Multifunctional application of a Janus sponge in photocatalytic degradation of multiple pollutants and oil-water separation

Abstract

The present invention relates to a multifunctional Janus sponge, which can efficiently and quickly photocatalytically degrade various pollutants such as rhodamine B, methylene blue, and tetracycline hydrochloride, as well as perform oil-water separation. First, BiOBr was prepared by a one-step synthesis method, and CAU-17MOF was grown in situ on the BiOBr material by a simple solvent thermal conversion method. BiOBr served as a template to support the growth of MOF and also as the Bi of MOF. 3+ Using a dip-coating method, a Janus sponge consisting of a superhydrophilic BiOBr / CAU-17@MS sponge and a superhydrophobic polydimethylsiloxane-modified PDMS@MS sponge was prepared. Due to its multiple wettabilities and interconnected, tortuous, three-dimensional porous channels, the resulting Janus sponge not only exhibited excellent degradation of rhodamine B, methylene blue, and tetracycline hydrochloride under visible light irradiation, but also demonstrated superior separation capabilities for oil-water mixtures. This Janus sponge has great potential for simultaneous removal of dyes and antibiotics, as well as oil / water separation.

Description

Technical Field

[0001] The present invention relates to the technical field of Janus materials, and in particular to a multifunctional application of a Janus porous sponge in photocatalytic degradation of various pollutants such as rhodamine B (RhB), methylene blue (MB), tetracycline hydrochloride (TC-HCl), and oil-water separation. Background Art

[0002] Water pollution is a growing problem, severely impacting ecosystems and human health. Due to the increasing volume of industrial oily wastewater and the frequent occurrence of oil spills, oil has become a major contaminant in water. Furthermore, dyes, due to their toxic, non-degradable, and carcinogenic properties, pose a serious threat to organisms and are increasingly becoming another dangerous water pollutant. The presence of these mixed pollutants in wastewater significantly increases the difficulty of treatment. Therefore, the development of effective wastewater purification materials and technologies that can simultaneously remove multiple pollutants is highly desirable.

[0003] Given that hydrophobic materials have high water resistance and hydrophilic materials have hydrophilic properties, the combination of hydrophobic and hydrophilic materials is expected to improve pollutant removal from wastewater and the separation of oil-water mixtures. With this in mind, our goal was to design a three-dimensional (3D) Janus material and adjust its dye and antibiotic degradation and oil-water separation capabilities by controlling the thickness of its hydrophobic and hydrophilic layers. To date, many 3D Janus materials have been reported, such as graphene / polyvinyl alcohol aerogels prepared by Li et al. and graphene oxide sponges prepared by Yun et al. Although they exhibit multiple wettabilities, their preparation processes are complex, require special equipment, and the dye degradation cycle is relatively long. Therefore, there is an urgent need to prepare a multifunctional Janus separation material through an inexpensive and direct method to simultaneously and efficiently degrade pollutants such as dyes and antibiotics and separate oil and water. Summary of the Invention

[0004] The present invention prepares a multifunctional Janus sponge. A hydrophilic sponge is prepared by a dip-coating method, and a super-hydrophobic sponge is prepared by hydrophobizing polydimethylsiloxane (PDMS). The obtained Janus sponge can not only efficiently photodegrade various pollutants such as rhodamine B (RhB), methylene blue (MB), and tetracycline hydrochloride (TC-HCl), but can also be used for oil-water separation.

[0005] To achieve the above objectives, the technical solutions of this application are as follows:

[0006] A Janus sponge, the preparation method of which comprises the following steps:

[0007] 1) Weighing bismuth nitrate pentahydrate and adding it to a mixed solution of deionized water and glycerol, ultrasonically treating it, and stirring it at room temperature until it is clear and transparent to obtain solution A; simultaneously, weighing potassium bromide and dissolving it in deionized water, stirring it until it is completely dissolved, to obtain solution B; adding solution B dropwise to solution A while stirring, the entire system is continuously stirred at a low speed for 1 hour, standing it at room temperature for 3 hours, washing it with water and alcohol, centrifuging it, and drying it to obtain BiOBr;

[0008] 2) BiOBr and 1,3,5-benzenetricarboxylic acid (H3BTC) were added to methanol and N,N-dimethylformamide (DMF), sonicated, and hydrothermally heated after vigorous magnetic stirring at room temperature. The mixture was washed with methanol, DMF, and methanol, centrifuged, and dried overnight to obtain BiOBr / CAU-17.

