CN106334526A - Preparation and application of manganese dioxide modified charcoal for removing 17beta-estradiol in water - Google Patents

Abstract

The invention relates to the preparation and application of manganese dioxide modified biochar for removing 17β-estradiol in water bodies. The main raw material of the biochar is agricultural and forestry waste, and the prepared raw material has a wide range of sources and is cheap. The specific steps of preparation are as follows: calcining the dried and ground biomass at high temperature to obtain biochar, and loading manganese dioxide nanoparticles on the surface of the biochar through the improved Murray synthesis method. The manganese dioxide modified biochar prepared by the method of the invention has a relatively high removal capacity for 17β-estradiol in water bodies. The preparation of manganese dioxide modified biochar is simple and cheap, and it is a cheap and efficient adsorbent. Moreover, the modification of manganese dioxide significantly improved the adsorption capacity of biochar, and the application potential was high.

Description

Preparation and application of manganese dioxide modified biochar for removing 17β-estradiol in water application

technical field

The invention belongs to the field of environmental functional materials and water treatment new technologies, and in particular relates to a preparation method and application of manganese dioxide modified biochar for removing 17β-estradiol in water.

Background technique

In recent years, there has been an increasing number of studies on exogenous chemical substances that interfere with the endocrine system of humans and animals, and affect health and reproduction. Environmental Estrogens (Environmental Estrogens) are a class of exogenous chemical substances that enter the environment. After they enter the organism, they can simulate or block natural hormones, stimulate or inhibit the biological effects of hormones, and interfere with hormone synthesis, transport, and clearance. process, altering the normal regulatory functions of the nervous, immune and endocrine systems, thereby causing hazards to wildlife and human health. Among all environmental estrogens, 17β-estradiol is the most widely used and most studied environmental estrogen. 17β-estradiol is more common in water bodies, and it is more harmful, even at extremely low concentrations, it will have a great impact on organisms. At present, there are many ways for 17β-estradiol to enter the water environment: (1) animal feces are used as farmland fertilizers to bring endocrine disrupting substances into the soil environment; (2) some endocrine disrupting substances enter the groundwater through the soil with rainwater; ( 3) Enter the water environment through the discharge of domestic sewage; (4) Artificial farms use external or synthetic hormones and other hormones with growth-promoting effects to improve breeding efficiency, thereby increasing the discharge of endocrine disrupting substances. However, conventional water treatment processes are difficult to remove 17β-estradiol from water, so it is urgent to develop technical methods that can effectively remove 17β-estradiol from water. Among them, the adsorption method has the advantages of simple equipment, convenient operation, low price and high efficiency, and has been applied in the treatment of 17β-estradiol. However, the sources of adsorbents currently used are not abundant, and the adsorption capacity of adsorbents is limited. Therefore, it is of great practical value and significance to develop an adsorbent with wide sources, low cost and strong adsorption capacity.

Biochar is a solid carbon material produced by pyrolysis of biomass such as crop straw, woody biomass, animal manure and solid waste under anaerobic conditions through different heat treatment processes. Applying biochar to soil has the functions of improving soil, improving fertility, and sequestering carbon. At the same time, it uses a wide range of raw materials and has excellent physical and chemical properties. Therefore, it is also often used as a low-cost adsorbent for the removal of water pollutants. However, the limited adsorption capacity limits its application in practical wastewater treatment. Manganese dioxide is loaded on the surface of biochar by appropriate methods to prepare composite biochar, which can increase its surface adsorption sites and improve the ability of biochar to remove 17β-estradiol pollutants.

Contents of the invention

The technical problem to be solved by the present invention is to develop a low-cost, high-efficiency manganese dioxide-modified biochar material that can be used to adsorb and treat 17β-estradiol pollutants for water bodies polluted by 17β-estradiol.

