Preparation method and application of intercalated layered double hydroxide material for activating calcium sulfite

Abstract

The invention belongs to the field of sewage treatment and advanced oxidation, and adopts a two-step hydrothermal synthesis technology to prepare a composite material molybdenum disulfide intercalation cobalt-manganese layered double hydroxide, and the molybdenum disulfide intercalation cobalt-manganese layered double hydroxide is applied to activated calcium sulfite to degrade chloroquine phosphate in water. The morphology of the LDH is not changed in ion exchange and vulcanization processes, and the growth of MoS2 is restrained in the LDH middle layer, so that the original aggregation structure is changed. Meanwhile, the layered agglomeration structure of LDH is also improved, the compound MoS2-coated LDH is relatively loose, and the specific surface area of the catalyst is effectively increased, so that the catalytic efficiency is improved. The method is simple to operate, and the prepared material has excellent reusability and stability and has certain application value in wastewater treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, in particular to a preparation method and application of an intercalated layered double hydroxide material for activating calcium sulfite. BACKGROUND

[0002] In recent years, sulfate-based advanced oxidation processes have been widely used in water treatment. Compared with other advanced oxidation methods, SO4 ·- has a higher oxidation potential (2.5-3.1V), more free radicals generated and a wider pH range. Among them, the persulfate (PS) advanced oxidation method mainly uses persulfate (PMS) and peroxymonosulfate (PDS), which has been widely studied in water treatment due to its high degradation efficiency, strong oxidation ability and wide applicability. However, due to the toxicity of persulfate residues and the formation of toxic by-products, it poses a certain risk to water. In recent years, sulfite has gradually become a substitute for persulfate due to its environmental, economic and stable characteristics. Sulfite produced by wet desulfurization can generate different sulfur oxide radicals, which has the advantages of wide source and low cost.

[0003] MoS2 is a typical layered transition metal sulfide, and MoS2 has been applied to various catalytic fields due to its abundant active sites, good arrangement and dispersion structure, and high electron mobility. In MoS2, the presence of Mo 4+ / Mo 6+ sites significantly increases the redox reaction rate of metal ions. Due to the presence of saturated S, MoS2 exhibits significant reduction performance, enabling it to effectively reduce high-valence metal ions to their corresponding low-valence states, thereby improving catalytic efficiency. However, due to its poor electrical conductivity and limited charge transfer kinetics, MoS2 exhibits suboptimal catalytic performance when used alone.

[0004] Layered double hydroxides (LDHs) have attracted extensive attention due to their unique structure, simple synthesis, reasonable price, variable chemical composition, interlayer anion exchange, and acid-base bifunctional groups. In addition, the presence of LDH allows for the maintenance of a weak alkaline pH during the reaction, which reduces the leaching of metal ions in the catalyst while also significantly reducing the leaching of metal ions in the catalyst. However, due to the layered structure of LDH and the electrostatic force, it is prone to accumulation and aggregation, resulting in a decrease in specific surface area and a significant reduction in available active sites, ultimately weakening its catalytic performance and reducing catalyst utilization. At the same time, researchers have found that by inserting different ions and substances into the interlayer of LDH, the activation efficiency of the composite material for oxidizing agents can be effectively improved, thereby improving the degradation efficiency of pollutants. SUMMARY

[0005] The application aims to provide a novel LDH-based composite material and a preparation method thereof, and apply the composite material to a reaction of catalytic degradation of chloroquine phosphate, wherein the preparation method is reasonable and simple, the catalytic oxidation performance is stable, and the catalytic oxidation efficiency is high.

[0006] The application adopts MoS2 intercalated cobalt-manganese layered double hydroxide (CoMn-LDH), due to the layered structure of LDH, the original aggregation structure of MoS2 can be adjusted by interlayer constraint to grow, so as to expose more active sites and increase the contact area of the two to improve the efficiency. Meanwhile, the composite material is relatively dispersed, avoiding the problem of easy stacking of LDH materials.

