Process for recycling and preparing waste activated carbon

Abstract

The invention discloses a preparation process for recycling waste activated carbon. The process comprises the following steps: carrying out a series of treatment and modification on the waste activated carbon, so that the waste activated carbon can be recycled. According to the method, the waste activated carbon is recycled, a series of corresponding treatment processes are executed, and then the treated waste activated carbon is modified by using the modifier, so that the activated carbon with the performance meeting the requirements is obtained; by adopting the method, a large amount of waste activated carbon produced by a factory can be effectively recycled, the treatment cost is reduced, resources can be recycled, and the economic benefit is high.

Description

Technical Field

[0001] The invention relates to the technical field of waste activated carbon treatment, in particular to a waste activated carbon recycling and preparation process. Background Art

[0002] The market demand for activated carbon is increasing day by day, and activated carbon has broad application prospects in the fields of environmental protection and new materials. With the upgrading of activated carbon industry technology, the market has gradually expanded from traditional application fields to environmental protection and new materials.

[0003] The huge sales volume of activated carbon also means an increase in the amount of waste activated carbon. Activated carbon used in industrial production is usually discarded directly, which not only wastes resources but also pollutes the environment. Even if it is treated, it is generally considered a hazardous waste, so its treatment cost is also high.

[0004] If waste activated carbon can be recycled through effective methods, it will not only reduce the cost of hazardous waste treatment, but also increase its reusability, which is beneficial to resource utilization. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation process for recycling waste activated carbon. The present invention effectively recycles waste activated carbon by treating it.

[0006] The technical solution of the present invention is a waste activated carbon recycling and preparation process, characterized in that it comprises the following steps:

[0007] S1. Pretreatment: pretreating the waste activated carbon to reduce the impedance of the activated carbon to obtain product A;

[0008] S2, drying: drying product A to obtain product B;

[0009] S3, crushing: crush product B into small particles to increase specific surface area, and obtain product C;

[0010] S4, modification treatment: surface modification treatment of product C is performed by heat treatment and chemical modifier to obtain product D;

[0011] S5, post-processing: post-process product D to remove impurities to obtain product E;

[0012] S6. Quality inspection: Inspect product E to ensure it meets the requirements.

[0013] In the above-mentioned waste activated carbon recycling and preparation process, the pretreatment described in S1 has the following specific contents:

[0014] The waste activated carbon is screened and cleaned to remove impurities and attachments on the surface.

[0015] In the above-mentioned waste activated carbon recycling and preparation process, the drying described in S2 is specifically as follows:

[0016] Dry product A to remove moisture.

[0017] In the above waste activated carbon recycling and preparation process, the crushing described in S3 is specifically as follows:

[0018] Product B is crushed to reduce its particle size and increase its specific surface area.

[0019] In the above-mentioned waste activated carbon recycling and preparation process, the modification treatment described in S4 is specifically as follows:

[0020] S4.1. Change the pore structure and surface properties of activated carbon through heat treatment and remove volatile substances in activated carbon, thereby improving the pore structure, adsorption performance and conductivity;

[0021] S4.2. By using acidic modifiers, alkaline modifiers, and loaded metals, specific functional groups or metal ions are introduced on the surface of activated carbon to improve its adsorption performance.

[0022] In the above-mentioned waste activated carbon recycling and preparation process, the post-treatment described in S5 is specifically as follows:

[0023] The D product is washed and dried to remove the residual modifier and impurities.

[0024] In the aforementioned waste activated carbon recycling and preparation process, the quality test described in S6 has a detection range of at least specific surface area, porosity, and adsorption performance.

[0025] Compared with the prior art, the present application recycles the waste activated carbon and performs a series of corresponding treatment processes, and then uses a modifier to modify the treated waste activated carbon, thereby obtaining activated carbon with performance that meets the requirements;

[0026] The method can effectively recycle and utilize large quantities of waste activated carbon produced by factories, thereby reducing processing costs and recycling resources, with high economic benefits. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the embodiments, but they are not intended to limit the present invention.

[0028] Embodiment. A waste activated carbon recycling and preparation process comprises the following steps:

[0029] S1. Pretreatment: pretreating the waste activated carbon to reduce the impedance of the activated carbon to obtain product A;

[0030] S2, drying: drying product A to obtain product B;

[0031] S3, crushing: crush product B into small particles to increase specific surface area, and obtain product C;

[0032] S4, modification treatment: surface modification treatment of product C is performed by heat treatment and chemical modifier to obtain product D;

[0033] S5, post-processing: post-process product D to remove impurities to obtain product E;

[0034] S6. Quality inspection: Inspect product E to ensure it meets the requirements.

