CN106179216A - The preparation method of a kind of Magnetic Activated hydro-thermal charcoal and application - Google Patents

Abstract

The invention relates to a preparation method and application of magnetically activated hydrothermal biochar, comprising the following steps: hydrothermally reacting aquatic plant powder and deionized water in a reactor to prepare hydrothermal biochar; , FeCl ₃ , ZnCl ₂ and deionized water are fully mixed and then dried; then the dried mixed sample is placed in a box-type atmosphere furnace, and is pyrolyzed at the target temperature under nitrogen protection conditions to prepare magnetically activated hydrothermal biochar , the magnetically activated hydrothermal biochar material prepared by this method can effectively adsorb and remove heavy metal lead and copper in a large amount of water. The composite material prepared by this method can also be added to the soil where lead and copper exceed the standard to reduce lead, The bioavailability of copper serves the purpose of preventing and controlling heavy metals.

Description

Preparation method and application of a magnetically activated hydrothermal biochar

technical field

The invention belongs to the technical field of water treatment, and in particular relates to a preparation method and application of magnetically activated hydrothermal biochar.

Background technique

With the rapid development of my country's economy, the demand for water resources is increasing, but at the same time, the pollution of water resources is also becoming more and more serious. Heavy metal pollution accounts for a considerable proportion of water pollution. Heavy metal pollution is easy to accumulate and expand in the biological chain, and is highly toxic. Therefore, excessive heavy metals in water and the problems caused by them have seriously endangered the ecological environment and human life and health. Among them, lead (Pb) pollution and copper (Cu) pollution in China are particularly serious. In recent years, there have been many incidents of lead pollution and copper pollution in my country. For example, in 2009 and 2010, incidents of blood lead exceeding the standard were exposed, and in 2010, Fujian Zijin Mining’s copper-containing acid wastewater leakage incident caused large-scale vicious pollution of the Tingjiang River.

There are a large number of treatment technologies including ion exchange, adsorption, coagulation, and membrane filtration, which are used to remove lead and copper in wastewater. Among these methods, adsorption is known as a more economical and simple treatment method. Therefore, there is an increasing need to find low-cost, high-capacity adsorbents for heavy metals such as lead and copper.

Recently, biochar made from agricultural waste (such as plant stalks, livestock manure, etc.) has attracted much attention due to its relatively simple raw materials, basically no toxic substances, and its positive role as an adsorbent in improving the water environment. . Biochar is a kind of highly aromatized refractory solid produced by pyrolysis and carbonization of plant biomass under complete or partial anoxic conditions. Porosity and a large number of surface negative charges show strong heavy metal adsorption capacity, and can adsorb various heavy metals including lead and copper. Therefore, biochar can be used as an adsorbent to adsorb lead and copper in polluted water.

However, the biochar produced by the traditional pyrolysis and carbonization method has problems such as low yield, low specific surface area, and difficulty in separation and recovery, which lead to limited practical applications.

Contents of the invention

The present invention aims to overcome the deficiencies of the prior art, and provides a method for preparing magnetically activated hydrothermal biochar by using aquatic plant waste as a raw material; it solves the problem of biochar yield and specific surface area prepared in the prior art Low and difficult to separate and recycle.

In order to solve the problems of the technologies described above, the present invention is achieved in that:

Using aquatic plant waste as a raw material, the method for preparing magnetically activated hydrothermal biochar can be implemented according to the following steps:

Step (1), naturally air-dry the aquatic plants so that the internal moisture content is lower than 10%, and then crush them through a 100-mesh sieve to obtain aquatic plant powder;

Step (2), weighing the aquatic plant powder described in step (1), putting it into a reaction kettle and adding deionized water;

Step (3) and step (2) put the reaction kettle into an oven, program the temperature to the target temperature, and keep the final temperature for pyrolysis for a period of time; after the pyrolysis process, take out the reaction product and wash it with ethanol and deionized water in sequence, Dry at 80 ℃ to prepare hydrothermal biochar;

Step (4), weighing the hydrothermal biochar described in step (3), grinding and pulverizing through a 100-mesh sieve to obtain hydrothermal biochar powder;

