Preparation method of multi-amino carbon quantum dot adsorption material
By pyrolyzing polyethyleneimine to synthesize nano-scale carbon quantum dots and grafting them on a chloromethyl polystyrene resin matrix, a new separation resin is formed, which solves the problems of poor adsorption capacity and insufficient regeneration ability of traditional adsorbents in the pickling cycle, and achieves efficient separation and regeneration of Zn(II) and Fe(II).
Patent Information
- Application Number
- CN202510160335.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-13
- Publication Date
- 2025-06-20
AI Technical Summary
Traditional adsorbents have problems with poor adsorption capacity or poor regeneration capacity during the pickling cycle, making it difficult to effectively separate zinc (II) and iron (II) ions and cause pollution to the environment.
Polyethyleneimine is synthesized into nano-scale carbon quantum dots by pyrolysis and grafted onto a chloromethyl polystyrene resin matrix to form a new separation resin, which increases the amine loading and adsorption sites.
The specific separation of Zn(II) and Fe(II) in an acidic environment is achieved, with higher adsorption amount and easy regeneration properties, and has significant advantages over traditional strong alkaline anion exchange resins.
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Figure CN120169332A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of adsorption technology, and in particular to a method for modifying chloromethyl polystyrene resin with carbon quantum dots. Background Art
[0002] The hydrochloric acid pickling process plays a vital role in ensuring the surface quality of steel, but as the number of pickling cycles increases, the pickling efficiency will gradually decrease. The used pickling solution contains acid, iron, zinc and chloride ions, which cause serious harm to the environment. Therefore, it is necessary to dispose of the spent pickling solution in a safe way to prevent environmental problems.
[0003] Adsorption is a reversible chemical reaction between water and solid phase ions, where specific ions in the aqueous phase are easily adsorbed by the functional groups of the adsorbent and thus absorbed by the adsorbent. Zinc-chloride ions exhibit anionic characteristics, while iron-chloride ions exhibit cationic characteristics. Previous studies have shown that effective separation of zinc (II) and iron (II) can be achieved by using a specialized hydrochloric acid mixture in combination with an adsorbent. However, traditional adsorbents usually have the disadvantages of poor adsorption capacity or poor regeneration ability, making them difficult to apply in practical industrial applications.
[0004] Polyethyleneimine has attracted the attention of researchers due to its rich amine properties, and its protonation property under acidic conditions, so it has the potential to be used as an anion adsorbent. However, due to its high molecular weight and size, it is difficult to enter the interior of porous materials, resulting in the inability to fully utilize the active sites of porous materials. In view of the problems in this technology, the present invention refers to polyethyleneimine as nanoscale carbon quantum dots through a pyrolysis method, making it easier to undergo grafting reactions on mesoporous and macroporous matrix materials, increasing the amount of amine loaded, thereby providing more adsorption sites in a limited volume. Summary of the invention
[0005] The purpose of the present invention is to provide a method for grafting carbon quantum dots rich in amino structures onto a chloromethyl polystyrene resin matrix, thereby preparing a new separation resin with a specific separation effect on Zn(II) and Fe(II) in an acidic environment. Compared with traditional strong alkaline anion exchange resins, the resin has a higher adsorption capacity for Zn(II) and is easy to regenerate.
[0006] To achieve the above object, the present invention provides a method for grafting carbon quantum dots rich in amine structure onto a chloromethyl polystyrene resin matrix, comprising the following steps:
[0007] 1. Preparation of carbon quantum dots rich in amino groups: Add 10 g of polyethyleneimine with a molecular weight of 600 to a 150 mL round-bottom flask, and then heat the solution to 175 °C using an oil bath. After heating for 10 min, immediately drop the obtained solution into 50 mL of deionized water and stir magnetically. Then cool the obtained solution to room temperature and dialyze it in a dialysis bag (1000 Da) for 3 days to remove the remaining molecular precursors. Subsequently, filter the dialysate through a PVDF ultrafiltration membrane with a diameter of 0.45 μm at 1 bar to remove large particles. Finally, rotary evaporate the dialysate (12 h), dry it in an oven for 24 h, and freeze-dry it for 12 h to obtain polyamino carbon quantum dots in the form of a golden solid.