[0035] The specific contents of the preprocessing described in S1 are as follows:

[0036] The waste activated carbon is screened and cleaned to remove impurities and attachments on the surface.

[0037] The selection criteria are as follows:

[0038] Particle size: According to the process requirements for subsequent reuse, the waste activated carbon is screened according to particle size;

[0039] Strength: Screen out waste activated carbon with higher strength; activated carbon with low strength is easy to break during recycling, producing too much powder, affecting adsorption performance and use effect; compressive strength is required to be greater than a certain value (usually 0.3-0.5MPa);

[0040] Impurity content: Choose waste activated carbon with less impurity content; impurities include dust, metal particles, etc.; the impurity content (mass fraction) should be less than 5%-10% to reduce interference with adsorption performance during reuse.

[0041] The cleaning standards are as follows:

[0042] Residual adsorbate removal rate: After cleaning, the waste activated carbon should remove adsorbed impurities and pollutants as much as possible; for waste activated carbon that adsorbs organic matter, the organic matter removal rate must reach more than 80%-90% to restore its adsorption performance;

[0043] Acidity (pH value): The pH value of the activated carbon after cleaning should be close to neutral (6-8); if the pH value is too high or too low, it will affect the adsorption performance and recycling effect of the activated carbon;

[0044] Surface cleanliness: From the appearance point of view, the surface of the activated carbon after cleaning should have no obvious stains, oil film and other attachments, and the surface should be clean, smooth and uniform in color.

[0045] Screening and cleaning process:

[0046] Mechanical screening: The vibration force generated by the motor of the vibrating screen makes the waste activated carbon reciprocate on the screen surface. Activated carbon particles of different particle sizes will pass through the screen with corresponding apertures to achieve particle size classification; the vibration frequency is about 10-20Hz, and the amplitude is between 3-8mm;

[0047] Combined cleaning: A method combining chemical cleaning and physical cleaning is adopted; first, the cleaning agent is determined according to the composition of impurities on the surface of the waste activated carbon. If the impurity surface contains impurities such as metal oxides and carbonates, 5% dilute hydrochloric acid or 5% dilute sulfuric acid is selected for soaking and cleaning. The soaking time is 2 hours, and the temperature is controlled at about 30°C to dissolve and remove impurities; if the impurities on the surface of the activated carbon are acidic impurities and oil stains, alkaline washing is performed, and 5% sodium hydroxide solution is used for cleaning. The soaking time is about 2 hours, and the temperature is about 30°C to dissolve and remove impurities; then physical cleaning is performed, and hot water (temperature about 70°C) is used to soak the waste activated carbon; part of the adsorbate is desorbed from the surface and pores of the activated carbon, and some water-soluble impurities can be removed at the same time; the soaking time is about 1 hour.

[0048] The drying described in S2 is specifically as follows:

[0049] Use a hot air dryer, place product A into the drying chamber of the dryer, and then let in hot air; the temperature of the hot air is generally controlled at around 110°C, and the drying time is 1-1.5 hours.

[0050] The specific contents of the crushing described in S3 are as follows:

[0051] Use a jaw crusher to squeeze and crush product B; feed product B into the feed port of the jaw crusher, and the movable jaw plate, driven by the eccentric shaft, periodically approaches and moves away from the static jaw plate to squeeze and crush it.

[0052] The modification treatment described in S4 is specifically as follows:

[0053] S4.1. Change the pore structure and surface properties of activated carbon through heat treatment and remove volatile substances in activated carbon, thereby improving the pore structure, adsorption performance and conductivity;

[0054] S4.2. By using acidic modifiers, alkaline modifiers, and loaded metals, specific functional groups or metal ions are introduced on the surface of activated carbon to improve its adsorption performance.

[0055] S4.1 The specific contents are:

[0056] By using the continuous rotation of the rotary kiln to make the incoming materials experience different temperature zones and reaction stages in the furnace, the coke is activated at high temperature using superheated steam, and the purpose of pore creation and opening is achieved through the ablation of carbon pore intervals and the combustion and removal of tar. The pore structure of activated carbon can be effectively changed and the number of pores can be increased, thereby improving its specific surface area and adsorption capacity.