Step (5), weighing the hydrothermal biochar powder described in step (4), mixing it with FeCl ₃ and ZnCl ₂ , adding it to deionized water to obtain a mixed sample;

Step (6), put the mixed sample described in step (5) into an air bath constant temperature oscillator and shake it at a certain speed and temperature for a certain period of time, take it out and dry it at a temperature of 80°C to obtain hydrothermal biochar powder, FeCl ₃ and _A thorough mixture of ZnCl2;

Step (7), weighing the sufficient mixture of hydrothermal biochar powder, FeCl ₃ and ZnCl ₂ described in step (6), placing it in a box-type atmosphere furnace, feeding nitrogen gas at a certain flow rate into the furnace; program heating to the target temperature, Keep the final temperature for a certain period of time for pyrolysis; after the pyrolysis process is over, take out the biochar after it is naturally cooled to room temperature, wash it with deionized water several times to neutrality; dry it at 80 ℃ to obtain magnetically activated hydrothermal biochar .

Further, the aquatic plant in the step (1) is one of reed, cattail or wild rice grass.

Further, in the step (2), the mass volume ratio of the aquatic plant powder to the deionized water is 1:50; wherein the mass unit of the aquatic plant powder is gram, and the unit of the volume of the deionized water is milliliter.

Further, the target temperature of the oven in the step (3) is 200°C; the pyrolysis lasts for 6 hours at the final temperature of 200°C.

Further, the mass volume ratio of hydrothermal biochar powder, FeCl ₃ , ZnCl ₂ and deionized water in the step (5) is 4:2:1:20, wherein the mass of aquatic plant powder, FeCl ₃ , ZnCl ₂ The unit is grams, and the unit of volume of deionized water is milliliters.

Further, the mixed samples in the step (6) were oscillated at a constant temperature of 150 r·min ⁻¹ in an air bath constant temperature shaker, and the shaking time was 24 h.

Further, in the step (7), the nitrogen flow rate in the box-type atmosphere furnace is 400 mL/min; the temperature program rate is controlled at 4 °C/min; the target temperature is 500 °C; and the final temperature pyrolysis at 500 °C lasts for 90 min.

The advantages and effects of the present invention are as follows:

The present invention utilizes aquatic plant waste widely existing near water bodies as raw materials, innovatively adopts a hydrothermal method with higher biochar production rate to prepare biochar, uses FeCl ₃ as magnetizer, ZnCl ₂ as activator, adopts novel A method for synchronously activating magnetized hydrothermal biochar to prepare magnetically activated hydrothermal biochar with high yield, large specific surface area and simple recovery, expanding the application field of hydrothermal biochar. Magnetically activated hydrothermal biochar can be used to treat water bodies polluted by heavy metals or for emergency treatment of water bodies polluted by heavy metals. It is a new, environmentally friendly and low-cost adsorbent with great potential. The preparation of magnetically activated hydrothermal biochar provides a way for the resource utilization of waste biomass, provides a "green" technology for organic pollution control, avoids environmental problems caused by waste biomass, and realizes "use waste to waste, circular economy "the goal of.

Compared with prior art, the present invention has following characteristics:

(1) The magnetically activated hydrothermal biochar provided by the present invention uses aquatic plant wastes which are very cheap and easy to obtain as raw materials.

(2) The magnetically activated hydrothermal biochar provided by the present invention is prepared by a hydrothermal method, and the yield of biochar prepared by this method is higher than that prepared by the traditional pyrolysis carbonization method.

(3) Compared with the existing biochar or biochar-like adsorbent technology, the magnetically activated hydrothermal biochar provided by the present invention has a larger specific surface area due to activation, and has a better adsorption effect on heavy metals such as lead and copper .

(4) The magnetically activated hydrothermal biochar provided by the present invention has strong magnetism and can be recovered by magnetic force after being used in water.

(5) The magnetically activated hydrothermal biochar prepared by the present invention has considerable stability, and can be desorbed and regenerated by pickling after adsorption and reused.

(6) The magnetically activated hydrothermal biochar prepared by the present invention can also provide additional environmental benefits, such as carbon sequestration and soil improvement.

(7) The preparation method provided by the present invention is simple, low in price and easy for industrial production.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The scope of protection of the present invention is not limited to the expression of the following content.

