Sustained-release nanomaterial coated with calcium peroxide by tea polyphenol complexing trivalent iron and application thereof

Abstract

This invention discloses a slow-release nanomaterial of calcium peroxide coated with ferric iron complexed by tea polyphenols and its application. The material has a core-shell structure, with a central layer of CaO2 nanoparticles and an outer shell consisting of a network structure encapsulating tea polyphenols and ferric ions. This material is produced by adding Fe to a system containing dissolved CaO2. 3+ It was obtained by centrifugation after mixing with tea polyphenol solution. This invention utilizes the complexation of Fe by tea polyphenols. 3+ A slow-release nanomaterial is formed by coating calcium peroxide, which can control the release rate of H2O2. Furthermore, compared to other controlled-release materials, the complexed iron ions on the coating layer of the slow-release nanomaterial provided by this invention can spontaneously dissociate, slowly releasing Fe. 3+ Simultaneously, by utilizing the reducing properties of tea polyphenols, the slowly released Fe... 3+ Reduced to Fe 2+ And Fe 2+ It can work in conjunction with CaO2 to improve the treatment effect of chlorophenol pollutants.

Description

Technical Field

[0001] This invention belongs to the field of groundwater treatment technology, specifically relating to a tea polyphenol-complexed ferric iron-coated calcium peroxide (CaO2@TP-Fe). 3+ Application of slow-release nanomaterials in the remediation of chlorophenol pollutants in groundwater. Background Technology

[0002] The water pollution problem caused by chlorophenols (CPs) is becoming increasingly prominent, as they are frequently detected in groundwater, exacerbating groundwater pollution. In recent years, rapid industrial and agricultural development, along with unreasonable human exploitation, have led to a surge in chlorophenol contamination. Currently, groundwater remediation primarily employs in-situ remediation techniques, but these techniques suffer from numerous problems, such as backdiffusion, concentration tailing, contaminant rebound, and catalyst lifetime issues. To address these problems and further improve the effectiveness of chlorophenol remediation, controlled-release technology has attracted widespread attention in the field of groundwater in-situ remediation.

[0003] By utilizing slow-release materials to extend the lifespan of active components, rebound phenomena can be controlled, and in-situ remediation effects can be improved. The application of controlled-release materials allows for the slow and sustained release of reactive compounds, thereby achieving long-term control and remediation of pollution sources. Slow-release materials that release reactive substances gradually reduce the non-selective consumption of oxidants and allow for long-term dissolution. This enables the oxidant to maintain a certain concentration for a relatively long effective period, thus effectively oxidizing pollutants.

[0004] However, currently common sustained-release materials employ the basic traditional Fenton system, which requires the exogenous addition of Fe-based materials to achieve only the effect of slowly releasing H2O2. 3+ The low reduction rate leads to low utilization of H2O2, increased non-selective consumption of active substances produced by the reaction, and difficulty in recycling the iron sludge generated by the reaction, which causes certain harm to the environment. Summary of the Invention

[0005] The purpose of this invention is to address the problem of poor performance of existing conventional wastewater treatment methods for groundwater contaminated with recalcitrant organic matter (especially water bodies contaminated with p-chlorophenol), by providing a network-structured modified iron-based catalyst coated with calcium peroxide nanocapsules (CaO2@TP-Fe). 3+ This paper describes an advanced oxidation technology that slowly releases hydrogen peroxide to address the problems mentioned in the background section, and also explains the preparation method of calcium peroxide nanocapsules coated with a network-structured modified iron-based catalyst.

[0006] In a first aspect, the present application provides a slow-release nanomaterial of tea polyphenol complexed trivalent iron coated calcium peroxide, which has a core-shell structure, with a CaO2 nanoparticle as the core layer and a reticular structure formed by wrapping tea polyphenol and trivalent iron ions as the shell layer. The slow-release nanomaterial of tea polyphenol complexed trivalent iron coated calcium peroxide is obtained by adding Fe 3 + and a tea polyphenol solution to a system for dissolving CaO2, and then centrifuging.

[0007] Preferably, the slow-release nanomaterial of tea polyphenol complexed trivalent iron coated calcium peroxide has a spherical morphology, with a particle size of 90-110 nm.

[0008] Preferably, the CaO2 is prepared by adding anhydrous calcium chloride and polyvinylpyrrolidone into anhydrous ethanol to dissolve, then adding ammonia water and hydrogen peroxide successively, continuing to stir, and then centrifuging and washing to obtain solid CaO2.

[0009] Preferably, the mass ratio of anhydrous calcium chloride to polyvinylpyrrolidone is 8:28.