[0007] To achieve the above-mentioned purpose, the technical scheme provided by the application is as follows: a preparation method of MoS2 intercalated cobalt-manganese layered double hydroxide catalyst, the preparation method comprises the following steps:

[0008] S1: Co(NO3)2·6H2O and Mn(NO3)2·4H2O are dissolved in 30 mL of deionized water to form a first solution; Na2MoO4·2H2O is dissolved in 20 mL of deionized water to form a second solution; NaOH is dissolved in 20 mL of deionized water to form a third solution;

[0009] S2: the first solution and the second solution obtained in S1 are simultaneously dropped into the third solution, and a mixed fourth solution is obtained by stirring under the action of a magnetic force;

[0010] S3: the fourth solution obtained in S2 is poured into the inner container of a hydrothermal reaction kettle, and after hydrothermal reaction, washing and drying, CoMn-LDH / MoO4 composite material is obtained. 2-

[0011] S4: the CoMn-LDH / MoO4 composite material obtained in S3 is dispersed in 60 mL of deionized water, CH4N2S is added, stirring and dissolving are performed, and after hydrothermal reaction, washing and drying, CoMn-LDH / MoS2 composite material is obtained. 2-

[0012] Preferably, the molar ratio of Co(NO3)2·6H2O, Mn(NO3)2·4H2O and Na2MoO4·2H2O in S1 is 2:1:0.2, and the molar concentration of NaOH is 0.125-0.2 mol / L.

[0013] Preferably, in S3, the pH value in the hydrothermal reaction is 10-11, the temperature of the hydrothermal reaction is 120 DEG C, the time of the hydrothermal reaction is 10 h, the drying temperature is 60 DEG C, and the drying time is 6 h.

[0014] ​​Preferably, in S4, the added amount of CH4N2S is 5 times the molar amount of Na2MoO4·2H2O, the temperature of the hydrothermal reaction is 200℃, the time of the hydrothermal reaction is 12h, the drying temperature is 60℃, and the drying time is 6h.

[0015] The application also provides a use of the above-mentioned molybdenum disulfide intercalated cobalt-manganese layered double hydroxide catalyst in advanced oxidation, in particular, the obtained molybdenum disulfide intercalated cobalt-manganese layered double hydroxide catalyst is used for activating sulfite to degrade chloroquine phosphate. The specific steps include the following: the molybdenum disulfide intercalated cobalt-manganese layered double hydroxide composite material is added into a solution of chloroquine phosphate with a concentration of 10-50mg / L at a ratio of 0.1-0.4g / L, sulfite with a concentration of 1-6mmol / L is added, the reaction temperature is room temperature, and the reaction time is 60min, so as to complete the degradation of chloroquine phosphate. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 : X-ray diffraction pattern of the new composite material prepared in Examples 1-2.

[0017] Figure 2 : Scanning electron microscope image of the new composite material prepared in Examples 1-2. Wherein, a is Co2Mn-LDH / MoS2; b is Co2Mn-LDH; c is MoS2.

[0018] Figure 3 : X-ray photoelectron spectroscopy pattern of the new composite material prepared in Example 2. Figure 4 : Structure diagram of the new composite material prepared in Example 2.

[0019] Figure 5 : Degradation curve of chloroquine phosphate by different systems.

[0020] Figure 6 : Degradation curve of chloroquine phosphate with different concentrations by the new composite material prepared in Example 2.

[0021] Figure 7 : Degradation curve of chloroquine phosphate by the new composite material prepared in Example 2 in the presence of ion influence. Wherein, a is Cl - , b is SO4 2- .

[0022] Figure 8 : Recycling use diagram of the new composite material prepared in Example 2.

[0023] Figure 9 : Degradation diagram of different pollutants by the new composite material prepared in Example 2. DETAILED DESCRIPTION

[0024] The specific embodiments of the present application are further illustrated in the following description with reference to the accompanying drawings and technical solutions. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application.

[0025] Example 1: Preparation of Co2Mn-LDH

[0026] 4mmol of Co(NO3)2·6H2O and 2mmol of Mn(NO3)2·4H2O were dissolved in 30mL of deionized water to form solution A; 0.5g of NaOH was dissolved in 20mL of deionized water to form solution B. Solution A was slowly dropped into solution B, and magnetic stirring was performed for 30min, and the pH was maintained at 10 during stirring. The solution was poured into an autoclave, which was placed in an oven at 120℃ for 10h of reaction. After reaction, the product was washed and dried to obtain Co2Mn-LDH.

[0027] Example 2: Preparation of Co2Mn-LDH@MoS2

[0028] 4mmol of Co(NO3)2·6H2O and 2mmol of Mn(NO3)2·4H2O were dissolved in 30mL of deionized water to form solution A; 0.4mmol of Na2MoO4·2H2O was dissolved in 20mL of deionized water to form solution B; 0.5g of NaOH was dissolved in 20mL of deionized water to form solution C. Solution A and solution B were slowly dropped into solution C at the same time, and magnetic stirring was performed for 30min, and the pH was maintained at 10 during stirring. The solution was poured into an autoclave, which was placed in an oven at 120℃ for 10h of reaction. After reaction, the product was washed and dried to obtain powder A. Powder A was dissolved in 60mL of deionized water, and 2mmol of CH4N2S was added, and magnetic stirring was performed for 30min. The solution was poured into an autoclave, which was placed in an oven at 200℃ for 12h of reaction. After reaction, the product was washed and dried to obtain Co2Mn-LDH@MoS2.

