An interpenetrating network adsorbent for adsorbing noble metals, its preparation method and applications

Abstract

This invention discloses an interpenetrating network adsorbent, which is a chitosan-terephthalaldehyde-polyethyleneimine crosslinked polymer, obtained by one-step solution polymerization of chitosan, terephthalaldehyde, and polyethyleneimine, and is effective against the heavy metal Au. 3+ It exhibits selective adsorption. The adsorbent of this invention is effective for Au. 3+ It has a large adsorption capacity; the adsorbent of this invention has a high adsorption capacity for Au. 3+ It exhibits excellent adsorption selectivity; the adsorbent of this invention can be repeatedly recycled after desorption, and after desorption, it is effective against Au. 3+ With an adsorption rate as high as 95.4%, it is an economical material that can reduce waste pollution and bring higher economic benefits. The synthesis conditions of the adsorbent of this invention are mild, the method is simple, the raw material cost is low, and it is easy to industrialize.

Description

Technical Field

[0001] This invention relates to the field of precious metal separation technology, specifically to an interpenetrating network adsorbent, its preparation method, and its applications. Background Technology

[0002] Precious metals have important applications in various industries such as electronics, aerospace, and chemicals. Recycling precious metals can reduce resource waste, save costs, and protect the environment. Recycling precious metals can reduce the extraction of mineral resources, thereby lowering mineral resource consumption. At the same time, recycling precious metals can also reduce pollutant emissions, avoid secondary pollution, and protect the ecological environment. In short, recycling precious metals has multiple benefits in terms of economy, environment, and society, and is a sustainable development measure.

[0003] There are many methods for recovering precious metals, such as solvent extraction, ion exchange, chemical precipitation, and adsorption. Compared with other methods, adsorption is considered the most reliable method for extracting metal ions. Many adsorbents are used for recovering precious metal ions, including inorganic nanoparticles, biomass, and synthetic polymers. Inorganic nanoparticles have a large adsorption capacity for precious metal ions, but are not suitable for recovering precious metal ions in industrial production. Biomass is an environmentally friendly and sustainable adsorbent, but its adsorption capacity for precious metal ions is relatively weak. CN114849658A discloses a sulfur-based chitosan fiber adsorbent for adsorbing Ag(I). Synthetic polymers are adsorbents that can efficiently and selectively adsorb precious metal ions in metallurgical wastewater, but they are non-renewable.

[0004] CN106758520A discloses a method for preparing a glutaraldehyde-crosslinked polyethyleneimine paper-based film. Biomass-synthetic polymer adsorbents can improve the adsorption capacity of biomass adsorbents for noble metal ions while reducing the amount of synthetic polymer used. CN114749158A discloses a polyethyleneimine / chitosan composite adsorbent using glutaraldehyde as a crosslinking agent, relating to the adsorption of Hg... 2+ and Pb 2+ While it exhibits selective adsorption, this adsorbent is clearly insufficient to meet the requirements for Au ion adsorption. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide an interpenetrating network adsorbent that effectively targets the heavy metal Au. 3+ It exhibits selective adsorption with an adsorption capacity as high as 657.28 mg / g and a fast adsorption rate. This invention also provides a preparation method and its applications. The preparation method employs a one-step solution polymerization process, which is simple, has mild synthesis conditions, low raw material costs, and is easily industrialized.

[0006] This invention is achieved through the following technical solution:

[0007] An interpenetrating network adsorbent for adsorbing precious metals is a chitosan-terephthalaldehyde-polyethyleneimine cross-linked polymer, obtained by one-step solution polymerization of chitosan, terephthalaldehyde, and polyethyleneimine. It is effective for adsorbing the heavy metal Au. 3+ It exhibits selective adsorption.

[0008] The mass ratio of chitosan, polyethyleneimine, and terephthalaldehyde is 0.4–0.1:0.1–0.4:0.5.

[0009] Specific surface area is 12.82–25.07 m². 2 / g.