The preparation method of a manganese dioxide modified biochar material proposed by the present invention is to load manganese dioxide on the surface of biochar to improve the adsorption capacity of biochar, and then apply the obtained material to remove 17β in water - Estradiol contamination. Specific steps are as follows:

(1) Preparation of biochar

The collected agricultural and forestry waste raw materials were repeatedly washed with water, and then dried at 70°C for 24 hours. The dried biomass is crushed to a particle size of less than 0.147mm, and passed through a 100-mesh sieve. The raw materials are then put into a tube-type atmosphere furnace for pyrolysis and firing. During the pyrolysis process, the quartz tube of the atmosphere furnace is kept sealed, and nitrogen gas is introduced into the tube at a flow rate of 50mL/min to maintain the exhaustion of the entire pyrolysis process. oxygen conditions. At room temperature, the temperature was increased to 580°C at a heating rate of 10°C/min, and the pyrolysis was continued for 4 hours at this temperature. Isolate the air, cool down naturally, and finally get biochar. Then the biochar was taken out, washed three times with deionized water, and dried in an oven at 60°C for 24 hours before use.

(2) Preparation of manganese dioxide modified biochar

A 10 mg/mL manganese chloride solution was first prepared, and then the solution was purified in nitrogen for 20 min to remove dissolved oxygen (DO). Then, 2 g of biochar was added to 50 mL of MnCl ₂ solution and stirred for 1 h under nitrogen purging to form a biochar-Mn ²⁺ mixture. Then, the ^biochar -Mn mixture was added dropwise to the stock solution containing 10 mL of potassium permanganate (4 mM) and sodium hydroxide (8 mM), stirring at 250 rpm during the reaction. After continuing to stir and react for 20 minutes, a biochar-nanometer manganese dioxide composite was produced, which was grown at room temperature (25±1° C.) for 24 hours. Afterwards, it was washed with deionized water until neutral, and dried in vacuum at 60° C. to obtain a manganese dioxide-modified biochar material.

In the above preparation method, the heating rate of the tube furnace is 10°C/min, the maximum temperature is 580°C, and the pyrolysis is continued for 4 hours under this temperature condition.

In the above preparation method, the raw material of biomass is agricultural and forestry waste, such as straw, rice husk, sawdust, peanut shell and the like.

In the above preparation method, the mass ratio of biochar to manganese chloride is 1:4, and the molar ratio of potassium permanganate to sodium hydroxide is 1:2.

The manganese dioxide modified biochar prepared by the method of the invention removes 17β-estradiol pollutants in water bodies.

Compared with the prior art, the present invention has the advantages of:

1. The raw materials for biochar preparation are agricultural and forestry wastes, which have a wide range of sources and are cheap.

2. The preparation method of the manganese dioxide modified biochar material of the present invention is simple and feasible, the production speed is fast and the cycle is short, no complicated chemical equipment is needed, and industrial production can be realized.

3. The product is non-toxic and environmentally friendly.

4. The manganese dioxide modified biochar of the present invention has high removal efficiency for 17β-estradiol pollutants.

Description of drawings

Fig. 1 is the scanning electron microscope schematic diagram of the manganese dioxide modified biochar of the embodiment of the present invention 1;

Fig. 2 is the adsorption amount of 17β-estradiol in water body by the manganese dioxide modified biochar of Example 3 of the present invention.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1:

A biochar raw material of the manganese dioxide modified biochar of the present invention is selected from agricultural by-product straw, and the specific preparation method is as follows:

The collected raw materials were washed with deionized water and dried at 70° C. for 24 hours. The dried material is crushed to a particle size of less than 0.147mm, and passed through a 100-mesh sieve. Afterwards, the raw materials were put into a tube-type atmosphere furnace for pyrolysis and firing. During the pyrolysis process, the quartz tube of the atmosphere furnace was kept sealed, and nitrogen was introduced into the tube at a flow rate of 50 mL/min to maintain the stability of the entire pyrolysis process. anaerobic conditions. At room temperature, the temperature was increased to 580°C at a heating rate of 10°C/min, and the pyrolysis was continued for 4 hours at this temperature. Isolate the air, cool down naturally, and finally get biochar. Then the biochar was taken out, washed three times with deionized water, and dried in an oven at 60°C for 24 hours before use.

