An oxygen-deficient ternary hydrotalcite-rich radical scavenger and a preparation method thereof

Abstract

This invention discloses an oxygen-deficient ternary layered double hydroxide (TLD) radical scavenger and its preparation method. By introducing tetravalent metal ions into the layered double hydroxide (TLD) layers and then selectively etching them with acid, this invention constructs a large number of oxygen-deficient sites on the LTD surface. This increases the electropositivity of the layers, which is beneficial for attracting free radicals. Simultaneously, it lowers the free energy for the removal of hydroxyl hydrogen from the LTD surface, exhibiting excellent scavenging ability for peroxyalkyl radicals (ROO•), DPPH•, and other free radicals, with a scavenging rate of over 99% for ROO•. Furthermore, the radical scavenger prepared by this invention is green and environmentally friendly, and has broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of free radical scavenger preparation technology, specifically relating to an oxygen-defective ternary hydrotalcite free radical scavenger and its preparation method. Background Technology

[0002] Polymers have a wide range of applications, but their carbon-hydrogen bonds (CH) have low dissociation energies, making them sensitive to ultraviolet radiation and thermal stress. External energy causes the CH bonds to homolytically cleave, generating primary alkyl radicals (R•). These R• radicals react with oxygen to form ROO• radicals. The ROO• radicals then abstract hydrogen atoms from neighboring polymer chains, generating hydroperoxides (ROOH) and releasing new R• radicals, constituting the rate-determining step of the aging chain reaction. This cycle leads to yellowing, cracking, and a decline in mechanical properties of plastics. Therefore, developing high-performance free radical scavenging materials to remove free radicals generated during polymer aging and to block the autocatalytic oxidation cycle is a crucial strategy for intervening in polymer aging. Besides ROO• radicals generated during polymer aging, various destructive reactive oxygen and nitrogen radicals, such as •O2, also exist in the biological environment. - Free radicals, including •OH radicals, •NO radicals, and DPPH• radicals. Extensive evidence suggests that the excessive generation of these free radicals is associated with the development and enhanced pathogenesis of various diseases. Therefore, the development and use of effective, non-toxic free radical scavengers to eliminate free radicals in the biological environment are essential for the treatment of related diseases. Summary of the Invention

[0003] The purpose of this invention is to provide an oxygen-defect-rich ternary layered double hydroxide (LDH) radical scavenger and its preparation method. This method utilizes the octahedral construction principle of LDHs, combining tetravalent metal ion doping with selective etching defect construction to design and prepare an oxygen-defect-rich ternary LDH radical scavenger. The introduction of oxygen defects improves surface positron charge and provides radical scavenging sites, significantly enhancing the radical scavenging performance.

[0004] The general formula of the oxygen-defect-rich ternary hydrotalcite free radical scavenger is M. 2+ 1-x-y M 3+ x M 4+ y (OH)2(A n- ) n- / 2 ·mH2O, where M 2+ Represents a divalent metal cation, specifically selected from Mg. 2+ Zn 2+ Ca 2+ Ni 2+ Fe 2+ One of them; M 3+Represents a trivalent metal cation, specifically selected from Al 3+ Ni 3+ Co 3+ Fe 3+ One of them; M 4+ Represents tetravalent metal ions, specifically selected from Ti. 4+ Zr 4+ Sn 4+ or Mn 4+ One of them; A n- It is one of carbonate, nitrate, and chloride ions, where n- is the valence of the anion; x is M. 3+ The mole fraction of all metal ions, y is M 4+ The mole fraction of all metal ions, with x+y ranging from 0.2 to 0.33; m represents the amount of water of crystallization, 0 to 6.

[0005] The preparation method of the oxygen-defect-rich ternary hydrotalcite free radical scavenger is as follows: weigh M 2+ M 3+ and M 4+ Soluble salts are dissolved in deionized water to prepare a mixed metal salt solution under ultrasonic and mechanical stirring conditions; NaOH and Na2CO3 are dissolved in deionized water to prepare a mixed alkali solution; the mixed alkali solution is added dropwise to the mixed metal salt solution and the pH is adjusted to 9-12. After nucleation, the solution is transferred to a high-pressure reactor and reacted at 40-140 °C, preferably 50-100 °C, for 0.1-30 h, preferably 4-18 h. After the reaction, the solution is centrifuged and washed until neutral, and then dried. The solution is then dispersed in water to form a suspension, etched with acid solution, and after etching, centrifuged and washed until neutral, and then dried to obtain an oxygen-defect-rich ternary hydrotalcite free radical scavenger.

