A spina date shell activated carbon adsorbent and a preparation method thereof
Patent Information
- Application Number
- CN202611118646.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-27
- Publication Date
- 2026-08-28
AI Technical Summary
目前活性炭的制备方法通常采用化学活化法和物理活化法，化学活化法需使用大量的磷酸、氯化锌等化学药剂，氯化锌法存在重金属残留、腐蚀设备、污染环境等缺陷；常规磷酸活化法所得产品以微孔为主，对较大分子污染物或特定重金属离子的吸附容量和选择性不理想
本发明提供了一种酸枣壳活性炭吸附剂及其制备方法。以农业废弃物酸枣壳为碳源制备活性炭，制备MA-酸枣壳活性炭与改性香草醛，共价连接，形成表面含硫脲、席夫碱等基团的吸附剂，增强了对重金属离子的吸附容量。本发明利用硝酸对活性炭进行氧化预处理，在炭表面可控引入羟基等含氧官能团，为后续硅烷偶联剂的锚定提供了充足的活性羟基位点。本发明采用3-氯丙基三甲氧基硅烷对预处理活性炭进行硅烷化改性，硅烷偶联剂水解后与表面羟基缩合，将反应性氯丙基共价连接于活性炭表面；再通过氯丙基与三聚氰胺上氨基的亲核取代反应，引入氨基，制得MA-酸枣壳活性炭。三聚氰胺分子上丰富的氨基基团能与重金属离子螯合物，增强化学吸附能力。本发明以香草醛与1,3-二氨基硫脲为原料缩合，构建含硫脲和席夫碱结构的香草醛-氨基硫脲中间体，随后利用中间体酚羟基与环氧氯丙烷的氯取代基团反应，得到端环氧基改性香草醛，具有硫脲基团、席夫碱基团和环氧端基，硫脲中的硫、氮原子及席夫碱的亚胺氮原子均为配位原子，能与重金属离子形成配合物，端环氧基可为后续分子共价接枝提供反应活性。本发明通过改性香草醛的端环氧基与MA-酸枣壳活性炭表面的氨基发生反应，将改性香草醛以共价键形式接枝于活性炭，构建出表面同时富含氨基、硫脲、席夫碱等多种配位基团的功能化吸附剂。增强对重金属离子的亲和力和吸附性，共价连接方式牢固，提升吸附剂循环稳定性。
Smart Images
Figure CN122644034A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of activated carbon adsorbent technology, specifically to a jujube shell activated carbon adsorbent and its preparation method. Background Technology
[0002] Activated carbon, due to its large specific surface area, well-developed pores, and abundant surface functional groups, is widely used in water treatment, air purification, and chemical separation. Current activated carbon mainly uses coal, wood, and coconut shells as raw materials. Jujube shells, a waste product generated during jujube processing, mainly consist of cellulose, hemicellulose, and lignin, and have a high fixed carbon content, making them an excellent raw material for preparing biomass activated carbon. However, current technologies for their resource utilization are limited. Current activated carbon preparation methods typically employ chemical activation and physical activation methods. Chemical activation requires large amounts of chemical agents such as phosphoric acid and zinc chloride. The zinc chloride method suffers from drawbacks such as heavy metal residues, equipment corrosion, and environmental pollution. Conventional phosphoric acid activation yields products primarily with micropores, resulting in unsatisfactory adsorption capacity and selectivity for larger molecular pollutants or specific heavy metal ions. Furthermore, traditional processes rarely modify the activated carbon, leading to insufficient surface chemical adsorption sites. Physical activation requires large amounts of high-temperature steam or flue gas, resulting in high energy consumption, long processing times, and low product yields. Therefore, it is necessary to develop a novel jujube shell activated carbon with excellent adsorption performance and its preparation method. Summary of the Invention
[0003] To address the shortcomings of existing technologies, this invention proposes a jujube shell activated carbon adsorbent and its preparation method.
