Waste charcoal regeneration method based on microwave heat and non-heat effect

Abstract

The invention discloses a waste biochar regeneration method based on microwave heat and non-heat effect, and relates to a waste biochar regeneration method. In order to solve the problems of pore blockage and insufficient pollutant fixing effect of the waste biochar, the method comprises the following steps: 1, respectively placing samples in a quartz reactor in a microwave device; 2, the temperature is increased to 1000 DEG C in a gradient mode; 3, performing synchronous microwave radiation on the sample; and 4, collecting the charcoal cooled to room temperature. Micro-plasma and hot spots caused by microwave heating have a catalytic effect, surface carbonization of the waste biochar is effectively accelerated, and therefore the pollutant fixing effect is improved. Furthermore, the microwave non-thermal effect causes biochar dipole molecules to rotate through high-frequency electromagnetic waves, new pores are generated in the biochar, and the pore volume and pore size distribution of the new biochar are obviously increased. And finally, expected results are obtained at the temperature of 500 DEG C and 700 DEG C, and the pore structure of the waste charcoal is obviously improved by applying high-frequency electromagnetic waves. The invention belongs to the technical field of waste recycling.

Description

Technical Field

[0001] The invention relates to a waste biochar regeneration method, belonging to the technical field of waste regeneration and utilization. Background Art

[0002] Biochar is widely used in wastewater treatment, soil remediation, plant root growth and other fields due to its excellent pore structure and rich functional groups. At present, the sources of materials used to prepare biochar are extremely wide, mainly sludge (sewage sludge, papermaking sludge, printing and dyeing sludge, etc.) and biomass (lignin, rice husk, rice, etc.). Pyrolysis, as a low-carbon and high-efficiency biochar material synthesis technology, has become a technical means commonly used in academia and industry.

[0003] At present, the application research of biochar is mainly focused on the adsorption efficiency of pollutants and the risk of toxic release. Although biochar has achieved good application results in actual engineering, the neglect of its subsequent recycling has led to major technical bottlenecks in the scale of the biochar market. The key to the problem of biochar recycling lies in the blockage of pore structure and the toxic release of adsorbed pollutants. Therefore, the development of biochar recycling technology is crucial to improving my country's core technology status in the world.

[0004] Microwaves cause frequent rotation of dipole molecules by emitting electromagnetic waves with a frequency of 300 MHz to 3000 GHz. Then, the friction between adjacent dipole molecules will generate a large amount of heat, and finally the biochar will be heated up quickly. Microplasmas and hot spots caused by microwave heating have been shown to have excellent catalytic effects. Based on this, it is speculated that the internal components of the biochar pore structure will be further catalytically cracked. At the same time, the non-thermal effect induced by microwaves will further accelerate the cracking of the components in the pores into small molecular components through the rotation and vibration of dipole molecules, and finally solve the problem of blockage of the pore structure of waste biochar. In addition, the further carbonization of the biochar pore structure will effectively enhance the pollutant fixation effect. The present invention has important practical significance for realizing the recycling of waste biochar. Summary of the invention

[0005] The present invention solves the problem of pore blockage and insufficient pollutant fixation of waste biochar, and further proposes a waste biochar regeneration method based on microwave thermal and non-thermal effects. The pore structure of biochar initially forms new charcoal at 300°C, and develops into a complete charcoal pore structure at 500°C. Based on this, the present invention sets up a gradient temperature increase experimental group to observe the changes in the pore structure of waste biochar treated with microwaves at 300°C-700°C, so as to determine the optimal experimental conditions.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problem is: the steps of the present invention include:

[0007] Step 1, placing samples in quartz reactors in a microwave device respectively;

[0008] Step 2, raising the temperature in the quartz reactor to 500° C. and 700° C. respectively;

[0009] Step 3, subjecting the sample to microwave radiation;

[0010] Step 4: Collect the biochar cooled to room temperature.

[0011] Furthermore, in step 2, the heating rate in the quartz reactor is 100° C. / min.

