CN116078191A - Preparation method of nano Jin Gaixing polysulfone membrane loaded on basis of dopamine coating - Google Patents
Preparation method of nano Jin Gaixing polysulfone membrane loaded on basis of dopamine coating Download PDFInfo
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Abstract
The invention discloses a preparation method of a nano Jin Gaixing polysulfone membrane based on a dopamine coating, which comprises the steps of preparing a polysulfone membrane matrix by a phase inversion method, soaking the polysulfone membrane matrix in alkaline dopamine solution, modifying a layer of Polydopamine (PDA) coating on the surface of a polysulfone membrane substrate material after self-polymerization reaction, then placing the substrate material modified with the PDA in chloroauric acid solution, and preparing nano gold particles in situ by utilizing weak reducibility and adhesiveness of the substrate material, so that PDA@Au is modified on the surface of the polysulfone membrane substrate material to form a functional composite material. The material is applied to rhodamine B dye wastewater, has a good removal effect on rhodamine B, and has good stability and high recycling rate.
Description
Technical Field
The invention belongs to the technical field of rhodamine B dye wastewater removal, and relates to a preparation method of a nano Jin Gaixing polysulfone membrane loaded on the basis of a dopamine coating.
Background
Along with the high-speed development of economy and society, the discharge amount of polluted wastewater is increased, the types of pollutants are increased, the surface water and the underground water are seriously polluted, and the economy and the ecological environment are seriously damaged. Among them, dye wastewater has carcinogenicity, teratogenicity and mutagenicity, and is one of the main factors threatening the environment and endangering human health. Currently, methods for treating dye wastewater include flocculation precipitation, physical adsorption, ion exchange, redox, membrane separation, biological treatment, and the like. The traditional adsorption and emerging catalysis technologies can have good removal effects, but have the problems of difficult recovery, easy secondary pollution and the like, so that finding a recoverable and reusable dye wastewater treatment method has important significance.
Compared with the traditional treatment methods such as adsorption, coagulation, oxidation, biodegradation and the like, the membrane separation technology has great potential in the aspect of treating dye wastewater with high chromaticity and high COD value due to the advantages of normal temperature operation, simple operation, low energy consumption, high efficiency, small occupied area, easy amplification, high cleaning efficiency and the like. Polysulfone membranes are commonly used as a separation membrane, and are commonly used as a base membrane of a composite membrane such as an ultrafiltration membrane because of good temperature resistance and solvent resistance, but polysulfone membranes are poor in hydrophilicity and cause membrane pollution, so researchers have been one of the problems of research and effort by researchers through developing different membrane materials and modifying the membrane materials so as to improve the hydrophilic performance of the membrane materials and efficiently adsorb pollutants in dye wastewater.
For example, chinese patent application No. 2022105223763 discloses a CoS/Ti 3 C 2 Preparation and application of the MXene composite material. The material fixes CoS nano particles on Ti by solvothermal method 3 C 2 Forming a composite material on the MXene film, wherein CoS nano particles in the obtained material are uniformly loaded on Ti 3 C 2 MXene nanoplatelet surfaces. The document loads cobalt sulphide nanoparticles on novel Ti 3 C 2 MXene material is applied to activating PMS under sunlight to degrade rhodamine B (RhB). Combines the advantages of metal cobalt sulfide and two-dimensional MXene material in the photocatalytic activation of PMS, realizes the oxidation of non-free radicals 1 O 2 ) The degradation process of the main photo-Fenton-like material overcomes SO in the traditional research 4 The radical quencher is limited by the OH in the process of degrading the organic pollutants, so that the efficient and rapid degradation of the colored pollutant RhB is realized, and a green and efficient new way is provided for the field of light-like Fenton environment treatment.
Disclosure of Invention
The invention aims to modify a polysulfone membrane for efficiently removing rhodamine B dye wastewater, and provides a preparation method of a nano Jin Gaixing polysulfone membrane based on a dopamine coating. The material is applied to rhodamine B fuel wastewater, has a good removal effect on rhodamine B, and has good stability and high recycling rate.
