CN114832776A - Acidized puffed active biochar adsorbing material as well as preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of polluted water treatment application, and provides an acidified and expanded activated biochar adsorption material and a preparation method and application thereof. The preparation method includes the following steps: S1, carbonizing the rice under protective gas to obtain biochar; S2, acidifying the biochar in a phosphoric acid solution to obtain acidified biochar; S3, under protective gas, acidifying the biochar Calcination is to obtain acidified and expanded activated biochar adsorption material. The invention uses the acidified and expanded activated biochar with high specific surface area and low preparation cost as the adsorbent, and realizes the efficient adsorption and removal of BPA in the water body. Stablize.

Description

An acidified puffed activated biochar adsorption material and its preparation method and application

technical field

The invention relates to the technical field of polluted water treatment applications, in particular to an acidified and expanded activated biochar adsorption material and a preparation method and application thereof.

Background technique

Bisphenol A (BPA) is widely used in the production process of epoxy resin, polycarbonate and other plastic products. It is a typical environmental endocrine disruptor. It has certain embryotoxicity and teratogenicity, and will increase the risk of ovarian cancer. , prostate cancer, asthma and leukemia risk. BPA cannot be completely removed in sewage treatment plants, so it will inevitably enter the natural environment, causing adverse effects on human health and ecological environment.

Biochar adsorption is an effective method to remove BPA from the environment. Biochar usually has a large specific surface area and abundant active sites, and can adsorb pollutants through electrostatic interaction, hydrogen bonding and π-π interactions, so it can be used as a convenient and efficient adsorbent for phenolic substances. In order to improve the adsorption performance of biochar, researchers have studied many methods of biochar activation, mainly including physical modification (steam activation, ultraviolet radiation, ball milling, etc.), chemical modification (acid modification, alkali modification, metal oxide modification, etc.) modification, etc.) and biological modification.

As a way of physical modification, puffing has been widely used in the preparation of three-dimensional degradable starch-based materials. There are various means of puffing, such as laser, infrared, microwave, electric current, etc. Among them, the microwave method has the advantages of simple operation, fast heating speed, strong controllability, uniform modification, safety and high efficiency, and has broad development prospects. The microwave puffing method uses microwaves to penetrate into the material and interact with polar molecules, so that the internal temperature of the material rises rapidly and the volume increases; at the same time, the appropriate water content in the material generates high-pressure water vapor at high temperature, thereby generating pores in the material. Therefore, the expanded material has a fluffy honeycomb structure inside, which has the advantages of light weight and high specific surface area.

Acid-base modification is a chemical modification method. Acid modification is that phosphoric acid or nitric acid interacts with the carbon structure to remove volatile substances on the surface and increase the oxygen-containing functional groups on the surface of biochar. Alkali modification is to use sodium hydroxide or potassium hydroxide to remove blockages in the pores of carbon materials, thereby opening new pores or expanding existing pores to increase the specific surface area or pore volume of activated carbon. However, there is currently a lack of comparison between puffed activated carbon materials and unpuffed materials, and no researchers have used puffing combined with acid-base modification to prepare adsorbent materials. Therefore, the mechanism of the effect of puffing and acid-base modification on the adsorption performance of materials still belongs to the field. blank.

Therefore, how to provide a puffed and acid-base modified adsorption material for the treatment of polluted water has become an urgent problem for those skilled in the art to solve.

SUMMARY OF THE INVENTION

In view of this, the present invention provides an acidified and expanded activated biochar adsorption material and a preparation method and application thereof. Compared with the existing adsorbents, the acidified and expanded activated biochar has the advantages of low processing cost, high adsorption per unit area, and environmental protection. The advantages of good benefit and other advantages provide a new method for removing bisphenol A in water.

In order to achieve the above object, the present invention adopts the following technical solutions:

A preparation method of an acidified puffed activated biochar adsorption material, comprising the following steps:

S1. Under the protective gas, the rice is carbonized to obtain biochar;

S2, acidizing the biochar in a phosphoric acid solution to obtain acidified biochar;

S3. Under the protective gas, the acidified biochar is calcined to obtain the acidified and expanded activated biochar adsorption material.

Further, the protective gas in the step S1 and the step S3 is independently nitrogen, argon or helium.

Further, the rice is composed of ordinary rice and puffed rice, wherein the mass ratio of ordinary rice and puffed rice is 0-1:1.

Further, the temperature of the carbonization reaction is 400-500° C., and the time is 0.5-3 h; the particle size of the biochar is ≥60 mesh.

Further, the mass ratio of the biochar to the phosphoric acid solution is 1:1-5; the mass fraction of the phosphoric acid solution is 35-45%; the acidizing treatment time in the step S2 is 8-15 h.

Further, the temperature of the calcination is 600-700°C, and the time is 1-5h.

