Method for regenerating waste coconut shell charcoal through microwave activation

Abstract

The invention relates to the field of industrial solid waste resource utilization, in particular to a method for regenerating waste coconut shell charcoal through microwave activation, which at least comprises the following steps: step 1, soaking waste coconut shell charcoal in alkali liquor under the condition of microwave radiation; step 2, carrying out ultrasonic treatment on the soaked waste coconut shell charcoal; a step; and 3, drying the waste coconut shell charcoal subjected to ultrasonic treatment to complete regeneration of the waste coconut shell charcoal. According to the method for regenerating the waste coconut shell charcoal through microwave activation, the waste coconut shell charcoal is soaked in the alkali liquor under the condition of microwave radiation and then subjected to ultrasonic treatment, regeneration of the waste coconut shell charcoal is achieved, activated carbon with the high methylene blue degradation rate and the good regeneration effect is obtained, the regeneration rate of the waste coconut shell charcoal exceeds 98%, and the regeneration rate of the waste coconut shell charcoal exceeds 98%. And the regeneration rate after seven times of cyclic regeneration can also be kept at 95% or above.

Description

Technical Field

[0001] The invention relates to the field of resource utilization of industrial solid waste, in particular to a method for regenerating waste coconut shell charcoal through microwave activation. Background Art

[0002] Coconut shell charcoal is obtained by burning and filtering the waste coconut shells and coconut shreds. It is a commonly used technology in production and life to absorb pollutants with coconut shell charcoal. Coconut shell charcoal has high absorption efficiency, simple operation and low price. However, the waste coconut shell charcoal after adsorption saturation usually has certain toxicity and will cause pollution. The waste coconut shell charcoal must be safely disposed of. If it is only treated by incineration or other improper methods, it will not only waste the valuable activated carbon, but also easily cause environmental pollution to the atmosphere, soil and groundwater.

[0003] At present, the microwave activation and regeneration technology of waste coconut shell charcoal can effectively remove harmful substances adsorbed by waste charcoal, restore adsorption performance, and achieve waste reduction and resource utilization; microwave heating regeneration has the advantages of low energy consumption compared with thermal regeneration, wet oxidation regeneration, electrochemical regeneration and solvent regeneration; the heating rate is fast, because the energy of microwaves is directly converted into heat, and no transfer process is required. At the same time, the activated carbon itself will absorb heat and heat up, burning a part of the carbon, expanding the pore size, and thus restoring the adsorption activity;

[0004] From the perspective of sustainable development, it is particularly urgent to develop a method to improve the resource utilization value of industrial solid waste such as waste coconut shell charcoal. Summary of the invention

[0005] In order to solve the problems of the prior art, the present invention provides a method for microwave activation and regeneration of waste coconut shell charcoal, the method comprising at least the following steps:

[0006] Step 1, soaking the waste coconut shell charcoal in an alkaline solution under microwave radiation;

[0007] Step 2, subjecting the soaked waste coconut shell charcoal to ultrasonic treatment;

[0008] Step 3: drying the waste coconut shell charcoal after ultrasonic treatment, thus completing the regeneration of the waste coconut shell charcoal.

[0009] Further, in step 1, the microwave irradiation conditions are: microwave irradiation power is 700W-1000W, and microwave irradiation time is 40-60s.

[0010] Further, in step 1, the concentration of the alkali solution is 1 mol / L-5 mol / L.

[0011] Furthermore, in step 1, the alkaline substance in the alkali solution is selected from at least one of strong bases; the strong base is KOH.

[0012] Furthermore, in step 1, the soaking time is at least 13 hours.

[0013] Furthermore, in step 2, during the ultrasonic treatment, the ultrasonic frequency is 300 MHz-300 GHz, and the treatment time is 15 to 30 minutes.

[0014] Furthermore, in step 3, the drying temperature is 90-120°C.

[0015] Furthermore, the method further comprises: drying the waste coconut shell charcoal before soaking the waste coconut shell charcoal;

[0016] The requirement for the drying process is that the moisture content of the waste coconut shell charcoal is less than 10%.