[0004] This invention is achieved through the following technical solution: A jujube shell activated carbon adsorbent is prepared by means of the following components in parts by weight: 10-15 parts of MA-jujube shell activated carbon and 5-8 parts of modified vanillin.
[0005] Furthermore, the preparation method of the MA-jujube shell activated carbon includes the following steps: L1. Wash the jujube shells to remove impurities, dry them at 105-110℃, pulverize them through a 60-80 mesh sieve to obtain jujube shell powder, place the jujube shell powder in a tube furnace, heat it to 450-500℃ at a heating rate of 10℃ / min under a nitrogen atmosphere of 200 mL / min, and keep it at a constant temperature for 2 h to obtain pre-carbonized material; L2. Mix KOH with the pre-carbonized material obtained in step L1, add deionized water and mix well. Stir at 500-600 rpm for 4-5 h, dry at 110℃, place in a tube furnace, heat to 800-900℃ at a heating rate of 5℃ / min under nitrogen protection of 200 mL / min, hold for 2 h, wash with 1 M HCl solution and deionized water until neutral, and dry at 110℃ to obtain jujube shell activated carbon; L3. Take the jujube shell activated carbon obtained in step L2 and add it to a 15-20 wt% nitric acid solution. Reflux at 80℃ for 3-4 h, filter, add the filter cake to distilled water and boil for 10-15 min, filter, repeat the operation 4 times, and dry at 105-110℃ to obtain pretreated activated carbon. L4. Disperse the pretreated activated carbon obtained in step L3 in anhydrous ethanol, add 3-chloropropyltrimethoxysilane, react at 80-90℃ for 0.5 h, then add 1 mol / L hydrochloric acid solution, continue the reaction for 4-5 h, cool to room temperature, filter, wash the filter cake with anhydrous ethanol and deionized water, and vacuum dry to obtain chlorinated activated carbon. L5. Melamine (MA) was added to toluene to obtain a melamine dispersion. The chlorinated activated carbon obtained in step L4 was dispersed in toluene to obtain a chlorinated activated carbon dispersion. The chlorinated activated carbon dispersion was added to the melamine dispersion, and triethylamine was added dropwise under stirring. The reaction was carried out at 100°C for 48 h. The mixture was filtered, the filter cake was washed until neutral, and then dried under vacuum to obtain MA-jujube shell activated carbon.
[0006] Furthermore, in step L2, the mass ratio of KOH to pre-carbonized material is 2-3:1.
[0007] Furthermore, in step L2, the mass concentration of the pre-carbonized material in deionized water is 20-30 mg / mL.
[0008] Furthermore, in step L3, the mass concentration of the jujube shell activated carbon in the nitric acid solution is 20-30 mg / mL.
[0009] Furthermore, in step L4, the mass concentration of the pretreated activated carbon in anhydrous ethanol is 15-20 mg / mL.
[0010] Further, in step L4, the ratio of 3-chloropropyltrimethoxysilane to pretreated activated carbon is 1-1.5 mL:1 g.
[0011] Furthermore, in step L4, the volume ratio of the hydrochloric acid solution to anhydrous ethanol is 1:50.
[0012] Furthermore, in step L5, the mass concentration of melamine in toluene is 4-6 mg / mL.
[0013] Furthermore, in step L5, the mass concentration of the chlorinated activated carbon in toluene is 4-6 mg / mL.
[0014] Furthermore, in step L5, the mass ratio of melamine to chlorinated activated carbon is 1-1.2:1.
[0015] Furthermore, in step L5, the ratio of melamine to triethylamine is 1 g: 1.1-1.2 mL.
