CN112441591A

CN112441591A - Green one-step hydrothermal synthesis method and application of manganese silicate microspheres

Info

Publication number: CN112441591A
Application number: CN202011224423.3A
Authority: CN
Inventors: 朱万诚; 郑宇宇; 孙盼盼; 张恒; 张历云
Original assignee: Qufu Normal University
Current assignee: Qufu Normal University
Priority date: 2020-11-05
Filing date: 2020-11-05
Publication date: 2021-03-05

Abstract

The invention relates to the field of inorganic material chemical industry, in particular to green one-step hydrothermal synthesis and application of manganese silicate microspheres. The method comprises the steps of carrying out hydrothermal reaction on soluble metal manganese salt, soluble silicate and ammonium salt under an alkaline condition to obtain manganese silicate microspheres; the obtained manganese silicate microsphere has the structure of Brauneite-1Q, Mn⁺ ²Mn₆ ⁺³SiO₁₂The particle size is 100-500 nm, the secondary structure is 3-6 nm, the specific surface area is 350-450 m²g^‑1Pore volume of 0.54-0.78 cc g^‑1(ii) a The prepared manganese silicate microspheres can be used for sewage treatment, have good degradation effect and can be recycled for multiple times, and finally, the manganese silicate microspheres also provideThe cost is low, and the sewage treatment method is simple and effective.

Description

Green one-step hydrothermal synthesis method and application of manganese silicate microspheres

Technical Field

The invention relates to the field of inorganic material chemical industry, in particular to green one-step hydrothermal synthesis and application of manganese silicate microspheres.

Background

Nowadays, with the industrial progress and social development, water pollution is becoming more and more serious, and the first environmental management problem in the world is already formed. The water pollution caused by industry contains more pollutants, has complex components, is not easy to purify in water, and is difficult to treat. For this reason, attempts have been made to develop efficient, practical and economical nanomaterials as catalysts or adsorbents to solve the water pollution problem. The Advanced Oxidation Processes (AOPs) have a wide application prospect in degrading organic pollutants. The most well-known catalysts include fenton and fenton-like type catalysts. The manganese compound, particularly the manganese oxide, is a typical Fenton-type catalyst, and has the advantages of low toxicity, rich sources, low cost, environmental friendliness and the like. In addition, the multivalence of manganese not only can improve the reactivity, but also can generate more kinds of compounds, thereby diversifying the application. Transition metal manganese silicate, as a silicate material with a high specific surface and a multilevel structure, has been widely used in the fields of adsorption, catalysis, energy storage, drug delivery, and the like. More importantly, compared with metals and metal oxides, the composite material has the advantages of lower cost, richer sources and more stable structure. In particular, the layered structure manganese silicate combines the high chemical activity of a manganese compound and the structural stability of the layered silicate, has obvious development prospect as a Fenton-like catalyst, and has high research value.