[0017] Beneficial effects of the present invention:

[0018] The method for microwave activation and regeneration of waste coconut shell charcoal of the present invention realizes the regeneration of waste coconut shell charcoal by soaking the waste coconut shell charcoal in alkali solution under microwave radiation conditions and then performing ultrasonic treatment, thereby obtaining activated carbon with high methylene blue degradation rate and good regeneration effect. The regeneration rate of the waste coconut shell charcoal exceeds 98%, and the regeneration rate can be maintained above 95% after seven cycles of regeneration. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of the microwave activation and regeneration method of waste coconut shell charcoal of the present invention;

[0020] Figure 2 This is a comparison chart of the regeneration rate of waste coconut shell charcoal after 7 cycles in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The method for regenerating waste coconut shell charcoal by microwave activation comprises at least the following steps:

[0023] Step 1, soaking the waste coconut shell charcoal in an alkaline solution under microwave radiation;

[0024] Step 2, subjecting the soaked waste coconut shell charcoal to ultrasonic treatment;

[0025] Step 3: drying the waste coconut shell charcoal after ultrasonic treatment, thus completing the regeneration of the waste coconut shell charcoal.

[0026] In step 1, the microwave irradiation conditions are:

[0027] The microwave irradiation power is 700W-1000W, and the microwave irradiation time is 40-60s.

[0028] The concentration of the alkali solution is 1 mol / L-5 mol / L.

[0029] The alkaline substance in the alkali solution is selected from at least one of strong bases; the strong base is KOH.

[0030] The soaking time is at least 13 hours.

[0031] In step 2, during the ultrasonic treatment, the ultrasonic frequency is 300 MHz-300 GHz, and the treatment time is 15 to 30 minutes.

[0032] In step 3, the drying temperature is 90-120°C.

[0033] The method further comprises: drying the waste coconut shell charcoal before soaking the waste coconut shell charcoal;

[0034] The requirements for the drying process are: the moisture content of the waste coconut shell charcoal is less than 10%;

[0035] Example 1

[0036] Step 1: Preliminary selection and drying of waste coconut shell charcoal. Waste coconut shell charcoal generally contains a small amount of impurities and a high moisture content. After the preliminary selection, the activated carbon is heated by the heat provided by the air heat pump or electric energy, and dried at 110°C to a waste coconut shell charcoal with a moisture content of 10% and enters the collection hopper;

[0037] Step 2: According to the material state, use a screw conveyor to load all the sieved dry waste coconut shell charcoal in the collection hopper into the microwave activation regeneration reactor;

[0038] Step 3: After the waste coconut shell charcoal enters the microwave activation regeneration reactor, it is fully stirred and mixed in multiple spiral stirring mechanisms, and the waste coconut shell charcoal is heated by 750W microwave radiation for 45s and soaked in 3mol / L alkali solution for 14 hours, and then treated with 350MHz ultrasound for 25 minutes to evaporate the water adsorbed in the activated carbon, and organic matter with different boiling points is eliminated from the activated carbon matrix in the form of volatilization, decomposition, carbonization and oxidation as the temperature increases, so that the temperature of the activated carbon in the microwave activation regeneration reactor is increased for activation, and the carbonized matter originally remaining in the micropores of the activated carbon is gasified into carbon dioxide gas under the joint action of microwave and water vapor, so that the surface of the activated carbon micropores is dredged, and a developed pore structure is formed inside the activated carbon, so that its adsorption performance is restored to become a better regenerated activated carbon;

[0039] Step 5: Then use a water-cooled conveyor to send it to the powder warehouse for storage.

[0040] The regeneration rate of methylene blue from waste coconut shell charcoal was 98.1%.