Fig. 1 is a process flow block diagram of the present invention;

Figure 2 is a scanning electron micrograph of magnetically activated hydrothermal reed biochar;

Figure 3 shows the adsorption effect of 10 g of magnetically activated hydrothermal reed biochar on 1 L of wastewater with a lead content of 100 mg/L.

Figure 4 shows the adsorption effect of 10 g of magnetically activated hydrothermal reed biochar on 1 L of wastewater with a copper content of 100 mg/L.

detailed description

In the embodiment of the present invention, the constant temperature shaking table produced by Aice Co., Ltd. is used for stirring, the MXQ box-type atmosphere furnace produced by Shanghai Weixing Furnace Co., Ltd. is used for high-temperature anaerobic cracking, and the Beifen Rayleigh WFX-310 atomic absorption The instrument was used to determine the concentration of heavy metals lead and copper.

Example Al

(1) Naturally air-dry the reeds so that the internal moisture content is lower than 10%, and then crush them through a 100-mesh sieve to obtain aquatic plant powder;

(2) Weigh the reed powder described in step (1), put it into the reaction kettle and add a certain amount of deionized water. The mass volume ratio of reed powder and deionized water is 1:50; wherein the mass unit of reed powder is gram, and the unit of volume of deionized water is milliliter;

(3) The reactor described in step (2) was put into an oven, and the temperature was raised to 200°C, and kept at the final temperature for pyrolysis for 6 hours; The hydrothermal reed biochar was obtained by drying under the bottom;

(4) Weighing the hydrothermal reed biochar described in step (3), grinding and pulverizing through a 100-mesh sieve to obtain hydrothermal reed biochar powder;

(5) Weigh a certain amount of hydrothermal reed biochar powder, FeCl ₃ , ZnCl ₂ , and deionized water in step (4) and mix them at a ratio of 4:2:1:2 to obtain a mixed sample. Wherein the mass unit of hydrothermal reed biochar powder, FeCl ₃ , ZnCl ₂ is gram, the unit of volume of deionized water is milliliter;

(6) Put the mixed sample described in step (5) into an air bath constant temperature shaker and shake it at a constant temperature of 150 r min ^-1 for 24 h, take it out and dry it at a temperature of 80°C to obtain hydrothermal reed biochar powder, A good mixture of FeCl ₃ and ZnCl ₂ .

(7) Weigh the sufficient mixture of hydrothermal reed biochar powder, FeCl ₃ and ZnCl ₂ described in step (6) and place it in a box-type atmosphere furnace. Introduce nitrogen gas at a flow rate of 400 mL/min into the furnace, and program the temperature rise rate to control 4 °C/min, the target temperature is 500 °C, and the pyrolysis lasts for 90 min at the final temperature of 500 °C. After the pyrolysis process was over, the reed biochar was naturally cooled to room temperature and then taken out, washed with deionized water several times until neutral, and dried at 80 °C to obtain magnetically activated hydrothermal reed biochar.

Example A2

(1) Naturally air-dry the cattail so that the internal moisture content is lower than 10%, and then crush it through a 100-mesh sieve to obtain aquatic plant powder;

(2) Weigh the cattail powder described in step (1), put it into the reaction kettle and add a certain amount of deionized water. The mass volume ratio of cattail powder and deionized water is 1:50; wherein the mass unit of cattail powder is gram, and the unit of deionized water volume is milliliter;

(3) The reactor described in step (2) was put into an oven, and the temperature was raised to 200°C, and kept at the final temperature for pyrolysis for 6 hours; The hydrothermal typha biochar was obtained by drying under the bottom;

(4) Weighing the hydrothermal typha biochar described in step (3), grinding and pulverizing through a 100-mesh sieve to obtain hydrothermal typha biochar powder;

(5) Weigh a certain amount of hydrothermal typha biochar powder, FeCl ₃ , ZnCl ₂ and deionized water in step (4) and mix them at a ratio of 4:2:1:20 to obtain a mixed sample. Wherein the mass unit of hydrothermal cattail biochar powder, FeCl ₃ , ZnCl ₂ is gram, and the unit of volume of deionized water is milliliter;

(6) Put the mixed sample described in step (5) into an air bath constant temperature shaker and shake it at a constant temperature of 150 r min ^-1 for 24 h, take it out and dry it at 80°C to obtain hydrothermal typha biochar powder, A good mixture of FeCl ₃ and ZnCl ₂ .