At present, a great deal of literature is available for the synthesis of manganese silicate microsphere materials. For example, Christopher Cheung Yec and the like are based on the St baby method, and TEOS is hydrolyzed and condensed under the catalysis of ammonia water to obtain SiO with the particle size of 270 nm₂Microspheres as hard template, Mn (AC)₂·4H₂O is a manganese source, and the reaction is carried out for 12.0 h at 180 ℃ to obtain Brauneite-1Q (Mn)²⁺Mn₆ ³⁺SiO₁₂Or Mn²⁺Mn³⁺ ₆[O₈|SiO₄]JCPDS No. 89-5661) as main phase, and has a specific surface area of 316.1 m²g^-1Application thereof to degradation of dyes: (ACS Nano，2014) (ii) a Shu Meng Hao et al uses carbon nano-tube (CNTs) as template, adds cation surfactant CTAB into ethanol solvent, and catalyzes TEOS hydrolytic polycondensation under alkaline condition to obtain silicon-coated carbon nano-tube (CNT @ SNTs), and then calcines CNT @ SNTs in air atmosphere to obtain SNTs, and uses SNTs as silicon source, MnCl₂·4H₂Adding ammonia water and ammonium chloride into O serving as a manganese source, and carrying out hydrothermal treatment for 10 hours to obtain Mn₇O₈(SiO₄) Hollow nanotube with specific surface area of 438 m²g^-1It was applied to the degradation of methylene blue (MeB) dye, under optimal degradation conditions, k =1.717 min^-1，Q=81.9 g L⁻¹g⁻¹（Adv. Funct. Mater. 2016) (ii) a Chinese patent document (1)CN201711134136.1) Discloses a synthesis method of double-layer hollow nano manganese silicate based on a bell-shaped template. Firstly, a ZIF-8@ mSiO template is adopted₂Taking tetrabutyl silicate and ZIF-8 as raw materials, taking water and methanol as solvents, adding a surfactant, and synthesizing under an alkaline condition. Secondly, dissolving manganese salt in deionized water, sequentially adding ammonium chloride and ammonia water, and adding the formed manganese ion complex into ZIF-8@ mSiO₂In a sol system, reacting for 4.0-48.0 h at 10-35 ℃ or 50-180 ℃ to obtain double-layer hollow nano manganese silicate Mn (SiO)₄) (ii) a Chinese patent document (1)CN201710422359.1) A hollow manganese silicate material and its synthesis are disclosed. It is based on St baby method, uses TEOS as raw material, and makes it undergo the process of hydrolytic polycondensation in organic solvent and alkaline buffer solution to obtain SiO whose grain size is less than or equal to 50 nm₂The microspheres are taken as a template, potassium permanganate is added, and the reaction is carried out in a hydrothermal/solvothermal reaction kettle at the temperature of 200 ℃ with 170-₅Si₃O₁₂JCPDS No. 37-0221).

However, the synthesis of the manganese silicate material adopts the hydrolysis synthesis of SiO by TEOS₂The microsphere or nanotube is used as hard template, manganese salt is added to synthesize manganese silicate material by hydrothermal method, and the synthesis process includes at least two stepsACS Nano，2014) Even a plurality of steps (Adv. Funct. Mater. 2016) Some systems also require a polymeric surfactant(s) ((R))CN201711134136.1& Adv. Funct. Mater. 2016) The synthesis process is complicated, and the organosilicon TEOS is hydrolyzed to synthesize SiO₂The microspheres are expensive, and organic solvent(s) needs to be reused in the hydrothermal process of some systemsCN201710422359.1) The method does not meet the requirements of environment-friendly and green processes, and the reported manganese silicate material has a common effect of dye degradation.

Disclosure of Invention

Aiming at the defects of complex synthesis process, poor greenness, high cost and the like of the manganese silicate material at the present stage, the invention provides a green one-step hydrothermal synthesis method of manganese silicate microspheres, which comprises the steps of carrying out hydrothermal reaction on soluble metal manganese salt, soluble silicate and ammonium salt under an alkaline condition to obtain the manganese silicate microspheres; the prepared manganese silicate microspheres can be used for sewage treatment, have good degradation effect, can be recycled for many times, and provide a simple and effective sewage treatment method with low cost.

The technical scheme of the invention is as follows:

a green one-step hydrothermal synthesis method of manganese silicate microspheres comprises the following steps: carrying out hydrothermal reaction on soluble metal manganese salt, soluble silicate and ammonium salt under an alkaline condition to obtain the manganese silicate microspheres.

The green one-step hydrothermal synthesis method of the manganese silicate microspheres comprises the following specific steps:

1) dissolving the soluble metal manganese salt and the ammonium salt in deionized water, and uniformly mixing to obtain a solution A;

2) uniformly mixing the solution A and an alkali source to obtain a solution B;

3) dropwise adding a silicate solution obtained by dissolving the soluble silicate into the solution B, and uniformly mixing to obtain a suspension C;

4) carrying out hydrothermal reaction on the suspension C, and cooling to room temperature to obtain a hydrothermal product;

5) and washing, filtering and drying the hydrothermal product to obtain the manganese silicate microspheres.