[0041] The above-mentioned microwave activated regeneration reactor is a horizontal structure as a whole, and a stirring structure is provided inside; the microwave activated regeneration reactor is provided with a feed port, a discharge port, an air inlet, an air outlet, and a microwave energy feeding port connected to the inside thereof, wherein the microwave energy feeding port is a microwave feeding port for inputting microwaves into the heating kettle, and is suitable for microwave heating kettles and various microwave heating reaction devices; the feed port is located on the upper side of one end of the microwave activated regeneration reactor, the discharge port is located on the lower side of the other end of the microwave activated regeneration reactor, the air inlet is located on the lower side of the middle part of the microwave activated regeneration reactor, the air outlet is located on the upper side of the microwave activated regeneration reactor and the discharge end, and the microwave energy feeding port is located on both sides or the top of the microwave activated regeneration reactor. When the microwave activated regeneration reactor is used, the air outlet is connected to the induced draft fan, and the pressure in the microwave activated regeneration reactor can be adjusted by adjusting the working frequency of the induced draft fan. The activated regeneration reactor is provided with a manhole structure for easy internal maintenance;

[0042] like Figure 2 As shown, the seven test processes for the regeneration of waste coconut shell charcoal are as follows:

[0043] Preparation of adsorption saturated coconut shell activated carbon: prepare 2000 ml of 50 mg / L methylene blue solution, weigh 0.2 g coconut shell carbon and put it into a 250 ml triangular pyramidal bottle, pour in 200 ml of the prepared methylene blue solution and seal the bottle mouth with a sealing film, then put it into an oscillator at 150 r / min, and take 3 ml of liquid at 1min, 3min, 5min, 10min, 15min, 20min, 30min, 45min, 60min, 120min, and 180min with a syringe at 30°C, filter with a 0.45μm water filter membrane, and measure the absorbance. After taking the sample, filter the remaining solution with a vacuum pump, put it into an oven after filtration, dry it at 110°C for 12 hours, weigh it after drying, and name the adsorption saturated waste coconut shell carbon;

[0044] Take the adsorption saturated waste coconut shell charcoal for the first regeneration: put 0.36g of adsorption saturated waste coconut shell charcoal into a polytetrafluoroethylene sleeve, add a KOH solution with a concentration of 3 mol / L, and then put it into a microwave oven at a temperature of 70°C, the microwave power is 750W, the microwave duration is 45s, and then it is subjected to ultrasonic waves at a frequency of 400MHz for 25 minutes, and then put into an oven and dried at 110°C to complete the regeneration of the waste coconut shell charcoal. The first waste coconut shell charcoal regeneration rate is 98.1%;

[0045] Second regeneration: put the weighed regenerated coconut shell charcoal into a polytetrafluoroethylene sleeve, add a KOH solution with a concentration of 3 mol / L, and then put it into a microwave oven with a microwave power of 750 W and a microwave duration of 45 s. Then perform ultrasonic waves at a frequency of 300 MHz for 25 minutes and then put it into an oven to dry at 110°C. After regeneration, an adsorption experiment was carried out. The regenerated coconut shell charcoal was added with a 50 mg / L methylene blue solution and placed in an oscillator at 150 r / min. 3 ml of sample was taken at 30°C for 1 min, 3 min, 5 min, 10 min, 30 min, 60 min, 120 min, and 180 min, respectively. The sample was filtered with a 0.45 μm water filter membrane, then filtered, dried at 110°C, and named.

[0046] The third to seventh regenerations were all carried out at a microwave power of 750 W and a microwave duration of 45 s, followed by an ultrasonic treatment at a frequency of 400 MHz for 25 minutes, and the products were ground and named.

[0047] Finally, through scanning electron microscopy, it was found that the regeneration effect was better when the pore size increased and the adsorbed substances decreased. After the seventh regeneration, it was found that the activated carbon still had adsorption capacity and could continue to regenerate after seven regenerations.

[0048] The methylene blue of the regenerated waste coconut shell charcoal can be observed by an electronic scanner. After the second regeneration, the size of the waste coconut shell charcoal is about 890nm, there are many holes on the entire surface and the regeneration rate of the waste coconut shell charcoal is 97.8%. After the third regeneration, the size of the waste coconut shell charcoal is about 810nm, and the regeneration rate of the waste coconut shell charcoal is 97%, indicating that the regeneration effect is good. After the fourth regeneration, the size of the waste coconut shell charcoal is about 716nm, and the regeneration rate of the waste coconut shell charcoal is 96.7%. After the fifth regeneration, the size of the waste coconut shell charcoal is about 626nm, and the regeneration rate of the waste coconut shell charcoal is 96.4%. The regeneration rate of the sixth waste coconut shell charcoal is 95.7%, and the regeneration rate of the seventh waste coconut shell charcoal is 95.3%; after the seventh regeneration, the waste coconut shell charcoal still has adsorption capacity and can continue to adsorb and regenerate.

