Selective separation of Pt 4+ Ion-imprinted membranes, their preparation methods and applications

Abstract

The application discloses a kind of selectively separating Pt 4+ Ion imprinting membrane, with polyvinylidene fluoride / polyamide-amine (PVDF / PAMAM) as mixed matrix, acrylamide (AM) as functional monomer, and N,N-methylene bisacrylamide (MBA) as crosslinking agent, Pt (IV) ion imprinting membrane is prepared by the interaction between Pt (IV) and functional monomer using phase inversion method.The selectively separating Pt 4+ Ion imprinting membrane prepared by the application has high interception rate and flux, and can separate Pt 4+ And a variety of metal ions at one time, and then high-purity concentrated Pt 4+ Solution can be obtained by simple treatment;It also has good antifouling performance and wide application prospect.

Description

Technical Field

[0001] This invention relates to Pt-containing 4+ The separation of ion-containing industrial wastewater specifically involves a selective separation method for Pt. 4+ Ion-imprinted membranes, their preparation methods, and applications. Background Technology

[0002] Platinum (Pt) is a naturally occurring white precious metal with stable chemical properties and superior performance. It can be used in jewelry, ornaments, and handicrafts, as well as in high-grade chemical apparatus, platinum crucibles, electrodes, and catalysts in chemical reactions. The platinum production process generates a large amount of wastewater, such as wastewater from platinum precipitation and wastewater from washing ammonium chloroplatinate. This wastewater often contains Pt. 4+ Excessive metal ions in wastewater not only cause the loss of precious metals, but also make subsequent wastewater treatment more difficult and increase the cost of wastewater treatment. Summary of the Invention:

[0003] To address the problems in the prior art, firstly, the object of the present invention is to provide a selective separation method for Pt. 4+ Ion-imprinted membranes.

[0004] The objective of this invention is achieved as follows:

[0005] A selective separation of Pt 4+ The ion-imprinted membrane was prepared by using polyvinylidene fluoride / polyamide-amine (PVDF / PAMAM) as a mixed matrix, acrylamide (AM) as a functional monomer, and N,N-methylenebisacrylamide (MBA) as a crosslinking agent. The Pt(Ⅳ) ion-imprinted membrane (Pt(Ⅳ)-P / P / IIM) was prepared by phase transition method through the interaction between Pt(Ⅳ) and the functional monomer.

[0006] To further improve the separation of Pt by ion-imprinted membranes 4+ The Pt(Ⅳ) ion-imprinted membrane was modified by immersion in a triethanolamine / polyethylene glycol (TEOA / PEG) solution (to obtain a Pt(Ⅳ)-P / P / TIIM membrane).

[0007] According to one embodiment of the present invention, the Pt(Ⅳ) ion-imprinted membrane is modified by immersion in a triethanolamine / polyethylene glycol (TEOA / PEG) solution at a temperature of 50-70°C. Further, the immersion modification time is 1-3 hours.

[0008] Secondly, the present invention provides the above-mentioned selective separation of Pt 4+ Methods for preparing ion-imprinted membranes.

[0009] The above selective separation of Pt 4+The preparation method of the ion-imprinted membrane includes the following steps: dissolving polyvinylidene fluoride (PVDF) powder in DMSO solution, then adding polyamide-amine (PAMAM), stirring at 50-70℃ for 8-15h to obtain a uniform pale yellow viscous solution, then adding H2PtCl6·6H2O, acrylamide (AM) and N,N-methylenebisacrylamide (MBA), and removing oxygen from the mixture with inert gas, carrying out a polymerization reaction at 50-70℃ for 3-5h, then cooling to room temperature and degassing, pouring the polymerized membrane solution onto a glass plate, immersing it in water to obtain the ion-imprinted membrane.

[0010] According to one embodiment of the present invention, the PAMAM is synthesized by a Michael addition reaction of methyl acrylate (MA) and ethylenediamine (EDA).

[0011] According to one embodiment of the present invention, the molar ratio of the functional monomer acrylamide (AM) to H2PtCl6·6H2O is 1:4-5.

[0012] According to one embodiment of the present invention, the molar ratio of N,N-methylenebisacrylamide (MBA) to H2PtCl6·6H2O is 1:4-5.