The present invention provides the acidified and expanded activated biochar adsorption material prepared by the above preparation method. The acidified and expanded activated biochar adsorption material has a specific surface area of 800-1200 m ² ·g ^-1 and a particle size of ≥60 mesh.

The present invention also provides the application of the above acidified puffed activated biochar adsorption material, comprising the following steps: mixing the acidified puffed activated biochar adsorption material and the water body polluted by bisphenol A, and then separating to obtain a water body from which bisphenol A has been removed;

The concentration of the acidified and expanded activated biochar adsorption material in the water body is 0.1-0.5 g·L ^-1 , and the concentration of bisphenol A in the water body is 1-40 mg·L ^-1 .

Further, the mixing is shaking or stirring, the temperature of the mixing is 20-30°C, and the time is ≥48h.

Further, the separation includes static separation or centrifugal separation;

The time of standing and separating is ≥24h;

The rotational speed of the centrifugal separation is 2000-6000 r·min ^-1 , and the time is 5-15 min.

As can be seen from the above-mentioned technical solutions, compared with the prior art, the beneficial effects of the present invention are as follows:

1. The acidified puffed activated biochar adsorption material prepared by the present invention is used as an adsorbent, with large adsorption capacity per unit area, simple operation and stable removal effect;

2. The present invention uses acidified and expanded activated biochar with high specific surface area and low preparation cost as adsorbent, and realizes high-efficiency adsorption and removal of BPA in water;

3. The present invention uses the acidified puffed activated biochar adsorption material to adsorb BPA and can be separated by centrifugation, which is beneficial to the recycling of the adsorbent and reduces the economic cost;

4. The present invention can use the expanded water vapor to generate more pores through the puffing process, which increases the specific surface area of the material, thereby increasing the amount of adsorption of BPA; the specific surface area of the material obtained by the combination of puffing and acid activation is higher than that of direct acid activation. The maximum adsorption capacity can be close to 400 mg·L ^-1 .

Description of drawings

Fig. 1 is the adsorption isotherm of the acidified puffed activated biochar adsorption material HP prepared in Example 1 to BPA;

FIG. 2 shows the adsorption isotherms of the three adsorbents C, HC and P prepared in Comparative Example 1 on BPA.

Detailed ways

The invention provides a preparation method of an acidified puffed activated biochar adsorption material, comprising the following steps:

S1. Under the protective gas, the rice is carbonized to obtain biochar;

S2, acidizing the biochar in a phosphoric acid solution to obtain acidified biochar;

S3. Under the protective gas, the acidified biochar is calcined to obtain the acidified and expanded activated biochar adsorption material.

In the present invention, the protective gas in the step S1 and the step S3 is independently nitrogen, argon or helium, preferably nitrogen or argon, more preferably nitrogen.

In the present invention, the rice is composed of ordinary rice and puffed rice, wherein the mass ratio of ordinary rice and puffed rice is 0-1:1, preferably 0.2-0.8:1, more preferably 0.4-0.6:1.

In the present invention, the puffed rice is prepared from ordinary rice by microwave puffing method.

In the present invention, the rice is dried before the carbonization reaction, and the drying temperature is 150-300°C, preferably 180-250°C, more preferably 200-220°C; the drying time is 8-20h, preferably 10 to 16 hours, more preferably 12 to 14 hours.

In the present invention, the temperature of the carbonization reaction is 400-500°C, preferably 420-480°C, more preferably 440-460°C; the time is 0.5-3h, preferably 1-2.5h, more preferably 1.5- 2h; the particle size of the biochar is ≥60 mesh, preferably ≥80 mesh, more preferably ≥100 mesh.

In the present invention, the mass ratio of the biochar to the phosphoric acid solution is 1:1-5, preferably 1:2-4, more preferably 1:3; the mass fraction of the phosphoric acid solution is 35-45%, It is preferably 38-42%, more preferably 39-41%; the acidification treatment time in the step S2 is 8-15h, preferably 9-14h, more preferably 10-12h.

In the present invention, the calcination temperature is 600-700°C, preferably 620-680°C, more preferably 640-660°C; the time is 1-5h, preferably 2-4h, and more preferably 3h.

The present invention provides the acidified and expanded activated biochar adsorption material prepared by the above preparation method, wherein the acidified and expanded activated biochar adsorption material has a specific surface area of 800-1200 m ² ·g ^-1 , preferably 850-1100 m ² ·g ^{- 1} , more preferably 900-100 m ² ·g ^-1 ; particle size ≥ 60 mesh, preferably ≥ 80 mesh, more preferably ≥ 100 mesh.

The invention also provides the application of the above acidified puffed activated biochar adsorption material, including the following steps: mixing the acidified puffed activated biochar adsorption material and bisphenol A polluted water, and then separating to obtain bisphenol A-removed water.