[0010] The method involves a one-step solution reaction, dissolving chitosan and polyethyleneimine in an acidic solution, then adding terephthalaldehyde. The reaction temperature is 20–50°C, and the reaction time is 1–6 hours. Currently, there is limited information on the heavy metal Au in the market. 3+ Reports of selective adsorption are extremely rare. This invention provides a method for the selective adsorption of the heavy metal Au. 3+ Interpenetrating network adsorbents with selective adsorption capabilities have contributed to the development of the heavy metal ion adsorption industry. Existing polyethyleneimine / chitosan composite adsorbents using glutaraldehyde as a crosslinking agent only address the adsorption of Hg. 2+ and Pb 2+ It has selective adsorption properties, while this invention is specifically for the heavy metal Au. 3+ Interpenetrating network adsorbents with selective adsorption, particularly for Hg. 2+ and Pb 2+ It does not have selective adsorption properties and is not effective against Au. 3+ The adsorption equilibrium time in the solution was 10 minutes, the adsorption efficiency was very high, and the effect was significant.

[0011] Interpenetrating network adsorbents for heavy metal Au under acidic conditions 3+ Applications of selective adsorption.

[0012] Interpenetrating network adsorbents at pH 1–6 for Au 3+ The adsorption rate and adsorption amount remain unchanged.

[0013] Interpenetrating network adsorbents at 25°C and pH 3 for Au 3+ The maximum adsorption capacity is 657.28 mg / g.

[0014] Interpenetrating network adsorbent at 25℃, 10 mg / L, pH=3 Au 3+ The adsorption equilibrium time in the solution was 10 min, the adsorption rate was 100%, and the adsorption rate was fast.

[0015] Interpenetrating network adsorbent at 25℃, 10 mg / L, pH=3 Au3+ Zn 2+ Pb 2+ Cu 2+ K + In the mixed solution, for Au 3+ The adsorption rate is 98.7%.

[0016] After three cycles of desorption using a thiourea / hydrochloric acid mixed solution, the interpenetrating network adsorbent was continued for the adsorption of heavy metal ions. The results showed that the interpenetrating network adsorbent of this invention, after desorption, effectively adsorbed Au ions. 3+ The adsorption rate is as high as 95.4%.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] (1) The adsorbent of the present invention for Au 3+ It has a large adsorption capacity;

[0019] (2) The adsorbent of the present invention for Au 3+ It exhibits excellent adsorption selectivity;

[0020] (3) The adsorbent of this invention can be repeatedly recycled after desorption. After desorption, it is effective against Au. 3+ With an adsorption rate as high as 95.4%, it is an energy-saving material that can reduce waste pollution and bring higher economic benefits;

[0021] (4) The synthesis conditions of the adsorbent of the present invention are mild, the method is simple, the raw material cost is low and it is easy to industrialize. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 The initial pH of the solution versus Au 3+ The effect of adsorption rate.

[0024] Figure 2 For adsorption time of Au 3+ The effect of adsorption rate and adsorption amount;

[0025] Figure 3 For the initial concentration of Au 3+ Effect of adsorption rate and adsorption amount

[0026] Figure 4 The results show the adsorption rates of different ions at pH=3.

[0027] Figure 5 For the number of loops in Au 3+The effects of adsorption rate and adsorption amount. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0029] Testing and Analysis

[0030] In the embodiments of the present invention, the specific surface area of ​​the adsorbent was measured using a specific surface area meter, and the Au content before and after adsorption was... 3+ The concentration of the solution was determined using a Shimadzu AA-6880 atomic absorption spectrophotometer (Japan). The relevant formulas are as follows:

[0031]

[0032]

[0033]

[0034] Among them, C t and C e Let represent the solution concentration at time t and at equilibrium, respectively; C0 represents the initial concentration of the solution; and q represent the solution concentration at equilibrium. t q e R and R represent the adsorption amount at time t, the adsorption amount at equilibrium, and the adsorption rate, respectively.

[0035] Example 1

[0036] 132 mg of chitosan and 33 mg of polyethyleneimine were dissolved in 50 mL of 0.1 mol / L acetic acid solution, and 165 mg of terephthalaldehyde was added. The mixture was reacted at 50 °C for 4 h, and the pH was adjusted to neutral by adding sodium bicarbonate solution. Impurities were removed by repeated washing with N,N-dimethylformamide and anhydrous ethanol. The mixture was dried to constant weight in a vacuum drying oven to obtain the interpenetrating network adsorbent. The specific surface area of ​​the interpenetrating network adsorbent was measured using a specific surface area analyzer. 5 mg of the interpenetrating network adsorbent was added to 20 mL of 100 mg / L Au solution at pH 3. 3+ The solution was placed in a 25°C constant temperature water bath shaker and shaken for 24 hours. After filtration, the adsorbed Au was analyzed by atomic absorption spectrometry. 3+ The solution was analyzed. The specific surface area of ​​the adsorbent was 12.82 m². 2 / g, for Au 3+ The adsorption capacity was 304.23 mg·g. -1 .

