Collagen fiber-based interface photo-thermal evaporator for purifying oil-containing seawater and preparation method of collagen fiber-based interface photo-thermal evaporator

Abstract

The invention relates to the technical field of seawater desalination, in particular to a collagenous fiber-based interface photo-thermal evaporator for purifying oil-containing seawater and a preparation method of the collagenous fiber-based interface photo-thermal evaporator. According to the collagenous fiber-based interface photo-thermal evaporator, a porous base material constructed by bonding hydroxypropyl methyl cellulose with collagenous fibers is used as a carrier, and a plant polyphenol-ferric ion coordination system is used as a modified load. Collagen fibers with a multi-layer structure are adopted as raw materials, and the collagenous fiber-based interface photo-thermal evaporator with good mechanical performance is prepared through a green and non-toxic process. The obtained collagenous fiber-based interface photo-thermal evaporator shows super wettability to a water phase and an oil phase, has underwater super-oleophobicity, shows excellent oil-in-water emulsion separation performance, and solves the technical problem that in the prior art, when a solar-driven interface photo-thermal evaporator is used for treating oil-containing seawater, the performance effect is poor. The integrated purification of the oil-containing seawater is realized.

Description

Technical Field

[0001] The invention relates to the technical field of seawater desalination, and in particular to a collagen fiber-based interfacial photothermal evaporator for purifying oil-containing seawater and a preparation method thereof. Background Art

[0002] Desalination is one of the important and effective strategies to alleviate the shortage of fresh water. In recent years, it has gradually become a research hotspot for many scholars at home and abroad. Solar energy is an inexhaustible and environmentally friendly energy. With the help of interfacial photothermal evaporators, solar energy can be converted into thermal energy to achieve seawater evaporation in a green way. 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 next few years.

[0003] Oily seawater is produced by leakage or discharge during oil extraction and transportation. Oily seawater not only damages the ecological environment, but also poses a serious threat to biological health, which has attracted great attention from researchers. When using a solar-driven interfacial photothermal evaporator to treat oily seawater, oil pollutants will enter the solar-driven interfacial photothermal evaporator during the photothermal evaporation process and occupy the transmission channel of seawater, resulting in a significant decrease in the evaporation performance of seawater. Therefore, although the development of solar-driven seawater desalination has made effective progress, the challenges brought by oily seawater still need to be addressed, especially the treatment of oil-water emulsions. Therefore, it is urgent to develop photothermal evaporation materials that can effectively purify oily seawater to achieve integrated purification of oily seawater.

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

[0005] The purpose of the present invention is to provide a collagen fiber-based interfacial photothermal evaporator for oil-containing seawater purification and a preparation method thereof, so as to solve the technical problem of poor performance of the solar-driven interfacial photothermal evaporator in the above-mentioned prior art when treating oil-containing seawater, and realize the integrated purification of oil-containing seawater.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a collagen fiber-based interfacial photothermal evaporator, which 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 load.

[0008] The present invention uses hydroxypropyl methylcellulose to bond collagen fibers to construct a porous substrate, and then further modifies it using a plant polyphenol-trivalent iron ion coordination system to prepare a collagen fiber-based interfacial photothermal evaporator with superwettability and good photothermal conversion performance. In the scheme of the present invention, the collagen fiber-based interfacial photothermal evaporator has a multi-level structure (the multi-scale structure of nanofibers-microfibers-collagen fiber bundles provides a capillary effect for liquid transport) and amphiphilicity, so it exhibits super affinity for water phase and oil phase and has underwater superoleophobicity. In addition, the presence of a multi-level structure can increase the diffuse reflection of sunlight in the evaporator, further improving its photothermal conversion performance. The plant polyphenol-trivalent iron ion coordination system combines with collagen molecules in the form of hydrogen bonds and coordination bonds, allowing the collagen fibers to be cross-linked, so that when used to modify collagen fibers, the product's compressive resistance and stability in water can be improved (see Fig.15 ). Therefore, the collagen fiber-based interfacial photothermal evaporator prepared by the present invention can prevent oil pollutants from entering the solar-driven interfacial photothermal evaporator and occupying the transmission channel of seawater, thereby improving the evaporation performance of seawater.