Secondly, a 10 mg/mL manganese chloride solution was prepared, and then the solution was purified in nitrogen for 20 min to remove dissolved oxygen (DO). Then, 2 g of biochar was added to 50 mL of MnCl ₂ solution and stirred for 1 h under nitrogen purging to form a biochar-Mn ²⁺ mixture. Then, the ^biochar -Mn mixture was added dropwise to the stock solution containing 10 mL of potassium permanganate (4 mM) and sodium hydroxide (8 mM), stirring at 250 rpm during the reaction. After continuing to stir and react for 20 minutes, a biochar-nanometer manganese dioxide composite was produced, which was grown at room temperature (25±1° C.) for 24 hours. Afterwards, it was washed with deionized water until neutral, and dried in vacuum at 60° C. to obtain a manganese dioxide-modified biochar material.

The appearance of the manganese dioxide modified biochar prepared above is black. Put it under a scanning electron microscope and observe its surface structure as shown in Figure 1. It can be observed that a large amount of manganese dioxide is distributed on the surface of the biochar.

Example 2:

The manganese dioxide modified biochar material of the present invention treats 17β-estradiol in water, comprising the following steps:

Take 100 mL of 0.4-6 mg/L 17β-estradiol solution in conical flasks, respectively add 5 mg of biochar and manganese dioxide modified biochar materials into each conical flask, place them in a constant temperature shaker in a water bath, and React at 25°C. After 24 hours, 10 mL of the solution was taken from each Erlenmeyer flask for centrifugation, and after centrifugation, it was filtered through a 0.45 μm filter membrane, and the filtrate was taken into a centrifuge tube. Fluorescence photometer was used to detect the solution concentration after reaction. The results are shown in Table 1:

Table 1: Adsorption data under different initial concentrations of 17β-estradiol

It can be seen from Table 1 that under different initial concentrations of 17β-estradiol, the adsorption capacity of manganese dioxide-modified biochar materials for 17β-estradiol in water is stronger than that of biochar. Under the condition of the initial concentration of 0.4mg/L, the manganese dioxide modified biochar has an adsorption capacity of 7.67mg/g, which increases with the increase of the initial concentration, and the adsorption capacity of the adsorbent reaches 92.91% under the condition of 6mg/L. mg/g.

Example 3:

The manganese dioxide modified biochar material of the present invention treats salt 17β-estradiol in water, comprising the following steps:

Add 5 mg of manganese dioxide modified biochar to 100 mL of 2 mg/L 17β-estradiol solution, place it in a constant temperature shaker in a water bath, and react at 25° C. At different time intervals, 10 mL of the solution was taken for centrifugation, filtered through a 0.45 μm filter membrane after centrifugation, and the filtrate was taken into a centrifuge tube. Fluorescence spectrophotometer was used to detect the concentration of the solution after reaction. The results of the adsorption capacity at different times are shown in Figure 2.

It can be seen from Figure 2 that the adsorption amount of 17β-estradiol in water by manganese dioxide modified biochar increases with time. Between 15min and 120min, the adsorption capacity increased rapidly, and began to reach saturation after 1440min. This shows that manganese dioxide modified biochar can quickly adsorb and treat 17β-estradiol in water.

Example 4:

The manganese dioxide modified biochar material of the present invention treats salt 17β-estradiol in water, comprising the following steps:

Five parts of 100 mL of 2 mg/L 17β-estradiol solution were prepared, and the pH was adjusted to 3, 5, 7, 9 and 11 with 1 mol/L NaOH and HCl, respectively. Add the above-mentioned modified biochar 5mg. Place in a water bath constant temperature shaker and react at 25°C. At different time intervals, 10 mL of the solution was taken for centrifugation, filtered through a 0.45 μm filter membrane after centrifugation, and the filtrate was taken into a centrifuge tube. Fluorescence spectrophotometer was used to detect the concentration of the solution after reaction. The adsorption results at different pH are shown in Table 2.