The technical scheme of the invention is as follows:
the preparation method of the nano Jin Gaixing polysulfone membrane based on the dopamine coating load sequentially comprises the following steps:
s1, preparation of PSF (PSF) of polysulfone-based membrane
S11, placing N, N-dimethylacetamide, polyethylene glycol and deionized water into a clean and dry conical flask, putting into a rotor, stirring on a magnetic stirrer, adding solid polysulfone particles, stirring for a period of time, transferring into a 65 ℃ constant-temperature heating magnetic stirrer, stirring for 24 hours, then transferring the conical flask into room temperature, standing for defoaming, obtaining polysulfone membrane liquid, and sealing for later use;
s12, taking polysulfone membrane liquid, placing the polysulfone membrane liquid on a clean glass plate, uniformly scraping the membrane casting liquid by using a scraper, and immersing the scraped liquid membrane into deionized water for 24 hours to obtain a polysulfone substrate material;
s2, preparation of polydopamine coating PSF/PDA
S21, weighing 2g of dopamine hydrochloride, uniformly dispersing the dopamine hydrochloride in 1000ml of Tris-HCl solution, and stirring the solution on a magnetic stirrer for 1h to obtain a dopamine solution;
s22, washing the polysulfone substrate material prepared in the step S12 with deionized water, drying at 40 ℃ for 1h, soaking the polysulfone substrate material in a dopamine solution, reacting at room temperature for 24h, taking out the coated dopamine modified polysulfone membrane, washing off the solution remained on the surface of the membrane with deionized water, and finally storing the dopamine modified membrane in the deionized water;
s3, preparation of gold-loaded composite material PSF/PDA@Au
S31, taking chloroauric acid mother liquor prepared by a chloroauric acid reagent sealed in a glass tube in vacuum, transferring the prepared chloroauric acid mother liquor into a brown bottle by using deionized water as a solvent, and storing in a refrigerator at 4 ℃;
s32, transferring 20mL of 0.01mol/L chloroauric acid mother solution into a small beaker by using a pipetting gun, diluting the mother solution to prepare 100mL of 2mmol/L chloroauric acid solution, soaking the dopamine modified membrane prepared in the S22 into the 2mmol/L chloroauric acid solution for 3 hours at room temperature, taking out the product, cleaning the product by using deionized water, removing residual reagent, and finally storing the product in the deionized water for standby to obtain the final dopamine-loaded Jin Gaixing polysulfone membrane.
As a limitation of the present invention:
in step S11, the mass ratio of the N, N-dimethylacetamide, polyethylene glycol, deionized water and polysulfone particles is 180:20:1:45.
the mass ratio of the N, N-dimethylacetamide, the polyethylene glycol and the polysulfone particles is critical to the preparation of the polysulfone membrane, and the membrane prepared in the proportion of the invention has better mechanical properties, can be bent and wound, is convenient to assemble, is simple to operate, is easy to realize automation, provides better support for the formation of the dopamine coating, and is not easy to damage in the adsorption and desorption test process.
In step S21, the pH of the Tris-HCl solution is 8.5 and the concentration is 10mmol/L.
In the step, the pH value and the concentration of the Tris-HCl solution have great influence on the self-polymerization reaction of dopamine on the surface of the sulfone membrane substrate material, and the thickness of the modified polydopamine coating is 0.005mm. When the pH and concentration are not the values of the present invention, it is effective for the self-polymerization reaction of dopamine in the base material, specifically, the concentration and pH mainly affect the particle size of dopamine, and under acidic conditions, a large amount of H in the solution + Suppressing the DA polymerization process; when the pH=5-8.5, the formed PDA particles are more obvious along with the increase of the pH, the surface of the film is rougher, and the modification effect is better; when pH is>At 8.5, PDA particles become smaller and the roughness of the film surface becomes smaller with increasing pH, mainly because PDA particles are not easily formed on the film surface due to instability of PDA in a strongly alkaline solution.
(III) in the step S31, the concentration of the chloroauric acid mother solution is 0.01mol/L.
The concentration of the chloroauric acid mother solution influences the quantity of nano gold particles loaded on the surface of the dopamine coating, so that the removal performance of the synthetic product on rhodamine B in the solution is further influenced.