In the present invention, the concentration of the acidified and expanded activated biochar adsorption material in the water body is 0.1-0.5 g·L ^-1 , preferably 0.2-0.4 g·L ^-1 , more preferably 0.3 g·L ^-1 ; The concentration of bisphenol A in the water body is 1-40 mg·L ^-1 , preferably 5-35 mg·L ^-1 , and more preferably 10-25 mg·L ^-1 .

In the present invention, the mixing is shaking or stirring, preferably stirring; the mixing temperature is 20-30°C, preferably 22-28°C, more preferably 24-26°C; time ≥ 48h, preferably ≥ 60h, more preferably ≥72h.

In the present invention, the separation includes static separation or centrifugal separation, preferably centrifugal separation;

The time for standing and separation is ≥24h, preferably ≥30h, more preferably ≥48h;

The rotational speed of the centrifugal separation is 2000～6000r·min ^-1 , preferably 3000～5500r·min ^-1 , more preferably 4000～5000r·min ^-1 ; the time is 5～15min, preferably 8～12min, more preferably for 10min.

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

The ordinary rice and puffed rice were mixed in a mass ratio of 0.5:1 and dried in a blast drying oven at 210 °C for 12 hours. The dried mixed rice was transferred to a muffle furnace at 450 °C, and carbonized for 1 hour in a nitrogen atmosphere. Biochar; after cooling to room temperature, grind the biochar with an agate mortar and pass through a 60-mesh sieve; mix the screened biochar and phosphoric acid solution (mass fraction 42.5%) in a mass ratio of 1:2, and stir evenly with a glass rod , stand for 12h to obtain acidified biochar; transfer the acidified biochar to a muffle furnace at 650°C, and calcine it in a nitrogen atmosphere for 2h to obtain an acidified and expanded activated biochar adsorption material HP; after it is lowered to room temperature, it is ground again with an agate mortar And pass through a 60-mesh sieve, then rinse with ultrapure water until neutral, dry and store in an airtight container for later use.

It was determined that the specific surface area of the acidified and expanded activated biochar adsorption material HP prepared in this example was 1023.78 m ² ·g ^-1 .

The acidified puffed activated biochar adsorption material HP prepared in this example was used to adsorb BPA in the water body. The specific test steps were as follows: Weigh 10 mg of the acidified puffed activated biochar adsorption material HP and put it in a 40 mL brown glass bottle, add 40 mL concentration The BPA solution between 1 and 40 mg·L ^-1 was shaken in a shaker for 48 hours at 25°C, and then centrifuged at 4000 r·min ^-1 for 15 minutes. The concentration of BPA in the supernatant was measured by a meter, and the test results are shown in Figure 1. It can be seen from Figure 1 that when the initial concentration of BPA in the water body is 40 mg·L ^-1 , the maximum adsorption capacity of the acid-expanded activated biochar adsorbent HP to BPA in the water body can reach 400 mg·g ^-1 , indicating that there is a good adsorption capacity. Effect.

Example 2

The ordinary rice and puffed rice were mixed in a mass ratio of 0.2:1 and dried in a blast drying oven at 250 ° C for 10 h. The dried mixed rice was transferred to a muffle furnace at 480 ° C, and carbonized in a nitrogen atmosphere for 2 h. Biochar; after cooling to room temperature, grind the biochar with an agate mortar and pass it through a 60-mesh sieve; mix the screened biochar and phosphoric acid solution (mass fraction 40%) in a mass ratio of 1:3, and stir evenly with a glass rod , stand for 10h to obtain acidified biochar; transfer the acidified biochar to a muffle furnace at 620°C, and calcine it in a nitrogen atmosphere for 4 hours to obtain an acidified and expanded activated biochar adsorption material HP2; after it is lowered to room temperature, it is ground again with an agate mortar And pass through a 60-mesh sieve, then rinse with ultrapure water until neutral, dry and store in an airtight container for later use.

It was determined that the specific surface area of the acidified and expanded activated biochar adsorption material HP2 prepared in this example was 1001.39 m ² ·g ^-1 .

Example 3

The ordinary rice and puffed rice were mixed in a mass ratio of 0.8:1 and dried in a blast drying oven at 180°C for 16h. The dried mixed rice was transferred to a muffle furnace at 420°C and carbonized for 2.5h in a nitrogen atmosphere. Biochar is obtained; after cooling to room temperature, the biochar is ground with an agate mortar and passed through a 60-mesh sieve; the screened biochar and phosphoric acid solution (mass fraction 36.5%) are mixed in a mass ratio of 1:4, and stirred with a glass rod Evenly, stand for 15 hours to obtain acidified biochar; transfer the acidified biochar to a muffle furnace at 670 ° C, and calcine it in a nitrogen atmosphere for 3 hours to obtain the acidified and expanded activated biochar adsorption material HP3; after cooling to room temperature, use an agate mortar again Grind and pass through a 60-mesh sieve, then rinse with ultrapure water until neutral, dry and store in an airtight container for later use.