[0009] 3) Half of a sponge with a size of 2 cm × 2 cm × 1 cm was immersed in an ethanol solution containing BiOBr / CAU-17 and dried to obtain a BiOBr / CAU-17-modified hydrophilic sponge;

[0010] 4) The unmodified portion of the sponge is immersed in a n-hexane solution containing a PDMS prepolymer and a curing agent, and cured to obtain a hydrophobic sponge on the PDMS-modified side. The entire sponge obtained at this time is a Janus sponge.

[0011] Furthermore, in the above-mentioned Janus sponge, in step 1), the molar ratio of bismuth nitrate pentahydrate to potassium bromide is 1:1; the volume of the mixed solution of deionized water and glycerol is 30 mL, wherein the volume ratio of deionized water to glycerol is 1:2.

[0012] Furthermore, in the above-mentioned Janus sponge, in step 2), the molar ratio of BiOBr:H3BTC is 1:3; and the volume ratio of methanol:DMF is 3:1.

[0013] Furthermore, in the above-mentioned Janus sponge, in step 2), the hydrothermal conditions are: temperature is 120° C., and time is 2 h.

[0014] Furthermore, in the above-mentioned Janus sponge, in step 3), the mass of BiOBr / CAU-17 is 0.6 g, the volume of the ethanol solution is 5 mL, and the immersion time is 1 min.

[0015] Furthermore, in the above-mentioned Janus sponge, in step 4), the mass ratio of PDMS:curing agent is 10:1, and the immersion time is 1 min.

[0016] The above-mentioned Janus sponge is used in the photocatalytic degradation of multiple pollutants. The method is as follows: the Janus sponge is immersed in 50 mL of an aqueous solution containing 25 ppm of pollutants. Before irradiation, the solution is ultrasonicated for 5 minutes and stirred in the dark for 30 minutes to achieve the adsorption-desorption equilibrium of the material for the pollutants; then the light source is turned on to carry out the photocatalytic degradation reaction. During the reaction, 4 mL of the irradiated solution is taken every 10 minutes, and the concentration change of the target pollutant is measured at the maximum absorption wavelength using a UV-visible spectrophotometer.

[0017] Furthermore, in the above application, the pollutant is rhodamine B, methylene blue or tetracycline hydrochloride; the maximum absorption wavelengths of rhodamine B, methylene blue and tetracycline hydrochloride are 553 nm, 664 nm and 356 nm respectively.

[0018] The above-mentioned Janus sponge is used to separate oil from an oil-water mixture. The method is as follows: placing a Janus sponge in the oil-water mixture, taking out the sponge full of oil, and completing the oil-water separation.

[0019] Furthermore, in the above application, the oil is one or more of n-hexane, dichloromethane, ethyl acetate, DMF, chloroform, motor oil, peanut oil and olive oil.

[0020] The beneficial effects of the present invention are:

[0021] 1. The photodegradation ability of BiOBr / CAU-17 sponge for RhB, MB and TC-HCl is much greater than that of BiOBr sponge. CAU-17MOF was in situ grown on BiOBr material by a simple solvent thermal conversion method. BiOBr served as a template to support MOF growth and also as Bi 3+ Source. Because BiOBr / CAU-17 has more . O 2- and h + and a faster interfacial charge transfer rate, so it has better photodegradation performance.

[0022] 2. Conventional superhydrophobic sponges can only perform oil-water separation but are ineffective at degrading pollutants in aqueous solutions. Hydrophilic sponges can effectively degrade pollutants in aqueous solutions but have poor oil-water separation capabilities. The Janus sponge prepared by the present invention perfectly solves these problems, achieving both efficient pollutant degradation and excellent oil-water separation capabilities.

