CN103182293A - Method for preparing manganese oxide nanowire by deposition on surface of natural porous diatomite - Google Patents

Abstract

The invention discloses a method for preparing a manganese oxide nanowire by deposition on the surface of natural porous diatomite. The method is characterized by comprising the following steps: 1, weighing a diatomite powder body, placing the diatomite powder body into a beaker filled with water, placing the beaker into a water bath pond, and stirring to prepare a diatomite suspension solution; 2, weighing ammonium persulfate (NH4)2S2O8, placing ammonium persulfate (NH4)2S2O8 into the diatomite suspension solution, magnetically stirring for more than 30 min, fully impregnating into the diatomite, weighing KMnO4, placing KMnO4 into a mortar, fully grinding, dissolving in water, dripping into the diatomite suspension solution, continuing to stir for more than 30 min, and cooling to the room temperature; and 3, transferring the solution into a reaction kettle for water bath/hydrothermal reaction at the temperature of 50-160 DEG C, ageing, cooling to the room temperature, washing by de-ionized water and absolute ethanol for multiple times, and drying to obtain a final sample. According to the method, the adsorption efficiency of a composite material on heavy metal ions is improved; and the method is low in production cost, simple in operation process and easy for industrial production.

Description

A preparation method of natural porous diatomite-based deposited manganese oxide nanowires

technical field

The invention relates to the field of materials, and relates to a method for depositing and preparing manganese oxide nanowires on the surface of diatom raw soil with a natural porous structure.

Background technique

Heavy metal ions and their compounds can cause severe pollution of crops and water bodies, and enter the human body through the biological chain, causing great harm to human health. The treatment of their pollutants has always attracted attention at home and abroad. At present, there are more than a dozen methods for the treatment of heavy metal polluted wastewater, but only the pharmaceutical method, electrocoagulation method, secondary membrane method and adsorption method can be applied on a large scale. In comparison, the adsorption method is simple, practical and widely used, but the application of the adsorption method is mainly limited by the adsorption performance of the material (adsorbent). Porous, large specific surface and abundant surface functional groups, it is an excellent heavy metal ion adsorption material, in which the ordered pore structure and reasonable pore size distribution of the material are particularly important. At present, the porous materials suitable for adsorbing heavy metal ions are mainly activated carbon, molecular sieve, porous fiber, etc. Due to the very high cost of molecular sieves and porous fibers, their industrial application is limited; only activated carbon is used commercially, and activated carbon has an irregular pore structure and an open-pore structure, which is easy to desorb and cannot meet the requirements of deep treatment of heavy metal ions. Therefore, the preparation and application of high-efficiency and low-cost adsorbents have become the technical key to restricting the adsorption method to treat heavy metal ions.

Diatomaceous earth is an inorganic mineral material with a natural long-range ordered microporous structure. The diameter of the small pores is 20-50nm, and the diameter of the large pores is 100-300nm. The main chemical composition is amorphous SiO ₂ . Due to the uncertainty of the number of silicon atoms in the network structure formed by mutual bridges, there are coordination defects and oxygen bridge defects in the network. Therefore, on the surface Si-O-"dangling bond", it is easy to combine H to form Si-OH, that is, the surface silicon hydroxyl group. Surface silanol groups are easily dissociated into Si-O ^- and H ⁺ in water, making the surface of diatomite negatively charged. Therefore, diatomaceous earth adsorbs heavy metal cations, has natural structural advantages, and has been used in industry. Due to the natural nature of the diatomite microporous structure, it is possible to greatly reduce the preparation cost of the heavy metal ion adsorption material. However, there are two problems when diatomite adsorbs heavy metal ^ions . One is that _{the specific} surface ^area _is low, and the ^adsorption capacity is affected _; ^- ; H ₂ AsO ₄ ^- , HAsO ₄ ^2- , AsO ₄ ^3- ; CrO ₄ ^2- , Cr ₂ O ₇ ^2- ) removal rate is low (lead, zinc, mercury, cadmium, chromium Among the six heavy metal ions including arsenic and arsenic, there are not only metal ions such as lead, zinc, mercury, and cadmium in positive valence states, but also acid anions in negative valence states, chromium,

Arsenic; in comparison, negative valence arsenic and chromium ions are more difficult to handle). How to effectively solve the above problems is the key to the preparation of diatomite-based adsorbents and their application in the treatment of heavy metal ion wastewater. Therefore, the use of surface treatment or modified diatomite for heavy metal ion adsorption treatment has become a research hotspot. Diatomite modified with iron salt or manganese salt has the best treatment effect, and its adsorption of heavy metal ions (including acid radical anions ) ability is significantly improved. So far, the modification of diatomite has been performed by the mechanical mixing (disordered compound) of modifiers (iron salts, manganese salts, aluminum salts, organic matter, etc.) At the expense of the microporous structure, the adsorption and removal efficiency of heavy metal ions is greatly affected.