[0013] Specifically, selective separation of Pt 4+ The method for preparing ion-imprinted membranes includes the following steps:

[0014] First, 7.5 g of PVDF powder was added to a hot DMSO solution, followed by 1.5 g of PAMAM. The mixture was heated to 60 °C and stirred overnight at 60 °C to obtain a uniform, pale yellow, viscous solution. Then, 0.518 g of H2PtCl6·6H2O, 0.284 g of AM, and 0.617 g of MBA were added. The oxygen in the mixture was removed with an inert gas, and the polymerization reaction was carried out at 60 °C for 4 hours. The mixture was then cooled to room temperature and degassed. The polymerized membrane solution was poured onto a glass plate and immersed in water to obtain Pt(Ⅳ)-P / P / IIM.

[0015] According to one embodiment of the present invention, in order to improve the performance of the membrane, the polymerized membrane solution is poured onto a glass plate and immersed in a TEOA / PEG solution at 60°C for 2 hours to obtain Pt(Ⅳ)-P / P / TIIM.

[0016] Thirdly, the present invention provides the application of the above-mentioned ion-imprinted membrane in the selective separation and enrichment of Pt(Ⅳ) ions in industrial wastewater.

[0017] Beneficial effects

[0018] This invention provides a method for selectively separating Pt 4+The ion-imprinted membrane of Pt(Ⅳ) is prepared by using polyvinylidene fluoride / polyamidoamine (PVDF / PAMAM) as a mixed matrix, acrylamide (AM) as a functional monomer, and N,N-methylenebisacrylamide (MBA) as a crosslinking agent. The membrane is fabricated via a phase transition method through the interaction between Pt(Ⅳ) and the functional monomer. This invention provides a selective separation membrane for Pt. 4+ The ion-imprinted membrane exhibits high rejection rate and flux, capable of converting Pt into plasma in a single pass. 4+ Pt can be separated from various metal ions and then subjected to simple processing to obtain high-purity Pt. 4+ The solution has good antifouling properties, thus extending the service life of the membrane. Attached Figure Description

[0019] Figure 1 These are the infrared spectra of PVDF film, PVDF / PAMAM film, Pt(Ⅳ)-P / P / IIM film, and Pt(Ⅳ)-P / P / TIIM film.

[0020] Figure 2 These are AFM images of PVDF membrane, PVDF / PAMAM membrane, Pt(Ⅳ)-P / P / IIM membrane, and Pt(Ⅳ)-P / P / TIIM membrane;

[0021] Figure 3 The water contact angles of PVDF membranes, PVDF / PAMAM membranes, Pt(Ⅳ)-P / P / IIM membranes, and Pt(Ⅳ)-P / P / TIIM membranes are as follows:

[0022] Figure 4 It is a miniature vacuum filtration device used in all membrane filtration experiments;

[0023] Figure 5 It is the selective adsorption of mixed ions by Pt(Ⅳ)-P / P / TIIM membranes and NIM membranes;

[0024] Figure 6 This is the result of Pt(Ⅳ)-P / P / TIIM membrane circulating filtration of water-BSA. Detailed Implementation

[0025] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other, and many specific details are set forth in the following description to provide a thorough understanding of the present invention.

[0026] In this invention, Pt(Ⅳ) is equivalent to Pt 4+ The ion Au(III) is equivalent to Au 3+ The ion, Pd(II), is equivalent to Pd.2+ The ion Cu(II) is equivalent to Cu 2+ The ion, Ni(II), is equivalent to Ni. 2+ ion.

[0027] Example 1: Selective Separation of Pt 4+ Preparation of ion-imprinted membranes

[0028] Dendrimer PAMAM is synthesized via a Michael addition reaction of methyl acrylate (MA) and ethylenediamine (EDA) (TCGFWPKMaiti, WAGodard, Structure of PAMAM Dendrimers: Generations 1 through 11, Macromolecules, 37 (2004), 6236-6254).