[0006] The concentration of the acid solution is 0.0001-5 mol / L, preferably 0.001-1 mol / L; the etching temperature does not exceed 100℃, preferably 25-50℃; and the etching time is 0.1-12 h, preferably 1-4 h.

[0007] The acid solution is selected from one or more of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, formic acid, and acetic acid.

[0008] The method of using the oxygen-rich ternary hydrotalcite free radical scavenger is as follows: add the free radical scavenger to a liquid containing free radicals and stir thoroughly to capture the free radicals therein.

[0009] The free radicals mentioned are peroxyalkyl radicals (ROO•), 1,1-diphenyl-2-trinitrophenylhydrazine radicals (DPPH•), nitric oxide radicals (•NO), hydroxyl radicals (•OH), and superoxide anion radicals (•O2).- One or more of them.

[0010] Beneficial Effects: This invention induces oxygen defect structures in LDHs by introducing tetravalent metal ion doping into the hydrotalcite layer, and further increases the number and concentration of oxygen defects during etching. The generation of oxygen defects leads to increased electropositivity, which is beneficial for attracting free radicals. At the same time, it lowers the reaction energy barrier for hydrogen removal from adjacent hydroxyl groups of metals such as Ti, promotes the quenching effect of hydrogen atom transfer on free radicals, and significantly improves the free radical scavenging performance. The developed oxygen-defect-rich ternary free radical scavenger exhibits excellent scavenging ability for peroxyalkyl radicals (ROO•), DPPH•, and •NO, with a scavenging rate of over 99% for ROO•. In addition, the free radical scavenger prepared by this invention is green and environmentally friendly, showing good application prospects. Attached Figure Description

[0011] Figure 1 Mg2Al obtained in Example 1 0.5 Ti 0.5 XRD pattern of -LDHs-HNO3; Figure 2 Mg2Al obtained in Example 1 0.5 Ti 0.5 SEM image of -LDHs-HNO3; Figure 3 Mg2Al obtained in Example 1 0.5 Ti 0.5 XPS O1s plot of -LDHs-HNO3; Figure 4 XPS O1s plot of Mg2Al-LDHs obtained in Comparative Example 1. Detailed Implementation Example 1

[0012] Step A: Weigh 15.39 g of magnesium nitrate hexahydrate (Mg(NO3)2•6H2O), 5.63 g of aluminum nitrate nonahydrate (Al(NO3)3•9H2O), and add 2.85 g of titanium tetrachloride (TiCl4) dropwise to 150 mL of deionized water. Prepare a mixed metal salt solution under ultrasonic and mechanical stirring conditions. Dissolve 9.60 g of NaOH and 2.54 g of Na2CO3 in deionized water to prepare a mixed alkaline solution. Add the alkaline solution dropwise to the mixed metal salt solution to adjust the pH to 10.0 (±0.2). After nucleation, transfer to a reaction vessel and stir at 60℃ for 18 h. After the reaction, centrifuge and wash until neutral, then dry to obtain Mg2Al. 0.5 Ti 0.5 -LDHs.

[0013] Step B: Add Mg2Al 0.5 Ti 0.5 -LDHs were dispersed in water, and nitric acid solution (concentration 0.0001 mol / L) was added. The mixture was etched at room temperature for 1 h. After etching, the mixture was centrifuged and washed until neutral, and then dried to obtain oxygen-rich defective Mg2Al. 0.5 Ti 0.5 -LDHs-HNO3 free radical scavengers.

[0014] The XRD-6000 X-ray powder diffractometer of Shimadzu Corporation, Japan, was used to analyze Mg2Al. 0.5 Ti 0.5 -LDHs-HNO3 was used for characterization. Figure 1 The image shows the XRD pattern of the sample obtained in Example 1. As can be seen from the image, diffraction peaks of the 003 and 006 crystal planes of LDHs appear, and there are no impurity peaks.

[0015] The morphology of the samples was characterized using a Supra 55 instrument from Zeiss GmbH, Germany. Figure 2 This is the SEM spectrum of the sample obtained in Example 1. As can be seen from the image, the synthesized Mg2Al... 0.5 Ti 0.5 -LDHs-HNO3 has a plate-like structure.