[0023] 3. The superhydrophobic modifier used in the present invention is a fluorine-free environmentally friendly reagent. The entire preparation method is very simple and does not require the use of expensive reagents, equipment, and harsh experimental conditions. The synthesized material has good stability, high separation efficiency, and strong circulation performance, which solves the problem of high production cost in the existing method for preparing Janus materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 are the XRD spectra of MS, BiOBr@MS, BiOBr / CAU-17@MS, and PDMS@MS.

[0025] Figure 2 FT-IR spectra of MS, BiOBr@MS, BiOBr / CAU-17@MS, and PDMS@MS.

[0026] Figure 3 This is a comparison of the photodegradation effects of BiOBr@MS and BiOBr / CAU-17@MS, where a: RhB, b: MB, and c: TC-HCl.

[0027] Figure 4 These are the water contact angle diagrams of BiOBr / CAU-17@MS and PDMS@MS, where a: the upward side of the sponge is the hydrophobic side surface of PDMS@MS, and b: the hydrophilic side surface of BiOBr / CAU-17@MS.

[0028] Figure 5 This is a test chart of the Janus sponge's adsorption capacity for different organic solvents and oils. DETAILED DESCRIPTION

[0029] Example 1 Preparation of a Janus sponge (I) Preparation of Janus sponge

[0030] 1) Preparation of BiOBr: 0.0485 g of bismuth nitrate pentahydrate was added to 30 mL of a mixed solution of deionized water and glycerol (volume ratio: 1:2). The mixed solution was then sonicated for 10 min and stirred at room temperature until clear and transparent, obtaining solution A. Simultaneously, 0.0119 g of potassium bromide was dissolved in 30 mL of deionized water and stirred until completely dissolved, obtaining solution B. Solution B was added dropwise to solution A with stirring. The entire system was stirred at a low speed for 1 h, then allowed to stand at room temperature for 3 h, washed with water and alcohol, centrifuged, and dried to obtain BiOBr.

[0031] 2) Preparation of BiOBr / CAU-17: BiOBr (1 mmol) and 1,3,5-benzenetricarboxylic acid (H3BTC) (3 mmol) were added to methanol (15 mL) and N,N-dimethylformamide (DMF) (5 mL). The mixture was sonicated and vigorously magnetically stirred at room temperature for 30 min. The mixture was heated at 120°C for 2 h, washed with methanol, DMF, and methanol, centrifuged, and dried overnight to obtain BiOBr / CAU-17.

[0032] 3) Half of a sponge (MS) (2 cm × 2 cm × 1 cm) was immersed in 5 mL of ethanol solution containing 0.6 g of BiOBr / CAU-17 for 1 min and dried to obtain a BiOBr / CAU-17-modified hydrophilic sponge, designated as BiOBr / CAU-17@MS.

[0033] 4) The unmodified half of the sponge (MS) was immersed in a n-hexane solution containing a PDMS prepolymer and a curing agent in a mass ratio of 10:1 for 1 min. The solution was cured to obtain a Janus sponge (PDMS modified side note: PDMS@MS, which imparts hydrophobicity).

[0034] (2) Characterization

[0035] By XRD ( Figure 1 ) and FT-IR( Figure 2 ) were used to characterize the materials. Figure 1 As shown in Figure 2, multiple strong diffraction peaks of BiOBr can be seen in BiOBr / CAU-17@MS, indicating that the structure of BiOBr exists in the BiOBr / CAU-17@MS system. Figure 2 As shown in the FTIR spectrum, 400-800 cm -1 The peak at 1091 cm is attributed to the vibration of O-Bi-O groups, proving the successful loading of BiOBr / CAU-17 composites on the sponge. -1 and 1260cm -1 The broad peaks are Si-O-Si and Si-CH3 stretching vibrations, indicating that PDMS is successfully deposited on the sponge. Both XRD and FT-IR prove the successful preparation of Janus sponge.