[0049] It is worth noting that the waste coconut shell charcoal is regenerated by soaking it in a certain concentration of alkali solution after specific microwave radiation, and then irradiating it with specific ultrasonic waves for a certain period of time, to obtain activated carbon with a high degradation rate of methylene blue and good regeneration ability; the regeneration rate of waste coconut shell charcoal exceeds 98%, and the regeneration rate can be maintained above 95% after seven cycles of regeneration;

[0050] Example 2, a method for regenerating waste coconut shell charcoal by microwave activation, comprising the following steps:

[0051] Step 1: Preliminary selection and drying of waste coconut shell charcoal. Waste coconut shell charcoal generally contains a small amount of impurities and a high moisture content. After the preliminary selection, the activated carbon is heated by the heat provided by the air heat pump or electric energy, and dried at 110°C to a waste coconut shell charcoal with a moisture content of 10% and enters the collection hopper;

[0052] Step 2: According to the material state, use a screw conveyor to load all the sieved dry waste coconut shell charcoal in the collection hopper into the microwave activation regeneration reactor;

[0053] Step 3: After the waste coconut shell charcoal enters the microwave activated regeneration reactor, it is fully stirred and mixed in multiple spiral stirring mechanisms, and at the same time, the waste coconut shell charcoal is heated by 900W microwave radiation for 45s and soaked in a 5mol / L alkali solution for 15 hours, and then subjected to 260GHz ultrasonic treatment for 25 minutes to evaporate the water adsorbed in the activated carbon, and organic matter with different boiling points is eliminated from the activated carbon matrix in the form of volatilization, decomposition, carbonization, and oxidation as the temperature increases, so that the temperature of the activated carbon in the microwave activated regeneration reactor is increased for activation, and the carbonized matter originally remaining in the activated carbon micropores is gasified into carbon dioxide gas under the combined action of microwaves and water vapor, so that the surface of the activated carbon micropores is unblocked, and a developed pore structure is formed inside the activated carbon, so that its adsorption performance is restored to become a better regenerated activated carbon;

[0054] Step 5: Then use a water-cooled conveyor to send it to the powder warehouse for storage.

[0055] The regeneration rate of methylene blue from waste coconut shell charcoal was 96.5%.

[0056] The above-mentioned microwave activated regeneration reactor is a horizontal structure as a whole, and a stirring structure is provided inside; the microwave activated regeneration reactor is provided with a feed port, a discharge port, an air inlet, an air outlet, and a microwave energy feeding port connected to the inside thereof, the feed port is located at the upper side of one end of the microwave activated regeneration reactor, the discharge port is located at the lower side of the other end of the microwave activated regeneration reactor, the air inlet is located at the lower side of the middle part of the microwave activated regeneration reactor, the air outlet is located at the upper side of the microwave activated regeneration reactor and the discharge end, and the microwave energy feeding port is located on both sides or the top of the microwave activated regeneration reactor. When the microwave activated regeneration reactor is used, the air outlet is connected to the induced draft fan, and the pressure in the microwave activated regeneration reactor can be adjusted by adjusting the working frequency of the induced draft fan. The activated regeneration reactor is provided with a manhole structure to facilitate internal maintenance;

[0057] Comparative Example 1:

[0058] A method for regenerating waste coconut shell charcoal by microwave activation comprises the following steps:

[0059] Step 1: Preliminary selection and drying of waste coconut shell charcoal. Waste coconut shell charcoal generally contains a small amount of impurities and a high moisture content. After the preliminary selection, the activated carbon is heated by the heat provided by the air heat pump or electric energy, and dried at 110°C to a waste coconut shell charcoal with a moisture content of 10% and enters the collection hopper;