[0010] Preferably, in the preparation process of CaO2, after the anhydrous calcium chloride and polyvinylpyrrolidone are dissolved, 0.08 mol / L ammonia water is added after continuous stirring in a 25℃ water bath for 30 minutes, and the stirring is continued for 5 minutes. Then, 1 mol / L hydrogen peroxide is slowly added, and the stirring is continued until the solution changes from colorless to blue. Then, the solution is centrifuged using a centrifuge, and washed with anhydrous ethanol three times.

[0011] Preferably, the molar ratio of Fe 3+ to tea polyphenol is (0.5-6):1.

[0012] Preferably, the molar ratio of CaO2 to tea polyphenol is (30-35):1.

[0013] In a second aspect, the present application provides the use of the slow-release nanomaterial of tea polyphenol complexed trivalent iron coated calcium peroxide as described above in the degradation of chlorophenol compounds in groundwater.

[0014] Preferably, the chlorophenol compound is specifically p-chlorophenol.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] 1. The present application forms a slow-release nanomaterial by complexing Fe 3+ coated calcium peroxide with tea polyphenol, which can control the release speed of H2O2; and, compared with other controlled-release materials, the complexed iron ions on the coating layer of the slow-release nanomaterial provided by the present application can self-dissociate and slowly release Fe 3+Simultaneously, by utilizing the reducing properties of tea polyphenols, the slowly released Fe... 3+ Reduced to Fe 2+ And Fe 2+ It can work in conjunction with CaO2 to improve the treatment effect of chlorophenol pollutants.

[0017] 2. The slow-release nanomaterial of tea polyphenol-complexed ferric iron coated calcium peroxide provided by this invention, wherein tea polyphenols and Fe... 3+ Coordination forms a metal-phenol network. Under slightly acidic conditions, tea polyphenols have strong reducing properties, and the coordination between the two can promote Fe... 3+ / Fe 2+ The cascade reaction of transformation controls the release rate of H2O2 and reduces the non-selective consumption of H2O2, allowing the oxidant to maintain a certain concentration for a relatively long effective period of time, thus enabling more sustained removal of pollutants from groundwater in in-situ remediation.

[0018] 3. In this invention, a slow-release nanomaterial containing ferric iron complexed with tea polyphenols and coated with calcium peroxide is used to slowly degrade the 4-CP system in groundwater. Multiple free radicals participate in the degradation of pollutants, with HO· being the core active substance. 1 O2 and O2 - • Due to its auxiliary role, the degradation of groundwater by 4-CP is less affected by different anions and cations and natural organic matter, and it has good degradation performance for different chlorophenols, showing great application prospects for the slow-release remediation of pollutants in groundwater.

[0019] 4. The catalyst provided by this invention has a good remediation effect on chlorophenol pollutants in groundwater, is less affected by different anions and cations and natural organic matter, and has good degradation performance for different chlorophenol substances, showing great application prospects for the slow-release remediation of pollutants in groundwater.

[0020] 5. The tea polyphenol (TP) used in this invention is a natural polyphenol, mainly composed of catechins in its structure. It has strong reducing properties under slightly acidic conditions. TP and Fe... 3+ Coordination can improve the utilization rate of H2O2, control the release rate of H2O2, and promote the generation of hydroxyl radicals. Attached Figure Description

[0021] Figure 1 This is a TEM image of the capsule prepared in Example 1 of the present invention.

[0022] Figure 2 The images show the XRD patterns of pure CaO2 and the material prepared in Example 1.

[0023] Figure 3 The graph shows the hydrogen peroxide production curves of capsules prepared using pure CaO2 in Examples 1-4 at pH=3.

[0024] Figure 4 This invention uses pure CaO2 and pure CaO2+Fe. 3+ The degradation curves of 4-CP by the capsules prepared in Examples 1-4 at pH=3.

[0025] Figure 5 The graph shows the degradation curves of 4-CP, 2-CP and 2,4-DCP of the capsules prepared in Example 1 of the present invention at pH=3. Detailed Implementation

[0026] The following specific examples further illustrate the content of this invention, but should not be construed as limiting the invention. Any simple modifications or substitutions made to the methods, steps, or conditions of this invention without departing from the spirit and essence of the invention are within the scope of this invention. Unless otherwise specified, the technical means used in the embodiments are conventional methods well known to those skilled in the art.

[0027] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0028] Example 1

[0029] A slow-release nanomaterial (CaO2@TP-Fe) containing tea polyphenols chelated with ferric iron and coated with calcium peroxide. 3+ It has a CaO2 core and is surrounded by a layer of TP-Fe. 3+ It has a network structure with a spherical morphology and an average particle size of 105 nm.

