Activated carbon with high adsorption capacity

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to activated carbon with high adsorption capacity. The chlorella protein nucleus is selected as a carbon source, and through secondary activation, the pore structure of the activated carbon is more developed, and the pore size distribution is more concentrated, so that the activated carbon is endowed with better performance.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to activated carbon with high adsorption capacity. Background Art

[0002] Power plant boilers, also known as "power plant boilers", refer to medium and large boilers in power plants that provide a specified amount and quality of steam to steam turbines. One of the main thermal equipment in thermal power plants. The water quality must meet the relevant requirements of "GB / T12145-2016 Water and Steam Quality for Thermal Power Generators and Steam Power Equipment"; such as iron and copper ion concentrations, TOC (total organic carbon), conductivity, etc. Therefore, under normal circumstances, tap water, river water, and sewage treated water that meets the discharge standards cannot meet the requirements and must be treated before use.

[0003] At present, general power plants use tap water or fresh water as raw water for boiler water preparation, and most of them use fiber filters, ion exchange systems and activated carbon filters alone or in combination to prepare relevant water.

[0004] The activated carbon filter uses adsorption to remove organic matter from the water, and can also remove residual chlorine, grease, colloidal silica and suspended matter in the water, thereby delaying the contamination of the anionic resin and extending the life of the resin.

[0005] However, unmodified activated carbon has few surface active groups and low porosity, resulting in poor adsorption performance. Therefore, modification of activated carbon becomes a necessary step in the further utilization of activated carbon; at the same time, the source of activated carbon also has a significant impact on its performance; so if you want to improve the adsorption performance of activated carbon, there are broad prospects from both the source of materials and modification. Summary of the invention

[0006] The invention provides activated carbon with high adsorption capacity, which has the function of obtaining better adsorption capacity by surface treatment of the activated carbon.

[0007] A high adsorption capacity activated carbon is prepared by the following preparation method, comprising the following steps:

[0008] S1 Carbonization treatment: Take the protein core of Chlorella vulgaris and carbonize it in a low-oxygen or anaerobic environment to obtain biochar A;

[0009] S2 activation: activating the biochar with phosphoric acid, washing and drying to obtain biochar B;

[0010] S3 secondary activation: Biochar B is activated again using water vapor to obtain activated carbon with high adsorption capacity.

[0011] Preferably, in the carbonization treatment of step S1: the temperature is maintained at ≥ 650°C; the holding time is ≥

[0012] 150min.

[0013] Preferably, in the carbonization treatment in step S1, carbonization is performed in a low-oxygen or oxygen-free environment to a nitrogen atmosphere.

[0014] Preferably, in the activation step S2, the phosphoric acid concentration is 75-80wt%, and the impregnation ratio is 6:14-20g / g.

[0015] Preferably, in the activation step S2: the activation temperature is 450-550°C, and the activation time is 70-85min.

[0016] Preferably, in the secondary activation in step S3: the activation temperature is ≥700°C, and the activation time is ≥60min.

[0017] Preferably, in the secondary activation in step S3, the mass ratio of water vapor to activated carbon is 0.5-0.8:1.

[0018] Preferably, after the secondary activation in step S3, washing and drying are performed.

[0019] The present invention uses chlorella protein core as raw material; chlorella has a high organic matter content and can be used as a good raw material for preparing biochar. Carbonization at high temperature can effectively remove volatile substances and increase the carbon content of activated carbon. Carbonization under a nitrogen atmosphere can prevent oxidation and help maintain the structural integrity of biochar.

[0020] The present invention uses phosphoric acid as an activator, which helps to form a developed pore structure. The specific activation temperature and activation time can effectively promote the reaction of phosphoric acid and biochar, forming more micropores and mesopores, thereby improving the adsorption capacity of activated carbon.

[0021] The key point of the present invention is to use water vapor for secondary activation, which can further increase the porosity and surface area of ​​the activated carbon. Under appropriate process conditions, the secondary activation can make the pore structure of the activated carbon more developed and the pore size distribution more concentrated, thereby giving the activated carbon better performance. DETAILED DESCRIPTION

[0022] In order to better understand the present invention, the present invention is further described below in conjunction with specific serial numbers, wherein the terms used in the serial numbers are for describing specific embodiments and do not constitute limitations on the scope of protection of the present invention.

