CN116020279A

CN116020279A - Rapid green polyphenol coating modification method with good universality, product and application thereof

Info

Publication number: CN116020279A
Application number: CN202310067946.9A
Authority: CN
Inventors: 王振兴; 朱琳; 何芳; 张进
Original assignee: Nanchang University
Current assignee: Nanchang University
Priority date: 2023-02-06
Filing date: 2023-02-06
Publication date: 2023-04-28

Abstract

The invention discloses a fast green polyphenol coating modification method with good universality, a product and application thereof. Washing the hydrophobic material with ethanol for a plurality of times to prewet; immersing the pre-wetted hydrophobic material into a silane coupling agent containing polyphenols and having amino groups and deionized water for super-hydrophilic modification; the modified film was taken out and rinsed thoroughly with deionized water. The prepared polyphenol coating modified super-hydrophilic membrane has a layered nanosphere structure and can be applied to purification of oily wastewater. The method is carried out in a pure water system, does not contain any toxic additive and oxidant, can realize the super-hydrophilic modification of various polymer hydrophobic membranes within 40 minutes, and greatly improves the modification efficiency. The modified PP film prepared by the method has ultrahigh pure water flux and higher oil-in-water emulsion separation efficiency, and has excellent mechanical stability, acid and alkali resistance and long-term stability in air. The method has the advantages of environmental protection, good universality, high modification efficiency and the like.

Description

Rapid green polyphenol coating modification method with good universality, product and application thereof

Technical Field

The invention belongs to the technical field of material modification, and particularly relates to a rapid green polyphenol coating modification method with good universality, a product and application thereof.

Background

With the rapid development of economy, industrial production and daily life produce large amounts of oily wastewater, most of which exist in the form of oil-in-water emulsions, and these emulsified oils are often difficult to treat, and seriously damage the ecological environment, affecting people's life. Therefore, there is an urgent need for efficient oil-water separation technology to treat oily wastewater and purify water resources. Conventional treatment methods of oily wastewater include gravity separation, ultrasonic separation, centrifugation, coagulation biological treatment and the like. However, the methods have the problems of low separation efficiency, complex process, secondary pollution and the like. The membrane separation technology has the advantages of simple technology, high separation efficiency and the like, and is widely applied to the water treatment process. At present, some membrane materials such as polyvinylidene fluoride (PVDF), polypropylene (PP), polytetrafluoroethylene (PTFE) and the like have hydrophobicity, and when the membrane materials are directly used for oil-water separation, oil drops and proteins in oil-in-water emulsion can be adsorbed, so that membrane pollution is caused, and the separation efficiency is obviously reduced. Therefore, superhydrophilic modification of these hydrophobic membranes is an effective way to solve the membrane fouling problem. In recent years, polyphenol coatings have received a great deal of attention in the surface modification of separation membranes, particularly in rapid modification, due to their versatility and versatility. As patent application CN112029146a discloses a superhydrophobic coating based on protein particles and a preparation method; patent application CN114515515 discloses a super-hydrophobic hollow MOFs modified hollow fiber composite membrane and application thereof; CN114425508A discloses a metal material with super-hydrophobic surface, a preparation method and application thereof, and an oil-water separation method; CN105064040a discloses a hydrophilic modification method for the surface of a porous hydrophobic material, which discloses coating modification based on polyphenol and a silane coupling agent, but the coating modification method has the defects of complex process, long time consumption, secondary pollution and the like. In addition, in order to improve the modification efficiency and shorten the formation time of the polyphenol coating, some additives are inevitably added in the modification processToxic oxidants (e.g. H ₂ O ₂ 、CuSO ₄ 、NaIO ₄ Etc.), the introduction of these oxidizing agents can lead to secondary pollution during the preparation process. Therefore, developing a fast, green, and versatile coating modification strategy remains a significant challenge.