[0012] Furthermore, in step 3, electromagnetic waves with a frequency between 300 MHz and 3000 GHz are emitted to the sample.

[0013] Furthermore, in order to maintain a strict inert atmosphere in the quartz reactor, pure argon gas is continuously injected into the quartz reactor to expel oxygen. After reaching a specified reaction time, the microwave device is turned off and high-purity argon gas is re-injected into the quartz reactor to remove residual gas.

[0014] Furthermore, the catalytic effect of microplasma and hot spots caused by microwave heating effectively accelerates the carbonization of the waste biochar surface, thereby improving the pollutant fixation effect; the microwave non-thermal effect causes the rotation of biochar dipole molecules through high-frequency electromagnetic waves, generating new pores inside the biochar, and significantly increasing the pore volume and pore size distribution of the new biochar, ultimately achieving the recycling of waste biochar.

[0015] Furthermore, in order to maintain a strict inert atmosphere in the quartz reactor, pure argon gas was continuously injected into the quartz reactor at a flow rate of 10 L / min for 20 minutes.

[0016] Furthermore, after reaching the designated reaction time, the microwave device was turned off, and high-purity argon gas was re-injected into the quartz reactor for 20 minutes.

[0017] Furthermore, ideal effects were obtained at 500°C and 700°C. Under this condition, applying high-frequency electromagnetic waves is beneficial to significantly improve the pore structure of waste biochar.

[0018] The beneficial effects of the present invention are:

[0019] (1) The catalytic effect of microplasma and hot spots caused by microwave heating effectively accelerates the carbonization of waste biochar surface, thereby improving the pollutant fixation effect. Furthermore, the non-thermal effect of microwaves causes the dipole molecules of biochar to rotate through high-frequency electromagnetic waves, generating new pores inside the biochar, and ultimately achieving the recycling of waste biochar.

[0020] (2) The biochar pyrolyzed at 500°C and 700°C was subjected to microwave treatment, and the pore characteristics of the biochar were analyzed using physical and chemical adsorption instruments. It was found that after microwave treatment, the pore volume of the new biochar increased significantly, and the pore size distribution further expanded; 500°C was determined to be the optimal condition, and the pore structure of the biochar was significantly improved at 700°C; the present invention solves the engineering bottleneck problems of pore blockage and insufficient pollutant fixation effect of waste biochar, and realizes the development of waste biochar recycling technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the pore structure characteristics of biochar at 500℃;

[0022] Figure 2 This is a schematic diagram of the pore structure characteristics of biochar at 700℃. DETAILED DESCRIPTION

[0023] Specific implementation method 1: Figure 1 As shown, a method for regenerating waste biochar based on microwave thermal and non-thermal effects, the specific steps include:

[0024] Step 1, placing samples in quartz reactors in a microwave device respectively;

[0025] Step 2, raising the temperature in the quartz reactor to 500° C. and 700° C. respectively; the heating rate in the quartz reactor is 100° C. / min;

[0026] Step 3, subjecting the sample to microwave radiation; emitting electromagnetic waves with a frequency between 300 MHz and 3000 GHz to the sample;

[0027] Step 4: Collect the biochar cooled to room temperature.

[0028] Specific implementation method 2: Figure 1 As shown, in order to maintain a strict inert atmosphere in the quartz reactor, pure argon gas is continuously injected into the quartz reactor to expel oxygen. After reaching the specified reaction time, the microwave device is turned off and high-purity argon gas is re-injected into the quartz reactor to remove residual gas.

[0029] In order to maintain a strict inert atmosphere in the quartz reactor, pure argon gas was continuously injected into the quartz reactor at a flow rate of 10 L / min for 20 minutes.

[0030] After the specified reaction time was reached, the microwave device was turned off and high-purity argon gas was re-injected into the quartz reactor for 20 minutes.