[0037] Example 2

[0038] 99 mg of chitosan and 66 mg of polyethyleneimine were dissolved in 50 mL of 0.1 mol / L acetic acid solution, and 165 mg of terephthalaldehyde was added. The mixture was reacted at 50 °C for 4 h, and the pH was adjusted to neutral by adding sodium bicarbonate solution. Impurities were removed by repeated washing with N,N-dimethylformamide and anhydrous ethanol. The mixture was dried to constant weight in a vacuum drying oven to obtain the interpenetrating network adsorbent. The specific surface area of ​​the interpenetrating network adsorbent was measured using a specific surface area analyzer. 5 mg of the interpenetrating network adsorbent was added to 20 mL of 100 mg / L Au solution at pH 3. 3+ The solution was placed in a 25°C constant temperature water bath shaker and shaken for 24 hours. After filtration, the adsorbed Au was analyzed by atomic absorption spectrometry. 3+ The solution was analyzed. The specific surface area of ​​the adsorbent was 19.24 m². 2 / g, for Au 3+ The adsorption capacity was 327.68 mg·g. -1 .

[0039] Example 3

[0040] 66 mg of chitosan and 99 mg of polyethyleneimine were dissolved in 50 mL of 0.1 mol / L acetic acid solution, and 165 mg of terephthalaldehyde was added. The mixture was reacted at 50 °C for 4 h, and the pH was adjusted to neutral by adding sodium bicarbonate solution. Impurities were removed by repeated washing with N,N-dimethylformamide and anhydrous ethanol. The mixture was dried to constant weight in a vacuum drying oven to obtain the interpenetrating network adsorbent. The specific surface area of ​​the interpenetrating network adsorbent was measured using a specific surface area analyzer. 5 mg of the interpenetrating network adsorbent was added to 20 mL of 100 mg / L Au solution at pH 3. 3+ The solution was placed in a 25°C constant temperature water bath shaker and shaken for 24 hours. After filtration, the adsorbed Au was analyzed by atomic absorption spectrometry. 3+ The solution was tested. The specific surface area of ​​the adsorbent was 25.07 m². 2 / g, for Au 3+ The adsorption capacity was 349.30 mg·g. -1 .

[0041] Example 4

[0042] 33 mg of chitosan and 132 mg of polyethyleneimine were dissolved in 50 mL of 0.1 mol / L acetic acid solution, and 165 mg of terephthalaldehyde was added. The mixture was reacted at 50 °C for 4 h, and the pH was adjusted to neutral by adding sodium bicarbonate solution. Impurities were removed by repeated washing with N,N-dimethylformamide and anhydrous ethanol. The mixture was dried to constant weight in a vacuum drying oven to obtain the interpenetrating network adsorbent. The specific surface area of ​​the interpenetrating network adsorbent was measured using a specific surface area analyzer. 5 mg of the interpenetrating network adsorbent was added to 20 mL of 100 mg / L Au solution at pH 3. 3+The solution was placed in a 25°C constant temperature water bath shaker and shaken for 24 hours. After filtration, the adsorbed Au was analyzed by atomic absorption spectrometry. 3+ The solution was tested. The specific surface area of ​​the adsorbent was 19.25 m². 2 / g, for Au 3+ The adsorption capacity was 337.51 mg·g. -1 .