[0029] First, 7.5g of PVDF powder was added to a hot DMSO solution, followed by 1.5g of PAMAM. The mixture was heated to 60°C and stirred overnight at 60°C to obtain a uniform, pale yellow, viscous solution. Then, 0.518g of H2PtCl6·6H2O, 0.284g of AM, and 0.617g of MBA were added, and the oxygen in the mixture was removed with an inert gas. The polymerization reaction was carried out at 60°C for 4 hours, followed by cooling to room temperature and degassing. The polymerized membrane solution was poured onto a glass plate and immersed in water to obtain a Pt(Ⅳ)-P / P / IIM membrane.

[0030] To improve the performance of ion-imprinted membranes, Pt(Ⅳ)-P / P / IIM membranes were modified. Pt(Ⅳ)-P / P / IIM membranes were obtained by immersing the membranes in a TEOA / PEG solution at 60°C for 2 hours.

[0031] Following the method described above, PVDF powder was used to prepare a PVDF membrane without the addition of dendritic polymer PAMAM, H2PtCl6·6H2O, AM, and MBA. Alternatively, PVDF / PAMAM membranes were prepared using PVDF powder with the addition of dendritic polymer PAMAM, but without the addition of H2PtCl6·6H2O, AM, and MBA.

[0032] The preparation method of non-ionic imprinted membrane is the same as that of ion-imprinted membrane, but without the addition of H2PtCl6·6H2O, and it is named NIM membrane.

[0033] The obtained ion-imprinted membrane was characterized using the KBr method of infrared spectroscopy in the range of 4000–400 cm⁻¹. -1 Scanning the FTIR spectrum of the sample to analyze the material's structure, such as... Figure 1 As shown: In the infrared spectrum of the PVDF film, 1192.57 cm⁻¹-1 The characteristic peaks are attributed to the stretching vibrations of the CF bonds, and the presence of CF peaks in the infrared spectra of all materials indicates the presence of a PVDF matrix in all materials. In the PVDF / PAMAM infrared spectrum, the peak at 1403.18 cm⁻¹... -1 The appearance of a CN stretching vibration peak at 1650.25 cm⁻¹ indicates that the PAMAM matrix has been successfully cross-linked with the PVDF membrane. This is also evident in the Pt(Ⅳ)-P / P / TIIM infrared spectrum. -1 The appearance of the C=C stretching vibration peak indicates that the ion-imprinted membrane polymerization was successful.

[0034] The successfully prepared PVDF films, PVDF / PAMAM films, Pt(Ⅳ)-P / P / IIM and Pt(Ⅳ)-P / P / TIIM were observed by atomic force microscopy, and the results are as follows: Figure 2 As shown, the Ra of the PVDF-based film is 38 nm, while the Ra of the PVDF / PAMAM film after incorporating PAMAM is 30.7 nm, indicating that the addition of the PAMAM matrix makes the film surface smoother. The polymerized film, observed under an atomic force microscope, shows an Ra increase to 127 nm, four times that of the previous film. While this film exhibits excellent retention, its rough surface easily traps contaminants. Using TEOA / PEG for surface modification forms a thin film with an Ra of 33.4 nm, and the surface becomes relatively smooth again. Meanwhile, as... Figure 3 As shown, after surface modification with TEOA / PEG, the contact angle with water is 61.5°. This indicates that the Pt(Ⅳ)-P / P / TIIM surface is smooth, and the antifouling effect of the membrane is greatly enhanced.

[0035] Filtration experiment

[0036] Use a filtration device (such as a feeder filter). Figure 4 The pure water flux (J) and retention rate (R) of the membrane were tested. All filtration tests were performed at 1 bar pressure, and the liquid concentrations before and after filtration were evaluated by inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine the retention rate. The pure water flux (J) was calculated according to formula (1), and the retention rate (R) was calculated according to formula (2):

[0037]

[0038]

[0039] Where Q is the volume of water that seeps in (liters), A is the area of ​​the membrane (square meters), and t is the time (hours) required for a certain volume of water to pass through. C f and C p These are the Pt values ​​in the solution before and after filtration. 4+The concentration (mg / L).