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

[0010] Hydroxypropyl methylcellulose is dissolved in water, and then collagen fibers are added, stirred for reaction, and then freeze-dried to obtain the porous substrate.

[0011] Hydroxypropyl methylcellulose is an environmentally friendly adhesive with low cost. Hydroxypropyl methylcellulose contains abundant hydroxyl groups on its molecular chain, which provides a good chemical structure basis for building a super-affinity porous substrate. Collagen fibers have a multi-level structure of nanofibers-microfibers-fiber bundles, which provide excellent liquid transport effects for subsequent applications in water treatment. In addition, collagen fibers contain abundant carboxyl groups, amino groups, and hydroxyl groups, which are conducive to the subsequent loading of plant polyphenol-trivalent iron ion coordination bodies.

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

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

[0014] Preferably, the plant polyphenol-ferric iron ion coordination system is tannic acid iron. The dark tannic acid iron is loaded on the porous substrate to increase the absorption of sunlight.

[0015] The second technical solution of the present invention is a method for preparing the above-mentioned collagen fiber-based interfacial photothermal evaporator, comprising the following steps:

[0016] Hydroxypropyl methylcellulose is dissolved in water, and then collagen fibers are added, stirred for reaction, and then freeze-dried to obtain a porous substrate;

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

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

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

[0020] Preferably, the molar ratio of the plant polyphenols 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 method of subjecting the porous substrate to a first reaction in a plant polyphenol solution and then adding an iron salt solution to a second reaction to obtain the collagen fiber-based interfacial photothermal evaporator specifically comprises:

[0023] The porous substrate is placed in a plant polyphenol ethanol solution with a concentration of 40 to 240 mmol / L for a first reaction at 40 to 60°C for 1 to 2 hours, an equal volume of a trivalent iron salt ethanol solution with a concentration of 40 to 240 mmol / L is added for a second reaction at 40 to 60°C for 1 to 2 hours, and vacuum drying is performed 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 oily seawater.

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

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

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

[0029] The present invention uses collagen fibers with a multi-level structure as raw materials, and prepares a 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 the water phase and the oil phase and has underwater super oleophobicity, showing excellent water-in-oil emulsion separation performance.

[0030] The collagen fiber-based interfacial photothermal evaporator porous material prepared by the present invention has a black appearance and good photothermal conversion performance. As an interfacial photothermal evaporator, it can effectively realize the desalination of seawater. Based on the above characteristics, the collagen fiber-based interfacial photothermal evaporator prepared by the present 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 the present invention is made of natural polymers, and green materials are mainly used in the preparation process. On the one hand, the collagen fiber-based interfacial photothermal evaporator prepared by the present invention is more environmentally friendly, safe and easy to recycle than other interfacial photothermal evaporator substrates (melamine foam, polyamide film, etc.). On the other hand, the present invention does not require the traditional solution foaming process, but directly constructs an irregular porous structure through the bonding of collagen fibers. After modification, the obtained collagen fiber-based interfacial photothermal evaporator shows a porous structure with high porosity and good mechanical properties, providing an excellent physical structure basis for realizing emulsion separation and seawater photothermal evaporation.

[0032] The present invention uses collagen fibers as raw materials, and utilizes the bonding effect of hydroxypropyl methylcellulose and the modification effect of the plant polyphenol-trivalent iron coordination system to prepare a collagen fiber-based interfacial photothermal evaporator with super amphiphilicity. The collagen fiber-based interfacial photothermal evaporator prepared by the present invention can separate oil-in-water emulsions stably for a long time, and can also efficiently realize the photothermal evaporation of seawater. Based on the above characteristics, the integrated purification process of oil-containing seawater based on the collagen fiber-based interfacial photothermal evaporator prepared by the present invention can directly obtain clean fresh water resources from oil-containing seawater. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 The actual pictures of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention and Comparative Example 1;

[0035] Figure 2The 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 interface photothermal evaporator prepared in Example 2, (b) is a scanning electron microscope image of the collagen fiber-based interface photothermal evaporator prepared in Comparative Example 1, (c) is a scanning electron microscope image of a single collagen fiber of the collagen fiber-based interface photothermal evaporator prepared in Example 2, (d) is a scanning electron microscope image of a single collagen fiber of the collagen fiber-based interface photothermal evaporator prepared in Comparative Example 1, and (e) is an element 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 the air by 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 the present invention to carbon trichloride under water;