[0036] Example 2 Application of Janus sponge in degradation of rhodamine B, methylene blue, and antibiotics (I) Method for photocatalytic degradation of pollutants using Janus sponge

[0037] The photodegradation performance of the Janus sponge was investigated. A prepared Janus sponge (2 cm × 2 cm × 1 cm) was immersed in a 50 mL RhB / MB / TC-HCl aqueous solution (25 ppm). (During pollutant degradation, the BiOBr / CAU-17@MS half of the sponge is hydrophilic and can be completely immersed in the aqueous solution, enabling photocatalytic degradation. However, the PDMS@MS half of the sponge is superhydrophobic and cannot be immersed in water, ultimately floating on the surface and failing to photocatalytically degrade.) Before irradiation, the solution was sonicated for 5 minutes. The reaction cell was stirred in the dark for 30 minutes to achieve adsorption-desorption equilibrium. The light source was then turned on for photocatalytic degradation. 4 mL of the irradiated solution was sampled every 10 minutes during the reaction. The concentration of the target pollutant was measured using a UV-visible spectrophotometer at the wavelengths of maximum absorption (553 nm, 664 nm, and 356 nm for RhB, MB, and TC-HCl, respectively). C / C0 is used to evaluate the photodegradation efficiency, where C is the residual pollutant concentration and C0 is the initial pollutant concentration.

[0038] (2) Comparison of the photocatalytic degradation effects of BiOBr@MS and BiOBr / CAU-17@MS

[0039] BiOBr@MS and BiOBr / CAU-17@MS were immersed in 50mL of RhB / MB / TC-HCl aqueous solution (25ppm) respectively. Before irradiation, the solution was ultrasonicated for 5min and continuously magnetically stirred in the dark for 30min to obtain a complete adsorption equilibrium between the photocatalyst and the pollutant. The light source was then turned on to carry out the photocatalytic degradation reaction. During the reaction, 4mL of the irradiated solution was taken every 10min. The concentration of the target pollutant was measured at the maximum absorption wavelength (553nm, 664nm and 356nm for RhB, MB and TC-HCl, respectively) using a UV-visible spectrophotometer. The photodegradation efficiency was evaluated using C / C0, where C is the residual pollutant concentration and C0 is the initial pollutant concentration. The degradation efficiency results are shown in Figure 2. Figure 3 .Depend on Figure 3 It can be seen that the introduction of CAU-17MOF significantly improves the degradation performance of the sponge on the three pollutants. The Janus sponge provided by the present invention has a good degradation effect on a variety of dyes and antibiotics.

[0040] Example 3 Application of Janus sponge in oil-water separation

[0041] The application of Janus sponges in oil-water separation was investigated. Adsorption capacity, a criterion for evaluating the performance of oil-absorbing materials, can be measured using the following procedure. A single Janus sponge was weighed and then placed in different types of oils and organic solvents for adsorption testing. After saturation, the sponge was removed and the surface oil and organic solvent were wiped off with filter paper. The oil-absorbed Janus sponge was then weighed. The adsorption capacity (Q) was calculated using the following equation:

[0042]

[0043] Among them, m0 and m1 are the weights of the Janus sponge before and after adsorption, respectively.

[0044] (1) Surface wettability of Janus sponge

[0045] The wetting ability of Janus materials is as follows Figure 4 As shown, Figure 4 In a, the upward side of the sponge is the hydrophobic side PDMS@MS. A water droplet can maintain a complete spherical shape on its surface for a long time. The contact angle measured by an optical contact angle meter is 155.7°. The downward side of the sponge is the hydrophilic side BiOBr / CAU-17@MS. The contact angle measured by an optical contact angle meter is 0°. The water droplet is instantly absorbed on the hydrophilic BiOBr / CAU-17@MS ( Figure 4 b). But the overall sponge is oleophilic.

[0046] (2) Saturated adsorption of different oils and organic solvents by Janus sponge

[0047] The saturated adsorption capacity of Janus sponge for three oils (motor oil, peanut oil, olive oil) or organic solvents (n-hexane, N, N-dimethylformamide, dichloromethane, chloroform, ethyl acetate) was investigated. Figure 5 The Janus sponge exhibited a high adsorption capacity for various oils and organic solvents, with saturated adsorption capacities ranging from 15.98 to 38.45 times its own mass. The recyclability of these oils and organic solvents was also evaluated, and after 16 cycles of adsorption and desorption, the adsorption capacity showed no significant decrease, demonstrating excellent recyclability.