Disclosure of Invention

Aiming at the problem that the modification efficiency and the environmental protection cannot be considered in the prior art, the invention aims to provide a rapid, green and good-universality polyphenol coating modification method which is used for rapid super-hydrophilization modification of various hydrophobic membranes so as to realize efficient separation of oil-in-water emulsion. The method has the advantages that the polyphenols and the silane coupling agent with amino groups are used as raw materials, the reaction rate is regulated and controlled by regulating and controlling the concentration ratio of the polyphenols and the silane coupling agent with amino groups, the formation time of the polyphenols coating is greatly shortened, and the modification efficiency of the polyphenols coating on the hydrophobic membrane is improved. The modification process is green and environment-friendly, is carried out in a pure water system, does not contain any toxic additive or oxidant, can realize the super-hydrophilization modification of various polymer hydrophobic membranes such as a polypropylene membrane (PP), a polyvinylidene fluoride membrane (PVDF), a polytetrafluoroethylene membrane (PTFE) and the like only in 40 minutes, and has good universality. Therefore, the modification strategy of the polyphenol coating not only improves the modification efficiency, but also solves the problem of secondary pollution caused by adding a toxic oxidant, and is more environment-friendly. The modification strategy is suitable for various hydrophobic materials, has a wide application range and has good application value.

The invention is realized by the following technical scheme:

the first aspect of the invention provides a rapid and universal polyphenol altering method, the modifying method comprises the following steps:

s1, washing a hydrophobic material with ethanol for multiple times to realize prewetting of the hydrophobic material;

s2, immersing the pre-wetted hydrophobic material into a mixed solution of a polyphenol substance, a silane coupling agent with an amino group and deionized water for reaction for 40 minutes, and performing super-hydrophilic modification to obtain a modified film;

and S3, taking out the modified membrane, and thoroughly flushing with deionized water to obtain the polyphenol coating modified super-hydrophilic membrane.

Furthermore, the invention has good universality and can be used for rapid super-hydrophilization modification of various polymer hydrophobic materials such as polypropylene films (PP), polyvinylidene fluoride films (PVDF), polytetrafluoroethylene films (PTFE) and the like.

Further, the polyphenol is Tannic Acid (TA); the silane coupling agent with amino group is 3-aminopropyl triethoxy silane (APTES). The green modification method of the invention is to react the polyphenols and the silane coupling agent with amino group in a pure water system, and no toxic oxidant is added in the modification process, thus being green and environment-friendly. Solves the problem of secondary pollution caused by adding toxic oxidant in the prior rapid modification method.

Further, the mass ratio of the polyphenol substance to the silane coupling agent having an amino group is 1:1 to 8, preferably 1:1, 1:2, 1:4, 1:8. The method takes the polyphenols and the silane coupling agent with amino groups as raw materials, and adjusts and controls the reaction rate by adjusting and controlling the concentration ratio of the polyphenols and the silane coupling agent with amino groups, so that the formation time of the polyphenols coating is greatly shortened, the modification efficiency of the polyphenols coating on the hydrophobic membrane is improved, and the problem of low modification efficiency of the polyphenols coating in the prior art is solved.

Further, before the hydrophobic material pre-wetted with ethanol is put into the mixed solution in step S2, the excess ethanol should be removed as much as possible, and the membrane pre-wetted with ethanol may be gently flicked. Because ethanol is a hydrolysis product of 3-aminopropyl triethoxysilane, hydrolysis of 3-aminopropyl triethoxysilane is inhibited, thereby affecting the rate of modification, and thus, in order to minimize the effect of ethanol on the reaction rate, the pre-wetted film may be gently flicked several times to remove excess ethanol before adding the ethanol pre-wetted hydrophobic film to the mixed solution.

The invention also provides a polyphenol coating modified super-hydrophilic membrane prepared by the modification method, and the polyphenol coating modified super-hydrophilic membrane has a layered nanosphere structure.

The super-hydrophilic film modified by the polyphenol coating shows super-hydrophilicity and underwater super-oleophobicity, and especially the modified PP film not only has ultra-high pure waterFlux (11990 Lm) ^-2 h ^-1 ) And higher oil-in-water emulsion separation efficiency (> 99.8%), and has excellent mechanical stability, acid and alkali resistance and long-term stability in air.

The third aspect of the invention provides application of the polyphenol coating modified super-hydrophilic film prepared by the modification method. The invention can realize the rapid super-hydrophilization modification of various hydrophobic membranes to realize the efficient separation of the oil-in-water emulsion, and can be used in the field of water purification, in particular to the treatment of oily wastewater.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, the polyphenols and the silane coupling agent with amino groups are used as raw materials, the concentration ratio and the reaction rate are regulated and controlled, so that the formation time of the polyphenol coating is greatly shortened, only 40 minutes is needed, and the modification efficiency of the polyphenol coating on the hydrophobic membrane is improved.