[0038] Figure 5 This is a test diagram of the compressive performance of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention and Comparative Example 1 in a dry state;

[0039] Figure 6 This is a diagram showing the effect of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention and Comparative Example 1 after being immersed in water;

[0040] Figure 7 This is a performance test result diagram of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention after being soaked in water;

[0041] Figure 8 The results of the UV-NIR spectrum absorption rate of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention and Comparative Example 1 in the range of 200-1000nm are shown;

[0042] Fig. 9 The thermal imaging analysis results of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention and Comparative Example 1 are shown;

[0043] Fig.10 Digital photos and optical microscope photos before and after the separation of n-dodecane-in-water emulsion (NE1) by the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention;

[0044] Fig.11 This is a separation performance diagram of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 of the present invention repeatedly separating the n-dodecane-in-water emulsion (NE1) 10 times;

[0045] Fig.12 An integrated purification device for oily seawater used in Verification Example 2 of the present invention;

[0046] Fig.13 This is a rendering of the emulsion separation capability of the integrated purification process for oil-containing seawater in Verification Example 2 of the present invention;

[0047] Fig.14 This is a rendering of the inorganic salt ion separation capability of the integrated purification process of oil-containing seawater in Verification Example 2 of the present invention;

[0048] Fig.15 This is a diagram showing the modification mechanism of collagen fibers by the tannic acid-iron coordination system in the technical solution of the present invention. DETAILED DESCRIPTION

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

[0050] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0051] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0052] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

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

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

[0055] (1) dissolving hydroxypropyl methylcellulose in water, then adding collagen fibers, stirring the mixture for reaction, introducing the mixture into a polytetrafluoroethylene mold, and freeze-drying the mixture to obtain a collagen fiber-based porous substrate;

[0056] (2) Soak the collagen fiber-based porous substrate in a tannic acid ethanol solution and perform a water bath oscillation reaction; then add an equal volume of ferric chloride ethanol solution and continue the water bath oscillation reaction. Finally, the modified collagen fiber-based porous substrate is vacuum dried to obtain a collagen fiber-based interfacial photothermal evaporator.

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

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

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

[0060] In a specific embodiment, 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 examples of the present invention are all commercially available products, and the sources of the raw materials do not affect the technical effects of the present invention.

[0062] Example 1

[0063] (1) 0.3 g of hydroxypropyl methylcellulose was dissolved in 100 mL of water, and then 1.5 g of collagen fibers were added, stirred for reaction (temperature 40° C., time 2 h), and then introduced into a polytetrafluoroethylene mold, and freeze-dried (temperature -70° C., time 48 h) 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 subjected to a water bath oscillation reaction (temperature 40°C, time 1 h); then an equal volume of a 40 mmol / L ferric chloride ethanol solution was added and the water bath oscillation reaction was continued (temperature 40°C, time 1 h). 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 3.0 g.

[0067] Example 3

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

[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] The same as Example 1, except that step (2) is omitted, that is, the tannic acid ethanol solution and ferric chloride ethanol solution are not used for impregnation modification.

[0075] Comparative Example 2

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

[0077] Comparative Example 3

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

[0079] Comparative Example 4

[0080] Same as Example 1, except that hydroxypropyl methylcellulose is replaced by 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] Test Example 1

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

[0087] (1) Porosity verification

[0088] The actual pictures of the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 and Comparative Example 1 are shown in Figure 1 The left picture shows the product of Example 2, and the right picture shows the product of Comparative Example 1. Figure 1It can be seen that the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 has a black appearance and has a good absorption effect on sunlight, thereby having an excellent photothermal conversion effect.