Nanostructured materials are materials with the most abundant surface active functional groups, especially ordered nanostructured materials, which can significantly increase the specific surface area of the material. Therefore, the preparation of nanostructured ordered iron or manganese oxides on diatomite algae trays not only increases its generality for the adsorption of heavy metal ions (while adapting to positive and negative valence heavy metal ions), but also increases At the same time, the active functional groups on the surface of the material can significantly increase the specific surface area of the composite material, and then significantly improve the adsorption efficiency of the composite material for heavy metal ions, which is of great practical significance.

Contents of the invention

The purpose of the present invention is to provide a method for preparing manganese oxide deposited diatomite with nano-wire characteristics, which further improves the composite material ( Adsorbent) on the adsorption efficiency of heavy metal ions. The method has low production cost, simple operation process and easy industrial production.

The manganese oxide nanowire deposited diatomite provided by the invention is synthesized from diatomite, potassium permanganate, ammonium persulfate, water, and a co-precipitation method. The material ratio of the synthesis process is: water: diatomite (weight ratio): potassium permanganate: ammonium persulfate = 120: 10: (4.56 ~ 10.635): (3.828 ~ 8.894)

A method for preparing diatomite supported by manganese oxide nanowires provided by the present invention is characterized in that it comprises the following steps:

In the first step, a certain amount of diatomite powder is weighed and put into a beaker filled with water, and the beaker is placed in a water bath for stirring to obtain a diatomite suspension.

The second step is to accurately weigh a certain amount of (NH ₄ ) ₂ S ₂ O ₈ into the suspension of diatomite, stir magnetically for more than 30 minutes, and fully impregnate the diatomite, then weigh a certain amount of KMnO ₄ for research. Grind thoroughly in a bowl and dissolve in water (the molar ratio of ammonium persulfate to potassium permanganate is 1:1 to 1:1.5), drop diatomaceous earth suspension, continue to stir for more than 30 minutes and then cool to room temperature.

The third step is to transfer the solution to the reaction kettle for 3-24 hours in a water bath at 50-160°C for aging, cool to room temperature, then wash with deionized water and absolute ethanol several times and dry to obtain manganese oxide nanowire-supported diatoms Final sample of soil microporous adsorbent material.

The present invention adopts the chemical precipitation method to deposit nanowire-type manganese oxide on the diatomite-based core to prepare a composite microporous adsorbent with good performance of adsorbing heavy metal acid radical anions, and the loaded composite microporous adsorbent obtained by adopting the process method , good adsorption for low concentration chromic acid solution.

Description of drawings:

Fig. 1 is the X-ray diffraction curve of the product of Example 1 and diatomite, wherein a is the X-ray diffraction curve of diatomite, and b is the X-ray diffraction curve of the product of Example 1.

Fig. 2 The scanning electron microscope image of the corresponding part of the product of Example 2 and the raw diatom soil, wherein, a is the scanning electron microscope image of the raw diatom soil, b is the scanning electron microscope image of the edge of the raw diatom soil disc, and c is the scanning electron microscope image of the original diatom soil disc, and c is embodiment 2 The SEM of the product, d is the scanning electron microscope image of the edge of the product of Example 2.

TEM and HRTEM pictures of the product of Fig. 3 Example 3 and diatom raw soil, wherein, a is the transmission electron microscope image of diatom raw soil, b is the TEM of the product of Example 3, and c is a partial enlargement of the edge of the product disk of Example 3 Figure projection electron microscope image, d is the HRTEM of embodiment 3.

Fig. 4 embodiment 4,5 product and diatom raw soil N Adsorption and desorption curve, wherein _, a is the N of diatom raw soil Absorption and desorption curve, b, c are embodiment 4, the N of ₅ products respectively Adsorption and desorption curve Desorption curve.

Fig. 5 embodiment 4, 5 product and diatom raw soil pore structure adsorption curve and pore size distribution curve, wherein, a is diatom raw soil, b, c are embodiment 4, 5 product pore size distribution curve respectively

Fig. 6 embodiment 1 product and after absorbing heavy metal chromium and diatomite raw soil Fourier transform infrared spectrum, wherein, a is diatom raw soil, b is manganese oxide deposited diatom raw soil, c is after absorbing heavy metal anion chromium Manganese oxide loaded diatom raw soil

Detailed ways

In this experiment, 5mg/L low-concentration chromic acid solution was prepared, and the removal rate of chromium ions could reach 96%.