The structure of the manganese silicate microsphere is Brauneite-1Q, Mn⁺²Mn₆ ⁺³SiO₁₂The particle size is 100-500 nm, the secondary structure is 3-6 nm, the specific surface area is 350-450 m²g^-1Pore volume of 0.54-0.78 cc g^-1。

The soluble metal manganese salt is at least one of manganese chloride, manganese sulfate and manganese acetate; the ammonium salt is at least one of ammonium chloride or ammonium sulfate; the alkali source is at least one of ammonia water and ethylenediamine; the soluble silicate is at least one of sodium silicate or potassium silicate.

In the soluble metal manganese salt, the ammonium salt and the soluble silicate, the molar ratio of manganese ions to ammonium ions to silicate groups is 0.70:1-4:0.10-0.50, and the molar ratio of the manganese ions to the alkali source is as follows: 0.70:0.01-0.04.

In the step 4), the temperature is controlled at 5-10 ℃ for min^-1The temperature is increased to 120 ℃ and 200 ℃, the reaction is carried out for 6.0 to 24.0 hours, and the reaction product is cooled to room temperature to obtain a hydrothermal product.

In the step 5), the hydrothermal product is washed by deionized water, then washed by ethanol, and filtered after washing.

Manganese silicate microspheres synthesized by any one of the above methods.

The manganese silicate microspheres obtained by the synthesis method are applied to sewage treatment.

Preferably, the above application, method is: putting the manganese silicate microspheres into sewage containing organic dye, and adding 30 wt% of H at 25-60 DEG C₂O₂And carrying out catalytic degradation.

Preferably, the organic dye contained in the organic dye sewage is: methylene blue (cationic dyes), rhodamine B (cationic dyes), methyl blue (anionic dyes).

The technical scheme of the invention has the following advantages:

1. the invention provides a green one-step synthesis method of manganese silicate microspheres, which is characterized in that a soluble metal manganese source is taken as a manganese source, soluble silicate is taken as a silicon source, ammonium salt is taken as a mineralizer, and hydrothermal reaction is carried out under an alkaline condition to obtain pure manganese silicate (Brauneite-1Q, Mn) with uniform size and narrow particle size distribution range⁺²Mn₆ ⁺³SiO₁₂) The particle size of the microsphere is 100-500 nm, the secondary structure is 3-6 nm, and the specific surface area is 350-450 m²g^-1Pore volume of 0.54-0.78 cc g^-1The method adopts a one-step hydrothermal method, is environment-friendly, simple to operate, mild in condition, low in energy consumption and easy to control the process, and is suitable for large-scale industrial popularization.

2. The manganese silicate microspheres provided by the invention can be used for sewage treatment, and are placed in sewage containing organic dye by adopting advanced oxidation technology (AOPs), and H is added₂O₂The method for performing Fenton-like catalytic degradation on organic dye has good degradation effect, can be recycled for many times, and provides a simple and effective sewage treatment method with low cost.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments or the technical solutions in the prior art are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 shows manganese silicate (Brauneite-1Q, Mn) synthesized in example 1⁺²Mn₆ ⁺³SiO₁₂) SEM spectra of the microspheres;

FIG. 2 shows manganese silicate (Brauneite-1Q, Mn) synthesized in example 1⁺²Mn₆ ⁺³SiO₁₂) XRD pattern of the microspheres;

FIG. 3 shows manganese silicate (Brauneite-1Q, Mn) synthesized in example 1⁺²Mn₆ ⁺³SiO₁₂) TEM photograph of the microspheres;

FIG. 4 shows manganese silicate (Brauneite-1Q, Mn) synthesized in example 4⁺²Mn₆ ⁺³SiO₁₂) SEM photograph of microspheres;

FIG. 5 shows manganese silicate (Brauneite-1Q, Mn) synthesized in example 6⁺²Mn₆ ⁺³SiO₁₂) MicrospheresXRD photograph of (a);

FIG. 6 shows manganese silicate (Brauneite-1Q, Mn) synthesized in example 1⁺²Mn₆ ⁺³SiO₁₂) The microspheres are added with H at 25 DEG C₂O₂And (min) time point of methylene blue ultraviolet-visible spectrum (UV-Vis).