[0089] Figure 2 The 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 interface photothermal evaporator prepared in Example 2, (b) is a scanning electron microscope image of the collagen fiber-based interface photothermal evaporator prepared in Comparative Example 1, (c) is a scanning electron microscope image of a single collagen fiber of the collagen fiber-based interface photothermal evaporator prepared in Example 2, (d) is a scanning electron microscope image of a single collagen fiber of the collagen fiber-based interface photothermal evaporator prepared in Comparative Example 1, and (e) is an element 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 the collagen molecules in the form of hydrogen bonds and coordination bonds, and attached to the surface of the collagen fibers, so that the collagen fibers can be cross-linked. Comparative Example 1 did not use tannic acid ethanol solution and ferric chloride ethanol solution for immersion modification, and the prepared product was a single collagen fiber, and there was no cross-linking effect between them.

[0090] Furthermore, the porosity of the above porous materials was measured using an AutoPore IV 9500 fully automatic mercury intrusion 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 the amphiphilicity of water and oil phases

[0095] The absorption time of water droplets and n-dodecane droplets in the air of the product of Example 2 of the present invention was tested respectively. The results are shown in Figure 3 , Figure 3 It shows that the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 has super affinity for water phase and oil phase, and the absorption time for water droplets is less than 0.06s, and the absorption time for n-dodecane droplets is less than 0.12s.

[0096] The contact angle of the product of Example 2 of the present invention to carbon trichloride under water was tested. The results are shown in Figure 4 ; Figure 4 It shows that the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 has excellent underwater superoleophobicity, and the underwater carbon trichloride contact angle is 158.3°.

[0097] The absorption time of water droplets and n-dodecane droplets and the underwater carbon trichloride contact angle of the remaining embodiments were verified, and 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 the characteristic of high porosity. The porosity of the products of Comparative Examples 2 and 5 decreased due to excessive addition of collagen fibers or too high concentration of the impregnation solution. Although Comparative Examples 1 and 6 ensured a high porosity structure, they were not fully cross-linked (tannic acid and ferric chloride were not modified or the amount was too small), resulting in the physical properties of the samples being unable to meet the requirements of subsequent applications in water environments. The sample prepared in Comparative Example 3 was unable to support its shape due to too little addition of collagen fibers. Comparative Example 4 used a different binder, resulting in a significant decrease in the underwater carbon trichloride contact angle.

[0101] (3) The ability of the products prepared in Example 2 and Comparative Example 1 to be deformed by extrusion under dry conditions (compression resistance test) was tested. The results are shown in Figure 5 ; Figure 5 It is shown that the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 exhibits better compressive resistance in a dry state compared with Comparative Example 1. The reason is that the tannic acid-iron coordination system cross-links the modified collagen fibers to support the porous material, thereby improving the compressive resistance of the product.

[0102] The products of Example 2 and Comparative Example 1 were placed in water and subjected to ultrasound for 30 minutes at room temperature and pressure to observe the product shapes. Figure 6-7 ; Figure 6-7 It shows that the product of Example 2 can maintain its original shape for a long time without collapse in a wet state in water, and can recover to its original shape when squeezed. However, the collagen fiber-based interfacial photothermal evaporator prepared in Comparative Example 1 is not cross-linked and modified with a tannic acid iron coordination system, so that the bonded collagen fibers fall apart in water, and the original structure is easily destroyed in water, which cannot meet subsequent practical applications. This shows that the product of the embodiment of the present invention exhibits good mechanical properties.

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

[0104] (5) Thermal imaging analysis was performed on the collagen fiber-based interface photothermal evaporator prepared in Example 2 and Comparative Example 1. Fig. 9 ; Fig. 9It is shown that after the collagen fiber-based interfacial photothermal evaporator prepared in Example 2 is irradiated with simulated sunlight, its surface temperature can reach 53.3°C in 80s with a fast heating rate, while the surface temperature of Comparative Example 1 is only 39.1°C and the heating rate is slower than that of Example 2.

[0105] (6) Emulsion separation performance verification

[0106] Preparation of oil-in-water emulsion: Slowly add 1 g of n-dodecane into 100 mL of distilled water, and stir at 2000 rpm for 60 min to obtain a water-in-dodecane emulsion, numbered NE1; slowly add 1 g of petroleum ether into 100 mL of distilled water, and stir at 2000 rpm for 60 min to obtain a water-in-petroleum ether emulsion, numbered NE2; slowly add 1 g of kerosene into 100 mL of distilled water, and stir at 2000 rpm for 60 min to obtain a water-in-kerosene emulsion, numbered NE3.