[0043] Example 5

[0044] 66 mg of chitosan and 99 mg of polyethyleneimine were dissolved in 50 mL of 0.1 mol / L acetic acid solution, and 165 mg of terephthalaldehyde was added. The mixture was reacted at 50 °C for 4 h, and the pH was adjusted to neutral by adding sodium bicarbonate solution. Impurities were removed by repeated washing with N,N-dimethylformamide and anhydrous ethanol. The mixture was then dried to constant weight in a vacuum drying oven to obtain the interpenetrating network adsorbent. A 10 mg·L⁻¹ solution was prepared. -1 Au 3+ Solution, Au 3+ The pH of the solutions was adjusted to 1–10, and 10 mL of each solution was transferred to centrifuge tubes. 5 mg of interpenetrating network adsorbent was added to each tube, and the tubes were then placed in a 25°C water bath shaker for 24 hours. After adsorption, the solutions were filtered, and the Au adsorption was analyzed using atomic absorption spectrometry. 3+ The solution was measured. Under conditions of pH ≤ 6, the interpenetrating network adsorbent for Au... 3+ The adsorption rate is 100% for all samples, as shown in the attached image. Figure 1 As shown.

[0045] Example 6

[0046] 66 mg of chitosan and 99 mg of polyethyleneimine were dissolved in 50 mL of 0.1 mol / L acetic acid solution, and 165 mg of terephthalaldehyde was added. The mixture was reacted at 50 °C for 4 h, and the pH was adjusted to neutral by adding sodium bicarbonate solution. Impurities were removed by repeated washing with N,N-dimethylformamide and anhydrous ethanol. The mixture was then dried to constant weight in a vacuum drying oven to obtain the interpenetrating network adsorbent. A concentration of 10 mg·L⁻¹ was prepared. -1 Au at pH=3 3+ For the solution, take 11 centrifuge tubes, add 20 mL of pH-adjusted solution to each tube, add 5 mg of interpenetrating network adsorbent to each tube, and incubate in a constant temperature water bath shaker at 25℃ for 0, 1, 3, 5, 8, 10, 20, 40, 60, 120 and 240 min respectively. After adsorption, filter and analyze the Au content of the adsorbed solution using atomic absorption spectrometry. 3+ The solution was measured. Results showed that the interpenetrating network adsorbent effectively absorbed Au within 10 minutes. 3+ To achieve 100% adsorption, such as... Figure 2 As shown.

[0047] Example 7

[0048] 66 mg of chitosan and 99 mg of polyethyleneimine were dissolved in 50 mL of 0.1 mol / L acetic acid solution, and 165 mg of terephthalaldehyde was added. The mixture was reacted at 50 °C for 4 h, and the pH was adjusted to neutral with sodium bicarbonate solution. Impurities were removed by repeated washing with N,N-dimethylformamide and anhydrous ethanol. The mixture was then dried to constant weight in a vacuum drying oven to obtain the interpenetrating network adsorbent. Concentrations of 5, 10, 15, 20, 50, 100, 250, and 450 mg·L⁻¹ were prepared. -1 Au 3+ The solution was prepared by adjusting the pH to 3. Eight centrifuge tubes were used, and 20 mL of the pH-adjusted solution was added to each tube. 5 mg of interpenetrating network adsorbent was then added to each tube. The tubes were incubated in a 25°C water bath for 24 hours to allow adsorption. After adsorption, the solution was filtered, and the Au content after adsorption was analyzed using atomic absorption spectrometry. 3+ The solution was analyzed. The results showed that the adsorbent was effective against Au. 3+ The maximum adsorption capacity is 657.28 mg / g, as shown in the attached image. Figure 3 As shown.

[0049] Example 8

[0050] 66 mg of chitosan and 99 mg of polyethyleneimine were dissolved in 50 mL of 0.1 mol / L acetic acid solution, and 165 mg of terephthalaldehyde was added. The mixture was reacted at 50 °C for 4 h, and the pH was adjusted to neutral by adding sodium bicarbonate solution. Impurities were removed by repeated washing with N,N-dimethylformamide and anhydrous ethanol. The mixture was then dried to constant weight in a vacuum drying oven to obtain the interpenetrating network adsorbent. A 10 mg / L solution was prepared. -1 Au at pH 3 3+ Solution. Then, based on the calculated results, weigh the other metal compounds and prepare a solution with a concentration of 10 mg·L⁻¹. -1 A solution of impurity ions with a pH of 3 was prepared, and finally the impurity ion solution and Au were added. 3+ Solution mixing to prepare Au 3+ With K + Cu 2+ Pb 2+ A solution with a molar concentration of 1:1 for the hetero-ions was prepared. 20 mL of this solution was added to a reaction tube, followed by 5 mg of interpenetrating network adsorbent. The mixture was shaken in a shaker at 25 °C for 20 min. After the reaction was complete, the solution was filtered, and the metal ions in the post-adsorption solution were determined using atomic absorption spectrometry. The results showed that the adsorbent was effective against Au. 3+ The adsorption rate is as high as 98.7%, while the adsorption rates for other metal ions are all below 4%, such as... Figure 4 As shown. Following the above configuration method, adsorption experiments for impurity ions at pH 5 and 6 were also conducted, and the results are shown in Tables 1 and 2 below. Figure 4 The results show that the interconnected network adsorbent prepared in this invention has selective adsorption properties for Au ions.

