CN103316632A - Bamboo reed biocarbon, preparation method, and method for strengthening ammonia-nitrogen absorbing ability - Google Patents

Abstract

The invention discloses a reed bamboo biochar, a preparation method and a method for strengthening ammonia nitrogen adsorption. The chopped and dried reed bamboo straw is added into a mild alkali reaction liquid for soaking for pretreatment, and the pretreated straw is washed to medium After drying, the Arundis biochar was obtained by anaerobic pyrolysis under nitrogen atmosphere; the Arundis biochar can be used for water treatment to strengthen ammonia nitrogen adsorption after being crushed and sieved. The biochar prepared by the method increases the specific surface area and pore size, and improves the adsorption performance of the biochar. The invention prepares the biochar by taking the reed bamboo straw as the raw material, which not only solves the disposal and treatment problems of the reed bamboo straw after harvesting, but also can be used for repairing polluted water bodies and soils, turning waste into treasure.

Description

A kind of reed bamboo biochar, preparation method and method for strengthening ammonia nitrogen adsorption

technical field

The invention relates to the improvement of water pollution treatment technology, specifically refers to a reed bamboo biochar, a preparation method of the reed bamboo biochar and a method for using the reed bamboo biochar to strengthen ammonia nitrogen adsorption, and belongs to the field of water treatment.

the

Background technique

Biochar is a solid product formed by high-temperature pyrolysis of biomass materials under anaerobic or anoxic conditions. Inorganic ions (such as Cu ²⁺ , Pb ²⁺ , Hg ²⁺ and NH ₄ ⁺ etc.) and organic compounds. At the same time, the highly aromatized structure of biochar makes it have high biological, chemical and thermal stability, and has great application potential in water body restoration and soil improvement. However, the effect of biochar obtained by the current preparation technology in water treatment is limited, and it is difficult to give full play to its potential and advantages.

Reed bamboo is a commonly used plant for wetland ecological restoration, but with the long-term operation of wetlands, the effective removal of pollutants needs to be achieved by harvesting reed bamboo regularly. For a long time, due to the lack of effective resource utilization technology, most of the reed bamboo stalks were directly returned to the field or burned, so that the harvested reed bamboo stalks could not be used in time, causing secondary pollution to the environment and a waste of resources. Therefore, how to recycle the harvested reed bamboo stalks is a problem to be solved before those skilled in the art.

the

Contents of the invention

Aiming at the insufficiency of traditional biochar in water treatment effect, the object of the present invention is to provide a kind of reed bamboo biochar, a preparation method of the reed bamboo biochar and a method for using the reed bamboo biochar to strengthen the adsorption of ammonia nitrogen. Bamboo biochar and method can greatly improve ammonia nitrogen adsorption performance.

The technical solution that the present invention realizes the above object is as follows:

A preparation method of reed bamboo biochar, carried out as follows,

(1) Raw material preparation: wash the reed bamboo stalks, cut them to 4-5cm, and dry them for later use;

(2) Pretreatment of reed bamboo straw: add the reed bamboo straw obtained in step (1) into the mild alkali reaction solution for soaking pretreatment. The mild alkali reaction solution is a mixed aqueous solution composed of NaOH and H ₂ O ₂ , wherein the mass fraction of NaOH 0.25~2%, H ₂ O ₂ mass fraction 0.14~1.01%, the balance is water; pretreatment parameters are: temperature 40~80℃, solid-liquid ratio (g/mL) 1:30~1:10, The treatment time is 4h-32h, and the pretreated reed bamboo stalks are washed with water until neutral and then dried for later use;

(3) Anaerobic pyrolysis of Arundis stalks pretreated in step (2) under nitrogen atmosphere to obtain Arundis biochar, wherein the pyrolysis temperature is 400-800°C, and the pyrolysis time is 1.5-2.5h;

(4) Put the Arundis biochar prepared in the step (3) into a pulverizer to crush, sieve, take 80-40 mesh Arundis biochar as the adsorption material, wash with deionized water to make the Arundis biochar The pH value is reduced to 7.5~8. Since the newly prepared biochar is alkaline, the pH is about 10~11. The purpose of washing is to reduce the pH of the biochar to 7.5~8, so as to prevent the ammonia nitrogen from volatilizing and escaping in the form of ammonia gas. Then put it into an oven and dry it to prepare the final Arundis biochar finished product.