FIG. 7 shows manganese silicate (Brauneite-1Q, Mn) synthesized in example 1⁺²Mn₆ ⁺³SiO₁₂) The microspheres are added with H at 60 DEG C₂O₂And (min) time point of methylene blue ultraviolet-visible spectrum (UV-Vis).

FIG. 8 shows manganese silicate (Brauneite-1Q, Mn) synthesized in example 1⁺²Mn₆ ⁺³SiO₁₂) The microspheres are added with H at 25 DEG C₂O₂And (min) rhodamine B ultraviolet-visible spectrum (UV-Vis) diagram.

FIG. 9 shows manganese silicate (Brauneite-1Q, Mn) synthesized in example 1⁺²Mn₆ ⁺³SiO₁₂) The microspheres are added with H at 25 DEG C₂O₂And (min) time point of methyl blue ultraviolet-visible spectrum (UV-Vis).

Detailed Description

The following examples are provided for the purpose of better understanding of the present invention, but are not intended to limit the scope of the present invention to the best mode and are not intended to limit the scope of the present invention, and any product that is equivalent or similar to the present invention as obtained by combining the present invention with other features of the prior art while remaining within the scope of the present invention.

The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps and conditions described in the literature in the field. All reagents or instruments are not indicated by manufacturers, and are conventional reagent products commercially available.

Example 1

A method for synthesizing manganese silicate microspheres comprises the following operations:

(1) 1.30 mmol of MnCl₂And 10 mmol NH₄Respectively dissolving Cl solid in 10 mL,In 10 mL of deionized water, the obtained NH was added₄The Cl solution was added dropwise to 10 mL of MnCl₂In the solution, magnetic stirring is carried out for 10 min at 250 rpm, and then colorless and transparent solution A is obtained;

(2) 2 mL of NH₃·H₂Quickly dripping O into the colorless transparent solution A to obtain a solution B, and magnetically stirring at 250 rpm

10 min；

(3) Adding 0.37 mmol of Na₂SiO₃Dissolving in 20 mL deionized water to obtain Na₂SiO₃Dropwise adding the mixture into the solution B, and magnetically stirring at 250 rpm for 10 min to obtain a suspension C;

(4) placing the suspension C in a hydrothermal kettle at 8 ℃ for min^-1The temperature is increased to 120 ℃ at the rate of temperature rise, and after the constant temperature reaction is carried out for 12.0 hours, the reaction product is naturally cooled to room temperature to obtain a hydrothermal product;

(5) and (3) sequentially washing the hydrothermal product with deionized water and absolute ethyl alcohol for three times respectively, filtering the washed product with a Buchner funnel, and drying the product at 60 ℃ for 18.0 hours to obtain a sample.

The sample prepared in this example had an X-ray diffraction (XRD) pattern obtained using a Miniflex type 600X-ray diffraction (XRD) instrument such as

FIG. 1 shows Brauneite-1Q, Mn in FIG. 1⁺²Mn₆ ⁺³SiO₁₂The XRD pattern of the microspheres is well matched with the XRD standard card number JCPDS No. 41-1367, which indicates that the product composition is relatively pure.