2. The preparation process of the polyphenol coating modification strategy is simple, no toxic oxidant is added in the preparation process, and the preparation method has the advantage of environmental protection.

3. The polyphenol coating modification strategy is suitable for various hydrophobic materials such as polypropylene films (PP), polyvinylidene fluoride films (PVDF), polytetrafluoroethylene films (PTFE) and the like, has a wide application range and has good application value.

4 the separation membrane modified by the polyphenol coating shows super hydrophilicity and underwater super oleophobic property, and more importantly, the modified PP membrane prepared by the method not only has ultrahigh pure water flux (11990L m ^-2 h ^-1 ) And high separation efficiency (> 99.8%) of oil-in-water emulsion, and has excellent mechanical stability, acid and alkali resistance and long-term stability in air.

Drawings

FIG. 1 is a schematic diagram of a preparation process of modified PP, modified PVDF and modified PTFE by modifying a polyphenol coating

FIG. 2 is a scanning electron microscope image of the original PP film and the PP film modified with the TA-APTES polyphenol coating of example 1.

Fig. 3 is a photograph of the original PP film and the PP film modified with TA-APTES polyphenol coating in example 1, and a corresponding photograph of water contact angle in air.

FIG. 4 is a scanning electron microscope image of the TA-APTES polyphenol coating TA-APTES modified polypropylene film (PP), polyvinylidene fluoride film (PVDF) and polytetrafluoroethylene film (PTFE) of example 1.

FIG. 5 is a graph showing flux and separation efficiency when the emulsion was separated by the modified PP film in example 1. In the figure, the abscissa PP- (TA-APTES) represents TA-APTES polyphenol coating modified PP film, and the left ordinate represents Water Flux (L m) ^-2 h ^-1 ) The right ordinate Oil reject represents the cut-off (%).

Fig. 6 is a stability test of the modified PP film in example 1.

Fig. 7 is a graph of water contact angle in air and water oil contact angle in water for modified PP films of varying mass to volume ratios of Tannic Acid (TA) and 3-aminopropyl triethoxysilane (APTES).

Detailed Description

The invention will be further described with reference to the accompanying drawings.

Example 1 modified preparation of polyphenol coating modified PP, modified PVDF, modified PTFE

The preparation process is schematically shown in figure 1.

The hydrophobic polypropylene film (PP), polyvinylidene fluoride film (PVDF), polytetrafluoroethylene film (PTFE) were first washed with ethanol multiple times, respectively, and then pre-wetted with ethanol before use.

Then, 50mg of Tannic Acid (TA) was added to the petri dish, and then 25mL of deionized water was added to dissolve it; after tannic acid was dissolved, 200mg of 3-aminopropyl triethoxysilane (APTES) was added to the tannic acid solution.

Subsequently, a polypropylene film (PP), a polyvinylidene fluoride film (PVDF), a polytetrafluoroethylene film (PTFE) pre-moistened with ethanol are gently flicked to remove as much excess ethanol as possible; then respectively immersing the mixture into the mixed solution for reaction for 40 minutes. The reaction was carried out at room temperature and the whole reaction was carried out on a shaker.

Taking out the modified polypropylene film (PP), polyvinylidene fluoride film (PVDF) and polytetrafluoroethylene film (PTFE), cleaning with deionized water, and naturally air-drying.

A scanning electron microscope image of the original and modified polypropylene films PP- (TA-APTES) is shown in fig. 2, and a scanning electron microscope image of the polypropylene film (PP), polyvinylidene fluoride film (PVDF), polytetrafluoroethylene film (PTFE) modified with TA-APTES coating is shown in fig. 4. It can be seen that the modified hydrophobic material of the polyphenol coating has a unique layered nanosphere structure.

The contact angle of water in air of the original polypropylene film (PP) and the modified polypropylene film PP- (TA-APTES) is shown in figure 3, and the polypropylene film PP- (TA-APTES) modified by the polyphenol coating has super-hydrophilicity.