[0008] 2. Preparation of polyamino carbon quantum dot adsorbent: Prepare an aqueous solution of polyamino carbon quantum dots with a mass fraction of 20%. Weigh 1.0 g of chloromethylated polystyrene matrix, add 10 mL of 1,4-dioxane, and swell it at room temperature for 12 h. Add the pre-swelled chloromethylated polystyrene matrix to a 150 mL four-necked flask equipped with a stirrer, a thermometer, and a dropping funnel. Then add 0.05 g of 4-dimethylaminopyridine, and load the pre-prepared polyamino carbon quantum dots into the dropping funnel and add them drop by drop. Adjust the pH value of the system to 10 and react continuously at 60 °C for 10 h. Separate the product using a suction funnel, wash it with deionized water until there is no chloride ion, and dry it in a forced-air drying oven at 60 °C for 12 h to obtain a dry polyamino carbon quantum dot adsorbent. Description of the Drawings
[0009] Figure 1 Infrared spectra of the carbon quantum dots and polyamino carbon quantum dot adsorbent provided in Example 1 of the present invention
[0010] Figure 2 Transmission electron micrographs of the carbon quantum dots and polyamino carbon quantum dot adsorbent provided in Example 1 of the present invention
[0011] Figure 3 XPS spectra of the polyamino carbon quantum dot adsorbent before and after modification provided in Example 1 of the present invention. The left Figure 1 is the total spectrum of the matrix, and the left Figure 2 is the total spectrum of the adsorbent. The right figure is the N1s peak deconvolution spectrum of the adsorbent
[0012] Figure 4 Scanning electron micrographs of the polyamino carbon quantum dot adsorbent provided in Example 1 of the present invention. The left figure is the matrix, and the right figure is the adsorbent
[0013] Figure 5 Nitrogen adsorption-desorption isotherms of the polyamino carbon quantum dot adsorbent provided in Example 1 of the present invention. The left figure is the matrix material, and the right figure is the adsorbent. Figure 6For the polyamine-functionalized carbon quantum dot adsorbent synthesized under different solvent conditions in Example 2 of the present invention, the adsorption capacity for Zn(II). Figure 7 For the polyamine-functionalized carbon quantum dot adsorbent under different mass fractions of polyamine-functionalized carbon quantum dots in Example 3 of the present invention, the adsorption capacity for Zn(II). Figure 8 For the polyamine-functionalized carbon quantum dot adsorbent obtained under different reaction temperatures in Example 4 of the present invention, the adsorption capacity for Zn(II). Figure 9 For the polyamine-functionalized carbon quantum dot adsorbent prepared under different reaction time conditions in Example 5 of the present invention, the adsorption capacity for Zn(II). Figure 10 In Example 6, when the polyamine-functionalized carbon quantum dot adsorption column adsorbs the pickling waste liquid of galvanized steel sheets in a steel plant, the graph of the change in the volume of waste liquid treated by the adsorption column and the concentrations of iron and zinc ions in the effluent of the adsorption column. Figure 11 In Example 6, after the polyamine-functionalized carbon quantum dot adsorption column is saturated, when it is regenerated by water rinsing, the graph of the change in the volume of rinsing water consumed and the concentrations of iron and zinc ions in the effluent of the adsorption column.
[0014] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.
[0015] Unless otherwise specified, the materials, reagents, etc. used in the following examples are all available from commercial sources.
[0016] In the implementation method, an explanation is given for Figure 9 -- Figure 11 ...
[0017] In order to clarify the technical solution and the object of the present invention, the present invention will be further described below with reference to the accompanying drawings and specific examples.
[0018] Appendix Explanation
[0019] Table 1 shows the analysis results of the nitrogen adsorption-desorption curves of the carbon quantum dots and the polyamine-functionalized carbon quantum dot adsorbent provided in Example 1 of the present invention.
[0020] Table 1
[0021] Detailed Implementation Modes
[0022] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.