Brauneite-1Q, Mn from this example⁺²Mn₆ ⁺³SiO₁₂A TEM photograph of the microspheres taken with a JEM-2010 Transmission Electron Microscope (TEM) is shown in FIG. 2, and Brauneite-1Q, Mn is shown in FIG. 2⁺²Mn₆ ⁺³SiO₁₂The microsphere is formed by assembling nano particles, the particle size is 110-220 nm, and the particle size distribution is uniform.

Example 2

(1) 1.30 mmol of MnCl₂And 10 mmol NH₄Dissolving Cl solid in 10 mL and 10 mL deionized water respectively to obtain NH₄The Cl solution was added dropwise to 10 mL of MnCl₂In the solution, magnetic stirring is carried out for 10 min at 250 rpm, and then colorless and transparent solution A is obtained;

10 min；

(4) placing the suspension C in a hydrothermal kettle at 8 ℃ for min^-1The temperature is increased to 120 ℃ at the rate of temperature rise, the reaction is carried out for 18.0 hours at constant temperature, and then the reaction product is naturally cooled to room temperature to obtain a hydrothermal product;

Manganese silicate (Brauneite-1Q, Mn) obtained in example 2⁺²Mn₆ ⁺³SiO₁₂) The particle size is 180-300 nm, and the particle size distribution is uniform.

Example 3

(2) 2 mL of NH₃·H₂Quickly dripping O into the colorless transparent solution A to obtain a solution B, and magnetically stirring at 250 rpm for 10 min;

(4) placing the suspension C in a hydrothermal kettle at 8 ℃ for min^-1The temperature is increased to 120 ℃ at the rate of temperature rise, and after the constant temperature reaction is carried out for 24.0 hours, the mixture is naturally cooled to room temperature to obtain a hydrothermal product;

Manganese silicate obtained in example 3 (Brauneite-1Q, Mn)⁺²Mn₆ ⁺³SiO₁₂) The particle size is 280-500 nm, and the particle size distribution is uniform.

Example 4

(1) 1.30 mmol Mn (AC)₂And 10 mmol NH₄Dissolving Cl solid in 10 mL and 10 mL deionized water respectively to obtain NH₄The Cl solution was added dropwise to 10 mL of MnCl₂In the solution, magnetic stirring is carried out for 10 min at 250 rpm, and then colorless and transparent solution A is obtained;

10 min；

Manganese silicate obtained in example 4 (Brauneite-1Q, Mn)⁺²Mn₆ ⁺³SiO₁₂) The particle size is 90-210 nm, and the particle size distribution is uniform.

Example 5

(1) adding 1.30 mmol of MnSO₄And 10 mmol NH₄Dissolving Cl solid in 10 mL and 10 mL deionized water respectively to obtain NH₄The Cl solution was added dropwise to 10 mL of MnCl₂In the solution, magnetic stirring is carried out for 10 min at 250 rpm, and then colorless and transparent solution A is obtained;

Manganese silicate obtained in example 5 (Brauneite-1Q, Mn)⁺²Mn₆ ⁺³SiO₁₂) The particle size is 60-100 nm, and the particle size distribution is uniform.

Example 6

(2) quickly dropwise adding 2 mL of ethylenediamine into the colorless transparent solution A to obtain a solution B, and magnetically stirring at 250 rpm for 10 min;

Manganese silicate (Brauneite-1Q, Mn) obtained in example 6⁺²Mn₆ ⁺³SiO₁₂) The particle size is 120-230 nm, and the particle size distribution is uniform.

Example 7

(3) 0.37 mmol of K₂SiO₃Dissolving in 20 mL deionized water to obtain K₂SiO₃Dropwise adding the mixture into the solution B, and magnetically stirring at 250 rpm for 10 min to obtain a suspension C;

Manganese silicate obtained in example 7 (Brauneite-1Q, Mn)⁺²Mn₆ ⁺³SiO₁₂) The particle size is 200-480 nm, and the particle size distribution is uniform.

Examples of the experiments

First, experiment purpose

The manganese silicate microspheres synthesized in experimental example 1 were examined for their adsorption-degradation effects on organic dyes.