[0107] The emulsion separation device consists of a latex tube, a peristaltic pump, a separation column and an iron stand. With the help of a peristaltic pump, the water-in-oil emulsion is pumped into the separation column (the collagen fiber-based interfacial photothermal evaporator prepared in the embodiment and the comparative example is filled in the separation column, and the filling height is 5 cm) through the latex tube, and the emulsion is separated by the collagen fiber-based interfacial photothermal evaporator, and finally the separated liquid is collected. The emulsion separation flux (F) of the collagen fiber-based interfacial photothermal evaporator is calculated according to the following formula:

[0108]

[0109] Where V is the volume of the oil-in-water emulsion, in L; S is the cross-sectional area of ​​the separation column, in m 2 ; t is the time of emulsion separation, unit: h.

[0110] The total organic carbon value (TOC) before and after the separation of the water-in-oil emulsion was measured by the Haifuda TOC-3000 total organic carbon analyzer, and the emulsion separation efficiency (E) of the collagen fiber-based interfacial photothermal evaporator was calculated according to the following formula:

[0111]

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

[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 separation effects of oil-in-water emulsions, with a separation flux greater than 4000 L·m -2 ·h -1 , the separation efficiency is greater than 99.95%; while in comparative example 2, excessive collagen fibers were used in the preparation, and the structure of the prepared collagen fiber-based interfacial photothermal evaporator was too dense, resulting in a decrease in the emulsion passing efficiency. Comparative example 4 used polyvinyl alcohol as an adhesive to assemble the collagen fiber-based material, resulting in a decrease in the wettability of the collagen-based material, thus showing an emulsion separation performance inferior to that of Examples 1-5. Comparative example 5 due to excessive tannic acid-Fe 3+ The ligand is loaded on the collagen fiber, resulting in a significant decrease in the separation flux of the sample for the emulsion. In comprehensive comparison, Example 2 has the best separation effect when the mass ratio of hydroxypropyl methylcellulose to collagen fiber is 1:10. Among them, Comparative Examples 1, 3 and 6 cannot maintain their original shape in water and cannot meet the application of emulsion separation and seawater evaporation, so performance testing was not carried out.

[0118] Digital photos and optical microscope photos of the collagen fiber-based interfacial photothermal evaporator before and after separation of n-dodecane emulsion (NE1) in water prepared in Example 2 are shown in Fig.10 . Fig.10 The results show that the product of the present invention can effectively remove the oil phase from the water phase, thereby obtaining clean water resources. Fig.11 After 10 separations, Example 2 can still maintain efficient emulsion separation performance. This shows that the collagen fiber-based interfacial photothermal evaporator prepared by the present invention has long-term stable water-in-oil emulsion separation performance and can be reused.

[0119] (7) Verification of seawater evaporation efficiency

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

[0121]

[0122] Where m0 is the mass of the seawater sample before photothermal evaporation, in kg; m tis the mass of the seawater sample after photothermal evaporation, in kg; S is the area of ​​the collagen fiber-based interface photothermal evaporator, in m 2 ; t is the photothermal evaporation time, unit: 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 of the examples prepared by the present invention all have excellent evaporation performance for seawater samples. However, the collagen fiber-based interfacial photothermal evaporator prepared in Comparative Example 2 has a dense structure, which leads to slow seawater transportation and water vapor evaporation, and its seawater evaporation efficiency is not as good as that of the examples. Comparative Example 4 uses polyvinyl alcohol as an adhesive to assemble collagen fiber-based materials, resulting in a decrease in the wettability of the collagen-based materials, thereby showing an evaporation efficiency that is not as good as that of Examples 1-5. Comparative Example 5 has an excessive amount of tannic acid-Fe 3+ The ligand loading leads to a decrease in the seawater transmission efficiency, thus affecting the evaporation efficiency.

[0127] Verification Example 2

[0128] Based on the above characteristics, the present invention designs an integrated purification process for oily seawater. The emulsion separation device in Verification Example 1 is connected in series with the photothermal evaporation device to form an integrated purification system for oily seawater ( Fig.12 ), the oily seawater first passes through an emulsion separation device and then directly enters a photothermal evaporation device for seawater desalination.

