Alkaline non-phosphorus nano-chelating chemical conversion agent, preparation method and application

Abstract

This invention discloses an alkaline, phosphorus-free nano-chelating agent, which, by weight percentage, is composed of the following components: 30%–40% sodium hydroxide, 6%–15% polyethylene terephthalate, 5%–10% polyglutamic acid, 1%–5% polysuccinimide, 11%–18% ammonium citrate, 2%–9% nano-silica, 2%–9% nano-alumina, and the balance being water. This phosphorus-free nano-chelating agent contains no phosphorus and will not cause phosphorus pollution during use. Compared to traditional phosphorus-containing chemicals, it is more environmentally friendly and helps reduce phosphorus content in water bodies, thereby mitigating environmental problems such as eutrophication.

Description

Technical Field

[0001] This invention relates to an alkaline phosphorus-free nano-chelating agent, its preparation method, and its application, which is particularly suitable for environmental remediation, water treatment, and metal wastewater treatment. Background Technology

[0002] Metal chelating agents can bind metal ions to the chelating agent through strong binding between the chelating agent molecules and the metal ions, turning them into stable compounds with larger molecular weights. This prevents the metal ions from functioning and can be used for detoxification, dyeing, scale inhibition, and other applications.

[0003] Some existing metal chelating agents contain irritating gases, others contain phosphorus, or are easily degradable, which can easily cause harm to the environment.

[0004] Chinese patent 201610637870.9 discloses a method for preparing a heavy metal chelating agent, including a precursor preparation step: mixing diethylenetriamine, carbon disulfide, and water to obtain a mixed solution; reacting the mixed solution with an alkali to obtain a chelating agent precursor; and a polymerization step: mixing the chelating agent precursor with 1,2-dibromoethane and heating to obtain a crude chelating agent; and separating and purifying the crude chelating agent to obtain a heavy metal chelating agent. The diethylenetriamine in this patent has an irritating odor and can corrode some metals, and the reaction produces harmful gases such as sulfur dioxide, which is detrimental to environmental protection.

[0005] Chinese Patent 201710109593.9 discloses an organophosphate heavy metal chelating agent: the organophosphate heavy metal chelating agent comprises the following components by weight percentage: chelating agent body: 90-98%; sodium tripolyphosphate: 2-10%; the chelating agent body is a phosphate-based heavy metal chelating agent. The organophosphate heavy metal chelating agent provided by this invention can reduce the leaching concentration of heavy metals and ensure that the solidified fly ash sample meets the leaching concentration limit. However, the contained organophosphates can cause secondary pollution to the environment, which is inconsistent with the concept of sustainable development.

[0006] Chinese Patent 201910172647.5 discloses a metal ion chelating agent and its preparation method. The metal ion chelating agent is phosphorus-free, has low corrosivity, strong iron removal ability, and can remove various metal ions. The chelating agent comprises the following raw materials in parts by weight: itaconic acid 10-25 parts, allyl polyoxyethylene ether 4-10 parts, 2-acrylamide-2-methylpropanesulfonic acid 5-15 parts, 30% sodium hydroxide aqueous solution 0.5-1.2 parts, 40% sodium persulfate aqueous solution 0.5-1.5 parts, 20% sodium bisulfite aqueous solution 0.3-0.8 parts, 20% ferrous sulfate aqueous solution 0.2-0.7 parts, polyaspartic acid 5-10 parts, polyepoxysuccinic acid 0-7 parts, iminodisuccinic acid tetrakis 5-10 parts, and water 38-45 parts. However, the raw materials for allyl polyoxyethylene ether (APEG) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) are expensive and difficult to biodegrade, causing secondary pollution to the environment. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an alkaline phosphorus-free nano-chelating agent. This chelating agent has a nanoparticle structure with a particle size of less than 100 nanometers and has the ability to efficiently remove heavy metal ions, organic pollutants and toxic and harmful substances. This chelating agent can achieve efficient adsorption and chelation under alkaline conditions without the need to add other chemical substances, and it has zero phosphorus emissions and is environmentally friendly.