Second, Experimental methods

The preparation concentration is 50 mg L^-1Methylene blue of (a), (b)Rhodamine B or methyl blue), measuring 50 mL of organic dye solution by using a measuring cylinder, adjusting the pH value of (or 0.1M HCl solution) by using 0.1M NaOH solution, and placing in a 100 mL conical flask; 10 mg of the manganese silicate (Brauneite-1Q, Mn) synthesized in example 1 was weighed⁺²Mn₆ ⁺³SiO₁₂) Adding the microspheres into the conical flask containing the organic dye solution; placing the mixture on a magnetic stirrer, adsorbing the mixture for 1.0H under the conditions of 25 ℃ or 60 ℃ and dark condition until the adsorption is balanced, and adding 5 mL of H into a conical flask₂O₂And 3 mL of solution is taken from the conical flask at intervals, a disposable syringe filter is used for filtering, the obtained filtrate is placed in an ultraviolet-visible spectrum (UV-Vis) instrument for characterization, and the corresponding absorbance of the organic dye solution at the time t is obtained.

The kinetic data were fitted to the following kinetic equation: -dC_t/dt=kC_tThen ln (C)₀/C_t) = kt, in the formula, C_tAnd k are the concentration and rate constant of the organic dye wastewater at the time t, respectively. Catalytic efficiency can also be evaluated with Q: q = (C)₀-C)V₀V'm, wherein Q (g L)⁻¹g⁻¹) 1 g of catalyst and 1L of 30 wt% H₂O₂Amount of organic dye degraded by solution C₀ (g L⁻¹) And C (g L)⁻¹) The initial concentration and the final concentration of the organic dye are respectively; v₀(mL) and V' (mL) are the volume of the dye solution and 30 wt% H, respectively₂O₂Volume of solution. The calculation method of the dye removal rate comprises the following steps: the absorbance of the dye wastewater was measured at 664 nm (554 nm or 598 nm) with an ultraviolet spectrophotometer, and the removal rate (%) = (A)₀-A)/A₀×100%，A₀The absorbance value before the reaction of the dye wastewater is shown, and A is the absorbance value after the reaction. And calculating to obtain a degradation rate constant k, a Q value and a removal rate according to a formula.

Third, experimental results

As shown in FIG. 6, after adsorption was carried out for 1.0H in the dark to reach adsorption equilibrium, 5 mL of H was added at room temperature₂O₂At 20 min, the methylene blue removal rate was 97.7%, at which time k =0.169 min^-1，Q=50.3 g L⁻¹g⁻¹. At 30 min, the removal rate of methylene blue is 99.9%, and the maximum absorption peak absorbance of the methylene blue at 664 nm approaches to 0.

As shown in FIG. 7, after adsorption is carried out for 1.0H under dark conditions until adsorption equilibrium is reached, 1 mL of H is added at 60 ℃₂O₂At 3 min, the methylene blue removal rate was 98.0%, at which time k =0.979 min^-1，Q=248.8 g L⁻¹g⁻¹. At 4 min, the removal rate of methylene blue is 99.1%, and the maximum absorption peak absorbance of methylene blue at 664 nm approaches to 0.

Braunite-1Q，Mn⁺²Mn₆ ⁺³SiO₁₂The effect of the microspheres as a catalyst for degrading methylene blue wastewater by adopting advanced oxidation technology AOPs is obviously higher than that of hollow tubular Brauneite-1Q, Mn⁺²Mn₆ ⁺³SiO₁₂(25ºC，10 mL H₂O₂K =0.060 min^-1，Q=24.7 g L⁻¹g⁻¹，60ºC，3 mL H₂O₂K =0.828 min^-1，Q=81.9 g L⁻¹g⁻¹，Adv. Funct. Mater. 2016) And nano disc-shaped MnTiO₃(30ºC，1.5 mL H₂O₂K =0.168 min^-1，Q=131.4 g L⁻¹g⁻¹，ACS Appl. Nano Mater. 2018). Brauneite-1Q, Mn synthesized based on the invention⁺²Mn₆ ⁺³SiO₁₂The microspheres as Fenton-like catalysts have good degradation effect in degrading methylene blue.

