.5g of collagen fiber, stir and react (temperature 40℃, time 2h), then pour into a polytetrafluoroethylene mold and freeze dry (temperature -70℃, time 48h) to obtain a collagen fiber-based porous substrate.

[0064] (2) The collagen fiber-based porous substrate was immersed in a 40 mmol / L tannic acid ethanol solution and reacted in a water bath with shaking (temperature 40℃, time 1h); then an equal volume of 40 mmol / L ferric chloride ethanol solution was added, and the reaction was continued in a water bath with shaking (temperature 40℃, time 1h). Finally, the modified collagen fiber-based porous substrate was vacuum dried to obtain a collagen fiber-based interfacial photothermal evaporator.

[0065] Example 2

[0066] Same as Example 1, except that the amount of collagen fiber added is 3.0g.

[0067] Example 3

[0068] Same as Example 1, except that the amount of collagen fiber added is 4.5g.

[0069] Example 4

[0070] Same as Example 1, except that the concentration of the ferric chloride ethanol solution is 120 mmol / L.

[0071] Example 5

[0072] Same as Example 1, except that the concentration of the tannic acid ethanol solution is 80 mmol / L and the concentration of the ferric chloride ethanol solution is 240 mmol / L.

[0073] Comparative Example 1

[0074] Same as Example 1, except that step (2) is omitted, that is, the modification by impregnation with tannic acid ethanol solution and ferric chloride ethanol solution is not used.

[0075] Comparative Example 2

[0076] Same as Example 1, except that the amount of collagen fiber added is 8g.

[0077] Comparative Example 3

[0078] Same as Example 1, except that the amount of collagen fiber added is 0.5g.

[0079] Comparative Example 4

[0080] Same as Example 1, except that hydroxypropyl methylcellulose is replaced with polyvinyl alcohol.

[0081] Comparative Example 5

[0082] Same as Example 1, except that the concentration of the tannic acid ethanol solution is 300 mmol / L and the concentration of the ferric chloride ethanol solution is 300 mmol / L.

[0083] Comparative Example 6

[0084] Same as Example 1, except that the concentration of the tannic acid ethanol solution is 10 mmol / L and the concentration of the ferric chloride ethanol solution is 10 mmol / L.

[0085] Experimental Example 1

[0086] The performance of the products prepared in the examples and comparative examples was verified.

[0087] (1) Porosity verification

[0088] Physical images of the collagen fiber-based interfacial photothermal evaporators prepared in Example 2 and Comparative Example 1 are shown below. Figure 1 The left image shows the product of Example 2, and the right image shows the product of Comparative Example 1; [The remaining text appears to be a fragmented and incomplete sentence, possibly due to OCR errors. A more accurate translation would require the full context.] Figure 1As can be seen, the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 has a black appearance. It exhibits a good absorption effect on sunlight, thus demonstrating excellent photothermal conversion efficiency.

[0089] Figure 2 These are microscopic images of the products prepared in Example 2 and Comparative Example 1 of the present invention, wherein (a) is a scanning electron microscope (SEM) image of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2, (b) is a SEM image of the collagen fiber-based interfacial photothermal evaporator prepared in Comparative Example 1, (c) is a SEM image of a single collagen fiber in the collagen fiber-based interfacial photothermal evaporator prepared in Example 2, (d) is a SEM image of a single collagen fiber in the collagen fiber-based interfacial photothermal evaporator prepared in Comparative Example 1, and (e) is an elemental distribution diagram of the collagen fiber-based interface prepared in Example 2. Figure 2 It can be seen that the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 has a porous structure inside, and the tannic acid-iron system is combined with collagen molecules in the form of hydrogen bonds and coordination bonds, and is attached to the surface of collagen fibers, so that the collagen fibers can be cross-linked. In contrast, Comparative Example 1 did not use tannic acid ethanol solution and ferric chloride ethanol solution for impregnation and modification, and the product prepared was a single collagen fiber with no cross-linking effect between them.

[0090] Furthermore, the porosity of the above porous materials was determined using an AutoPore IV 9500 fully automated mercury porosimetry instrument.

[0091] The porosity verification results are shown in Table 1.