[0030] This slow-release nanomaterial (CaO2@TP-Fe) is composed of tea polyphenols and ferric iron-coated calcium peroxide. 3+ The preparation method of ) includes the following steps:

[0031] Step 1: Weigh 8g of anhydrous calcium chloride and 28g of polyvinylpyrrolidone, add 800mL of anhydrous ethanol, and dissolve by sonication. Control the water bath temperature at 25℃, stir continuously for 30 minutes, then add 80mL of ammonia (0.80M), continue stirring for 5 minutes, then slowly add 40mL of hydrogen peroxide (1M), continue stirring for 40 minutes. The solution color changes from colorless to light blue. Then centrifuge (15000rpm, 15min) and wash three times with anhydrous ethanol to obtain CaO2 nanospheres.

[0032] Step 2: Weigh 3.5 mg of CaO2 nanospheres, add 5 mL of anhydrous ethanol, and sonicate until completely dissolved. Then add 1 mL of FeCl3 solution (1.2 mg / mL), sonicate for 10 seconds, and then add 1 mL of tea polyphenol solution (2.5 mg / mL), sonicating for 10 seconds. The solution turns blackish-purple. Finally, centrifuge (13000 rpm, 10 min), wash three times with anhydrous ethanol, and dry the precipitate under vacuum at 60℃ to obtain CaO2@TP-Fe 3+ Nanocapsule materials. The resulting CaO2@TP-Fe 3+ The morphology of nanocapsule materials is as follows Figure 1 As shown, the catalyst is composed of nanospheres encapsulated in a mesh-like structure, with an average particle size of 105 nm.

[0033] The CaO2@TP-Fe obtained using the above preparation method 3+ The process of treating wastewater containing chlorophenol compounds using nanocapsule materials is as follows:

[0034] The obtained CaO2@TP-Fe 3+ The nanocapsule material was placed in polluted water, and the pH was adjusted to open TP-Fe under slightly acidic conditions. 3+ The "gate" releases H2O2 in a slow-release manner and activates it in situ to produce active substances, thereby achieving the degradation of p-chlorophenol (4-CP) in groundwater.

[0035] Pure CaO2 and CaO2@TP-Fe 3+ Comparison of nanocapsule materials as follows Figure 2 As shown, the main diffraction peaks of the CaO2 crystal are still present, indicating that TP-Fe 3+ The coating of nanomaterials did not change the crystal structure of CaO2.

[0036] Example 2

[0037] A slow-release nanomaterial (CaO2@TP-Fe) containing tea polyphenols chelated with ferric iron and coated with calcium peroxide. 3+ The difference between this embodiment and Embodiment 1 is that in step two of the preparation method of the slow-release nanomaterial of calcium peroxide coated with trivalent iron by tea polyphenol complex, tea polyphenol (TP) and Fe... 3+ The molar ratio of the substances was changed from 1:6 to 1:3. Other steps and parameters were the same as in Example 1.

[0038] Example 3

[0039] A slow-release nanomaterial (CaO2@TP-Fe) containing tea polyphenols chelated with ferric iron and coated with calcium peroxide. 3+The difference between this embodiment and Embodiment 1 is that in step two of the preparation method of the slow-release nanomaterial of calcium peroxide coated with trivalent iron by tea polyphenol complex, tea polyphenol (TP) and Fe... 3+ The molar ratio of the substances was changed from 1:6 to 1:1. Other steps and parameters were the same as in Example 1.

[0040] Example 4

[0041] A slow-release nanomaterial (CaO2@TP-Fe) containing tea polyphenols chelated with ferric iron and coated with calcium peroxide. 3+ The difference between this embodiment and Embodiment 1 is that in step two of the preparation method of the slow-release nanomaterial of calcium peroxide coated with trivalent iron by tea polyphenol complex, tea polyphenol (TP) and Fe... 3+ The molar ratio of the substances was changed from 1:6 to 2:1. Other steps and parameters were the same as in Example 1.

[0042] The comparison of hydrogen peroxide production under pH 3 conditions is as follows: (The text includes a series of seemingly unrelated sentences and phrases, which are not translated as they are not part of the main text.) Figure 3 As shown. Previous research has discovered TP-Fe 3+ The thickness of the network film is affected by Fe 3+ Concentration effect, from Figure 3 It can be seen from this that when Fe 3+ Only when the molar ratio of TP to Fe is 6:1 can capsules with constant film thickness and roughness be formed. Therefore, when the ratio is less than 6:1, TP-Fe... 3+ The coating effect is not ideal. Therefore, when Fe... 3+ When the molar ratio of CaO2@TP-Fe is 6:1, 3 + It not only demonstrates excellent performance in controlling the release of H2O2, but also makes full use of the released H2O2, reducing the non-selective consumption of active substances.

[0043] Example 5

[0044] A method for degrading 4-CP in groundwater comprises the following steps: adding a slow-release nanomaterial containing tea polyphenols complexed with ferric iron and coated with calcium peroxide, as provided in Examples 1, 2, 3, and 4, to the water to be treated. The water to be treated is groundwater.