[0057] S4.2 The specific contents are:

[0058] Acidic modifier: A 30% nitric acid solution and a 35% sulfuric acid solution are mixed in a volume ratio of 1:2 to prepare a modifier, which is used for waste activated carbon with a large specific surface area and the original performance needs to be retained; a 30% nitric acid solution and a 35% sulfuric acid solution are mixed in a volume ratio of 3:2 to prepare a modifier, which is used to remove a large amount of organic matter adsorbed in waste activated carbon and restore the adsorption of activated carbon;

[0059] Alkaline modifier: A 3 mol / L sodium hydroxide solution and a 10% ammonia solution are mixed in a volume ratio of 1:3 to prepare a modifier, which is used to remove the acidic groups on the surface of activated carbon and increase the alkaline groups, which is beneficial to the pore expansion of the activated carbon surface, improve the pore structure, and enhance the adsorption performance;

[0060] Loading metal: Use copper nitrate (Cu(NO3)2) with a concentration of 0.5 mol / L as the raw material for loading metallic copper. Activated carbon loaded with copper has applications in catalytic reactions, gas adsorption, etc. Copper ions can interact with the functional groups on the surface of activated carbon to improve the adsorption performance and catalytic activity of activated carbon;

[0061] Addition ratio: the ratio of acidic modifier to sample volume mass ratio (mL / g) is 4:1; the ratio of alkaline modifier to sample volume mass ratio (mL / g) is 3:1, and the ratio of loaded metal copper nitrate solution to activated carbon is 1:10;

[0062] Treatment process: Acid modification: Place the pretreated activated carbon into an acidic modifier solution with a solid-liquid ratio (ratio of activated carbon mass to modifier solution volume) of 1:4. Soak for about 5 hours at a temperature of about 60°C, filter the modified activated carbon from the solution, rinse repeatedly with deionized water until the pH value of the rinse liquid is close to neutral, and then dry the activated carbon in an oven at a temperature of about 100°C for 8 hours;

[0063] Alkaline modification: Place the pretreated activated carbon into an alkaline modifier solution with a solid-liquid ratio (ratio of activated carbon mass to modifier solution volume) of 1:3. Soak for about 4 hours at a temperature of about 50°C, filter out the activated carbon, rinse with deionized water until neutral, and then dry the activated carbon in an oven at a temperature of about 100°C for 8 hours;

[0064] Metal loading: immerse the activated carbon in a 0.5 mol / L copper nitrate solution with a solid-liquid ratio (ratio of activated carbon mass to modifier solution volume) of 10:1, soak it at a temperature of about 50°C for about 6 hours, filter out the metal-loaded activated carbon, rinse it with deionized water to remove the metal ions not loaded on the surface, and then dry it at 100°C for 10 hours.

[0065] The specific contents of the post-processing described in S5 are as follows:

[0066] The D product is washed and dried to remove the residual modifier and impurities.

[0067] The quality inspection described in S6 has a detection range of at least specific surface area, porosity, and adsorption performance.

[0068] Specific surface area detection: Grind the modified waste activated carbon sample to a uniform particle size within a certain particle size range so that the gas can fully contact the surface of the sample. Dry the ground sample at 100℃-150℃ for about 2 hours to remove the moisture and other volatile substances adsorbed in the sample. Prepare a specific surface area analyzer, load the sample to be tested into a closed test tube sample tube of a certain volume, and inject a certain pressure (relative pressure of about 0.25Mpa) of adsorbate gas nitrogen into the sample tube. Determine the adsorption amount of the adsorbate gas nitrogen by the sample to be tested based on the pressure / weight change before and after adsorption, and then calculate the specific surface area. By gradually adding and withdrawing the adsorbate gas, the adsorption isotherm and desorption isotherm are obtained to analyze the specific surface area and pore structure of the sample.

[0069] Porosity test: The waste activated carbon sample is made into a suitable shape and size, dried to remove moisture and other volatile substances, and placed in the sample cell of the mercury intrusion instrument. Mercury is injected into the pores of the sample under a certain pressure. As the pressure increases, mercury will gradually fill into pores of different sizes. By measuring the relationship between the volume of injected mercury and pressure, information such as the pore size distribution and pore volume of the sample can be obtained, and then the porosity can be calculated.

[0070] Adsorption performance test: prepare 1 mol / L iodine standard solution, potassium iodide solution, sodium thiosulfate standard solution and other reagents, weigh a certain amount of modified waste activated carbon sample, grind it to a uniform particle size, put the sample into an iodine adsorption bottle, add an appropriate amount of iodine standard solution and potassium iodide solution, and perform adsorption reaction at a certain temperature and time (room temperature around 20°C, duration around 30 minutes) to allow iodine molecules to be adsorbed by activated carbon. After the adsorption reaction is completed, titrate the remaining iodine with sodium thiosulfate standard solution, and calculate the amount of iodine adsorbed by activated carbon based on the consumption of the titration, thereby obtaining the iodine adsorption value.