Further, during the pretreatment of Arundis stalks in the (2) step, the mass fraction of NaOH in the mild alkali reaction solution is preferably 1-1.5%, and the mass fraction of H ₂ O ₂ is preferably 0.3-0.6%; the pretreatment temperature is preferably 55-70 °C, the solid-to-liquid ratio (g/ml) is preferably 1:15-25, and the pretreatment time is preferably 15-28h.

The reed bamboo biochar of the present invention is prepared by the above method.

Ammonia-nitrogen adsorption treatment can be enhanced by adding the Arundis biochar prepared by the above method into the water to be treated.

In the present invention, by performing mild alkali oxidation pretreatment on the reed bamboo straw before pyrolysis and carbonization, its own super strong lignocellulose crystal structure is destroyed, and the elemental composition of biochar is changed. The scanning electron micrograph analysis of the two biochars obtained from the treated Arundis stalks showed that the skeleton structure of the prepared biochars collapsed significantly compared with the biochars prepared without pretreatment, and the specific surface area and pore size increased; the analysis of the biochars of the two biochars Element composition: After pretreatment, the C, H, and N contents of the reed bamboo biochar decreased, the O content increased, the ratio of H/C and (C+H)/O decreased, and the ratio of (O+N)/C Increase. These can show that the biochar prepared after mild alkali oxidation pretreatment has stronger aromaticity, higher degree of polymerization, weakened reducibility, and increased surface polarity, all of which are conducive to the increase of biochar adsorption and improve the adsorption capacity of biochar. Performance, experiments have confirmed that this is indeed the case.

The invention prepares the biochar by taking the reed bamboo straw as the raw material, which not only solves the disposal and treatment problems of the wetland plant reed bamboo straw after harvesting, but also can be used to restore polluted water bodies and soils, turning waste into treasure.

the

Description of drawings

Fig. 1—Scanning electron micrographs of biochar prepared from Arundis stalks without pretreatment (a) and with mild alkali pretreatment (b).

Figure 2 - Comparison of the adsorption performance of biochar prepared from Arundos arundis stalks without pretreatment and mild alkali pretreatment on ammonia nitrogen.

the

Detailed ways

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

The preparation method of reed bamboo biochar of the present invention, its steps are:

(1) Raw material preparation: wash the reed bamboo stalks, cut them to 4-5cm, and dry them for later use;

(2) Pretreatment of reed bamboo straw: add the reed bamboo straw obtained in step (1) into the mild alkali reaction solution for soaking pretreatment. The mild alkali reaction solution is a mixed aqueous solution composed of NaOH and H ₂ O ₂ , wherein the mass fraction of NaOH 0.25~2%, H ₂ O ₂ mass fraction 0.14~1.01%, the balance is water; pretreatment parameters are: temperature 40~80℃, solid-liquid ratio (g/mL) 1:30~1:10, The treatment time is 4h to 32h, and the pretreated straw is washed with water until it is neutral, and then dried for later use;

(3) Anaerobic pyrolysis of Arundis stalks pretreated in step (2) under nitrogen atmosphere to obtain Arundis biochar, wherein the pyrolysis temperature is 400-800°C, and the pyrolysis time is 1.5-2.5h;

(4) Put the prepared Arundis biochar into a pulverizer, crush it, and sieve it. Take 80-40 mesh Arundis biochar as the adsorption material, and wash it several times with deionized water. Since the newly prepared biochar is alkaline , the pH is about 10~11, and the purpose of washing is to reduce the pH of the biochar to 7.5~8, so as to prevent the ammonia nitrogen from volatilizing and escaping in the state of ammonia gas, and then put it in an oven for drying for later use;

During the pretreatment of reed bamboo stalks in the (2) step, the mass fraction of NaOH in the mild alkali reaction solution is preferably 1-1.5%, and the mass fraction of H ₂ 0 ₂ is preferably 0.3-0.6%; the pretreatment temperature is preferably 55-70°C, solid The liquid ratio (g/ml) is preferably 1:15-25, and the pretreatment time is preferably 15-28h. More preferably, the mass fraction of NaOH in the mild alkaline reaction solution is preferably 1.24%, and the mass fraction of H ₂ O ₂ is preferably 0.35%; the pretreatment temperature is preferably 64°C, the solid-liquid ratio (g/ml) is preferably 1:22.2, and the pretreatment time is preferably 26.5h. The mass fraction of NaOH in the mild alkaline reaction liquid is 1.14%, and the mass fraction of H ₂ O ₂ is 0.46%; the pretreatment temperature is 55°C, the solid-liquid ratio (g/ml) is 1:18, and the pretreatment time is 20h.