[0092] Table 1

[0093] —— Porosity, % —— Porosity, % Example 1 97.01 Comparative Example 1 98.42 Example 2 95.84 Comparative Example 2 83.16 Example 3 93.86 Comparative Example 3 98.41 Example 4 96.47 Comparative Example 4 96.23 Example 5 95.47 Comparative Example 5 89.41 —— —— Comparative Example 6 98.10

[0094] (2) Verification of amphiphilicity in aqueous and oil phases

[0095] The absorption time of the product of Example 2 of this invention for water droplets and n-dodecane droplets in air was tested respectively, and the results are shown in [the table below]. Figure 3 , Figure 3 The results show that the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 has superaffinity to both aqueous and oil phases, with an absorption time of less than 0.06 s for water droplets and less than 0.12 s for n-dodecane droplets.

[0096] The contact angle of the product of Example 2 of this invention with carbon trichloride underwater was tested, and the results are shown in [the table below]. Figure 4 ; Figure 4 The results show that the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 has excellent underwater superoleophobicity, with an underwater carbon trichloride contact angle of 158.3°.

[0097] The absorption time of water droplets and n-dodecane droplets and the underwater carbon trichloride contact angle of the other embodiments were also verified. The statistical results are shown in Table 2.

[0098] Table 2

[0099]

[0100] Table 1-2 shows that the products of the embodiments of the present invention exhibit high porosity. Comparative Examples 2 and 5 show decreased porosity due to excessive collagen fiber addition or excessively high impregnation solution concentration. Comparative Examples 1 and 6, while maintaining a high porosity structure, lacked sufficient cross-linking (due to insufficient or no modification with tannic acid and ferric chloride), resulting in physical properties that did not meet the requirements for subsequent applications in aquatic environments. The sample prepared in Comparative Example 3 lacked sufficient collagen fiber addition, failing to support its shape. Comparative Example 4 showed a significant decrease in the underwater carbon trichloride contact angle due to the use of different binders.

[0101] (3) The ability of the products prepared in Example 2 and Comparative Example 1 to undergo extrusion deformation under drying conditions (compression resistance test) was tested, and the results are shown in […]. Figure 5 ; Figure 5 The results show that, compared to Comparative Example 1, the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 exhibits better compressive strength in the dry state. This is because the tannic acid-iron coordination system crosslinks and modifies the collagen fibers to support the porous material, thereby improving the product's compressive strength.

[0102] The products of Example 2 and Comparative Example 1 were placed in water and sonicated for 30 minutes under normal temperature and pressure. The product shapes were then observed. The results are shown below. Figure 6-7 ; Figure 6-7 The results show that the product of Example 2 can maintain its original shape for a long time without collapsing when wet in water, and can recover its original shape when squeezed. However, the collagen fiber-based interfacial photothermal evaporator prepared in Comparative Example 1 did not undergo cross-linking modification of the tannic acid iron coordination system, which caused the bonded collagen fibers to break apart in water. As a result, the original structure in water is easily destroyed and cannot meet the requirements of subsequent practical applications. This shows that the product of the present invention exhibits good mechanical properties.

[0103] (4) The absorbance of the collagen fiber-based interfacial photothermal evaporators prepared in Example 2 and Comparative Example 1 in the ultraviolet-near infrared spectrum range of 200-1000 nm was analyzed. The results are shown in […]. Figure 8 . Figure 8 The results show that the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 has a significantly higher absorption rate in the ultraviolet and near-infrared spectrum in the 200-100 nm range than that in Comparative Example 1.

[0104] (5) Thermal imaging analysis was performed on the collagen fiber-based interfacial photothermal evaporators prepared in Example 2 and Comparative Example 1. The results are shown below. Figure 9 ; Figure 9The results show that the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 can reach a surface temperature of 53.3°C in 80 seconds after being irradiated with simulated sunlight, with a fast heating rate. In contrast, the surface temperature of Comparative Example 1 is only 39.1°C and the heating rate is not as fast as that of Example 2.

[0105] (6) Validation of emulsion separation performance

[0106] Preparation of oil-in-water emulsions: 1 g of n-dodecane was slowly added dropwise to 100 mL of distilled water, and the mixture was stirred at 2000 rpm for 60 min to obtain an n-dodecane emulsion, designated NE1; 1 g of petroleum ether was slowly added dropwise to 100 mL of distilled water, and the mixture was stirred at 2000 rpm for 60 min to obtain a petroleum ether emulsion, designated NE2; 1 g of kerosene was slowly added dropwise to 100 mL of distilled water, and the mixture was stirred at 2000 rpm for 60 min to obtain a kerosene emulsion, designated NE3.