[0023] Example 1
[0024] The present invention provides a method for grafting carbon quantum dots rich in amine groups onto a chloromethylated polystyrene resin matrix, comprising the following steps:
[0025] Prepare an aqueous solution of multi-amine carbon quantum dots with a mass fraction of 20%. Weigh 1.0 g of the chloromethylated polystyrene matrix, add 10 ml of 1,4-dioxane, and swell it at room temperature for 12 h. Add the pre-swollen chloromethylated polystyrene matrix to a 150 ml four-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, then add 0.05 g of 4-dimethylaminopyridine. Load the pre-prepared multi-amine carbon quantum dots into the dropping funnel and add them drop by drop. Adjust the pH value of the system to 10 and continuously react at 60 °C for 10 h. Separate the product using a suction funnel, wash it with deionized water until no chloride ions are present, and place it in a blast drying oven at 60 °C for drying for 12 h to obtain a dried multi-amine carbon quantum dot adsorbent material.
[0026] FTIR infrared analysis shows that Figure 1 as shown, a broad peak of N-H vibration appears at 3272 cm -1 for the multi-amine carbon quantum dots. Characteristic peaks of typical PEI appear at 1659, 1359, and 756 cm -1 . For the multi-amine carbon quantum dot adsorbent material, a shifted N-H vibration absorption peak is found at 3400 cm -1 . Moreover, typical PEI peaks are observed at 1659, 1585, and 1395 cm -1 , proving that the multi-amine carbon quantum dots are successfully grafted onto the chloromethylated polystyrene matrix.
[0027] Figure 2 is the transmission electron microscopy image of the multi-amine carbon quantum dots, and the image shows that the synthesized multi-amine carbon quantum dots are nano-sized materials. Figure 3 is the XPS image of the multi-amine carbon quantum dot adsorbent material. Compared with the chloromethylated polystyrene matrix, characteristic peaks of the N element newly appear in the modified adsorbent material. The 399.1 eV and 400.7 eV of N1s are the two characteristic peaks of N-H and C-N respectively.
[0028] Figure 4SEM image of the polyamine-functionalized carbon quantum dot adsorbent material. Compared with the unmodified chloromethylated polystyrene matrix, the surface roughness of the modified resin is significantly increased. A large number of bumps appear on the surface of the modified resin, and the pores of the resin are significantly reduced. These results indicate that the polyamine-functionalized carbon quantum dots have been successfully grafted onto the chloromethylated polystyrene matrix.
[0029] Figure 5 N2 adsorption / desorption isotherms and pore size distribution curves of the polyamine-functionalized carbon quantum dot adsorbent material. The images show that both the modified and unmodified materials exhibit type-IV adsorption isotherms with obvious hysteresis loops, indicating that the samples have mesoporous and macroporous structures. The specific surface area, pore size, and pore volume of the polyamine-functionalized carbon quantum dot adsorbent material are all reduced compared to those before modification, indicating the successful grafting of polyamine-functionalized carbon quantum dots into the pores of the chloromethylated polystyrene matrix.
[0030] Example 2
[0031] The present invention provides a method for grafting carbon quantum dots with amine-rich structures onto a chloromethylated polystyrene resin matrix, which includes the following steps:
[0032] Prepare an aqueous solution of polyamine-functionalized carbon quantum dots with a mass fraction of 20%. Weigh 1.0 g of the chloromethylated polystyrene matrix, and add 10 ml of 1,4-dioxane, cyclohexane, and N,N-dimethylformamide respectively, and swell at room temperature for 12 h. Add the pre-swollen chloromethylated polystyrene matrix into a 150 ml four-necked flask equipped with a stirrer, thermometer, and dropping funnel, then add 0.05 g of 4-dimethylaminopyridine, and load the pre-prepared polyamine-functionalized carbon quantum dots into the dropping funnel and add dropwise. Adjust the pH value of the system to 10, and continuously react at 60 °C for 10 h. Separate the product using a suction funnel, wash with deionized water until no chloride ions are detected, and dry in a blast drying oven at 60 °C for 12 h to obtain the dried polyamine-functionalized carbon quantum dot adsorbent material.