[0129] 5 g of kerosene was slowly added to 500 mL of Bohai Sea water and stirred at 2000 rpm for 60 min to obtain an oily seawater sample. The collagen fiber-based interfacial photothermal evaporator prepared in Example 2 was used in an integrated purification process for oily seawater. 500 mL of oily seawater was continuously separated. The separation flux and separation efficiency at different processing volumes were calculated, see Fig.13 ; Fig.13 It shows that the integrated purification process of oil-containing seawater of the present invention has a high separation flux and separation efficiency; the concentration of inorganic salt ions in seawater before and after treatment is statistically analyzed. Fig.14 ; Fig.14 It is shown that the seawater after emulsion separation is directly subjected to photothermal evaporation, which further effectively removes inorganic salt ions in the seawater, thereby obtaining clean fresh water resources, and the treated water resources meet the WHO water quality standards for drinking water. The integrated purification process based on the collagen fiber-based interface photothermal evaporator of the present invention can maintain efficient emulsion separation capabilities.

[0130] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A collagen fiber-based interfacial photothermal evaporator, characterized in that: The collagen fiber-based interfacial photothermal evaporator uses a porous substrate constructed by bonding hydroxypropyl methylcellulose to collagen fibers as a carrier, and a plant polyphenol-trivalent iron ion coordination system as a modified load.

2. The collagen fiber-based interfacial photothermal evaporator according to claim 1, characterized in that: The method for preparing the porous substrate comprises the following steps: Hydroxypropyl methylcellulose is dissolved in water, and then collagen fibers are added, stirred for reaction, and then freeze-dried to obtain the porous substrate.

3. The collagen fiber-based interfacial photothermal evaporator according to claim 2, characterized in that: The mass ratio of the hydroxypropyl methylcellulose to the collagen fiber is 1:(5-15).

4. The collagen fiber-based interfacial photothermal evaporator according to claim 1, characterized in that: The plant polyphenol-ferric ion coordination system is tannic acid iron.

5. A method for preparing a collagen fiber-based interfacial photothermal evaporator according to any one of claims 1 to 4, characterized in that: The following steps are involved: Hydroxypropyl methylcellulose is dissolved in water, and then collagen fibers are added, stirred for reaction, and then freeze-dried to obtain a porous substrate; The porous substrate is subjected to a first reaction in a plant polyphenol solution, and then an iron salt solution is added thereto for a second reaction to obtain the collagen fiber-based interfacial photothermal evaporator.

6. The preparation method according to claim 5, characterized in that: The reaction temperature is 40-60°C and the reaction time is 2-4h; and / or, The freeze drying temperature is -70 to -50°C and the time is 48 to 72 hours; and / or, The molar ratio of the plant polyphenols in the plant polyphenol solution to the iron salt in the iron salt solution is 1:1 to 1:3; and / or, The specific steps of subjecting the porous substrate to a first reaction in a plant polyphenol solution and then adding an iron salt solution to a second reaction to obtain the collagen fiber-based interfacial photothermal evaporator include: The porous substrate is placed in a plant polyphenol ethanol solution with a concentration of 40 to 240 mmol / L, and a first reaction is carried out at 40-60°C for 1-2 hours. Then, an equal volume of a trivalent iron salt ethanol solution with a concentration of 40 to 240 mmol / L is added, and a second reaction is carried out at 40-60°C for 1-2 hours. The collagen fiber-based interfacial photothermal evaporator is obtained by vacuum drying.

7. Use of the collagen fiber-based interfacial photothermal evaporator according to any one of claims 1 to 4 in seawater purification.

8. The use according to claim 7, characterized in that: The seawater is oily seawater.

9. An integrated purification system for oily seawater, characterized in that: It comprises a serially connected emulsion separation device and the collagen fiber-based interfacial photothermal evaporator according to any one of claims 1 to 4; the emulsion separation device comprises a separation column filled with the collagen fiber-based interfacial photothermal evaporator according to any one of claims 1 to 4.

10. An integrated purification method for oily seawater, characterized in that: The use of the integrated purification system of claim 9 comprises the following steps: purifying the oily seawater by passing the oily seawater through the emulsion separation device and the collagen fiber-based interfacial photothermal evaporator of the integrated purification system in sequence.

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