[0051] Table 1 Results of selective adsorption of heteroions at pH 5

[0052] pH-5 Before adsorption After adsorption Adsorption rate Au 8.6306 0.1441 98.33％ K 2.1846 2.0378 6.72％ Zn 1.3614 1.3553 0.45％ Gu 2.1192 2.1139 0.25％ Pb 1.111 1.0994 1.04％ Fe 1.2375 1.2147 1.84％

[0053] Table 2 Results of selective adsorption of heteroions at pH 6

[0054]

[0055]

[0056] Example 9

[0057] 66 mg of chitosan and 99 mg of polyethyleneimine were dissolved in 50 mL of 0.1 mol / L acetic acid solution, and 165 mg of terephthalaldehyde was added. The mixture was reacted at 50 °C for 4 h, and the pH was adjusted to neutral with sodium bicarbonate solution. Impurities were removed by repeated washing with N,N-dimethylformamide and anhydrous ethanol. The mixture was dried to constant weight in a vacuum drying oven to obtain the interpenetrating network adsorbent. 20 mL of desorbent (1 mol / L thiourea / hydrochloric acid mixed solution) was added to a 50 mL centrifuge tube, followed by 10 mg of the adsorbed interpenetrating network adsorbent. The tube was placed in a constant temperature water bath shaker at 25 °C for 4 h, then filtered and dried. The desorbed interpenetrating network adsorbent was then added to a 10 mg·L⁻¹ solution. -1 Au at pH 3 3+ In the solution, adsorption was performed in a constant temperature water bath shaker at 25℃ for 20 min. After adsorption, the solution was filtered, and the concentrations of the original solution and the residual solution after adsorption were determined using atomic absorption spectrometry. After being reused three times, the adsorption rate still reached 95.37%, as shown in the attached figure. Figure 5 As shown.

[0058] Comparative Example 1 is similar to Example 1, except that the raw materials are chitosan and terephthalaldehyde, and the specific surface area of ​​this adsorbent is 4.23 m². 2 / g, for Au 3+ The adsorption capacity was 198.57 mg·g. -1 .

[0059] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An interpenetrating network adsorbent for adsorbing precious metals, specifically for the adsorption of heavy metal Au under acidic conditions. 3+ The application of selective adsorption is characterized by: The interpenetrating network adsorbent is a chitosan-terephthalaldehyde-polyethyleneimine crosspolymer, obtained by one-step solution polymerization of chitosan, terephthalaldehyde, and polyethyleneimine. It is effective against the heavy metal Au. 3+ It exhibits selective adsorption; the mass ratio of chitosan, polyethyleneimine, and terephthalaldehyde is 0.4–0.1:0.1–0.4:0.

5. The specific surface area of ​​the interpenetrating network adsorbent is 12.82–25.07 m². 2 / g; The interpenetrating network adsorbent is prepared by a one-step solution method, in which chitosan and polyethyleneimine are dissolved in acetic acid solution, and terephthalaldehyde is added. The reaction temperature is 20-50℃ and the reaction time is 1-6h. Among them, the interpenetrating network adsorbent at 25℃ and pH=3 is effective for Au. 3+ The maximum adsorption capacity is 657.28 mg / g; Among them, the interpenetrating network adsorbent at 25℃, 10 mg / L, and pH=3 in Au 3+ The adsorption equilibrium time in the solution was 10 min, and the adsorption rate was 100%. Among them, the interpenetrating network adsorbent at 25℃, 10 mg / L, and pH=3 in Au 3+ Zn 2+ Pb 2+ Cu 2+ K + In the mixed solution, for Au 3+ The adsorption rate is 98.7%.

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