[0008] The alkaline, phosphorus-free nano-chelating agent shown in this invention is made from the following components by weight percentage:

[0009]

[0010] The sodium hydroxide can adjust the pH value.

[0011] The polyethylene terephthalate is prepared by esterification of terephthalic acid and ethylene glycol under the action of a catalyst, and then polycondensation to form a long polymer chain of polyethylene terephthalate, which is conducive to promoting chelation effect, strengthening the adsorption of metal ions, and making the metal chelate more stable.

[0012] The polyglutamic acid, polysuccinimide, and ammonium citrate have a chelating effect, which can adsorb metal ions.

[0013] The nano-silicon oxide and nano-alumina are the main raw materials for synthesizing nanomaterials.

[0014] Preferably, an alkaline, phosphorus-free nano-chelating agent has the following composition by weight percentage:

[0015]

[0016] Preferably, the weight ratio of polysuccinimide to ammonium citrate is 1:(2-15).

[0017] More preferably, an alkaline, phosphorus-free nano-chelating agent has the following composition by weight percentage:

[0018]

[0019]

[0020] More preferably, an alkaline, phosphorus-free nano-chelating agent has the following composition by weight percentage:

[0021]

[0022] More preferably, an alkaline, phosphorus-free nano-chelating agent has the following composition by weight percentage:

[0023]

[0024] The present invention also provides a method for preparing the alkaline phosphorus-free nano-chelating agent, comprising the following steps:

[0025] (1) Add water to polyethylene terephthalate, polyglutamic acid and polysuccinimide, stir and dissolve at 25-35℃, add sodium hydroxide to adjust the pH to 8.0-9.0, seal and purge with nitrogen for 20-30 minutes.

[0026] (2) Add ammonium citrate to the mixed solution in step (1), stir evenly, and heat to 50℃-60℃.

[0027] (3) Add nano-silica and nano-alumina to the solution after treatment in step (2) in sequence, continue to heat to 70-80℃, stir magnetically for 2-2.5 hours, and cool to obtain a light yellow transparent liquid, which is the phosphorus-free nano chelating agent.

[0028] The present invention also includes the application of the alkaline phosphorus-free nano-chelating agent in environmental remediation, water treatment and metal wastewater treatment.

[0029] The chemical reaction principle of the alkaline phosphorus-free nano-chelating agent of this invention is as follows:

[0030] This chelating agent uses polyethylene terephthalate as a matrix, and forms a cyclic polymer under the action of polyglutamic acid, polysuccinimide and ammonium citrate. Then, two nanomaterials, nano-silica and nano-alumina, are added, which makes the nanoparticles continuously adsorbed on the polymer surface, further improving its corrosion resistance and wear resistance.

[0031] The beneficial effects of this invention are as follows:

[0032] (1) This phosphorus-free nano-chelating agent does not contain phosphorus and will not cause phosphorus pollution during use. Compared with traditional phosphorus-containing chemical agents, it is more environmentally friendly and helps reduce the phosphorus content in water bodies, thereby mitigating environmental problems such as eutrophication. (2) This phosphorus-free nano-chelating agent can operate efficiently at room temperature, that is, it can quickly and effectively complete its mission without increasing energy consumption. This can greatly improve work efficiency and reduce production costs for industrial production and practical applications. (3) The application of nanotechnology gives this chelating agent higher activity and a larger surface area, which can more effectively bind with the target substance. It can not only improve the chelation effect, but also reduce the amount of chemical agent used, further reducing the burden on the environment. Detailed Implementation

[0033] The preparation method of the alkaline phosphorus-free nano-chelating agent provided by the present invention will be described below with specific embodiments.

[0034] The sources of raw materials in the examples and comparative examples are as follows:

[0035] Sodium hydroxide: supplied by Shanghai Gancheng Chemical Technology Co., Ltd., caustic soda flakes mesh size: 50 mesh, CAS number 497-19-8, model IS-I, industrial grade, NaOH content ≥99%.