[0016] Furthermore, the method for preparing the modified vanillin includes the following steps: V1. Vanillin was dissolved in anhydrous ethanol to obtain a vanillin solution. 1,3-Diaminothiourea was dissolved in anhydrous ethanol to obtain a 1,3-diaminothiourea solution. Under nitrogen protection, the vanillin solution was added to the 1,3-diaminothiourea solution, and the mixture was stirred and refluxed at 80°C for 3-4 h. After cooling to room temperature, the mixture was filtered, the filter cake was washed with ethanol, and dried to obtain vanillin-aminothiourea. V2. The vanillin-aminothiourea, epichlorohydrin and tetrabutylammonium bromide obtained in step V1 were mixed and stirred at 80-90℃ for 6-8 h under N2 atmosphere. After cooling to room temperature, 20wt% NaOH aqueous solution was added dropwise and the reaction was continued for 5-6 h. After the reaction was completed, the mixture was washed with saturated sodium chloride solution and deionized water. The organic phase was dried with anhydrous sodium sulfate, and epichlorohydrin was removed by rotary evaporation. The precipitate was precipitated in diethyl ether and dried under vacuum to obtain modified vanillin.
[0017] Furthermore, in step V1, the concentration of vanillin in anhydrous ethanol is 1 mmol / mL.
[0018] Further, in step V1, the molar concentration of the 1,3-diaminothiourea in anhydrous ethanol is 0.5 mmol / mL.
[0019] Further, in step V1, the molar ratio of vanillin to 1,3-diaminothiourea is 2:1.
[0020] Further, in step V2, the ratio of vanillin-aminothiourea, epichlorohydrin, tetrabutylammonium bromide, and NaOH solution is 50 g: 200-250 mL: 2-3 g: 200 mL.
[0021] Furthermore, the present invention also provides a method for preparing the jujube shell activated carbon adsorbent, comprising the following steps: S1. Under nitrogen protection, modified vanillin and MA-jujube shell activated carbon were added to DMF and mixed well. Triethylamine was added and the mixture was reacted at 70-80℃ for 6-8 h. S2. After the reaction in step S1 is completed, cool to room temperature, filter, wash the filter cake with DMF, anhydrous ethanol and deionized water, and dry under vacuum to obtain jujube shell activated carbon adsorbent.
[0022] Further, in step S1, the mass concentration of the MA-jujube shell activated carbon in DMF is 10-20 mg / mL.
[0023] Further, in step S1, the ratio of triethylamine to modified vanillin is 0.04-0.06 mL:1 g.
[0024] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a jujube shell activated carbon adsorbent and its preparation method. Activated carbon is prepared using agricultural waste jujube shells as the carbon source. MA-jujube shell activated carbon is then prepared and covalently linked with modified vanillin to form an adsorbent with surface-containing thiourea and Schiff base groups, enhancing its adsorption capacity for heavy metal ions. This invention utilizes nitric acid for oxidative pretreatment of the activated carbon, controllably introducing oxygen-containing functional groups such as hydroxyl groups onto the carbon surface, providing sufficient active hydroxyl sites for subsequent anchoring of silane coupling agents. This invention employs 3-chloropropyltrimethoxysilane to silanize the pretreated activated carbon. After hydrolysis, the silane coupling agent condenses with surface hydroxyl groups, covalently linking reactive chloropropyl groups to the activated carbon surface. Then, through a nucleophilic substitution reaction between the chloropropyl groups and the amino groups on melamine, amino groups are introduced, yielding MA-jujube shell activated carbon. The abundant amino groups on the melamine molecule can chelate with heavy metal ions, enhancing its chemical adsorption capacity. This invention uses vanillin and 1,3-diaminothiourea as raw materials for condensation to construct a vanillin-aminothiourea intermediate containing thiourea and Schiff base structures. Subsequently, the phenolic hydroxyl group of the intermediate reacts with the chlorinated substituent group of epichlorohydrin to obtain terminally epoxy-modified vanillin, possessing thiourea groups, Schiff base groups, and epoxy end groups. The sulfur and nitrogen atoms in the thiourea and the imine nitrogen atom in the Schiff base are all coordinating atoms, capable of forming complexes with heavy metal ions. The terminal epoxy groups provide reactivity for subsequent covalent grafting. This invention further utilizes the reaction of the terminal epoxy groups of modified vanillin with the amino groups on the surface of MA-jujube shell activated carbon to covalently graft the modified vanillin onto the activated carbon, constructing a functionalized adsorbent with a surface simultaneously rich in multiple coordinating groups such as amino groups, thiourea groups, and Schiff bases. This enhances the affinity and adsorption capacity for heavy metal ions, and the covalent connection is robust, improving the adsorbent's cycle stability. Attached Figure Description
[0025] Figure 1 The adsorption performance of the adsorbents described in Examples 1-3 and Comparative Examples 1-3 of this invention; Figure 2 The cycling performance of the adsorbents described in Examples 1-3 and Comparative Examples 1-3 of this invention is shown. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. However, this invention is not limited to the following embodiments. It should be noted that, unless otherwise specified, all chemical reagents involved in this invention are purchased through commercial channels.