[0048] (3) Method of separating oil from oil-water mixture using Janus sponge

[0049] Place a Janus sponge in the oil-water mixture and take out the sponge full of oil to complete the oil-water separation.

[0050] The oil is one or more of n-hexane, dichloromethane, ethyl acetate, DMF, chloroform, motor oil, peanut oil and olive oil.

Claims

1. A Janus sponge, characterized in that The preparation method comprises the following steps: 1) Weigh bismuth nitrate pentahydrate and add it to a mixed solution of deionized water and glycerol. Ultrasonicate the solution and stir at room temperature until it becomes clear and transparent to obtain solution A. Simultaneously, weigh potassium bromide and dissolve it in deionized water. Stir until it is completely dissolved to obtain solution B. Add solution B dropwise to solution A while stirring. The entire system is stirred at a low speed for 1 hour. The solution is allowed to stand at room temperature for 3 hours, washed with water and alcohol, centrifuged, and dried to obtain BiOBr. 2) BiOBr and 1,3,5-benzenetricarboxylic acid (H3BTC) were added to methanol and N,N-dimethylformamide (DMF), sonicated, and hydrothermally heated after vigorous magnetic stirring at room temperature. The mixture was washed with methanol, DMF, and methanol, centrifuged, and dried overnight to obtain BiOBr / CAU-17. 3) Half of a 2 cm × 2 cm × 1 cm sponge was immersed in an ethanol solution containing BiOBr / CAU-17 and dried to obtain a BiOBr / CAU-17-modified hydrophilic sponge; 4) The unmodified half of the sponge is immersed in a hexane solution containing PDMS prepolymer and curing agent, and cured to obtain a hydrophobic sponge on the PDMS-modified side. The entire sponge obtained at this time is the Janus sponge.

2. A Janus sponge according to claim 1, characterized in that, In step 1), the molar ratio of bismuth nitrate pentahydrate to potassium bromide is 1:1; the volume of the mixed solution of deionized water and glycerol is 30 mL, wherein the volume ratio of deionized water to glycerol is 1:

2.

3. A Janus sponge according to claim 1, characterized in that, In step 2), the molar ratio of BiOBr:H3BTC is 1:3; the volume ratio of methanol:DMF is 3:

1.

4. A Janus sponge according to claim 1, characterized in that In step 2), the hydrothermal conditions are: temperature 120° C., time 2 h.

5. A Janus sponge according to claim 1, characterized in that, In step 3), the mass of BiOBr / CAU-17 is 0.6 g, the volume of the ethanol solution is 5 mL, and the immersion time is 1 min.

6. A Janus sponge according to claim 1, characterized in that, In step 4), the mass ratio of PDMS to curing agent is 10:1, and the immersion time is 1 min.

7. Use of the Janus sponge according to claim 1 in photocatalytic degradation of various pollutants and separation of oils from oil-water mixtures, characterized in that: The photocatalytic degradation method for various pollutants is as follows: a Janus sponge is immersed in a 50 mL aqueous solution containing 25 ppm of pollutants. Before irradiation, the solution is ultrasonicated for 5 minutes and stirred in the dark for 30 minutes to achieve adsorption-desorption equilibrium. The light source is then turned on to allow the photocatalytic degradation reaction to proceed. During the reaction, 4 mL of the irradiated solution is sampled every 10 minutes, and the concentration change of the target pollutant is measured at the wavelength of maximum absorption using a UV-visible spectrophotometer. The method for separating oil from an oil-water mixture is as follows: a Janus sponge is placed in the oil-water mixture, and the sponge filled with oil is taken out to complete the oil-water separation.

8. The use according to claim 7, characterized in that The pollutants are rhodamine B, methylene blue or tetracycline hydrochloride; the maximum absorption wavelengths of rhodamine B, methylene blue and tetracycline hydrochloride are 553 nm, 664 nm and 356 nm respectively.

9. The use according to claim 7, characterized in that The oil is one or more of n-hexane, dichloromethane, ethyl acetate, DMF, chloroform, engine oil, peanut oil and olive oil.

Images