[0036] Polyethylene terephthalate: Hubei Shishun Biotechnology Co., Ltd., Product No.: SS12545, CAS No.: 25038-59-9, Purity: 99.00%.

[0037] Polyglutamic acid: provided by Shanxi Xinno Biotechnology Co., Ltd., premium grade ≥99%, product number: XN-0312-18.

[0038] Polysuccinimide: Manufacturer is Hubei Longxin Chemical Industry Co., Ltd., product number lx9689, content ≥99%, CAS number: 5608-40-6.

[0039] Ammonium citrate: supplied by Hubei Chengfeng Chemical Co., Ltd., CAS No.: 3458-72-8, purity ≥99%.

[0040] Nano-silica: Provided by Hubei Huifu Nanomaterials Co., Ltd., item number FA-35, CAS number 112945-52-5, effective ingredient content: ≥99.8%.

[0041] Nano-alumina: Keneng (Xi'an) Materials Technology Co., Ltd., model KN-Al2O3-001, CAS No.: 1344-28-1, content ≥99.99%.

[0042] Example 1

[0043] First, dissolve 8% polyethylene terephthalate, 5% polyglutamic acid, and 2% polysuccinimide in water at approximately 30°C by stirring. Adjust the pH to 8.0-10.0 with 30% sodium hydroxide, seal the solution, and purge with nitrogen for 25 minutes. Add 12% ammonium citrate to the mixture, stir until homogeneous, and heat to 50-60°C. Finally, add 3% nano-silica and 3% nano-alumina sequentially, continue heating to approximately 75°C, and magnetically stir for 2 hours. Cool to obtain a pale yellow transparent liquid, which is the phosphorus-free nano-chelating agent. This is designated as Sample 1.

[0044] Example 2

[0045] First, dissolve 10% polyethylene terephthalate, 7% polyglutamic acid, and 3% polysuccinimide in water at approximately 30°C by stirring. Adjust the pH to 8.0-10.0 with 35% sodium hydroxide, seal the solution, and purge with nitrogen for 25 minutes. Add 13% ammonium citrate to the mixture, stir until homogeneous, and heat to 50-60°C. Finally, add 5% nano-silica and 5% nano-alumina sequentially, continue heating to approximately 75°C, and magnetically stir for 2 hours. Cool to obtain a pale yellow transparent liquid, which is the phosphorus-free nano-chelating agent. This is designated as Sample 2.

[0046] Example 3

[0047] First, dissolve 12% polyethylene terephthalate, 8% polyglutamic acid, and 4% polysuccinimide in water at approximately 30°C by stirring. Adjust the pH to 8.0-10.0 with 38% sodium hydroxide, seal the solution, and purge with nitrogen for 25 minutes. Add 15% ammonium citrate to the mixture, stir until homogeneous, and heat to 50-60°C. Finally, add 6% nano-silica and 6% nano-alumina sequentially, continue heating to approximately 75°C, and magnetically stir for 2 hours. Cool to obtain a pale yellow transparent liquid, which is the phosphorus-free nano-chelating agent. This is designated as Sample 3.

[0048] Example 4

[0049] First, dissolve 15% polyethylene terephthalate, 10% polyglutamic acid, and 5% polysuccinimide in water at approximately 30°C by stirring. Adjust the pH to 8.0-10.0 with 40% sodium hydroxide, seal the solution, and purge with nitrogen for 25 minutes. Add 18% ammonium citrate to the mixture, stir until homogeneous, and heat to 50-60°C. Finally, add 8% nano-silica and 8% nano-alumina sequentially, continue heating to approximately 75°C, and magnetically stir for 2 hours. Cool to obtain a pale yellow transparent liquid, which is the phosphorus-free nano-chelating agent. This is designated as Sample 4.