[0029] The X-ray diffraction pattern of the above-prepared cobalt-manganese layered double hydroxide and molybdenum disulfide intercalated cobalt-manganese layered double hydroxide composite material is shown in Figure 1 As can be seen from the figure, the Co2Mn-LDH@MoS2 material retains the characteristic peaks of the LDH material, and new characteristic peaks (002) and (100) of MoS2 are added, indicating that the two are successfully combined together.

[0030] The scanning electron microscope image of the above-prepared cobalt-manganese layered double hydroxide and molybdenum disulfide intercalated cobalt-manganese layered double hydroxide composite material is shown in Figure 2 As can be seen from the figure, the molybdenum disulfide Figure 2 c) shows a typical flower-like structure, and the average diameter of each molybdenum disulfide microsphere is about 1μm. Figure 2In a(Co2Mn-LDH@MoS2), no particles similar in morphology to MoS2 were found, indicating that the morphology of LDH did not change during ion exchange and sulfidation, and the constrained growth of the interlayer of LDH can change the original aggregation structure of MoS2. Figure 2 b is Co2Mn-LDH, which exhibits obvious layered agglomeration structure, while the LDH in the composite is relatively loose, effectively increasing the specific surface area of the catalyst and thus improving the catalytic efficiency.

[0031] The X-ray photoelectron spectrogram of the above-prepared molybdenum disulfide intercalated cobalt-manganese layered double hydroxide composite material is shown in Figure 3 It is proved that MoS2 has been successfully combined with Co2Mn-LDH. The structural diagram of the above-prepared molybdenum disulfide intercalated cobalt-manganese layered double hydroxide composite material is shown in Figure 4 It can be seen that MoS2 is intercalated into the interlayer of Co2Mn-LDH.

[0032] Example 3.

[0033] In this example, the initial conditions of all degradation experiments are consistent. The catalyst dosage is 0.2 g / L, the oxidant dosage is 5 mM, and the pollutant concentration is 20 mg / L. As shown in Figure 5 CaSO3 alone shows limited degradation efficiency, and the catalyst alone only shows small adsorption performance. In order to verify the catalytic effect of MoS2, MoS2 and CaSO3 are added to the system at the same time. Compared with the addition of CaSO3 alone, the MoS2 / CaSO3 system has no significant effect on the degradation of CQP. The degradation rate of Co2Mn-LDH can reach 80.7%, and the intercalated material Co2Mn-LDH@MoS2 has a degradation rate of up to 95.5% for chloroquine phosphate in 60 min. It can be seen that the activation effect of Co2Mn-LDH@MoS2 is significant.

[0034] Example 4.

[0035] In this example, the catalyst dosage is 0.2 g / L, the oxidant dosage is 5 mM, and the pollutant concentration is 10-50 mg / L. As shown in Figure 6 At concentrations of 10 mg / L and 20 mg / L, the degradation curves show almost the same trend, and the final degradation efficiency of both is more than 95%. When the concentration increases to 30 mg / L, the initial degradation rate of the reaction decreases significantly, and the final degradation efficiency decreases by 7%. However, when the initial concentration rises to 50 mg / L, the degradation efficiency of CQP decreases due to the lack of enough free radicals to remove the target pollutant. Even in a high concentration environment, chloroquine phosphate can still achieve a removal rate of more than 85%. It can be seen that Co2Mn-LDH@MoS2 exhibits excellent activation ability in degrading chloroquine phosphate.

[0036] Example 5.

[0037] In this example, the initial conditions for all degradation experiments were consistent: catalyst dosage was 0.2 g / L, oxidant dosage was 5 mM, and pollutant concentration was 20 mg / L. Based on this, common ions found in water (Cl-) were artificially introduced. - and SO4 2- ).like Figure 7 As shown in Figure a, 5 mM Cl is added to the solution. - Afterwards, the degradation rate of CQP decreased by 3.8%. With the increase of Cl... - As the concentration gradually increased, the degradation efficiency reached 90.4% and 88.9% at 25 mM and 50 mM, respectively. Figure 7 As shown in b, with Cl - Similar to the effect of low concentrations of SO4 2- The effect on degradation was minimal. At high concentrations, a significant inhibitory effect was observed in the first 20 minutes of degradation. However, this inhibitory effect weakened over time, eventually resulting in a degradation rate of 86.7%. This demonstrates that Co2Mn-LDH@MoS2 still exhibits excellent activation ability in the presence of ionic influences.