And (IV) in the step S12, the thickness of the polysulfone substrate material is 0.07-0.085mm, and in the step S32, the thickness of the dopamine coating-based loaded nano gold in the dopamine coating-loaded nano Jin Gaixing polysulfone membrane material is 0.005mm.
The invention also has the limit that the dopamine-loaded Jin Gaixing polysulfone membrane composite material is applied to the removal of rhodamine B dye wastewater, when the pH value of a solution is 6 and the reaction time is 100min, the degradation rate of rhodamine B is 98% when the initial concentration is 8.5mg/L, and the removal rate can still reach 92.67% after 4 adsorption cycles.
According to the technical scheme, the steps are closely related as a whole, and are mutually influenced and cannot be split.
By adopting the technical scheme, the invention has the following beneficial effects:
the preparation method is simple, the process is easy to control, the polysulfone base membrane is prepared by adopting a phase inversion method, gold is successfully loaded on a substrate by utilizing the adhesiveness and the reduction performance of polydopamine, and the PSF/PAD@Au composite material is obtained, and the contact angle of the composite material is reduced and the hydrophilicity is obviously improved after the composite material is modified by dopamine. Because dopamine has a viscous small molecule with a structure containing amine and catechol functional groups, the catechol groups of the dopamine are easily oxidized into quinone groups in the alkaline environment (pH=8.5) and in the presence of oxygen, and then the phenolic hydroxyl groups and the quinone groups undergo inverse disproportionation to generate semi-quinone free radicals which are coupled into cross-linking bonds, so that a polydopamine layer is formed on the surface of a substrate material. The polydopamine surface has strong adhesiveness and contains a large number of active functional groups capable of secondary reaction such as phenolic hydroxyl groups, amino groups and the like, and the active functional groups have strong adsorption performance and certain reducibility, so that not only can metal ions be attached to a carrier, but also the adsorbed metal ions can be reduced into metal simple substances, and the metal simple substances are loaded on the surface of the material to form the composite material. Because the surface of the gold nanoparticle is provided with a large number of high-activity sites, the gold nanoparticle can be easily combined with other atoms, rhodamine B with positive charges in dye wastewater can be adsorbed on the surface of the gold nanoparticle through electrostatic action, and the unique pi-pi structure of polydopamine can be used for highly enriching pollutants such as rhodamine B, so that the rhodamine B pollutants can be efficiently adsorbed in cooperation with nano-sized gold, and the effect of better removing rhodamine B can be achieved.
The composite material has good removal effect on the dye RhB, the optimal initial concentration of the dye RhB is 8.5mg/L, the optimal adsorption time is 100min, the optimal pH is 6, and the solution temperature has little influence on the removal rate of the RhB; the result of the cycle experiment shows that after 4 adsorption cycles, the removal rate can still reach 92.67%, which shows that PSF/PAD@Au has better stability and can be repeatedly used.
The method is suitable for preparing the dopamine-loaded Jin Gaixing polysulfone membrane, and is further used for removing rhodamine B in dye wastewater.
The following detailed description of the invention refers to the accompanying drawings.
Drawings
FIG. 1 is a technical scheme of a composite material prepared in example 1 of the present invention;
FIG. 2 is a rhodamine B standard chart;
FIG. 3 is an infrared spectrum of PSF, PSF/PDA, PSF/PDA@Au;
FIG. 4 is an XPS plot of PSF, PSF/PDA, PSF/PDA@Au;
FIG. 5 is an SEM of PSF, PSF/PDA, PDA-PSF/Au, wherein: (a) -PSF film surface; (b) -PSF/PDA film surface; (c) -PSF/PDA@Au film surface; (d) -PSF/PDA@Au film surface after adsorption;
fig. 6 is a graph of contact angle measurements of the effect of dopamine modification on the hydrophilic properties of polysulfone membranes, wherein: left graph-PSF film contact angle; right panel-PSF/PDA film contact angle;
FIG. 7 is a graph showing the effect of adsorption time on RhB removal rate;
FIG. 8 is a graph showing the effect of rhodamine B solution at different concentrations on RhB removal at 25 ℃;
FIG. 9 is a graph showing the effect of rhodamine B solution pH on RhB removal;
FIG. 10 is a graph showing the effect of temperature on RhB removal;
FIG. 11 is a graph showing the effect of the number of adsorption cycles of the PSF/PDA@Au film on rhodamine B removal rate.