Example 1

1. Weigh 4.2g of diatomaceous earth and suspend it in 50mL of water, and place it in a constant temperature water bath and stir to form a uniform suspension.

2. Weigh 3.7g of ammonium persulfate and add it to the diatomite suspension, stir with constant temperature magnetic force to fully impregnate it into the diatomite, add 4.424g of potassium permanganate and continue stirring to fully react and then cool to room temperature.

3. Transfer the solution to a reactor at 90°C for 12 hours in a water bath for aging, cool to room temperature, wash with deionized water and absolute ethanol several times, and dry.

Example 2

1. Weigh 4.2g of diatomaceous earth and suspend it in 50mL of water, and place it in a constant temperature water bath and stir to form a uniform suspension.

2. Weigh 4.146g of ammonium persulfate and add it to the diatomite suspension, stir with constant temperature magnetic force to fully impregnate the diatomite, then add 4.957g of potassium permanganate and continue stirring at constant temperature for one hour to fully react and then cool to room temperature.

3. Transfer the solution to a reactor in a water bath at 50°C for 24 hours for aging, cool to room temperature, wash with deionized water and absolute ethanol several times, and dry.

Example 3

1. Weigh 4.2g of diatomaceous earth and suspend it in 50mL of water, and place it in a constant temperature water bath and stir to form a uniform suspension.

2. Weigh 3.06g of ammonium persulfate and add it to the diatomite suspension, stir it with a constant temperature magnetic force to fully impregnate it into the diatomite, then add 3.66g of potassium permanganate and continue stirring at a constant temperature for one and a half hours to fully react and then cool to room temperature .

3. Transfer the solution to a reaction kettle for 16 hours in a water bath at 120°C for aging, cool to room temperature, wash with deionized water and absolute ethanol several times, and dry.

Example 4

1. Weigh 4.2g of diatomaceous earth and suspend it in 50mL of water, and place it in a constant temperature water bath and stir to form a uniform suspension.

2. Weigh 2.422g of ammonium persulfate and add it to the diatomite suspension, stir it with constant temperature magnetic force to fully impregnate it into the diatomite, then add 2.898g of potassium permanganate and continue stirring at constant temperature for half an hour to fully react and then cool to room temperature .

3. Transfer the solution into a reaction kettle to react in a water bath at 160°C for 8 hours for aging, cool to room temperature, wash with deionized water and absolute ethanol several times, and then dry.

Example 5

1. Weigh 4.2g of diatomaceous earth and suspend it in 50mL of water, and place it in a constant temperature water bath and stir to form a uniform suspension.

2. Weigh 1.595g of ammonium persulfate and add it to the diatomite suspension, stir it with a constant temperature magnetic force to fully impregnate it into the diatomite, add 1.9g of potassium permanganate and continue stirring at a constant temperature for half an hour to fully react and then cool to room temperature .

3. Transfer the solution to a reactor at 90°C for 3 hours in a water bath for aging, cool to room temperature, wash with deionized water and absolute ethanol several times, and dry.

Table 1

Sample serial number Example 1 Example 2 Example 3 Example 4 Example 5 Removal rate% 96% 84% 83% 86% 80%

Claims (1)

1. the preparation method of a natural porous diatom soil matrix deposition manganese oxide nanowire is characterized in that, may further comprise the steps:

The weight of material proportioning of preparation process is: water: diatomite: potassium permanganate: ammonium persulfate=120:10:(4.56～10.635): (3.828～8.894);

The first step takes by weighing the diatomite powder and puts into the beaker that fills water, and places sea water bath to stir in beaker, makes the diatomite suspension;

In second step, take by weighing ammonium persulfate (NH again ₄) ₂S ₂O ₈Go in the diatomaceous suspension, fully be impregnated into diatomite more than the magnetic agitation 30min after, take by weighing KMnO ₄Splash into diatomite suspension earlier after soluble in water after abundant grinding the in the mortar, continuation is cooled to room temperature after stirring more than the 30min;

The 3rd step changed solution over to that 50-160 ℃ of water-bath 3-24h carries out ageing in the reactor, was cooled to room temperature, afterwards obtained final sample after the drying for several times with deionized water and absolute ethanol washing then.

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