[0027] Example 1: A jujube shell activated carbon adsorbent, the raw materials for preparation include the following components in parts by weight: 15 parts of MA-jujube shell activated carbon and 8 parts of modified vanillin.
[0028] The preparation method of MA-jujube shell activated carbon includes the following steps: L1. Wash the jujube shells to remove impurities, dry them at 110℃, pulverize them through an 80-mesh sieve to obtain jujube shell powder, place the jujube shell powder in a tube furnace, heat it to 500℃ at a heating rate of 10℃ / min under a nitrogen atmosphere of 200 mL / min, and keep it at a constant temperature for 2 h to obtain pre-carbonized material. L2. KOH was mixed with the pre-carbonized material obtained in step L1 at a mass ratio of 3:1. The mixture was added to deionized water and mixed well. The mass concentration of the pre-carbonized material in the deionized water was 30 mg / mL. The mixture was stirred at 600 rpm for 5 h and dried at 110 °C. After drying, the mixture was placed in a tube furnace and heated to 900 °C at a heating rate of 5 °C / min under nitrogen protection at a rate of 200 mL / min. The temperature was maintained for 2 h. The mixture was washed with 1 M HCl solution and deionized water until neutral and dried at 110 °C to obtain jujube shell activated carbon. L3. Take the jujube shell activated carbon obtained in step L2 and add it to a 20wt% nitric acid solution. The mass concentration of the jujube shell activated carbon in the nitric acid solution is 30 mg / mL. Reflux at 80℃ for 4 h, filter, add the filter cake to distilled water and boil for 15 min, filter, repeat the operation 4 times, and dry at 110℃ to obtain pretreated activated carbon. L4. Disperse the pretreated activated carbon obtained in step L3 in anhydrous ethanol. The mass concentration of the pretreated activated carbon in anhydrous ethanol is 20 mg / mL. Add 3-chloropropyltrimethoxysilane. The volume ratio of 3-chloropropyltrimethoxysilane to pretreated activated carbon is 1.5 mL:1 g. React at 90℃ for 0.5 h. Then add 1 mol / L hydrochloric acid solution. The volume ratio of hydrochloric acid solution to anhydrous ethanol is 1:50. Continue to react for 5 h. Cool to room temperature, filter, wash the filter cake with anhydrous ethanol and deionized water, and dry under vacuum to obtain chlorinated activated carbon. L5. Melamine (MA) was added to toluene at a mass concentration of 6 mg / mL to obtain a melamine dispersion. The chlorinated activated carbon obtained in step L4 was dispersed in toluene at a mass concentration of 6 mg / mL to obtain a chlorinated activated carbon dispersion. The mass ratio of melamine to chlorinated activated carbon was 1.2:1. The chlorinated activated carbon dispersion was added to the melamine dispersion, and triethylamine was added dropwise with stirring at a mass ratio of 1 g:1.2 mL. The reaction was carried out at 100℃ for 48 h. The mixture was then filtered, the filter cake was washed until neutral, and dried under vacuum to obtain MA-jujube shell activated carbon.