[0050] Comparative Example 1

[0051] First, dissolve 15% polyethylene terephthalate, 10% polyglutamic acid, and 18% polysuccinimide in water at approximately 30°C by stirring. Adjust the pH to 8.0-10.0 with 40% sodium hydroxide, seal the solution, and purge with nitrogen for 25 minutes. Add 5% ammonium citrate to the mixture, stir until homogeneous, and heat to 50-60°C. Finally, add 8% nano-silica and 8% nano-alumina sequentially, continue heating to approximately 75°C, and magnetically stir for 2 hours. Cool to obtain a pale yellow transparent liquid, which is the phosphorus-free nano-chelating agent. This is designated as Sample 5.

[0052] Comparative Example 2

[0053] First, dissolve 15% polyethylene terephthalate, 10% polyglutamic acid, and 23% polysuccinimide in water at approximately 30°C by stirring. Adjust the pH to 8.0-10.0 with 40% sodium hydroxide, seal the mixture, and purge with nitrogen for 25 minutes. Heat to 50-60°C. Finally, add 8% nano-silica and 8% nano-alumina sequentially, continue heating to approximately 75°C, and magnetically stir for 2 hours. Cool to obtain a pale yellow, transparent liquid, which is the phosphorus-free nano-chelating agent. This is designated as Sample 6.

[0054] Comparative Example 3

[0055] First, dissolve 15% polyethylene terephthalate and 10% polyglutamic acid in water at approximately 30°C by stirring. Adjust the pH to 8.0-10.0 with 40% sodium hydroxide, seal the solution, and purge with nitrogen for 25 minutes. Add 23% ammonium citrate to the mixture, stir until homogeneous, and heat to 50-60°C. Finally, add 8% nano-silica and 8% nano-alumina sequentially, continue heating to approximately 75°C, and magnetically stir for 2 hours. Cool to obtain a pale yellow transparent liquid, which is the phosphorus-free nano-chelating agent. This is designated as Sample 7.

[0056] Experiment 1: Verify the adsorption performance of the phosphorus-free nano-chelating agent of the present invention on metal ions.

[0057] Test method: 1 L of composite heavy metal wastewater was prepared using CrCl3·6H2O, CuSO4·5H2O, PbSO4·H2O, NiCl2·6H2O, and CdCl2·5H2O, with the concentrations of chromium, copper, lead, nickel, and cadmium ions respectively set at 4.0 mg / L. 0.5 g each of the samples obtained in Examples 1-4 and Comparative Examples 1-3 were added, stirred for 10 minutes, allowed to stand for 15 minutes, and the resulting precipitate was filtered. The percentage of each heavy metal ion adsorbed by the phosphorus-free nano-chelating agent was then determined using atomic absorption spectrometry. Specific data are shown in Table 1 below.

[0058] Table 1. Percentage of metal ions adsorbed by phosphorus-free nano-chelating agents

[0059] serial number Chromium ions copper ions lead ions Nickel ions Cadmium ions Sample 1 97.3％ 98.7％ 97.5％ 97.1％ 97.9％ Sample 2 98.1％ 99.1％ 98.8％ 98.4％ 98.7％ Sample 3 98.9％ 99.3％ 99.2％ 99.0％ 99.1％ Sample 4 99.4％ 99.7％ 99.6％ 99.6％ 99.5％ Sample 5 95.4％ 97.9％ 93.1％ 95.6％ 95.1％ Sample 6 90.1％ 93.2％ 92.4％ 94.3％ 94.2％ Sample 7 96.7％ 98.3％ 94.6％ 96.7％ 96.0％

[0060] As can be seen from Table 1, the phosphorus-free nano-chelating agent of the present invention has a high adsorption rate for copper ions, and the ability to adsorb metal ions is stronger with the increase of alkali content.