[0060] Step 2: According to the material state, use a screw conveyor to load all the sieved dry waste coconut shell charcoal in the collection hopper into the microwave activation regeneration reactor;

[0061] Step 3: After the waste coconut shell charcoal enters the microwave activated regeneration reactor, it is fully stirred and mixed in multiple spiral stirring mechanisms, and at the same time, the waste coconut shell charcoal is heated by 650W microwave radiation for 40s and soaked in 0.5mol / L alkali solution for 13 hours, and then treated with 280GHz ultrasound for 25 minutes to evaporate the water adsorbed in the activated carbon, and organic matter with different boiling points is eliminated from the activated carbon matrix in the form of volatilization, decomposition, carbonization, and oxidation as the temperature increases, so that the temperature of the activated carbon in the microwave activated regeneration reactor is increased for activation, and the carbonized matter originally remaining in the micropores of the activated carbon is gasified into carbon dioxide gas under the joint action of microwaves and water vapor, so that the surface of the activated carbon micropores is dredged, and a developed pore structure is formed inside the activated carbon, so that its adsorption performance is restored to become a better regenerated activated carbon;

[0062] Step 5: Then use a water-cooled conveyor to send it to the powder warehouse for storage.

[0063] The regeneration rate of methylene blue from waste coconut shell charcoal was 90.7%.

[0064] Comparative Example 2:

[0065] Step 1: Preliminary selection and drying of waste coconut shell charcoal. Waste coconut shell charcoal generally contains a small amount of impurities and a high moisture content. After the preliminary selection, the activated carbon is heated by the heat provided by the air heat pump or electric energy, and dried at 110°C to a waste coconut shell charcoal with a moisture content of 10% and enters the collection hopper;

[0066] Step 2: According to the material state, use a screw conveyor to load all the sieved dry waste coconut shell charcoal in the collection hopper into the microwave activation regeneration reactor;

[0067] Step 3: After the waste coconut shell charcoal enters the microwave activated regeneration reactor, it is fully stirred and mixed in multiple spiral stirring mechanisms, and the waste coconut shell charcoal is heated by 750W microwave radiation for 45s and soaked in 0.6mol / L alkali solution for 12 hours, and then treated with 280GHz ultrasound for 25 minutes to evaporate the water adsorbed in the activated carbon, and organic matter with different boiling points is eliminated from the activated carbon matrix in the form of volatilization, decomposition, carbonization and oxidation as the temperature increases, so that the temperature of the activated carbon in the microwave activated regeneration reactor is increased for activation, and the carbonized matter originally remaining in the micropores of the activated carbon is gasified into carbon dioxide gas under the joint action of microwave and water vapor, so that the surface of the activated carbon micropores is dredged, and a developed pore structure is formed inside the activated carbon, so that its adsorption performance is restored to become a better regenerated activated carbon;

[0068] Step 5: Then use a water-cooled conveyor to send it to the powder warehouse for storage.

[0069] The regeneration rate of methylene blue detected in waste coconut shell charcoal is 92.5%;

[0070] Comparative Example 3:

[0071] Step 1: Preliminary selection and drying of waste coconut shell charcoal. Waste coconut shell charcoal generally contains a small amount of impurities and a high moisture content. After the preliminary selection, the activated carbon is heated by the heat provided by the air heat pump or electric energy, and dried at 110°C to a waste coconut shell charcoal with a moisture content of 10% and enters the collection hopper;

[0072] Step 2: According to the material state, use a screw conveyor to load all the sieved dry waste coconut shell charcoal in the collection hopper into the microwave activation regeneration reactor;