In the (3) step, when Arundox stalks are pyrolyzed to prepare Arundox biochar, the pyrolysis temperature is preferably 500° C., and the pyrolysis time is preferably 2 hours.

Ammonia-nitrogen adsorption treatment can be enhanced by adding the Arundis biochar prepared by the above method into the water to be treated.

In order to illustrate the properties of the Arundis biochar prepared by the present invention, the present invention prepares the Arundis biochar according to the method respectively, and simultaneously prepares the Arundo biochar by the method without pretreatment, and then compares the two kinds of Arundo biochar traits for comparative analysis. The above preparation process is the same except whether there is a pretreatment step or not. In the pretreatment step, the mass fraction of NaOH in the mild alkali reaction solution is 1.24%, and the mass fraction of H ₂ O ₂ is 0.35%; the pretreatment temperature is 64°C, the solid-liquid ratio (g/ml) is 1:22.2, and the pretreatment time It is 26.5h.

Then Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction analysis (XRD) were used to compare and analyze the properties of the pretreated and untreated biochars, and simultaneously determine the properties of the two biochars. specific surface area and pore size. The following table is the elemental composition analysis table of biochar.

Elemental composition

As shown in the above table, the content of C, H, and N of the biochar prepared after pretreatment decreased, the content of O increased, the ratio of H/C and (C+H)/O decreased, and the ratio of (O+N)/C ratio increases. The decrease of the H/C ratio indicates that the biochar prepared by the pretreatment of Arundis stalks has stronger aromaticity and a higher degree of polymerization; the decrease of the (C+H)/O ratio indicates that the reducibility of the biochar is weakened; (O+N) The increase in the ratio of /C indicates that the polarity of the biochar surface increases. Therefore, it can be judged that the adsorption performance of the prepared biochar can be improved by pretreating Arundis stalks with mild alkali oxidation.

The specific surface area of the biochar prepared from Arundis stalks with mild alkali pretreatment was 821.31 m ² /g and the pore diameter was 35.8 nm, while the specific surface area of the biochar prepared without pretreatment was 345.92 m ² /g and the pore diameter was 5.1nm. Comparing the SEM images of the two kinds of biochar under 2000 times magnification (see Figure 1), the analysis shows that the mild alkali oxidation treatment of Arundis stalks destroys the super strong crystal structure of lignocellulose, and the skeleton structure of the prepared biochar is lower than that of untreated biochar. The biochar prepared by pretreatment collapsed obviously. The increase of specific surface area and pore size is conducive to the adsorption.

In order to further verify the adsorption effect of the biochar prepared after treatment, the inventors carried out an adsorption test according to the following steps.

Test procedure: Weigh 0.5g each of the pretreated and untreated Arundis biochar, add it to a 250ml Erlenmeyer flask, add 100ml ammonia nitrogen solution, and choose three initial concentrations of ammonia nitrogen: 2mmol/L, 4mmol/L, 8mmol/L L and pH were both adjusted to 7. Put it into a constant temperature oscillator, set the temperature at 25°C, and the rotation speed at 150rpm, take water samples at regular intervals, measure the concentration of ammonia nitrogen, and calculate the adsorption amount of Arundis biochar.

Among the present invention, the bamboo biochar is calculated according to the following formula to the adsorption capacity of ammonia nitrogen:

In the formula, C _o and C _e are the initial concentration of ammonia nitrogen and the concentration after adsorption equilibrium, V is the volume (L) of ammonia nitrogen solution, and W is the mass (g) of Arundis biochar.

Embodiment one:

Weigh 0.5g of Arundis biochar prepared by mild alkali treatment and untreated, respectively, and add each into a 250ml Erlenmeyer flask, and then add 100ml of ammonia nitrogen solution with a concentration of 2mmol/L, using concentrations of 0.001, 0.01, 0.1, 1.0 and 2.0mol/L of HCl and NaOH are used to adjust the pH of the solution to make the pH value 7. Put it into a constant temperature oscillator, set the temperature at 25°C, and the rotation speed at 150rpm, take water samples at regular intervals, measure the ammonia nitrogen concentration, and calculate the adsorption amount of Arundis biochar. The test results are shown in Figure 2a. When the initial concentration of the ammonia nitrogen solution was 2mmol/L, after 72 hours of the adsorption test, the adsorption of ammonia nitrogen by the two biochars was in an equilibrium state. is 0.45mg/g, and the adsorption capacity of untreated Arundis biochar is 0.33mg/g.