[0061] In addition, Comparative Example 1 replaced the amounts of polysuccinimide and ammonium citrate used in Example 4; Comparative Example 2 removed ammonium citrate from Example 4, and the amount of polysuccinimide used was the sum of the amounts of polysuccinimide and ammonium citrate used in Example 4; Comparative Example 3 removed polysuccinimide from Example 4, and the amount of ammonium citrate used was the sum of the amounts of polysuccinimide and ammonium citrate used in Example 4. As can be seen from Comparative Example 1 in Table 1, a lower amount of polysuccinimide resulted in better performance than ammonium citrate. As can be seen from Comparative Examples 2-3 in Table 1, polysuccinimide and ammonium citrate have a synergistic effect.

[0062] Experiment 2: Verify the corrosion resistance of the phosphorus-free nano-chelating agent of the present invention. Specific data are shown in Table 2 below.

[0063] Specific test method: The experiment adopted the static closed immersion method, referring to the corrosion test procedure specified in "ASTM G31-2012a Standard for Laboratory Immersion Corrosion of Metals". The temperature was selected as 50℃, the rotation speed was controlled at 80r / min, and 20# steel was used as the test plate. The corrosion situation was evaluated after 24 hours.

[0064] Table 2 Evaluation of the corrosion resistance of phosphorus-free nano-chelating agents

[0065] serial number pH (1% aqueous solution) Corrosion rate (mm / a) Test board morphology Sample 1 8.4 0.5851 gray Sample 2 8.9 0.5782 bright Sample 3 9.2 0.5716 bright Sample 4 9.6 0.5684 bright

[0066] As can be seen from Table 2, the phosphorus-free nano-chelating agent corrodes the test plate more slowly as the pH value increases, and the test plate is bright with no pitting or whitening.

[0067] The above experimental data show that the alkaline phosphorus-free nano-chelating agent provided by this invention has the ability to efficiently remove heavy metal ions, organic pollutants and toxic and harmful substances. This chelating agent can achieve efficient adsorption and chelation under alkaline conditions without the need to add other chemical substances, making it an environmentally friendly chelating agent.

[0068] The applicant declares that this invention illustrates the preparation technology and application of an alkaline phosphorus-free nano-chelating agent through the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. An alkaline, phosphorus-free nano-chelating agent, characterized in that, It is made of the following components by weight percentage: 30%–40% sodium hydroxide, 6%–15% polyethylene terephthalate, 5%–10% polyglutamic acid, 1%–5% polysuccinimide, 11%–18% ammonium citrate, 2%–9% nano-silica, 2%–9% nano-alumina, and the balance being water.

2. The alkaline phosphorus-free nano-chelating agent according to claim 1, characterized in that, It is made of the following components by weight percentage: sodium hydroxide 30-35%, polyethylene terephthalate 8-12%, polyglutamic acid 5-8%, polysuccinimide 2-4%, ammonium citrate 12-15%, nano-silica 3-6%, nano-alumina 3-6%, and the balance being water.

3. The alkaline phosphorus-free nano-chelating agent according to claim 1, characterized in that, The weight ratio of polysuccinimide to ammonium citrate is 1:(2-15).

4. The alkaline phosphorus-free nano-chelating agent according to claim 2 is made of the following components by weight percentage: sodium hydroxide 38%, polyethylene terephthalate 12%, polyglutamic acid 8%, polysuccinimide 4%, ammonium citrate 15%, nano-silica 6%, and nano-alumina 6%.

5. The method for preparing the alkaline phosphorus-free nano-chelating agent according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Add water to polyethylene terephthalate, polyglutamic acid and polysuccinimide, stir and dissolve at 25-35℃, add sodium hydroxide to adjust the pH to 8.0-9.0, seal and purge with nitrogen for 20-30 minutes. (2) Add ammonium citrate to the mixed solution in step (1), stir evenly, and heat to 50℃-60℃. (3) Add nano-silica and nano-alumina to the solution after treatment in step (2) in sequence, continue to heat to 70-80℃, stir for 2-2.5 hours, and cool to obtain a light yellow transparent liquid, which is the phosphorus-free nano chelating agent.

6. The application of the alkaline phosphorus-free nano-chelating agent according to any one of claims 1-4 in environmental remediation, water treatment and metal wastewater treatment.

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