[0073] Step 3: After the waste coconut shell charcoal enters the microwave activation regeneration reactor, it is fully stirred and mixed in multiple spiral stirring mechanisms, and at the same time, the waste coconut shell charcoal is heated by 680W microwave radiation for 45s and soaked in 0.6mol / L alkali solution for 12 hours, and then treated with 310GHz ultrasound for 25 minutes to evaporate the water adsorbed in the activated carbon, and organic matter with different boiling points is eliminated from the activated carbon matrix in the form of volatilization, decomposition, carbonization, and oxidation as the temperature increases, so that the temperature of the activated carbon in the microwave activation regeneration reactor is increased for activation, and the carbonized matter originally remaining in the micropores of the activated carbon is gasified into carbon dioxide gas under the joint action of microwaves and water vapor, so that the surface of the activated carbon micropores is dredged, and a developed pore structure is formed inside the activated carbon, so that its adsorption performance is restored to become a better regenerated activated carbon;

[0074] Step 5: Then use a water-cooled conveyor to send it to the powder warehouse for storage.

[0075] The regeneration rate of methylene blue from waste coconut shell charcoal was 93.3%.

[0076] The above-mentioned microwave activated regeneration reactor is a horizontal structure as a whole, and a stirring structure is provided inside; the microwave activated regeneration reactor is provided with a feed port, a discharge port, an air inlet, an air outlet, and a microwave energy feeding port connected to the inside thereof, the feed port is located at the upper side of one end of the microwave activated regeneration reactor, the discharge port is located at the lower side of the other end of the microwave activated regeneration reactor, the air inlet is located at the lower side of the middle part of the microwave activated regeneration reactor, the air outlet is located at the upper side of the microwave activated regeneration reactor and the discharge end, and the microwave energy feeding port is located on both sides or the top of the microwave activated regeneration reactor. When the microwave activated regeneration reactor is used, the air outlet is connected to the induced draft fan, and the pressure in the microwave activated regeneration reactor can be adjusted by adjusting the working frequency of the induced draft fan. The activated regeneration reactor is provided with a manhole structure for easy internal maintenance.

[0077] It is worth noting that the method of microwave activation and regeneration of waste coconut shell charcoal achieves the regeneration of waste coconut shell charcoal by soaking the waste coconut shell charcoal in alkali solution under microwave radiation conditions and then performing ultrasonic treatment, thereby obtaining activated carbon with a high methylene blue degradation rate and good regeneration effect. The regeneration rate of waste coconut shell charcoal exceeds 98%, and the regeneration rate can be maintained above 95% after seven cycles of regeneration.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for regenerating waste coconut shell charcoal by microwave activation, characterized in that: The method comprises at least the following steps: Step 1, soaking the waste coconut shell charcoal in an alkaline solution under microwave radiation; Step 2, subjecting the soaked waste coconut shell charcoal to ultrasonic treatment; Step 3: drying the waste coconut shell charcoal after ultrasonic treatment, thus completing the regeneration of the waste coconut shell charcoal.

2. The method for regenerating waste coconut shell charcoal by microwave activation according to claim 1, characterized in that: In step 1, the microwave irradiation conditions are: The microwave irradiation power is 700W-1000W, and the microwave irradiation time is 40-60s.

3. The method for regenerating waste coconut shell charcoal by microwave activation according to claim 1, characterized in that: In step 1, the concentration of the alkali solution is 1 mol / L-5 mol / L.

4. The method for regenerating waste coconut shell charcoal by microwave activation according to claim 1, characterized in that: In step 1, the alkaline substance in the alkali solution is selected from at least one of strong bases; the strong base is KOH.

5. The method for regenerating waste coconut shell charcoal by microwave activation according to claim 1, characterized in that: In step 1, the soaking time is at least 13 hours.

6. The method for regenerating waste coconut shell charcoal by microwave activation according to claim 1, characterized in that: In step 2, during the ultrasonic treatment, the ultrasonic frequency is 300 MHz-300 GHz, and the treatment time is 15 to 30 minutes.

7. The method for regenerating waste coconut shell charcoal by microwave activation according to claim 1, characterized in that: In step 3, the drying temperature is 90-120°C.

8. The method for regenerating waste coconut shell charcoal by microwave activation according to claim 1, characterized in that: The method further comprises: drying the waste coconut shell charcoal before soaking the waste coconut shell charcoal; The requirement for the drying process is that the moisture content of the waste coconut shell charcoal is less than 10%.

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