[0107] The emulsion separation device consists of latex tubing, a peristaltic pump, a separation column, and an iron stand. Using the peristaltic pump, the oil-in-water emulsion is pumped through the latex tubing into the separation column (the collagen fiber-based interfacial photothermal evaporator prepared in the examples and comparative examples is filled into the separation column to a height of 5 cm). Emulsion separation is achieved through the collagen fiber-based interfacial photothermal evaporator, and the separated liquid is finally collected. The emulsion separation flux (F) of the collagen fiber-based interfacial photothermal evaporator is calculated using the following formula:

[0108]

[0109] In the formula, V is the volume of the oil-in-water emulsion, in liters (L); S is the cross-sectional area of ​​the separation column, in meters (m²). 2 t is the emulsion separation time, in hours.

[0110] The total organic carbon (TOC) values ​​before and after oil-in-water emulsion separation were determined using a Haifuda TOC-3000 total organic carbon analyzer. The emulsion separation efficiency (E) of the collagen fiber-based interfacial photothermal evaporator was calculated using the following formula:

[0111]

[0112] In the formula, TOC0 is the total organic carbon content before oil-in-water emulsion separation, in mg / L; TOC1 is the total organic carbon content after oil-in-water emulsion separation.

[0113] The experimental results are shown in Table 3.

[0114] Table 3

[0115]

[0116]

[0117] Analysis of the data in Table 3 shows that Examples 1-5 exhibit excellent oil-in-water emulsion separation performance, with a separation flux greater than 4000 L·m⁻¹. -2 ·h -1 The separation efficiency of Comparative Example 1 was greater than 99.95%. However, Comparative Example 2 used excessive collagen fibers, resulting in an overly dense collagen fiber-based interfacial photothermal evaporator structure, which reduced the emulsion throughput efficiency. Comparative Example 4 used polyvinyl alcohol as a binder to assemble the collagen fiber-based material, leading to decreased wettability and thus exhibiting emulsion separation performance inferior to Examples 1-5. Comparative Example 5, due to excessive tannin-Fe... 3+ The loading of coordination compounds onto collagen fibers significantly reduced the separation flux of the emulsion. Based on comprehensive comparison, Example 2, with a mass ratio of hydroxypropyl methylcellulose to collagen fibers of 1:10, exhibited the best separation performance. Comparative Examples 1, 3, and 6 could not maintain their original shape in water and therefore could not meet the requirements for emulsion separation and seawater evaporation applications; therefore, performance testing was not conducted.

[0118] Digital and optical microscope images of the collagen fiber-based interfacial photothermal evaporator-prepared water-encapsulated n-dodecane emulsion (NE1) before and after separation are shown in Example 2. Figure 10 . Figure 10 The results show that the product of this invention can effectively remove the oil phase from the aqueous phase, thereby obtaining clean water resources. Example 2 shows the separation effect of separating a water-in-water n-dodecane emulsion (NE1) after 10 reuses. Figure 11 After 10 separations, Example 2 still maintained high emulsion separation performance. This indicates that the collagen fiber-based interfacial photothermal evaporator prepared by this invention has stable oil-in-water emulsion separation performance over a long period of time and can be reused.

[0119] (7) Verification of seawater evaporation efficiency

[0120] A 3.0% (w / w) sodium chloride solution (simulating normal seawater) and a 10.0% (w / w) sodium chloride solution (simulating Dead Sea seawater) were used to test the seawater desalination performance of the collagen fiber-based interfacial photothermal evaporators prepared in the examples and comparative examples. The collagen fiber-based interfacial photothermal evaporators were embedded in circular polystyrene foam (insulation layer) and then placed in a circular container containing seawater samples. A xenon lamp light source (CLE-LAB500) from Zhongjiao Jinyuan was used to simulate sunlight to irradiate the seawater samples, and the mass change of the seawater samples was recorded in real time. The seawater evaporation efficiency (R) of the collagen fiber-based interfacial photothermal evaporator was calculated using the following formula:

[0121]

[0122] In the formula, m0 is the mass of the seawater sample before photothermal evaporation, in kg; m tS is the mass of the seawater sample after photothermal evaporation, in kg; S is the area of ​​the collagen fiber-based interfacial photothermal evaporator, in m². 2 t is the photothermal evaporation time, in hours (h).

[0123] The experimental results are shown in Table 4.

[0124] Table 4

[0125]

[0126] Analysis of the data in Table 4 shows that the products prepared in the embodiments of this invention all exhibit excellent evaporation performance on seawater samples. However, the collagen fiber-based interfacial photothermal evaporator prepared in Comparative Example 2 has a dense structure, resulting in slower seawater transport and water vapor evaporation, and its seawater evaporation efficiency is lower than that of the embodiments. Comparative Example 4 uses polyvinyl alcohol as a binder to assemble the collagen fiber-based material, leading to a decrease in the wettability of the collagen-based material, thus exhibiting a lower evaporation efficiency than Examples 1-5. Comparative Example 5, due to excessive tannic acid-Fe... 3+ Coordination loading leads to a decrease in seawater transport efficiency, which in turn affects evaporation efficiency.