Detailed Description
In the following examples, the reagents described were all commercially available unless otherwise specified, and the following experimental methods and detection methods were all employed according to the conventional experimental methods and detection methods unless otherwise specified.
Embodiment of preparation method of nano Jin Gaixing polysulfone membrane loaded on basis of dopamine coating
1. The technical route of the preparation method of the dopamine-loaded Jin Gaixing polysulfone membrane in the embodiment is as shown in fig. 1, and the preparation method is sequentially carried out according to the following step sequence:
s1 preparation of polysulfone-based Membrane (PSF)
Placing N, N-dimethylacetamide, polyethylene glycol and deionized water into a clean and dry conical flask, placing the conical flask into a rotor, stirring the conical flask, adding solid polysulfone particles into the magnetic stirrer, stirring the mixture for a period of time, then transferring the mixture into a 65 ℃ constant-temperature heating magnetic stirrer, stirring the mixture for 24 hours, then transferring the conical flask into room temperature, standing the mixture for defoaming to obtain polysulfone membrane liquid, and sealing the polysulfone membrane liquid for standby, wherein the mass ratio of the N, N-dimethylacetamide, the polyethylene glycol, the deionized water and the polysulfone particles is 180:20:1:45.
taking a certain amount (2 mL) of polysulfone membrane liquid, placing the polysulfone membrane liquid on a clean glass plate, uniformly scraping the membrane casting liquid by using a scraper, immersing the scraped liquid membrane into deionized water for 24 hours to obtain a polysulfone substrate material with the thickness of 0.079mm.
S2, preparation of Polydopamine coating (PSF/PDA)
The preparation process of the 2g/L dopamine solution comprises the following steps: firstly, weighing 2g of dopamine hydrochloride, uniformly dispersing in 1000ml of Tris-HCl (PH=8.5, 10 mmol/L) solution, stirring on a magnetic stirrer for 1h to obtain a dopamine solution, washing the polysulfone membrane obtained in the previous step with deionized water, drying at 40 ℃ for 1h, soaking the polysulfone membrane in the dopamine solution, reacting at room temperature for 24h, taking out the coated dopamine-modified polysulfone membrane, washing the solution remained on the surface of the membrane with deionized water, and finally storing the dopamine-modified membrane in the deionized water.
S3, preparation of gold-loaded composite material (PSF/PDA@Au)
Preparing chloroauric acid solution: 1g of chloroauric acid crystal sealed in a glass tube in vacuum is prepared into 0.01mol/L chloroauric acid mother solution, the solvent is deionized water, and the prepared chloroauric acid mother solution is transferred into a brown bottle and stored in a refrigerator at 4 ℃.
20mL of the chloroauric acid mother solution at 0.01mol/L was removed by a pipette, and the mother solution was diluted to prepare 100mL of a chloroauric acid solution at 2 mmol/L. Under the condition of room temperature, soaking the polysulfone membrane substrate with the polydopamine coating in 2mmol/L chloroauric acid solution for 3 hours, taking out the product, cleaning with deionized water, removing the residual reagent, and finally storing the product in deionized water for standby to obtain the final dopamine-loaded Jin Gaixing polysulfone membrane (PSF/PDA@Au), wherein the thickness of the dopamine coating loaded nano gold in the material is 0.005mm.
2. Performance analysis determination
Performance measurements and characterization were performed on one of the above-described dopamine-coating-based supported nano Jin Gaixing polysulfone membranes (PSF/pda@au) and a control group.
Control group: (1) polysulfone-based membranes (PSFs) were prepared in the same manner as in step S1 of this example.
(2) The preparation method of the dopamine-modified polysulfone membrane PSF/PDA is the same as the steps S1 and S2 in the embodiment.