[0016] Shimadzu Axis Supra type photoelectron spectroscopy (XPS) was used to study Mg2Al 0.5 Ti 0.5 -LDHs-HNO3 samples were characterized for oxygen defect. Figure 3 XPS results showed that Mg2Al was measured 0.5 Ti 0.5 -LDHs-HNO3 has abundant oxygen vacancies.

[0017] Application Example 1: ROO• free radical scavenging experiment: 0.5 mM luminol was dissolved in 100 mL of 0.1 M NaOH solution. 1.90 mg of tert-butyl hydroperoxide (t-BuOOH) was weighed and added to the above solution to prepare a 100 μM reaction solution. 0.2 g of the powder from Example 1 was added to 10 mL of the reaction solution and stirred in the dark for 1 h. The absorbance of the supernatant at 350 nm was measured using a UV spectrophotometer. The ROO• free radical scavenging rate was calculated as follows: ROO• radical scavenging rate / % = [(A0 − A x ) / (A0)]×100, where A0 is the blank absorbance, A x The absorbance is the value of the sample after the addition of LDHs. The absorbance after the addition of Mg2Al was calculated. 0.5Ti 0.5 -LDHs-HNO3 resulted in a 99.23% removal rate of ROO•.

[0018] Application Example 2: DPPH free radical scavenging experiment: 6.31 mg of DPPH powder was weighed and dissolved in anhydrous ethanol to a final volume of 100 μM. 0.2 g of the powder from Example 1 was added to 10 mL of the reaction solution and stirred in the dark for 1 h. The absorption peak at 517 nm of the supernatant was measured using a UV spectrophotometer. The calculated value of Mg2Al added... 0.5 Ti 0.5 The clearance rate of DPPH• after LDHs-HNO3 was 69.84%.

[0019] Application Example 3: • NO free radical scavenging experiment: 0.2 g of the powder from Example 1 was mixed with 10 mL of Griess reagent and stirred continuously for 1 h in the dark. The supernatant was collected, and the absorption peak at 510 nm was measured using a UV spectrophotometer. The calculated absorption peak was obtained after adding Mg2Al. 0.5 Ti 0.5 The clearance rate of •NO after -LDHs-HNO3 was 61.01%.

[0020] Application Example 4: • OH radical scavenging experiment: A mixture of 0.1 M H₂O₂, 0.5 mM FeSO₄, and 0.2 mM TPA was prepared by dissolving in 100 mL of deionized water. 0.2 g of the powder from Example 1 was added to 10 mL of the aforementioned solution and stirred in the dark for 1 h. The supernatant was collected, and the signal intensity at 425 nm was recorded using a fluorescence spectrophotometer. The radical scavenging rate was calculated as follows: • OH radical scavenging rate / % = [(C₀− C₀) / [C₀− C₀] ... x ) / (C0)]×100, where C0 is the blank fluorescence intensity, C x The fluorescence intensity is given after the addition of LDHs to the sample. The values ​​after the addition of Mg2Al were calculated. 0.5 Ti 0.5 The removal rate of •OH by -LDHs-HNO3 was 59.00%.

[0021] Application Example 5: •O2 − Free radical scavenging experiment: A mixed reaction solution containing 0.5 mM KO2 and 0.2 mM NBT was prepared (100 mL deionized water as the substrate). 0.2 g of the powder from Example 1 was added to 10 mL of the aforementioned solution and stirred in the dark for 1 h. The supernatant was collected, and its intensity at 560 nm was measured using a UV spectrophotometer. The calculated value of the added Mg2Al... 0.5Ti 0.5 -LDHs-HNO3 against O2 − The clearance rate was 72.75%. Example 2

[0022] Step A: Weigh 8.925 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O), 4.040 g of ferric nitrate nonahydrate (Fe(NO3)3·9H2O), and 1.17 g of zirconium tetrachloride (ZrCl4) into 150 mL of deionized water and prepare a mixed metal salt solution under ultrasonic and mechanical stirring conditions; dissolve 4.80 g of NaOH and 3.18 g of Na2CO3 in deionized water to prepare a mixed alkaline solution; add the alkaline solution dropwise to the mixed metal salt solution to adjust the pH to 9.5 (±0.2). After nucleation, transfer to a reaction vessel and stir at 70℃ for 24 h. After the reaction, centrifuge and wash until neutral, then dry to obtain Zn3Fe1Zr 0.5 -LDHs.