[0033] Take 5 g of the above-prepared polyamine-functionalized carbon quantum dot adsorbent material and add it to a mixed solution of ZnCl2 and FeCl2 with a Zn(II) concentration of 0.3 mol / L, an Fe(II) concentration of 1 mol / L, and a pH value of 1, stir at 25 °C for 1 h, and measure the concentrations of Zn(II) and Fe(II) in the solution after adsorption using an inductively coupled plasma emission spectrometer.
[0034] As Figure 6 shown, when 1,4-dioxane is used, the adsorption capacity for Zn(II) can reach 199.18 mg / g. Therefore, 1,4-dioxane can be considered as the optimal solvent.
[0035] Example 3
[0036] The present invention provides a method for grafting carbon quantum dots rich in amino groups onto a chloromethylated polystyrene resin matrix, comprising the following steps:
[0037] Prepare aqueous solutions of polyamino carbon quantum dots with mass fractions of 1%, 10%, 20%, and 30% respectively. Weigh 1.0 g of the chloromethylated polystyrene matrix, add 10 ml of 1,4-dioxane, and swell it at room temperature for 12 h. Add the pre-swollen chloromethylated polystyrene matrix into a 150 ml four-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, then add 0.05 g of 4-dimethylaminopyridine. Load the pre-prepared polyamino carbon quantum dots into the dropping funnel and add them drop by drop. Adjust the pH value of the system to 10 and continuously react at 60 °C for 10 h. Separate the product using a suction funnel, wash it with deionized water until there is no chloride ion, and place it in a blast drying oven at 60 °C for drying for 12 h to obtain a dried polyamino carbon quantum dot adsorbent material.
[0038] Take 5 g of the polyamino carbon quantum dot adsorbent material prepared above respectively, and put it into a mixed solution of ZnCl2 and FeCl2 with a Zn(II) concentration of 0.3 mol / L, an Fe(II) concentration of 1 mol / L, and a pH value of 1. Stir at 25 °C for 1 h, and measure the concentrations of Zn(II) and Fe(II) in the adsorbed solution using an inductively coupled plasma emission spectrometer.
[0039] As Figure 7 shown, when the polyamino carbon quantum dots are prepared with a mass fraction of 20%, the obtained polyamino carbon quantum dot adsorbent material has the largest adsorption capacity for Zn(II). Therefore, the polyamino carbon quantum dots should use a mass fraction of 20% as the optimal concentration.
[0040] Example 4
[0041] The present invention provides a method for grafting carbon quantum dots rich in amino groups onto a chloromethylated polystyrene resin matrix, comprising the following steps:
[0042] Prepare an aqueous solution of polyamino carbon quantum dots with a mass fraction of 20%. Weigh 1.0 g of the chloromethylated polystyrene matrix, add 10 ml of 1,4-dioxane, and swell it at room temperature for 12 h. Add the pre-swollen chloromethylated polystyrene matrix into a 150 ml four-necked flask equipped with a stirrer, a thermometer, and a dropping funnel, then add 0.05 g of 4-dimethylaminopyridine. Load the pre-prepared polyamino carbon quantum dots into the dropping funnel and add them drop by drop. Adjust the pH value of the system to 10 and continuously react at 20, 40, 60, and 80 °C for 10 h respectively. Separate the product using a suction funnel, wash it with deionized water until there is no chloride ion, and place it in a blast drying oven at 60 °C for drying for 12 h to obtain a dried polyamino carbon quantum dot adsorbent material.
[0043] Take 5 g of the polyamino carbon quantum dot adsorbent material prepared above respectively, and put it into a mixed solution of ZnCl2 and FeCl2 with a Zn(II) concentration of 0.3 mol / L, an Fe(II) concentration of 1 mol / L, and a pH value of 1. Stir at 25 °C for 1 h, and measure the concentrations of Zn(II) and Fe(II) in the adsorbed solution with an inductively coupled plasma emission spectrometer.
[0044] As Figure 8 shown, when the reaction temperature is 60 - 80 °C, the increase in the adsorption capacity of the obtained polyamino carbon quantum dot adsorbent material for Zn(II) tends to level off. Therefore, considering energy conservation, 60 °C is used as the reaction temperature.