[0023] Specific implementation methods, unless otherwise specified, are conventional experimental methods, and the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0024] The sources of some raw materials used in the present invention are as follows: Table 1:

[0025] Table 1

[0026] name Product Name / Model / Other Name Source (Manufacturer) Chlorella Chlorella pyrenoid Guangzhou Tianjia Biotechnology Co., Ltd. Phosphoric acid Industrial Grade Jinan Shanhai Chemical Technology Co., Ltd. Potassium hydroxide / Jinan Jinhao Chemical Co., Ltd. Sodium hydroxide / Jinan Jinhao Chemical Co., Ltd. oxalic acid / Jinan Jinhao Chemical Co., Ltd. Coconut fiber Commercial waste Vegetable Market Bagasse Commercial waste Vegetable Market Nitrogen / Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0027] Preparation of primary activated carbon

[0028] The preparation of primary activated carbon comprises the following steps:

[0029] 1. Take all the raw materials and cut them into pieces no larger than 3cm 3 small pieces; rinse with distilled water and air-dry for 2 days, place in an oven at 105℃ to dry for 10 hours; then place in a blender and grind through a 30-mesh sieve.

[0030] 2. Place the sieved powder in a muffle furnace and protect it with nitrogen; heat it to 650°C at a rate of 5°C / min and keep it warm for 150 minutes; after natural cooling, take it out and crush it through a 100-mesh sieve.

[0031] 3. The carbonized powder was soaked in 80wt% phosphoric acid with an impregnation ratio of 6:17 (g phosphoric acid: g powder) at 100°C for 60 min;

[0032] 4. After soaking, place the mixture in a muffle furnace, heat it to 500°C at a rate of 5°C / min, and keep it warm for 70 minutes; after natural cooling, wash it repeatedly until it is neutral, then dry and cool it to obtain primary activated carbon.

[0033] Performance test of primary activated carbon

[0034] Test method:

[0035] The adsorption materials prepared in each embodiment and each comparative example were added into the simulated sewage at an addition amount of 30 g / L. After stirring and adsorbing at 60 rpm for 90 min, the corresponding pollutant content in the simulated sewage was detected and the removal rate was calculated.

[0036] The simulated sewage contains:

[0037] Nickel chloride content is 10mg / L

[0038] Zinc chloride content is 50mg / L

[0039] Copper sulfate content is 60mg / L

[0040] The content of iron nitrate is 60ml / L

[0041] At the same time, hydrochloric acid was used to adjust the pH to 5.

[0042] The results are shown in Table 2.

[0043] Table 2 Adsorption results

[0044]

[0045] The results in Table 2 show that although Chlorella 2+ The adsorption rate is slightly lower than that of coconut palm fiber, but its comprehensive adsorption capacity is higher than that of bagasse and coconut palm fiber. It is also possible that this method is not the best choice for coconut palm fiber and bagasse, but this problem is not the research direction of the present invention, so it will not be further studied.

[0046] Experimental study on activation parameters of Chlorella vulgaris

[0047] The preparation method of the once activated activated carbon with Chlorella as the raw material was used as the standard sample, and the following parameter changes were made.

[0048] Chlorella Sample No. 1:

[0049] The difference from the standard sample is that in step 3, the phosphoric acid concentration is 75 wt % and the impregnation ratio is 6:20.

[0050] Chlorella Sample No. 2:

[0051] The difference from the standard sample is that in step 3, the phosphoric acid concentration is 80 wt % and the impregnation ratio is 6:14.

[0052] Chlorella Sample No. 3:

[0053] The difference from the standard sample is that in step 4, the temperature is raised to 450°C and kept at this temperature for 85 minutes.

[0054] Chlorella Sample No. 4:

[0055] The difference from the standard sample is that in step 4, the temperature is raised to 550°C and kept at this temperature for 70 minutes.

[0056] The adsorption test was carried out using the same test method as above, and the results are shown in Table 3.

[0057] Table 3 Adsorption results

[0058]

[0059] The results in Table 3 show that the phosphoric acid concentration in step 3 is 75-80wt%, the impregnation ratio is within 6:14-20; the temperature in step 4 is 450-550°C, and the activation (insulation) time is 70-85°C. Although the adsorption effect has certain fluctuations, it is within a narrow range.