1. Rhodamine standard curve
0.1g of rhodamine B is weighed and dissolved in a 1000mL volumetric flask to prepare 200mg/L of rhodamine B solution, the rhodamine B solution is diluted to 1,2,3,4,5 and 6mg/L respectively, the absorbance is measured at 554nm, a concentration-absorbance curve (shown in figure 2) is obtained, and a standard curve equation y=0.2729x+0.0529 and R 2 =0.9952。
2. Characterization of Performance
2.1 FT-IR analysis
FIG. 3 shows the infrared spectra of PSF, PSF/PDA, PSF/PDA@Au and after adsorption. As can be seen from the graph, the PSF is 1250cm -1 At which there appears an s=o stretching vibration peak and 1591cm -1 The formants of aromatic hydrocarbon c=c are characteristic peaks of polysulfone membranes; furthermore, 1439cm -1 、1522cm -1 Is PDA deposited on PSF film surfaceThe resulting two characteristic peaks correspond to C=C stretching vibration and N-H bending vibration, respectively, indicating successful modification of the PDA to the PSF base film. The s=o stretching vibration peak disappeared after gold loading, because the nano gold covered the surface of the base film.
2.2 XPS analysis
The chemical composition of the material was analyzed by electron spectroscopy (XPS), and as can be seen from FIG. 4, both the C1s peak (284 eV) and the O1s peak (531 eV) appear on the XPS full spectrum, which indicates that the chemical composition of the material after modification remains stable. The N1s peak on the surface of the material treated by the dopamine solution is enhanced, which indicates that the polydopamine is successfully modified to the surface of the basilar membrane. An Au4f peak appears at 83eV, indicating successful gold loading onto the dopamine-modified polysulfone membrane. After adsorption of rhodamine B, a Cl2p (197 eV) peak appears, which proves that rhodamine B is successfully adsorbed.
2.3 SEM analysis
Microscopic morphologies of the polysulfone-based film (control (1)), the PDA-modified polysulfone film (control (2)) and the product composite (PSF/pda@au) prepared in this example were observed by SEM. As a result, as shown in FIG. 5, it was found that the PSF surface was rough (FIG. 5 a), whereas the PDA-modified polysulfone film was more dense and smooth (FIG. 5 b). From fig. 5c, it can be observed that due to the adhesion and aggregation of dopamine, a uniformly dispersed white spot appears, which indicates that gold particles on the surface of PSF/PDA@Au are dispersed on the surface of a polysulfone membrane adhered by PDA, and the PDA forms a complete covering layer on the surface of the PSF membrane, so that gold is successfully loaded on the polydopamine coating. Fig. 5d is an electron microscope image after rhodamine B is adsorbed, and it can be seen that gold particles in the composite material are uniformly and stably dispersed.
2.4 contact Angle analysis
Since the polymeric materials are generally hydrophobic, affecting the adsorption and catalytic efficiency of the materials, their wettability properties are characterized by measuring the water contact angle of the material surface, and the measurement results are shown in fig. 6. From the graph, the water contact angle of the basal lamina (control group (1)) is 65.19 degrees, the water contact angle of the polydopamine modified membrane material (control group (2)) is reduced to 57.48 degrees, which indicates that the contact angle is reduced after dopamine modification, and the surface of the polydopamine coating contains abundant hydrophilic catechol and amino active groups, so that the surface hydrophilicity of the composite material is directly increased, and the hydrophilic performance of the modified material is obviously improved.