[0045] To determine the processing effectiveness of this embodiment, the following experiment was conducted:

[0046] Take 10 mL of 100 mg / L 4-CP solution and 90 mL of deionized water into a 150 mL brown wide-mouth bottle, then add 10 mg of the test material. Control the water temperature at 20 °C, place a stir bar in the bottle, and place the bottle on a magnetic stirrer to carry out the reaction. Set the reaction time to 8 h. At each fixed time point, take 1 mL of the reaction solution and separate the precipitate using a 0.22 μm filter. Repeat the experiment twice.

[0047] Four experimental groups and two control groups were set up. Experimental groups 1-4 were respectively treated with a slow-release nanomaterial containing tea polyphenols chelated with ferric iron and coated with calcium peroxide, as described in Examples 1, 2, 3, and 4. Control group 1 was treated with pure CaO2. Control group 2 was treated with pure CaO2 and Fe... 3+ As the test subject material; the results obtained are as follows Figure 4 As shown. Different proportions of CaO2@TP-Fe were evaluated. 3+ Nanocapsules, CaO2+Fe 3+ The degradation performance of 4-CP by CaO2 slow-release degradation, from Figure 4 It can be seen from this that: when n(TP):n(Fe 3+ When the ratio of CaO2 to TP-Fe is 1:6, 3+ Nanocapsules exhibit excellent Fenton-like reactivity and can serve as a high-performance slow-release material for remediating groundwater contaminants.

[0048] The following is a comparative experiment on the decomposition of different chlorophenols (p-chlorophenol, 2-chlorophenol, 2,4-dichlorophenol) using the slow-release nanomaterial of tea polyphenol complexed with ferric iron and coated with calcium peroxide provided in Example 1:

[0049] Take 10 mL of a 100 mg / L chlorophenol solution and 90 mL of deionized water in a 150 mL brown wide-mouth bottle, then add 10 mg of CaO2@TP-Fe. 3+ The water temperature was controlled at 20℃, a stir bar was placed in the water, and the mixture was placed on a magnetic stirrer for reaction. The reaction time was set at 8 hours. At each fixed time point, 1 mL of the reaction solution was taken out and the precipitate was separated using a 0.22 μm filter. The experiment was repeated twice.

[0050] Three experimental groups were set up; the chlorophenols used in the three experiments were p-chlorophenol, 2-chlorophenol, and 2,4-dichlorophenol, respectively; the results are as follows: Figure 5 As shown; from Figure 5 It can be seen that the CaO2@TP-Fe provided in Example 1 3+ Nanocapsule materials exhibit excellent degradation effects on various chlorophenols.

Claims

1. The application of slow-release nanomaterials containing tea polyphenols complexed with ferric iron and coated with calcium peroxide in the degradation of chlorophenol compounds in groundwater, characterized in that: The slow-release nanomaterial containing tea polyphenols, ferric iron, and calcium peroxide exhibits a core-shell structure. The central layer consists of CaO2 nanoparticles, while the outer shell is a network structure encapsulating tea polyphenols and ferric iron ions. This slow-release nanomaterial is produced by adding Fe to a system containing dissolved CaO2. 3+ Fe was obtained by centrifugation after mixing with tea polyphenol solution. 3+ The molar ratio of CaO2 to tea polyphenols is 6:1; the molar ratio of CaO2 to tea polyphenols is (30-35):

1.

2. The application according to claim 1, characterized in that: The slow-release nanomaterial containing tea polyphenols, ferric iron complexed with calcium peroxide, exhibits a spherical morphology with a particle size of 90 nm to 110 nm.

3. The application according to claim 1, characterized in that: The preparation process of CaO2 is as follows: anhydrous calcium chloride and polyvinylpyrrolidone are dissolved in anhydrous ethanol, then ammonia water and hydrogen peroxide are added in sequence and stirred. After centrifugation and washing, solid CaO2 is obtained.

4. The application according to claim 3, characterized in that: The mass ratio of anhydrous calcium chloride to polyvinylpyrrolidone is 8:

28.

5. The application according to claim 3, characterized in that: In the preparation of CaO2, after anhydrous calcium chloride and polyvinylpyrrolidone are dissolved, the mixture is stirred continuously in a 25°C water bath for 30 minutes, then 0.08 mol / L ammonia water is added and stirring is continued for 5 minutes. Then, 1 mol / L hydrogen peroxide is slowly added and stirring is continued until the solution changes from colorless to blue. The solution is then centrifuged and washed three times with anhydrous ethanol.

6. The application according to claim 1, characterized in that: Add Fe to the system of dissolving CaO2 3+ The specific process for preparing the tea polyphenol solution is as follows: FeCl3 is added to an ethanol solution containing dissolved CaO2, followed by ultrasonic treatment; then the tea polyphenol solution is added, followed by ultrasonic treatment.

7. The application according to claim 1, characterized in that: The chlorophenolic compound mentioned is specifically p-chlorophenol.

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