[0045] Example 5
[0046] The present invention provides a method for grafting carbon quantum dots rich in amino groups onto a chloromethylated polystyrene resin matrix, including the following steps:
[0047] Prepare an aqueous solution of polyamino carbon quantum dots with a mass fraction of 20%. Weigh 1.0 g of the chloromethylated polystyrene matrix, add 10 ml of 1,4 - dioxane, and swell it at room temperature for 12 h. Add the pre - swollen chloromethylated polystyrene matrix into a 150 - ml four - necked flask equipped with a stirrer, a thermometer, and a dropping funnel, then add 0.05 g of 4 - dimethylaminopyridine. Load the pre - prepared polyamino carbon quantum dots into the dropping funnel and add them drop by drop. Adjust the pH value of the system to 10 and react continuously at 60 °C for 2, 6, 10, and 14 h respectively. Separate the product using a suction funnel, wash it with deionized water until there is no chloride ion, and place it in a blast drying oven at 60 °C for drying for 12 h to obtain a dry polyamino carbon quantum dot adsorbent material.
[0048] Take 5 g of the polyamino carbon quantum dot adsorbent material prepared above respectively, and put it into a mixed solution of ZnCl2 and FeCl2 with a Zn(II) concentration of 0.3 mol / L, an Fe(II) concentration of 1 mol / L, and a pH value of 1. Stir at 25 °C for 1 h, and measure the concentrations of Zn(II) and Fe(II) in the adsorbed solution with an inductively coupled plasma emission spectrometer.
[0049] As Figure 9 shown, when the reaction time reaches 10 h, the increase in the adsorption capacity of the obtained polyamino carbon quantum dot adsorbent material for Zn(II) tends to level off. Therefore, the reaction time can be set to about 10 h.
[0050] Example 6
[0051] The pickling waste liquid used in the present invention is generated by a steel plant in Heilongjiang Province, with a zinc ion concentration of 6.561 g / L and a ferrous ion concentration of 111.76 g / L. 50 ml of the prepared polyamine-based carbon quantum dot adsorbent material was loaded into a Teflon column with a diameter of 25 mm and a height of 200 mm by the wet column packing method. A peristaltic pump was used for the separation and regeneration experiments.
[0052] As Figure 10 shown, when the effluent volume is less than 420 ml, the effluent zinc ion concentration is less than 500 mg / L, and when the effluent volume reaches 690 ml, the resin adsorption is completely saturated. As Figure 11 shown, during the regeneration process, only 290 ml of deionized water is required to completely regenerate the adsorbent material.
Claims
1. A method for preparing a polyamine-based carbon quantum dot adsorption material, comprising the following steps:
1. Preparation of carbon quantum dots rich in amine structure: 10g of polyethyleneimine with a molecular weight of 600 was added to a 150mL round-bottom flask, and the solution was heated to 175°C using an oil bath. After heating for 10min, the resulting solution was immediately added dropwise to 50mL of deionized water with magnetic stirring. The resulting solution was then cooled to room temperature and dialyzed in a dialysis bag (1000Da) for 3 days to remove the remaining molecular precursors. Subsequently, the dialysate was filtered at 1bar with a PVDF ultrafiltration membrane with a diameter of 0.45μm to remove large particles. Finally, the dialysate was rotary evaporated (12h), oven dried for 24h, and freeze-dried for 12h to obtain polyamine carbon quantum dots from gold solids.
2. Preparation of polyamine-based carbon quantum dots adsorption material: The polyamine-based carbon quantum dots are configured into an aqueous solution with a mass fraction of 20%. Weigh 1.0g of chloromethyl polystyrene matrix, add 10ml 1,4-dioxane and swell for 12h at room temperature. Add the pre-swollen chloromethyl polystyrene matrix to a 150ml four-necked flask equipped with a stirrer, a thermometer and a dropping funnel, then add 0.05g 4-dimethylaminopyridine, and put the pre-configured polyamine carbon quantum dots into the dropping funnel and add dropwise. Adjust the pH value of the system to 10 and react continuously at 60°C for 10h. Separate the product with a suction funnel, wash with deionized water until there is no chloride ion, and place it in a forced air drying oven at 60°C for 12h to obtain a dry polyamine carbon quantum dot adsorption material.