3. Study of adsorption and Desorption Properties of materials
In order to explore the dye removal effect of the polysulfone-based membrane and the modified material, the polysulfone-based membrane (control group (1)), the dopamine-modified polysulfone membrane (control group (2)) and the product nano gold-loaded dopamine coating modified polysulfone membrane (PSF/PDA@Au) prepared in the embodiment are compared, and the removal effect of the composite material on rhodamine B is tested. The specific process is as follows:
cutting the film into pieces of 3X 3cm 2 The influence of the initial concentration, adsorption time, pH value and temperature of rhodamine B and the recycling effect of the membrane are studied. The removal rate of rhodamine B solution by the membrane after the adsorption reaction is expressed by a formula:
M t (%)=C 0 -C t /C 0 ×100%
wherein: m in the formula t -removal rate of dye,%;
C 0 -initial concentration of dye, mg/L;
C t -initial dye concentration at time t, mg/L;
soaking the composite film after adsorbing the dye in absolute ethyl alcohol for 12 hours, desorbing the dye, measuring absorbance values before and after the rhodamine B solution reacts by using an ultraviolet-visible spectrophotometer, calculating the concentration of the rhodamine B solution according to a standard curve of the rhodamine B, and expressing the decolorization rate of the modified film to the rhodamine B solution by using a formula:
DR(%)=C t /C 0 ×100%
wherein, DR-decoloration rate in the formula,%; c (C) 0 -initial concentration of dye, mg/L; c (C) t -initial dye concentration at time t, mg/L;
3.1 Effect of adsorption time on removal Rate
The area is 3X 3cm 2 PSF, PSF/PDA and PSF/PAD@Au with a thickness of 0.089mm were added to rhodamine B (50 mL,8.5 mg/L) solution, respectively, and the relation between the removal amount and the adsorption time was examined at a time interval of 10 min. As can be seen from FIG. 7, the PSF/PAD@Au pairThe removal effect of rhodamine B is optimal, and the PSF film and the PSF/PDA film have little removal effect on rhodamine B. The removal rate of the complex film loaded with Au to rhodamine B is gradually increased along with the extension of time, and the removal rate of the complex film to rhodamine B is gradually stabilized at 100min, which indicates that the adsorption sites on the surface of the complex film are saturated, and the adsorption quantity reaches the maximum. Therefore, the optimal adsorption time was determined to be 100min.
3.2 Effect of initial concentration on removal Rate
50mL of rhodamine B solution with mass concentration of 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5 and 9.5mg/L is prepared, and the adding area is 3 multiplied by 3cm 2 The result of the PSF/PAD@Au material of (2) was shown in FIG. 8 by vibration adsorption at 25℃for 100min and measurement of absorbance A. As shown in the graph, as the initial concentration of the dye is continuously increased, the removal rate is gradually increased, when the initial concentration of rhodamine B reaches 8.5mg/L, the removal rate reaches 98.72%, and the initial concentration of rhodamine B is continuously increased, so that the removal rate is kept unchanged. This is probably due to the limited adsorption sites on the surface of the material, and when the rhodamine B concentration in the solution is too high, part of rhodamine B molecules cannot approach the active sites, so that the initial dye concentration is continuously increased, and the removal rate of the rhodamine B by the composite membrane is kept unchanged.
3.3 Effect of solution pH on removal Rate
As can be seen from FIG. 9, the empty membrane and the dopamine-modified polysulfone membrane have little removal effect on rhodamine B, so that only the removal effect of the PSF/PAD@Au membrane on rhodamine B is examined later, and the area is taken to be 3X 3cm 2 Drying composite film with thickness of 0.089mm, regulating pH value of 8.5mg/L rhodamine B solution to 2, 4, 6, 8, 10 and 12 respectively with 0.1mol/L diluted sodium hydroxide and diluted hydrochloric acid, and adding 3×3cm 2 The adsorption test was performed at a temperature of 25℃and the absorbance was measured and calculated.
The change in removal rate of rhodamine B with pH for the PSF/PAD@Au film is shown in FIG. 9. In the initial stage, the removal rate of rhodamine B by the composite film increases along with the increase of the pH value of the solution; at pH 6, the composite membrane had the best removal rate for rhodamine B (mt=98.72%) and the removal rate was relatively reduced by continuing to increase the pH of the solution. Under acidic conditionsThe lower shows lower rhodamine B removal rate mainly because rhodamine B molecules are cationic dyes, H + Competing with rhodamine B for adsorption binding sites; with the weakening of the acidity, the electrostatic attraction between the cationic molecules of the rhodamine B and the negative charges on the surface of the material is enhanced, so that the composite membrane has higher removal rate of the rhodamine B, and the removal rate reaches the maximum when the pH value is 6; and the pH value is continuously increased, rhodamine B molecules are ionized, and the rhodamine B is in a zwitterionic form, so that the electrostatic attraction between the rhodamine B and the surface of the material is weakened, and the removal rate is reduced.