Embodiment two:

Weigh 0.5g of Arundos rex biochar prepared by mild alkali treatment and untreated, respectively, and add each into a 250ml Erlenmeyer flask. 2.0mol/L of HCl and NaOH adjusted the pH of the solution to make the pH value 7. Put it into a constant temperature oscillator, set the temperature at 25°C, and the rotation speed at 150rpm, take water samples at regular intervals, measure the ammonia nitrogen concentration, and calculate the adsorption amount of Arundis biochar. The test results are shown in Figure 2b. When the initial concentration of ammonia nitrogen solution was 4mmol/L, after 72 hours of adsorption test, the adsorption of ammonia nitrogen by the two biochars was in an equilibrium state. is 0.8mg/g, and the adsorption capacity of untreated Luzhu biochar is 0.6mg/g.

Embodiment three:

Weigh 0.5 g of Arundos rex biochar prepared by mild alkali treatment and untreated, respectively, and add each into a 250 ml conical flask, add 100 ml of ammonia nitrogen solution with a concentration of 8 mmol/L, and adopt concentrations of 0.001, 0.01, 0.1, 1.0 and 2.0mol/L of HCl and NaOH adjusted the pH of the solution to make the pH value 7. Put it into a constant temperature oscillator, set the temperature at 25°C, and the rotation speed at 150rpm, take water samples at regular intervals, measure the ammonia nitrogen concentration, and calculate the adsorption amount of Arundis biochar. The test results are shown in Figure 2c. When the initial concentration of ammonia nitrogen solution is 8mmol/L, after 72 hours of adsorption test, the adsorption of ammonia nitrogen by the two biochars is in a balanced state, and the adsorption amount of ammonia nitrogen is basically the same, about 1.1mg /g.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (5)

1. the preparation method of a giantreed charcoal is characterized in that: carries out as follows,

(1) raw material preparation: the giantreed stalk is cleaned, prescinded to 4 ~ 5cm dry for standby;

(2) giantreed stalk preliminary treatment: the giantreed stalk that (1) step was obtained adds dipping pretreatment in the irenine reactant liquor, and the irenine reactant liquor is NaOH and H ₂O ₂The mixed aqueous solution that forms, wherein the NaOH mass fraction is 0.25～2%, H ₂O ₂Mass fraction is 0.14～1.01 %, and surplus is water; Pretreatment parameter is: 40～80 ℃ of temperature, and solid-to-liquid ratio (g/mL) 1:30～1:10, processing time 4h～32h washes with water to neutral post-drying giantreed stalk after pretreatment for subsequent use;

(3) with the pyrogenically prepared giantreed charcoal of (2) step pretreated giantreed stalk anoxybiotic under nitrogen atmosphere, wherein pyrolysis temperature is 400 ~ 800 ℃, and pyrolysis time is 1.5 ~ 2.5h;

(4) the giantreed charcoal of (3) step preparation is put into pulverizer broken, sieve, get 80 ~ 40 purpose giantreed charcoals as sorbing material,, put into afterwards the baking oven oven dry and namely prepare final giantreed charcoal finished product so that the pH value of giantreed charcoal is reduced to 7.5 ~ 8 with the deionized water washing.

2. the preparation method of giantreed charcoal according to claim 1 is characterized in that: during described (2) step giantreed stalk preliminary treatment, and the preferred 1-1.5% of NaOH mass fraction in the irenine reactant liquor, H ₂0 ₂The preferred 0.3-0.6% of mass fraction; The preferred 55-70 of pretreatment temperature ℃, the preferred 1:15-25 of solid-to-liquid ratio (g/ml), the preferred 15-28h of pretreatment time.

3. the preparation method of giantreed charcoal according to claim 1 is characterized in that: when described (3) step, the pyrolysis of giantreed stalk prepared the giantreed charcoal, pyrolysis temperature was preferably 500 ℃, and pyrolysis time is preferably 2h.

4. a giantreed charcoal is characterized in that: prepare by claim 1 or 2 or 3 described methods.

5. a method of strengthening giantreed charcoal absorption ammonia nitrogen is characterized in that: giantreed charcoal claimed in claim 4 is added can strengthen the ammonia nitrogen absorption processing in the pending water.

Images