(7) Weigh the sufficient mixture of hydrothermal cattail biochar powder, FeCl ₃ and ZnCl ₂ described in step (6) and place it in a box-type atmosphere furnace. Introduce nitrogen gas at a flow rate of 400 mL/min into the furnace, and program the temperature rise rate to control 4 °C/min, the target temperature is 500 °C, and the pyrolysis lasts for 90 min at the final temperature of 500 °C. After the pyrolysis process was completed, the Typha biochar was naturally cooled to room temperature and then taken out, washed with deionized water several times until neutral, and dried at 80 °C to obtain the magnetically activated hydrothermal Typha biochar.

Example A3

(1) Naturally air-dry Zizizania so that the internal moisture content is lower than 10%, and then crush it through a 100-mesh sieve to obtain aquatic plant powder;

(2) Weigh the Zizania zizizi powder described in step (1), put it into the reaction kettle and add a certain amount of deionized water. The mass-to-volume ratio of Zizania zizizi powder and deionized water is 1:50; wherein the mass unit of Zizizania zizania powder is gram, and the unit of volume of deionized water is milliliter;

(3) The reactor described in step (2) was put into an oven, and the temperature was raised to 200°C, and kept at the final temperature for pyrolysis for 6 hours; The water-heated water-heated water-heated Zizania japonica biochar was obtained by drying at the bottom;

(4) Weighing the hydrothermal water-heated Zizania japonica biochar described in step (3), grinding and pulverizing through a 100-mesh sieve to obtain hydrothermal water-heated water-heated Zizania zizizia biochar powder;

(5) Weigh a certain amount of hydrothermal Znaria biochar powder, FeCl ₃ , ZnCl ₂ , and deionized water in step (4) and mix them at a ratio of 4:2:1:2 to obtain a mixed sample. Among them, the mass unit of hydrothermal water-heated Zizania japonica biochar powder, FeCl ₃ , and ZnCl ₂ is grams, and the unit of volume of deionized water is milliliters;

(6) Put the mixed sample described in step (5) into an air bath constant temperature shaker and shake it at a constant temperature of 150 r min ^-1 for 24 h, take it out and dry it at 80°C to obtain hydrothermal Zizania japonica biochar powder , FeCl ₃ and a thorough mixture of ZnCl ₂ .

(7) Weigh the sufficient mixture of water-heated Zizania japonica biochar powder, FeCl ₃ and ZnCl ₂ in step (6) and place it in a box-type atmosphere furnace. The temperature was controlled at 4 °C/min, the target temperature was 500 °C, and the pyrolysis at the final temperature of 500 °C lasted for 90 min. After the pyrolysis process, the Zizania japonica biochar was naturally cooled to room temperature and then taken out, washed with deionized water several times until neutral, and dried at 80 °C to obtain the magnetically activated hydrothermal Zizania japonica biochar.

Referring to the results of scanning electron microscopy in Figure 1, it can be seen that the surface of the activated hydrothermal biochar is smooth, with many holes and micropores, which leads to the expansion of the specific surface area of the biochar, which is more conducive to providing more adsorption for the modified biochar location.

Referring to Figure 2, it can be seen that the hydrothermal biochar prepared by the synchronous magnetization activation method has good magnetic properties and can be recovered by magnets.

The adsorption effect of magnetically activated hydrothermal biochar on lead and copper is obvious (see Figures 3 and 4). When 10 g of magnetically activated hydrothermal reed biochar was added to 1 L of high-lead water with a concentration of 100 mg·L ^-1 , the adsorption of lead tended to be stable in the first 20 minutes, and the lead content decreased rapidly within 20 minutes. The lead removal rate reached 78.78% at 20 minutes, and reached the highest at 85.22% at 320 minutes. When 10 g of magnetically activated hydrothermal reed biochar was added to 1 L of high-copper water with a concentration of 100 mg·L ^-1 , the adsorption of lead tended to be stable in the initial 40 min, and the lead content decreased rapidly within 40 min. The removal rate of lead reached 82.52% at the 40th minute, and the lead removal rate reached the highest at 87.31% at the 320th minute. A higher adsorption rate is of great significance for practical applications, and a faster adsorption rate can ensure a higher removal efficiency.