The modified polypropylene film PP- (TA-APTES) has excellent mechanical stability, acid and alkali resistance and long-term stability in air. As shown in FIG. 6, a series of stability tests were performed on modified polypropylene films PP- (TA-APTES). As shown in FIG. 6 (a), after 10 times of cyclic washing experiments are carried out on the modified polypropylene film PP- (TA-APTES) and 10 times of cyclic washing are carried out, the modified polypropylene film PP- (TA-APTES) can still maintain super-hydrophilic and underwater super-oleophobic performance. As shown in fig. 6 (b), the modified polypropylene film PP- (TA-Aplets) was subjected to ultrasonic treatment for 10 minutes, and the water contact angle and the underwater oil contact angle of the modified polypropylene film PP- (TA-Aplets) after the ultrasonic treatment were maintained at 0 ° and 160 °, respectively, indicating that the modified polypropylene film PP- (TA-Aplets) has excellent mechanical stability. As shown in fig. 6 (c), the modified polypropylene film PP- (TA-APTES) was immersed in solutions of different pH values (ph=2, 3, 5, 9, 11) for 12 hours, and the underwater oil contact angle of the polypropylene film PP- (TA-APTES) was greater than 150 ° under all pH conditions, indicating that the polypropylene film PP- (TA-APTES) had good acid-base resistance. As shown in FIG. 6 (d), the modified polypropylene film PP- (TA-APTES) was exposed to air for various times (10 days, 20 days, 30 days), and even if exposed to air for 30 days, PP-3 had an underwater oil contact angle of about 157℃and still had underwater superoleophobicity, indicating that PP-3 had long-term stability in air.

Example 2

The modification procedure is the same as in example 1, except that the concentration ratio of Tannic Acid (TA) to 3-aminopropyl triethoxysilane (APTES) is controlled, the reaction rate is controlled, the mass ratio of polyphenols to silane coupling agent with amino group is respectively 1:1, 1:2, 1:4 and 1:8, the water contact angle and underwater oil contact angle in the air of the PP film modified by each concentration ratio are shown in FIG. 7, and the hydrophilicity and underwater superoleophobicity of the modified PP film are better along with the increase of the dosage of 3-aminopropyl triethoxysilane (APTES) in the same reaction time (40 min).

EXAMPLE 3 application of polyphenol coating modified super hydrophilic Membrane to purification of oily wastewater

Testing of TA-APTES polyphenol coating modified PP membrane separation oil-in-water emulsion prepared in example 1. And (5) placing the modified PP film in a vacuum filtration system for oil-water separation. The oil-in-water emulsion is prepared by stirring soybean oil, a surfactant and water. As shown in FIG. 5, the emulsion separation efficiency of the modified PP film is more than 99.8 percent through experiments, and the modified PP film has high oil-water separation efficiency.

The foregoing description of the preferred embodiments of the present invention has been presented only in terms of those specific and detailed descriptions, and is not, therefore, to be construed as limiting the scope of the invention. It should be noted that modifications, improvements and substitutions can be made by those skilled in the art without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims

1. The rapid green and good-universality polyphenol coating modification method is characterized by comprising the following steps of:

s2, immersing the pre-wetted hydrophobic material into a silane coupling agent containing polyphenol substances and having amino groups and deionized water for super-hydrophilic modification to obtain a modified film;

2. The rapid green and universal polyphenol coating modification method according to claim 1, wherein the method comprises the following steps: the polyphenol substance is tannic acid; the silane coupling agent with amino group is 3-aminopropyl triethoxy silane.

3. The rapid green and universal polyphenol coating modification method according to claim 1, wherein the method comprises the following steps: the hydrophobic material is one of a polypropylene film, a polyvinylidene fluoride film and a polytetrafluoroethylene film.

4. The rapid green and universal polyphenol coating modification method according to claim 1, wherein the method comprises the following steps: the mass ratio of the polyphenols to the silane coupling agent with amino groups is 1:1-8.

5. The rapid green and universal polyphenol coating modification method according to claim 1, wherein the method comprises the following steps: ethanol on the surface of the hydrophobic material is removed before the step S2.

6. The modified super hydrophilic film of the polyphenol coating prepared by the modification method of any one of claims 1 to 5.

7. The polyphenol coating modified superhydrophilic film of claim 6, wherein: the polyphenol coating modified super-hydrophilic membrane has a layered nanosphere structure.

8. The modified super-hydrophilic membrane with the polyphenol coating prepared by the modification method of any one of claims 1 to 5 is applied to purification of oily wastewater.

9. The use according to claim 8, characterized in that: the polyphenol coating modified super-hydrophilic membrane is used for high-efficiency separation of oil-in-water emulsion.