[0040] Wastewater contains metal ions, making selective retention experiments essential. The experiment used 20 mL of 20 mg·L⁻¹ solution. -1 A solution containing a mixture of Pt(Ⅳ), Au(III), Pd(II), Cu(II), and Ni(II) ions was filtered. The results showed that Pt(Ⅳ)-P / P / TIIM selectively retained Pt in the mixed ionic solution. 4+ At a pressure of 1 bar, a pH of 4, and a concentration of 20 mg·L⁻¹ -1 At room temperature, its rejection rate and flux were 94.24% and 414.01 L·m⁻¹, respectively. -2 ·h -1 .like Figure 5 As shown, Pt(Ⅳ)-P / P / TIIM and NIM are related to Pt 4+ The retention rates were 94.24% and 75.48%, respectively. This indicates that, compared with other materials, Pt(Ⅳ)-P / P / TIIM has a better retention rate than Pt. 4+ It has stronger selective retention.

[0041] Referring to the above embodiments, the fouling experiment was conducted by alternating feed solutions of water and contaminant solutions. Water and a contaminant solution prepared with BSA (bovine serum albumin) were used to investigate the membrane's antifouling effect. The initial water flux was recorded as 414.01 L·m⁻¹. -2 ·h -1 Then, the contaminant was used instead of feed for continuous filtration. Next, the membrane under test was removed and washed with pure water for 30 minutes according to the contaminant solution. Finally, the water / contaminant flux of the washed membrane was measured again, and three water-BSA cycles were performed. The antifouling effect of Pt(Ⅳ)-P / P / TIIM was as follows: Figure 6 As shown, after multiple cycles, the water flux of Pt(Ⅳ)-P / P / TIIM still reached 129.64 L·m. -2 ·h -1 It also has a significant inhibitory effect on BSA.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for selectively separating Pt 4+ The method for preparing the ion-imprinted membrane Pt(Ⅳ)-P / P / TIIM is characterized by, Using polyvinylidene fluoride / polyamide-amine (PVDF / PAMAM) as a mixed matrix, acrylamide (AM) as a functional monomer, and N,N-methylenebisacrylamide (MBA) as a crosslinking agent, ion-imprinted membranes were prepared by phase transition method through the interaction between Pt(Ⅳ) and the functional monomer. The preparation method includes the following steps: dissolving polyvinylidene fluoride (PVDF) powder in DMSO solution, then adding dendritic polymer polyamide-amine (PAMAM), stirring at 50-70℃ for 8-15 h to obtain a uniform pale yellow viscous solution, then adding H2PtCl6·6H2O, acrylamide (AM) and N,N-methylenebisacrylamide (MBA), and removing oxygen from the mixture with inert gas, carrying out a polymerization reaction at 50-70℃ for 3-5 h, then cooling to room temperature and degassing, pouring the polymerized membrane solution onto a glass plate, immersing it in water to obtain an ion-imprinted membrane, and then modifying the ion-imprinted membrane by soaking it in triethanolamine / polyethylene glycol (TEOA / PEG) solution to obtain the ion-imprinted membrane Pt(Ⅳ)-P / P / TIIM; The molar ratio of the functional monomer acrylamide (AM) to H2PtCl6·6H2O is 1:4-5; the molar ratio of N,N-methylenebisacrylamide (MBA) to H2PtCl6·6H2O is 1:4-5.

2. The preparation method according to claim 1, characterized in that, The ion-imprinted membrane is modified by immersion in a triethanolamine / polyethylene glycol (TEOA / PEG) solution at a temperature of 50-70°C.

3. The preparation method according to claim 1, characterized in that, The soaking modification time is 1-3 hours.

4. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: First, PVDF powder was added to a hot DMSO solution, followed by PAMAM, and the mixture was heated to 60°C and stirred overnight at 60°C to obtain a uniform, pale yellow, viscous solution. Then, H2PtCl6·6H2O, AM, and MBA were added, and the oxygen in the mixture was removed with an inert gas. The polymerization reaction was carried out at 60°C for 4 hours, and then cooled to room temperature and degassed. The polymerized membrane solution was poured onto a glass plate and immersed in water to obtain an ion-imprinted membrane.

5. The preparation method according to claim 4, characterized in that, The ion-imprinted membrane Pt(Ⅳ)-P / P / TIIM was obtained by immersing the membrane in TEOA / PEG solution at 60℃ for 2 hours.

6. The application of the ion-imprinted membrane Pt(Ⅳ)-P / P / TIIM prepared by any one of the preparation methods of claims 1-5 for the selective separation and enrichment of Pt(Ⅳ) ions in industrial wastewater.

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