[0031] In this embodiment, the source of waste biochar: biochar has a wide range of sources, including biochar prepared from sludge, lignin, rice husks, rice, etc., and specifically uses waste biochar generated from projects such as industrial wastewater treatment and soil remediation;

[0032] The microwave device includes a microwave cavity, a quartz reactor, a waveguide, a magnetron, a PC fuzzy logic algorithm, a power regulator, an infrared thermometer and a gas flow meter;

[0033] Waste biochar microwave test process:

[0034] Step 1: Use the newly prepared biochar as the control group, collect the waste biochar produced in different engineering application scenarios as the experimental group, and conduct batch experiments by setting different microwave frequencies as variables;

[0035] Step 2, placing the samples in quartz reactors in the microwave chamber respectively;

[0036] Step 3: The temperature is raised to 300-700°C at a rate of 100°C / min. After reaching the set temperature, the sample is subjected to microwave irradiation, emitting electromagnetic waves with a frequency between 300 MHz and 3000 GHz, which cause the dipole molecules of the waste biochar to rotate and generate new pores inside the biochar;

[0037] Step 4: Collect the biochar cooled to room temperature for performance evaluation.

[0038] Among them, the catalytic effect of microplasma and hot spots caused by microwave heating effectively accelerated the carbonization of the waste biochar surface, thereby improving the pollutant fixation effect; the microwave non-thermal effect caused the rotation of biochar dipole molecules through high-frequency electromagnetic waves, generating new pores inside the biochar, and significantly increasing the pore volume and pore size distribution of the new biochar, ultimately achieving the recycling of waste biochar.

[0039] Among them, 500℃ and 700℃ are both ideal pyrolysis conditions. Under these conditions, applying high-frequency electromagnetic waves can significantly improve the pore structure of waste biochar.

[0040] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for regenerating waste biochar based on microwave thermal and non-thermal effects, characterized in that: The specific steps include: Step 1, placing samples in quartz reactors in a microwave device respectively; Step 2, gradually increasing the temperature in the quartz reactor to 500° C. and 700° C.; Step 3, subjecting the sample to microwave radiation; Step 4: Collect the biochar cooled to room temperature.

2. The method for regenerating waste biochar based on microwave thermal and non-thermal effects according to claim 1, characterized in that: The heating rate in the quartz reactor in step 2 is 100°C / min.

3. The method for regenerating waste biochar based on microwave thermal and non-thermal effects according to claim 1, characterized in that: In step 3, electromagnetic waves with a frequency between 300 MHz and 3000 GHz are emitted to the sample.

4. The method for regenerating waste biochar based on microwave thermal and non-thermal effects according to claim 1, characterized in that: In order to maintain a strict inert atmosphere in the quartz reactor, pure argon gas is continuously injected into the quartz reactor to expel oxygen. After reaching the specified reaction time, the microwave device is turned off and high-purity argon gas is re-injected into the quartz reactor to remove residual gas.

5. The method for regenerating waste biochar based on microwave thermal and non-thermal effects according to claim 4, characterized in that: The catalytic effect of microplasmas and hot spots caused by microwave heating effectively accelerates the carbonization of the waste biochar surface, thereby improving the pollutant fixation effect; the microwave non-thermal effect causes the rotation of biochar dipole molecules through high-frequency electromagnetic waves, generating new pores inside the biochar, and significantly increasing the pore volume and pore size distribution of the new biochar, ultimately achieving the recycling of waste biochar.

6. The method for regenerating waste biochar based on microwave thermal and non-thermal effects according to claim 4, characterized in that: In order to maintain a strict inert atmosphere in the quartz reactor, pure argon gas was continuously injected into the quartz reactor at a flow rate of 10 L / min for 20 minutes.

7. The method for regenerating waste biochar based on microwave thermal and non-thermal effects according to claim 4, characterized in that: After the specified reaction time was reached, the microwave device was turned off and high-purity argon gas was re-injected into the quartz reactor for 20 minutes.

8. The method for regenerating waste biochar based on microwave thermal and non-thermal effects according to claim 5, characterized in that: 500℃ and 700℃ are both favorable pyrolysis conditions. Applying high-frequency electromagnetic waves can significantly improve the pore structure of waste biochar.

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