[0127] Verification Example 2

[0128] Based on the above characteristics, this invention designs an integrated purification process for oily seawater. The emulsion separation device and the photothermal evaporation device from Verification Example 1 are connected in series to form an integrated purification system for oily seawater. Figure 12 The oily seawater is first passed through an emulsion separator and then directly fed into a photothermal evaporation unit for desalination.

[0129] 5g of kerosene was slowly added dropwise to 500mL of Bohai Sea water, and the mixture was stirred at 2000rpm for 60min to obtain an oily seawater sample. The collagen fiber-based interfacial photothermal evaporator prepared in Example 2 was used in an integrated oil-seawater purification process. 500mL of oily seawater was continuously separated. The separation flux and separation efficiency at different throughputs were statistically analyzed, see [link to data]. Figure 13 ; Figure 13 The integrated purification process for oily seawater of the present invention demonstrates high separation flux and efficiency; the concentrations of inorganic salt ions in seawater before and after treatment are shown in the figure. Figure 14 ; Figure 14 The results show that seawater after emulsion separation is directly subjected to photothermal evaporation, which further effectively removes inorganic salt ions from the seawater, resulting in clean freshwater resources. The treated water resources meet WHO standards for drinking water quality. This invention utilizes an integrated purification process based on a collagen fiber-based interfacial photothermal evaporator to maintain highly efficient emulsion separation capabilities.

[0130] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a collagen fiber-based interfacial photothermal evaporator for integrated purification of oily seawater, characterized in that, The collagen fiber-based interfacial photothermal evaporator uses a porous substrate constructed by bonding collagen fibers with hydroxypropyl methylcellulose as a carrier and a plant polyphenol-ferric ion coordination system as a modified loading material. The method for preparing the porous substrate includes the following steps: Hydroxypropyl methylcellulose was dissolved in water, then collagen fibers were added, and after stirring and reaction, the porous substrate was obtained by freeze drying. The mass ratio of hydroxypropyl methylcellulose to collagen fiber is 1:(5-15); The plant polyphenol-ferric ion coordination system is ferric tannin; The preparation method includes the following steps: Hydroxypropyl methylcellulose was dissolved in water, then collagen fibers were added, and after stirring and reaction, the mixture was freeze-dried to obtain a porous substrate. The porous substrate is subjected to a first reaction in a plant polyphenol solution, followed by a second reaction in an iron salt solution to obtain the collagen fiber-based interfacial photothermal evaporator. The reaction is carried out at a temperature of 40-60℃ for a time of 2-4 hours; and / or, The freeze-drying temperature is -70 to -50°C, and the time is 48-72 hours; and / or, The molar ratio of plant polyphenols in the plant polyphenol solution to iron salts in the iron salt solution is 1:1 to 1:3; and / or, The specific steps for obtaining the collagen fiber-based interfacial photothermal evaporator by performing a first reaction in a plant polyphenol solution followed by adding an iron salt solution for a second reaction include: The porous substrate was placed in a plant polyphenol ethanol solution with a concentration of 40-240 mmol / L and subjected to a first reaction at 40-60°C for 1-2 hours. Then, an equal volume of ferric salt ethanol solution with a concentration of 40-240 mmol / L was added and subjected to a second reaction at 40-60°C for 1-2 hours. The substrate was then vacuum dried to obtain the collagen fiber-based interfacial photothermal evaporator.

2. The application of a collagen fiber-based interfacial photothermal evaporator prepared according to the method described in claim 1 in seawater purification.

3. The application according to claim 2, characterized in that, The seawater in question is oil-containing seawater.

4. An integrated purification system for oily seawater, characterized in that, The device includes an emulsion separation unit connected in series and a collagen fiber-based interfacial photothermal evaporator obtained by the preparation method of claim 1; the emulsion separation unit includes a separation column filled with the collagen fiber-based interfacial photothermal evaporator obtained by the preparation method of claim 1.

5. An integrated purification method for oily seawater, characterized in that, Using the integrated purification system according to claim 4, the method includes the following steps: oily seawater is sequentially passed through the emulsion separation device and the collagen fiber-based interfacial photothermal evaporator of the integrated purification system to purify the oily seawater.

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