[0071] The effect of this application is verified by the following experiments

[0072] Experimental methods:

[0073] The modified activated carbon samples were pretreated to remove moisture and other impurities adsorbed on the surface. The treated samples were placed in a nitrogen adsorption instrument and subjected to a nitrogen adsorption experiment within a set temperature and pressure range (the temperature was set at around -200°C and the relative pressure was around 0.25 MPa). The instrument automatically recorded the adsorption data under different pressures and obtained results such as specific surface area and pore size distribution through software analysis.

[0074] Weigh a certain amount of modified activated carbon sample, put it into an iodine adsorption bottle, add 1 mol / L iodine standard solution and potassium iodide solution, and carry out adsorption reaction at a specific temperature and time (room temperature around 20°C, duration around 30 minutes). After the adsorption is completed, titrate the remaining iodine with sodium thiosulfate standard solution to calculate the iodine adsorption value of the activated carbon.

[0075] Specific surface area and pore structure detection: Use nitrogen adsorption method to detect, pre-treat the modified activated carbon sample to remove moisture and other impurities adsorbed on the surface, put the treated sample into nitrogen adsorption instrument, and conduct nitrogen adsorption experiment within the set temperature and pressure range (temperature set at about -200 ° C, relative pressure at about 0.25 MPa). The instrument automatically records the adsorption data under different pressures, and obtains the specific surface area and pore size distribution results through software analysis.

[0076] Experimental principle: At low temperatures (liquid nitrogen temperature -196°C), the surface of activated carbon will adsorb nitrogen. By measuring the amount of nitrogen adsorbed under different pressures, the adsorption isotherm can be obtained. Based on the data of the adsorption isotherm, the specific surface area of ​​the activated carbon can be calculated using the special BET equation. At the same time, pore structure information such as pore size distribution can also be analyzed.

[0077] Adsorption performance test: Weigh a certain amount of modified activated carbon sample, put it into an iodine adsorption bottle, add 1 mol / L iodine standard solution and potassium iodide solution, and carry out adsorption reaction at a specific temperature and time (room temperature around 20°C, duration around 30 minutes). After the adsorption is completed, titrate the remaining iodine with sodium thiosulfate standard solution to calculate the iodine adsorption value of the activated carbon.

[0078] Experimental principle: Iodine molecules will be adsorbed by activated carbon under certain conditions. By measuring the amount of iodine adsorbed by activated carbon, its adsorption capacity for small molecules can be reflected.

Claims

1. A waste activated carbon recycling and preparation process, characterized in that: The steps include: S1. Pretreatment: pretreating the waste activated carbon to reduce the impedance of the activated carbon to obtain product A; S2, drying: drying product A to obtain product B; S3, crushing: crush product B into small particles to increase specific surface area, and obtain product C; S4, modification treatment: surface modification treatment of product C is performed by heat treatment and chemical modifier to obtain product D; S5, post-processing: post-process product D to remove impurities to obtain product E; S6. Quality inspection: Inspect product E to ensure it meets the requirements.

2. A waste activated carbon recycling and preparation process according to claim 1, characterized in that: The specific contents of the preprocessing described in S1 are as follows: The waste activated carbon is screened and cleaned to remove impurities and attachments on the surface.

3. The waste activated carbon recycling and preparation process according to claim 1, characterized in that: The drying described in S2 is specifically as follows: Dry product A to remove moisture.

4. The waste activated carbon recycling and preparation process according to claim 1, characterized in that: The specific contents of the crushing described in S3 are as follows: Product B is crushed to reduce its particle size and increase its specific surface area.

5. The waste activated carbon recycling and preparation process according to claim 1, characterized in that: The modification treatment described in S4 is specifically as follows: S4.

1. Change the pore structure and surface properties of activated carbon through heat treatment and remove volatile substances in activated carbon, thereby improving the pore structure, adsorption performance and conductivity; S4.

2. By using acidic modifiers, alkaline modifiers, and loaded metals, specific functional groups or metal ions are introduced on the surface of activated carbon to improve its adsorption performance.

6. The waste activated carbon recycling and preparation process according to claim 1, characterized in that: The specific contents of the post-processing described in S5 are as follows: The D product is washed and dried to remove the residual modifier and impurities.

7. The waste activated carbon recycling process according to claim 1, characterized in that: The quality inspection described in S6 has a detection range of at least specific surface area, porosity, and adsorption performance.