[0060] Preparation of secondary activated carbon

[0061] Example 1: Secondary activation with steam

[0062] The following steps are involved:

[0063] 1. Preheat the activation furnace to 700℃ and then put in the Chlorella standard sample.

[0064] 2. Introduce water vapor and maintain the temperature for 60 minutes; during this process, the amount of water vapor introduced is 0.5 times the mass of the Chlorella standard sample.

[0065] 3. After natural cooling, wash repeatedly until neutral, then dry and cool to obtain secondary activated carbon.

[0066] Example 2: Secondary activation with steam

[0067] The difference from the first embodiment is that in step 1, the activation furnace is preheated to 650°C.

[0068] Example 3: Secondary activation with steam

[0069] The difference from Example 1 is that in step 2, the amount of water vapor introduced is 0.8 times the mass of the Chlorella standard sample.

[0070] Example 4: Secondary activation with steam

[0071] The difference from Example 1 is that in step 2, the amount of water vapor introduced is 1 times the mass of the Chlorella standard sample.

[0072] Example 5: Secondary activation of sodium hydroxide

[0073] The following steps are involved:

[0074] 1. Take a standard sample of Chlorella and add 5.5 mol / L NaOH solution to mix, with a solid-liquid ratio of 20:1 (1 g Chlorella to 20 ml NaOH solution).

[0075] 2. Stir at 60℃ for 4h to mix evenly, wash several times until neutral, then dry in an oven at 105℃, pass through a 100-mesh sieve to obtain secondary activated carbon.

[0076] Example 6: Secondary activation of sodium hydroxide

[0077] The difference from Example 5 is that in step 1, 5.5 mol / L KOH solution is used instead of NaOH solution.

[0078] Example 7 Oxalic acid secondary activation

[0079] The difference from Example 5 is that in step 1, 5.5 mol / L oxalic acid solution is used instead of NaOH solution; and in step 2, the stirring temperature is 100°C.

[0080] The adsorption test was carried out using the same test method as above, and the results are shown in Table 4.

[0081] Table 4 Adsorption results

[0082]

[0083] The results of Table 4 show that not all secondary activation methods can improve adsorption capacity. Overactivation or incorrect test parameters (Examples 2 and 4) may lead to excessive development of the pore structure of activated carbon, thereby forming too many micropores, which may be interconnected to form larger pores, resulting in a reduction in specific surface area. In addition, overactivation may also destroy the skeleton structure of activated carbon and reduce its adsorption capacity. In addition, due to excessive increase in functional groups on the surface of activated carbon, these functional groups may compete with adsorbates for adsorption, thereby reducing the adsorption capacity of activated carbon for specific adsorbates.

[0084] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A method for preparing activated carbon with high adsorption capacity, characterized in that: The following steps are involved: S1 Carbonization treatment: Take the protein core of Chlorella vulgaris and carbonize it in a low-oxygen or anaerobic environment to obtain biochar A; S2 activation: activating the biochar with phosphoric acid, washing and drying to obtain biochar B; S3 secondary activation: biochar B is activated again using water vapor; Obtain activated carbon with high adsorption capacity.

2. The preparation method according to claim 1, characterized in that: In the carbonization treatment of step S1, the temperature is maintained at ≥ 650°C and the insulation time is ≥ 150 min.

3. The preparation method according to claim 1, characterized in that: In the carbonization treatment of step S1: carbonization is carried out in a low oxygen or oxygen-free environment to a nitrogen atmosphere.

4. The preparation method according to claim 1, characterized in that: In the activation step S2, the phosphoric acid concentration is 75-80 wt % and the impregnation ratio is 6:14-20 g / g.

5. The preparation method according to claim 1, characterized in that: In the activation step S2, the activation temperature is 450-550° C. and the activation time is 70-85 min.

6. The preparation method according to claim 1, characterized in that: In the secondary activation of step S3: the activation temperature is ≥700°C, and the activation time is ≥60min.

7. The preparation method according to claim 1, characterized in that: In the step S3 of secondary activation, the mass ratio of water vapor to activated carbon is 0.5-0.8:

1.

8. The preparation method according to claim 1, characterized in that: After the secondary activation in step S3, the product is washed and dried.

9. A high adsorption capacity activated carbon, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 8.

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