As shown in FIG. 8, after adsorption was carried out for 1.0H in the dark to reach adsorption equilibrium, 5 mL of H was added at room temperature₂O₂And at 60 min, the removal rate of rhodamine B is 94.2%, and the absorbance of the maximum absorption peak of rhodamine B at 554 nm approaches to 0.

As shown in FIG. 9, after adsorption was carried out for 1.0H in the dark to reach adsorption equilibrium, 5 mL of H was added at room temperature₂O₂At 15 min, the removal rate of methyl blue is 97.8%, and the absorbance of the maximum absorption peak of methyl blue at 598 nm approaches to 0.

It should be understood that the foregoing embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. All embodiments need not be, and cannot be, exhaustive. And obvious variations or modifications derived therefrom are within the scope of the invention.

Claims

1. A green one-step hydrothermal synthesis method of manganese silicate microspheres is characterized by comprising the following steps: carrying out hydrothermal reaction on soluble metal manganese salt, soluble silicate and ammonium salt under an alkaline condition to obtain the manganese silicate microspheres.

2. The green one-step hydrothermal synthesis method of manganese silicate microspheres according to claim 1, comprising the following specific steps:

2) uniformly mixing the solution A and an alkali source to obtain a solution B;

3. The green one-step hydrothermal synthesis method of manganese silicate microspheres according to claim 1 or 2, wherein the obtained manganese silicate microspheres have a structure of Brauneite-1Q, Mn⁺²Mn₆ ⁺³SiO₁₂The particle size is 100-500 nm, the secondary structure is 3-6 nm, the specific surface area is 350-450 m²g^-1Pore volume of 0.54-0.78 cc g^-1。

4. The green one-step hydrothermal synthesis method of manganese silicate microspheres according to claim 2, wherein the soluble metal manganese salt is at least one of manganese chloride, manganese sulfate and manganese acetate; the ammonium salt is at least one of ammonium chloride or ammonium sulfate; the alkali source is at least one of ammonia water and ethylenediamine; the soluble silicate is at least one of sodium silicate or potassium silicate; in the soluble metal manganese salt, the ammonium salt and the soluble silicate, the molar ratio of manganese ions to ammonium ions to silicate groups is 0.70:1-4:0.10-0.50, and the molar ratio of the manganese ions to the alkali source is as follows: 0.70:0.01-0.04.

5. The green one-step hydrothermal synthesis method of manganese silicate microspheres according to any one of claims 2 to 4, characterized in that in the step 4), 5-10 ℃ for min^-1The temperature is increased to 120 ℃ and 200 ℃, the reaction is carried out for 6.0 to 24.0 hours, and the reaction product is cooled to room temperature to obtain a hydrothermal product.

6. The green one-step hydrothermal synthesis method of manganese silicate microspheres according to claim 2, wherein in the step 5), the hydrothermal product is sequentially washed with deionized water, then with ethanol, and then is subjected to suction filtration after washing.

7. Manganese silicate microspheres synthesized by the method of any one of claims 1 to 6.

8. Manganese silicate microspheres obtained by the synthesis method according to any one of claims 1 to 6, or manganese silicate microspheres according to claim 7, for use in sewage treatment.

9. The application of the manganese silicate microspheres in sewage treatment according to claim 8, wherein the manganese silicate microspheres are placed in sewage containing organic dye, and H is added at 25-60 ℃₂O₂And carrying out catalytic degradation.

10. The use of claim 9 for wastewater treatment, wherein the organic dye contained in the organic dye wastewater is: methylene blue, rhodamine B and methyl blue.