[0023] Step B: Add Zn3Fe1Zr 0.5 -LDHs were dispersed in water, and etched at 35°C for 2 h with 0.1 mol / L hydrochloric acid (HCl) solution. After etching, the mixture was centrifuged and washed until neutral, and then dried to obtain oxygen-rich defect Zn3Fe1Zr. 0.5 -LDHs-HCl free radical scavenger.

[0024] Application Example 6: • NO free radical scavenging experiment: 0.2 g of the powder from Example 2 was mixed with 10 mL of Griess reagent and stirred continuously for 1 h in the dark. The supernatant was collected, and the absorption peak at 510 nm was measured using a UV spectrophotometer. The calculated value of the added Zn3Fe1Zr was... 0.5 The removal rate of •NO after -LDHs-HCl was 69.61%. Example 3

[0025] Step A: Weigh 11.63 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O), 7.50 g of aluminum nitrate nonahydrate (Al(NO3)3·9H2O), and 1.75 g of tin tetrachloride pentahydrate (SnCl4·5H2O) into 150 mL of deionized water. Prepare a mixed metal salt solution under ultrasonic and mechanical stirring conditions. Dissolve 6.00 g of NaOH and 3.18 g of Na2CO3 in deionized water to prepare a mixed alkaline solution. Add the alkaline solution dropwise to the mixed metal salt solution to adjust the pH to 10.5 (±0.2). After nucleation, transfer the solution to a reaction vessel and stir at 80℃ for 12 h. After the reaction, centrifuge and wash until neutral, then dry to obtain Ni4Al2Sn. 0.5-LDHs.

[0026] Step B: Ni4Al2Sn 0.5 -LDHs were dispersed in water, and etched at 40°C for 2.5 h with acetic acid solution (concentration 0.5 mol / L). After etching, the mixture was centrifuged and washed until neutral, and then dried to obtain oxygen-rich defect Ni4Al2Sn. 0.5 -LDHs-HAc free radical scavengers.

[0027] Application Example 7: DPPH free radical scavenging experiment: 6.31 mg of DPPH powder was weighed and dissolved in anhydrous ethanol to a final volume of 100 μM. 0.2 g of the powder from Example 2 was added to 10 mL of the reaction solution and stirred in the dark for 1 h. The absorption peak at 517 nm of the supernatant was measured using a UV spectrophotometer. The calculated value of the added Ni4Al2Sn... 0.5 The clearance rate of DPPH• after -LDHs-HAc was 72.59%.

[0028] Comparative Example 1: 15.39 g of magnesium nitrate hexahydrate (Mg(NO3)2•6H2O) and 7.77 g of aluminum nitrate nonahydrate (Al(NO3)3•9H2O) were weighed into 150 mL of deionized water and mixed into a metal salt solution under ultrasonic and mechanical stirring conditions. 9.60 g of NaOH and 2.54 g of Na2CO3 were dissolved in deionized water to prepare a mixed alkaline solution. The alkaline solution was added dropwise to the mixed metal salt solution to adjust the pH to 9.0 (±0.5). After nucleation, the solution was transferred to a reaction vessel and stirred at 100℃ for 15 h. After the reaction, the solution was centrifuged, washed until neutral, and dried to obtain Mg2Al-LDHs.

[0029] Comparative application example 1: ROO• free radical scavenging experiment: 0.5 mM luminol was dissolved in 100 mL of 0.1 M NaOH solution. 1.90 mg of tert-butyl hydroperoxide (t-BuOOH) was weighed and added to the above solution to prepare a 100 μM reaction solution. 0.2 g of the powder from Comparative Example 1 was added to 10 mL of the reaction solution and stirred in the dark for 1 h. The absorbance of the supernatant at 350 nm was measured using a UV spectrophotometer. The calculated scavenging rate of ROO• after adding Mg2Al-LDHs was 27.33%.