[0029] The preparation method of modified vanillin includes the following steps: V1. Vanillin was dissolved in anhydrous ethanol to obtain a vanillin solution with a concentration of 1 mmol / mL. 1,3-Diaminothiourea was dissolved in anhydrous ethanol to obtain a 1,3-diaminothiourea solution with a concentration of 0.5 mmol / mL. The molar ratio of vanillin to 1,3-diaminothiourea was 2:1. Under nitrogen protection, the vanillin solution was added to the 1,3-diaminothiourea solution, and the mixture was stirred and refluxed at 80°C for 4 h. After cooling to room temperature, the mixture was filtered, the filter cake was washed with ethanol, and dried to obtain vanillin-aminothiourea. V2. The vanillin-aminothiourea, epichlorohydrin and tetrabutylammonium bromide obtained in step V1 were mixed and stirred at 90°C for 8 h under N2 atmosphere. After cooling to room temperature, 20 wt% NaOH aqueous solution was added dropwise. The ratio of vanillin-aminothiourea, epichlorohydrin, tetrabutylammonium bromide and NaOH solution was 50 g:250 mL:3 g:200 mL. The reaction was continued for 6 h. After the reaction was completed, the mixture was washed with saturated sodium chloride solution and deionized water. The organic phase was dried with anhydrous sodium sulfate, and epichlorohydrin was removed by rotary evaporation. The precipitate was precipitated in diethyl ether and dried under vacuum to obtain modified vanillin.
[0030] This embodiment also provides a method for preparing the jujube shell activated carbon adsorbent, including the following steps: S1. Under nitrogen protection, modified vanillin and MA-jujube shell activated carbon were added to DMF and mixed well. The mass concentration of MA-jujube shell activated carbon in DMF was 20 mg / mL. Triethylamine was added, and the ratio of triethylamine to modified vanillin was 0.06 mL: 1 g. The reaction was carried out at 80℃ for 8 h. S2. After the reaction in step S1 is completed, cool to room temperature, filter, wash the filter cake with DMF, anhydrous ethanol and deionized water, and dry under vacuum to obtain jujube shell activated carbon adsorbent.
[0031] Example 2: A jujube shell activated carbon adsorbent, the raw materials for preparation include the following components in parts by weight: 10 parts of MA-jujube shell activated carbon and 5 parts of modified vanillin.
[0032] The preparation method of MA-jujube shell activated carbon includes the following steps: L1. Wash the jujube shells to remove impurities, dry them at 105℃, pulverize them through a 60-mesh sieve to obtain jujube shell powder, place the jujube shell powder in a tube furnace, heat it to 450℃ at a heating rate of 10℃ / min under a nitrogen atmosphere of 200 mL / min, and keep it at a constant temperature for 2 h to obtain pre-carbonized material. L2. KOH was mixed with the pre-carbonized material obtained in step L1 at a mass ratio of 2:1. The mixture was added to deionized water and mixed well. The mass concentration of the pre-carbonized material in the deionized water was 20 mg / mL. The mixture was stirred at 500 rpm for 4 h and dried at 110 °C. After drying, the mixture was placed in a tube furnace and heated to 800 °C at a heating rate of 5 °C / min under nitrogen protection at a rate of 200 mL / min. The temperature was maintained for 2 h. The mixture was washed with 1 M HCl solution and deionized water until neutral and dried at 110 °C to obtain jujube shell activated carbon. L3. Take the jujube shell activated carbon obtained in step L2 and add it to a 15wt% nitric acid solution. The mass concentration of the jujube shell activated carbon in the nitric acid solution is 20 mg / mL. Reflux at 80℃ for 3 h, filter, add the filter cake to distilled water and boil for 10 min, filter, repeat the operation 4 times, and dry at 105℃ to obtain pretreated activated carbon. L4. Disperse the pretreated activated carbon obtained in step L3 in anhydrous ethanol. The mass