3.4 Effect of temperature on rhodamine B removal Rate
50mL of 8.5mg/L rhodamine B solution was removed and placed in a small beaker, and the solution was added to the flask in an area of 3X 3cm 2 The PSF/PAD@Au of (2) is respectively subjected to oscillation adsorption for 100min at 25 ℃,35 ℃,45 ℃,55 ℃ and 65 ℃ to obtain the removal effect curve of the composite material on rhodamine B at different temperatures according to a method of 1.6, and the removal effect curve is shown in figure 10. As can be seen from fig. 10, the removal rate of the dye rhodamine B by PSF/pda@au slightly increases with increasing solution temperature. Under the condition of 65 ℃, the removal rate of rhodamine B is 98.95 percent, which is improved by 0.23 percent compared with the removal rate (98.72 percent) of the rhodamine B at 25 ℃, which shows that the influence of the solution temperature on the removal rate of the rhodamine B is smaller.
3.5 cycle use Properties
And (3) soaking the PSF/PAD@Au composite film after dye adsorption in absolute ethyl alcohol for 12 hours, then cleaning with deionized water, and finally drying at 60 ℃ for 2 hours. After the PSF/PAD@Au composite film is regenerated, an adsorption experiment is carried out, the composite film is soaked in rhodamine B solution, vibration adsorption is carried out for 100min at 25 ℃, the absorbance is measured, the removal rate of the composite film to rhodamine B is calculated, and the result is shown in figure 11. It can be seen that after 4 adsorption cycles, the removal rate of the PSF/PAD@Au composite film to rhodamine B is 98.72%, 97.94%, 95.22% and 92.67%, respectively, so that the PSF/PAD@Au composite film can be recycled in 4 adsorption cycles.
According to the invention, the polysulfone base membrane is prepared by adopting a phase inversion method, and gold is successfully loaded on the substrate by utilizing the adhesiveness and the reduction performance of polydopamine, so that the PSF/PAD@Au composite material is obtained. Tests of methods such as FESEM, FTIR, XPS and the like show that Au is successfully synthesized and successfully loaded on the substrate material, and a contact angle test result shows that the contact angle is reduced after dopamine modification, and the hydrophilicity is obviously improved.
The experimental results show that: the composite material has good removal effect on dye RhB, the optimal initial concentration of dye RhB is 8.5mg/L, the optimal adsorption time is 100min, the optimal pH is 6, and the solution temperature has little influence on the removal rate of RhB. The result of the cycle experiment shows that after 4 adsorption cycles, the removal rate can still reach 92.67%, which shows that PSF/PAD@Au has better stability and can be repeatedly used.
Comparative example
In this example, a series of composite membranes were prepared and a series of adsorption and desorption performance study experiments were performed on the membranes, and the experimental process was the same as that of the above example except that: the composite membrane material and the preparation method thereof are different, and concretely comprise the following steps:
group A: the PSF/Au composite film is prepared by the group, the preparation process of the PSF base film is the same as that of the embodiment S1 of the invention, and the PSF/Au composite film is obtained by soaking the PSF base film in 2mmol/L chloroauric acid solution for 3h after the PSF base film is prepared.
Group B: the PSF/PAD@Ag composite film is similar to the above embodiment of the invention in preparation process, and is different only in that: the 2mmol/L chloroauric acid solution is silver ammonia solution.
Group C: the PVDF/PAD@Fe composite film is similar to the above embodiment of the invention in preparation process, and is different only in that: the PSF in S1 was replaced with existing commercial PVDF and the 2mmol/L chloroauric acid solution was a ferrous sulfate solution.