[0030] Comparative Example 2: Step A: Weigh 15.39 g magnesium nitrate hexahydrate (Mg(NO3)2•6H2O) and 7.77 g aluminum nitrate nonahydrate (Al(NO3)3•9H2O) into 150 mL of deionized water and prepare a mixed metal salt solution under ultrasonic and mechanical stirring conditions; dissolve 9.60 g NaOH and 2.54 g Na2CO3 in deionized water to prepare a mixed alkaline solution; add the alkaline solution dropwise to the mixed metal salt solution to adjust the pH value to 9.0 (±0.5). After nucleation, transfer to a reaction vessel and stir at 100℃ for 15 h. After the reaction is completed, centrifuge and wash until neutral, dry, and obtain Mg2Al-LDHs.

[0031] Step B: Disperse Mg2Al-LDHs in water, add nitric acid solution (concentration of 0.0001 mol / L), and etch at room temperature for 1 h. After etching, centrifuge and wash until neutral, and dry to obtain Mg2Al-LDHs-HNO3.

[0032] Compare with application example 2: ROO• free radical scavenging experiment: 0.5 mM luminol was dissolved in 100 mL of 0.1 M NaOH solution. 1.90 mg of tert-butyl hydroperoxide (t-BuOOH) was weighed and added to the above solution to prepare a 100 μM reaction solution. 0.2 g of the powder from Comparative Example 2 was added to 10 mL of the reaction solution and stirred in the dark for 1 h. The absorbance of the supernatant at 350 nm was measured using a UV spectrophotometer. The calculated scavenging rate of ROO• after adding Mg2Al-LDHs-HNO3 was 43.72%.

Claims

1. A ternary hydrotalcite free radical scavenger rich in oxygen vacancies, characterized in that, The general formula for the capture agent is M. 2+ 1-x-y M 3+ x M 4+ y (OH)2(A n- ) n- / 2 ·mH2O, where M 2+ Represents a divalent metal cation, specifically selected from Mg. 2+ Zn 2+ Ca 2+ Ni 2+ Fe 2+ One of them; M 3+ Represents a trivalent metal cation, specifically selected from Al 3+ Ni 3+ Co 3+ Fe 3+ One of them; M 4 + Represents tetravalent metal ions, specifically selected from Ti. 4+ Zr 4+ Sn 4+ or Mn 4+ One of them; A n- It is one of carbonate, nitrate, and chloride ions, where n- is the valence of the anion; x is M. 3+ The mole fraction of all metal ions, y is M 4+ The mole fraction of all metal ions, with x+y ranging from 0.2 to 0.33; m represents the amount of water of crystallization, 0 to 6.

2. A process for the preparation of an oxygen-deficient ternary hydrotalcite radical scavenger-enriched composition, characterized in that, The specific operation of the preparation method is as follows: weigh M 2+ M 3+ and M 4+ The soluble salts are dissolved in deionized water and mixed metal salt solutions are prepared under ultrasonic and mechanical stirring conditions. NaOH and Na2CO3 are dissolved in deionized water to prepare mixed alkaline solutions. The mixed alkaline solutions are added dropwise to the mixed metal salt solutions and the pH is adjusted to 9-12. After nucleation, the solutions are transferred to a high-pressure reactor and reacted at 40-140℃, preferably 50-100℃, for 0.1-30 h, preferably 4-18 h. After the reaction, the solutions are centrifuged and washed until neutral, and then dried. The solutions are then dispersed in water to form a suspension, etched with acid solution, and after etching, centrifuged and washed until neutral, and then dried to obtain oxygen-defect-rich ternary hydrotalcite free radical scavenger.

3. The preparation method according to claim 2, characterized in that, The concentration of the acid solution is 0.0001-5 mol / L, preferably 0.001-1 mol / L; the etching temperature does not exceed 100 ℃, preferably 25-50 ℃; and the etching time is 0.1-12 h, preferably 1-4 h.

4. The preparation method according to claim 2, characterized in that, The acid solution is selected from one or more of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, formic acid, and acetic acid.

5. The use of the oxygen-deficient ternary hydrotalcite radical scavenger prepared according to any one of claims 1 to 4, characterized in that, The specific operation of the method is as follows: add the free radical scavenger to the liquid containing free radicals and stir thoroughly to capture the free radicals therein.

6. The method of use of claim 5, wherein, The free radical is one or more of the following: peroxyalkyl free radical, 1,1-diphenyl-2-trinitrophenylhydrazine free radical, nitric oxide free radical, hydroxyl free radical, and superoxide anion free radical.

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