Table 2: Adsorption capacity data at different pH values

It can be seen from Table 2 that different pH conditions have effects on the adsorption. Higher pH was not conducive to the removal of 17β-estradiol by the adsorbent, and the adsorption amount decreased gradually with the increase of pH.

The above are only preferred implementations of the present invention, and the scope of protection of the present invention is not limited to the above examples, and various technological solutions that have no substantial difference from the concept of the present invention are within the scope of protection of the present invention.

Claims (6)

1. a kind of manganese dioxide modification biological Carbon Materials removing 17 beta estradiols in water body are it is characterised in that utilize titanium dioxide Manganese is modified to charcoal, improves the adsorption capacity of material.

2. the manganese dioxide modification biological Carbon Materials of 17 beta estradiols in a kind of a kind of as claimed in claim 1 removal water body Preparation method, comprises the following steps:

The agriculture and forestry organic waste material collected raw material deionized water is cleaned, dries 24 hours at 70 DEG C.By the material after drying Feed powder is broken to particle diameter and is less than 0.147mm, and crosses 100 mesh sieves.Afterwards, raw material are put into pyrolysis in tube-type atmosphere furnace to fire, heat The quartzy seal of tube of atmosphere furnace is kept, the flow velocity with 50ml/min is passed through nitrogen into pipe simultaneously, to keep with this in solution preocess The anaerobic condition of whole pyrolytic process.At room temperature, the heating rate heating of 10 DEG C/min rises to 580 DEG C, and in this temperature Under the conditions of be persistently pyrolyzed 4 hours.Isolation air, Temperature fall, finally obtain biological carbon.Then biological carbon is taken out, spend from Sub- water washing 3 times, is placed in 60 DEG C of drying in oven 24h stand-by.

Secondly, prepare 4mm manganese chloride solution, be then passed through nitrogen in this solution, purify 20min to remove dissolved oxygen (do).Afterwards, by the mncl of 15ml₂It is added in solution in the above-mentioned charcoal preparing of 2g, and under the purification of nitrogen, stir Mix 1h and form charcoal-mn²⁺Compound.Then, dropwise by charcoal-mn²⁺Mixture be added to 10ml potassium permanganate (4mm), In the mixed liquor of NaOH (8mm), stirred with 250 revs/min of rotating speed in course of reaction.After continuously stirred reaction 20min, treat After charcoal-nano-manganese dioxide compound is formed, place it in growth 24h in room temperature (25 ± 1 DEG C).Afterwards, use deionization It is washed to neutrality, be vacuum dried at 60 DEG C, obtain manganese dioxide modification biological Carbon Materials.

3. a kind of remove as claimed in claim 2 except the manganese dioxide modification biological Carbon Materials of 17 beta estradiols in water body Preparation method it is characterised in that the raw material selection agricultural by-products of charcoal, such as stalk, rice husk, wood chip, peanut shell etc..

4. a kind of preparation removing the manganese dioxide modification biological Carbon Materials of 17 beta estradiols in water body as claimed in claim 2 Method it is characterised in that in the preparation of described composite charcoal and manganese chloride mass ratio be 1:4, potassium permanganate and hydrogen The mol ratio of sodium oxide molybdena is 1:2.

5. a kind of preparation removing the manganese dioxide modification biological Carbon Materials of 17 beta estradiols in water body as claimed in claim 2 Method is it is characterised in that in the preparation of described composite, the heating rate of tube furnace is 10 DEG C/min, and maximum temperature is 580 DEG C, and be persistently pyrolyzed under this temperature conditions 4 hours.

6. a kind of use removing the manganese dioxide modification biological Carbon Materials of 17 beta estradiols in water body as claimed in claim 2 It is characterised in that removing 17 beta estradiols in water body with described material, removal ability is higher on way, and adsorbent preparation is simple, material Material is easy to get, and has higher application potential.