And (3) carrying out an adsorption and desorption performance research experiment of rhodamine B on the composite membrane prepared in the A-C group, wherein the removal rate of the rhodamine B is specifically as follows after 4 adsorption cycles according to the initial concentration of 8.5mg/L, the adsorption time of 100min and the pH of 6:
group of | Removal rate of rhodamine B (%) |
Group A | 37.68 |
Group B | 82.51 |
Group C | 74.45 |
Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (6)
1. The preparation method of the nano Jin Gaixing polysulfone membrane based on the dopamine coating is characterized by sequentially carrying out the following steps:
s1, preparation of PSF (PSF) of polysulfone-based membrane
S11, placing N, N-dimethylacetamide, polyethylene glycol and deionized water into a clean and dry conical flask, putting into a rotor, stirring on a magnetic stirrer, adding solid polysulfone particles, stirring for a period of time, transferring into a 65 ℃ constant-temperature heating magnetic stirrer, stirring for 24 hours, then transferring the conical flask into room temperature, standing for defoaming, obtaining polysulfone membrane liquid, and sealing for later use;
s12, taking polysulfone membrane liquid, placing the polysulfone membrane liquid on a clean glass plate, uniformly scraping the membrane casting liquid by using a scraper, and immersing the scraped liquid membrane into deionized water for 24 hours to obtain a polysulfone substrate material;
s2, preparation of polydopamine coating PSF/PDA
S21, weighing 2g of dopamine hydrochloride, uniformly dispersing the dopamine hydrochloride in 1000ml of Tris-HCl solution, and stirring the solution on a magnetic stirrer for 1h to obtain a dopamine solution;
s22, washing the polysulfone substrate material prepared in the step S12 with deionized water, drying at 40 ℃ for 1h, soaking the polysulfone substrate material in a dopamine solution, reacting at room temperature for 24h, taking out the coated dopamine modified polysulfone membrane, washing off the solution remained on the surface of the membrane with deionized water, and finally storing the dopamine modified membrane in the deionized water;
s3, preparation of nano-gold loaded composite material PSF/PDA@Au
S31, taking chloroauric acid mother liquor prepared by vacuum-sealed chloroauric acid crystals in a glass tube, transferring the prepared chloroauric acid mother liquor into a brown bottle, and storing in a refrigerator at 4 ℃;
s32, transferring 20mL of 0.01mol/L chloroauric acid mother solution into a small beaker by using a pipetting gun, diluting the mother solution to prepare 100mL of 2mmol/L chloroauric acid solution, soaking the dopamine modified membrane prepared in the S22 into the 2mmol/L chloroauric acid solution for 3 hours at room temperature, taking out the product, cleaning the product by using deionized water, removing residual reagent, and finally storing the product in the deionized water for standby to obtain the final dopamine-loaded Jin Gaixing polysulfone membrane.
2. The method for preparing the dopamine-coating-based nano Jin Gaixing polysulfone membrane according to claim 1, wherein in step S11, the mass ratio of the N, N-dimethylacetamide, polyethylene glycol, deionized water and polysulfone particles is 180:20:1:45.
3. the method for preparing the dopamine-coating-based nano Jin Gaixing polysulfone membrane according to claim 1, wherein in step S21, the pH of the Tris-HCl solution is 8.5 and the concentration is 10mmol/L.
4. The method for preparing the dopamine-coating-based nano Jin Gaixing polysulfone membrane according to claim 1, wherein in the step S31, the concentration of the chloroauric acid mother solution is 0.01mol/L.
5. The method for preparing the dopamine-coating-based nano Jin Gaixing polysulfone membrane according to claim 1, wherein in the step S12, the thickness of the polysulfone substrate material is 0.07-0.085mm;
in the step S32, the thickness of the dopamine coating loaded nano gold in the polysulfone membrane material based on the dopamine coating loaded nano Jin Gaixing is 0.005mm.
6. The method for preparing the nano Jin Gaixing polysulfone membrane based on the dopamine coating according to any one of claims 1-5, wherein the composite material of the dopamine-loaded Jin Gaixing polysulfone membrane is applied to the removal of rhodamine B dye wastewater, and when the pH of a solution is 6 and the reaction time is 100min, the degradation rate of rhodamine B is 98% when the initial concentration is 8.5mg/L, and the removal rate can still reach 92.67% after 4 adsorption cycles.
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