After the adsorption of magnetically activated hydrothermal biochar, the adsorption quickly reaches equilibrium, and lead and copper are quickly adsorbed and removed. The magnetically activated hydrothermal biochar after adsorption can be recovered by magnets, and then eluted by acid solution for reuse.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. A preparation method for magnetically activated hydrothermal biochar, characterized in that it may further comprise the steps: Step (1), naturally air-dry the aquatic plants so that the internal moisture content is lower than 10%, and then crush them through a 100-mesh sieve to obtain aquatic plant powder; Step (2), weighing the aquatic plant powder described in step (1), putting it into a reaction kettle and adding deionized water; Step (3) and step (2) put the reaction kettle into an oven, program the temperature to the target temperature, and keep the final temperature for pyrolysis for a period of time; after the pyrolysis process, take out the reaction product and wash it with ethanol and deionized water in sequence, Dry at 80 ℃ to prepare hydrothermal biochar; Step (4), weighing the hydrothermal biochar described in step (3), grinding and pulverizing through a 100-mesh sieve to obtain hydrothermal biochar powder; Step (5), weighing the hydrothermal biochar powder described in step (4), mixing it with FeCl ₃ and ZnCl ₂ , adding it to deionized water to obtain a mixed sample; Step (6), put the mixed sample described in step (5) into an air bath constant temperature oscillator and shake it at a certain speed and temperature for a certain period of time, take it out and dry it at a temperature of 80°C to obtain hydrothermal biochar powder, FeCl ₃ and _A thorough mixture of ZnCl2; Step (7), weighing the sufficient mixture of hydrothermal biochar powder, FeCl ₃ and ZnCl ₂ described in step (6), placing it in a box-type atmosphere furnace, feeding nitrogen gas at a certain flow rate into the furnace; program heating to the target temperature, Keep the final temperature for a certain period of time for pyrolysis; after the pyrolysis process is over, take out the biochar after it is naturally cooled to room temperature, wash it with deionized water several times to neutrality; dry it at 80 ℃ to obtain magnetically activated hydrothermal biochar . 2 . The method for preparing magnetically activated hydrothermal biochar according to claim 1 , wherein the aquatic plant in the step (1) is one of reeds, cattails or wild rice plants. 3 . 3. A method for preparing magnetically activated hydrothermal biochar according to claim 1, characterized in that: in the step (2), the mass-to-volume ratio of aquatic plant powder to deionized water is 1:50; wherein The mass unit of the aquatic plant powder is grams, and the unit of deionized water volume is milliliters. 4. A method for preparing magnetically activated hydrothermal biochar according to claim 1, characterized in that: the target temperature of the oven in the step (3) is 200°C; the pyrolysis at the final temperature of 200°C lasts for 6 h. 5. A method for preparing magnetically activated hydrothermal biochar according to claim 1, characterized in that: the mass volume of hydrothermal biochar powder, FeCl ₃ , ZnCl ₂ and deionized water in the step (5) The ratio is 4:2:1:20, wherein the mass unit of aquatic plant powder, FeCl ₃ , ZnCl ₂ is gram, and the unit of volume of deionized water is milliliter. 6. A method for preparing magnetically activated hydrothermal biochar according to claim 1, characterized in that: in the step (6), the mixed sample is oscillated at a constant temperature of 150 r·min ⁻¹ in an air bath constant temperature oscillator, and the vibration The time is 24 hours. 7. A method for preparing magnetically activated hydrothermal biochar according to claim 1, characterized in that: the nitrogen flow rate in the box-type atmosphere furnace in the step (7) is 400 mL/min; the programmed temperature rise rate is controlled by 4 °C/min; the target temperature is 500 °C; the pyrolysis lasts for 90 min at the final temperature of 500 °C. 8. A method for preparing magnetically activated hydrothermal biochar according to claim 1, characterized in that the magnetically activated hydrothermal biochar is used to adsorb and remove heavy metals lead and copper in water or soil.