It was determined that the specific surface area of the acidified and expanded activated biochar adsorption material HP3 prepared in this example was 998.19 m ² ·g ^-1 .

Comparative Example 1

The preparation steps are the same as in Example 1, except that only ordinary rice is used to prepare the biochar adsorption material C;

The preparation steps of biochar adsorption material C are the same as those of biochar adsorption material C, the difference is that only ordinary rice is acidified to prepare biochar adsorption material HC;

The preparation steps of the biochar adsorption material C are the same, except that only ordinary rice is puffed to prepare the biochar adsorption material P;

The above three kinds of biochar adsorption materials were used to adsorb BPA in the water body, and the specific test steps were the same as those in Example 1, and the test results were shown in Figure 2. It can be seen from Figure 2 that the maximum adsorption capacity of BPA by the three carbon materials is all lower than 50 mg·g ^-1 , which indicates that the expanded water vapor can be used to generate more pores through the expansion process, which increases the specific surface area of the material. , and then also increased the adsorption capacity of BPA; the material obtained by swelling combined with acid activation has a larger specific surface area and better adsorption effect than direct acid activation.

Comparative Example 2

Using modified reed (specific surface area of 952m ² ·g ^-1 ) as adsorbent, bisphenol A in water was adsorbed. The specific test steps are the same as in Example 1. The test results are: when the initial concentration of bisphenol A in the water is 40 mg·L ^-1 , the maximum adsorption capacity of the modified reed material for bisphenol A in the water is 132.22 mg·g ^-1 .

Comparative Example 3

Commercial activated carbon (with a specific surface area of 985 m ² ·g ^-1 ) was used as an adsorbent to adsorb bisphenol A in water. The specific test steps are the same as in Example 1. The test results are: when the initial concentration of bisphenol A in the water is 40 mg·L ^-1 , the maximum adsorption capacity of the modified reed material for bisphenol A in the water is 300 mg·g ^-1 .

It can be seen from the test results of Comparative Example 2 and Comparative Example 3 that, compared with the prior art, the acidified and expanded activated biochar adsorption material prepared by the present invention has better adsorption effect on bisphenol A in water.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The preparation method of the acidification puffing active biochar adsorbing material is characterized by comprising the following steps:

s1, under the protection gas, carrying out carbonization reaction on the rice to obtain biochar;

s2, acidifying the biochar in a phosphoric acid solution to obtain acidified biochar;

and S3, calcining the acidified biochar under protective gas to obtain the acidified puffed activated biochar adsorbing material.

2. The method of claim 1, wherein the shielding gas in steps S1 and S3 is nitrogen, argon or helium.

3. The preparation method according to claim 2, wherein the rice consists of ordinary rice and puffed rice, and the mass ratio of the ordinary rice to the puffed rice is 0-1: 1.

4. the preparation method according to claim 3, wherein the temperature of the carbonization reaction is 400 to 500 ℃ and the time is 0.5 to 3 hours; the particle size of the biochar is more than or equal to 60 meshes.

5. The method according to claim 2 or 4, wherein the mass ratio of the biochar to the phosphoric acid solution is 1: 1-5; the mass fraction of the phosphoric acid solution is 35-45%; and the time of the acidification treatment in the step S2 is 8-15 h.

6. The preparation method according to claim 5, wherein the calcining temperature is 600-700 ℃ and the calcining time is 1-5 h.

7. The acidized puffed active biochar adsorbing material prepared by the preparation method of any one of claims 1 to 6, wherein the acidized puffed active biochar adsorbing material has a specific surface area of 800-1200 m ² ·g ^-1 The grain diameter is more than or equal to 60 meshes.

8. Use of the acidified expanded activated charcoal adsorbent material of claim 7, comprising the steps of: mixing the acidified puffed activated charcoal adsorbing material and the water body polluted by the bisphenol A, and then separating to obtain a water body without the bisphenol A;

the concentration of the acidified puffed active biochar adsorbing material in a water body is 0.1-0.5 g.L ^-1 The concentration of bisphenol A in the water body is 1-40 mg.L ^-1 。

9. The use according to claim 8, wherein the mixing is shaking or stirring, the temperature of the mixing is 20-30 ℃, and the time is more than or equal to 48 hours.

10. Use according to claim 8, wherein the separation comprises standing separation or centrifugation;

the standing separation time is not less than 24 hours;

the rotating speed of the centrifugal separation is 2000-6000 r.min ^-1 The time is 5-15 min.

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