[0038] Example 6.

[0039] In this example, the initial conditions for all degradation experiments were consistent. The catalyst dosage was 0.2 g / L, the oxidant dosage was 5 mM, and the pollutant concentration was 20 mg / L. After the reaction, the solid material was subjected to solid-liquid separation using a vacuum filter, washed, dried, and then the pollutant solution was added back in. CaSO3 was then added for oxidative degradation, and this process was repeated five times. Figure 8 As shown, after 5 cycles, the degradation rate of chloroquine phosphate by Co2Mn-LDH@MoS2 / CaSO3 still reached over 90%. This demonstrates that Co2Mn-LDH@MoS2 exhibits excellent reusability.

[0040] Example 7.

[0041] In this example, the initial conditions for all degradation experiments were consistent. The catalyst dosage was 0.2 g / L, the oxidant dosage was 5 mM, and the pollutant concentration was 20 mg / L. Based on this, chloroquine phosphate was replaced with other pollutants, including methyl orange (MO), acesulfame K (ACE), tetracycline (TC), hydroxychloroquine sulfate (HCQ), and metronidazole (MNZ), for degradation analysis. Figure 9As shown, the system has good degradation ability for MNZ, which can remove 99.5% of MNZ within 10 min. The degradation rates of MO, TC, ACE and HCQ are 95.7%, 79.5%, 73.7% and 91.2%, respectively. The selected pollutants include dyes, food additives, antibiotics and drugs, indicating that the Co2Mn-LDH@MoS2 / CaSO3 system can degrade a variety of pollutants.

Claims

1. A method for preparing an intercalated layered double hydroxide material for activating calcium sulfite, characterized in that, the method comprises the following steps: S1: dissolving Co (NO 3) 2·6H 2O and Mn (NO 3) 2·4H 2O in deionized water to form a first solution; dissolving Na 2MoO 4·2H 2O in deionized water to form a second solution; dissolving NaOH in deionized water to form a third solution; S2: simultaneously dropping the first solution and the second solution obtained in S1 into the third solution, and stirring under the action of magnetic force to obtain a mixed fourth solution; In S1, the molar ratio of Co (NO 3) 2·6H 2O, Mn (NO 3) 2·4H 2O and Na 2MoO 4·2H 2O is 2:1:0.2, and the molar concentration of NaOH is 0.125-0.2 mol / L. S3: pour the fourth solution obtained in S2 into the inner container of a hydrothermal reaction kettle, and after hydrothermal reaction, washing and drying, CoMn-LDH / MoO4 is obtained 2- composites; S4: The CoMn-LDH / MoO4 obtained in S3 is dispersed in deionized water, CH4N2S is added, and stirred and dissolved, and after hydrothermal reaction, washing and drying, a CoMn-LDH / MoS2 composite material is obtained. 2- The composite material is dispersed in deionized water, CH4N2S is added, and stirred and dissolved, and after hydrothermal reaction, washing and drying, a CoMn-LDH / MoS2 composite material is obtained.

2. The production method according to claim 1, characterized by, In S3, the pH value of the hydrothermal reaction is 10-11, the temperature of the hydrothermal reaction is 120℃, the time of the hydrothermal reaction is 10h, the drying temperature is 60℃, and the drying time is 6h.

3. The preparation method according to claim 1, characterized in that, In S4, the addition amount of CH 4N 2S is 5 times the molar amount of Na 2MoO 4·2H 2O.

4. The method of claim 1, wherein, In S4, the temperature of the hydrothermal reaction is 200℃, the time of the hydrothermal reaction is 12h, the drying temperature is 60℃, and the drying time is 6h.

5. The preparation method according to claim 1, characterized in that, 6.The molybdenum disulfide intercalated layered double hydroxide material prepared by the method according to any one of claims 1-5. The method comprises the following steps: using the molybdenum disulfide intercalated layered double hydroxide material according to claim 6 as a catalyst for activating sulfite to degrade pollutants in a solution.

7. A method of degrading a pollutant, characterized by, The pollutants include at least one of dyes, antibiotics, drugs and food additives.

8. The method of claim 7, wherein, ​ 9. The method of claim 7, wherein, The concentration of the catalyst is 0.1-0.4 g·L -1 The concentration of the sulfite is 1-6 mmol·L -1 The concentration of the pollutant is 10-50 mg·L -1 The pH of the solution is 3-11.

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