concentration of the pretreated activated carbon in anhydrous ethanol is 15 mg / mL. Add 3-chloropropyltrimethoxysilane. The volume ratio of 3-chloropropyltrimethoxysilane to pretreated activated carbon is 1 mL:1 g. React at 80℃ for 0.5 h. Then add 1 mol / L hydrochloric acid solution. The volume ratio of hydrochloric acid solution to anhydrous ethanol is 1:50. Continue to react for 4 h. Cool to room temperature, filter, wash the filter cake with anhydrous ethanol and deionized water, and vacuum dry to obtain chlorinated activated carbon. L5. Melamine (MA) was added to toluene at a mass concentration of 4 mg / mL to obtain a melamine dispersion. The chlorinated activated carbon obtained in step L4 was dispersed in toluene at a mass concentration of 4 mg / mL to obtain a chlorinated activated carbon dispersion. The mass ratio of melamine to chlorinated activated carbon was 1:1. The chlorinated activated carbon dispersion was added to the melamine dispersion, and triethylamine was added dropwise with stirring at a mass ratio of 1 g:1.1 mL. The reaction was carried out at 100℃ for 48 h. The mixture was then filtered, the filter cake was washed until neutral, and dried under vacuum to obtain MA-jujube shell activated carbon.
[0033] The preparation method of modified vanillin includes the following steps: V1. Vanillin was dissolved in anhydrous ethanol to obtain a vanillin solution with a concentration of 1 mmol / mL. 1,3-Diaminothiourea was dissolved in anhydrous ethanol to obtain a 1,3-diaminothiourea solution with a concentration of 0.5 mmol / mL. The molar ratio of vanillin to 1,3-diaminothiourea was 2:1. Under nitrogen protection, the vanillin solution was added to the 1,3-diaminothiourea solution, and the mixture was stirred and refluxed at 80°C for 3 h. After cooling to room temperature, the mixture was filtered, the filter cake was washed with ethanol, and dried to obtain vanillin-aminothiourea. V2. The vanillin-aminothiourea, epichlorohydrin and tetrabutylammonium bromide obtained in step V1 were mixed and stirred at 80°C for 6 h under N2 atmosphere. After cooling to room temperature, 20 wt% NaOH aqueous solution was added dropwise. The ratio of vanillin-aminothiourea, epichlorohydrin, tetrabutylammonium bromide and NaOH solution was 50 g:200 mL:2 g:200 mL. The reaction was continued for 5 h. After the reaction was completed, the mixture was washed with saturated sodium chloride solution and deionized water. The organic phase was dried with anhydrous sodium sulfate, and epichlorohydrin was removed by rotary evaporation. The precipitate was precipitated in diethyl ether and dried under vacuum to obtain modified vanillin.
[0034] This embodiment also provides a method for preparing the jujube shell activated carbon adsorbent, including the following steps: S1. Under nitrogen protection, modified vanillin and MA-jujube shell activated carbon were added to DMF and mixed well. The mass concentration of MA-jujube shell activated carbon in DMF was 10 mg / mL. Triethylamine was added, and the ratio of triethylamine to modified vanillin was 0.04 mL: 1 g. The reaction was carried out at 70℃ for 6 h. S2. After the reaction in step S1 is completed, cool to room temperature, filter, wash the filter cake with DMF, anhydrous ethanol and deionized water, and dry under vacuum to obtain jujube shell activated carbon adsorbent.
[0035] Example 3: A jujube shell activated carbon adsorbent, the raw materials for preparation include the following components in parts by weight: 12 parts of MA-jujube shell activated carbon and 6 parts of modified vanillin.
[0036] The preparation method of MA-jujube shell activated carbon includes the following steps: L1. Wash the jujube shells to remove impurities, dry them at 108℃, pulverize them through a 70-mesh sieve to obtain jujube shell powder, place the jujube shell powder in a tube furnace, heat it to 480℃ at a heating rate of 10℃ / min under a nitrogen atmosphere of 200 mL / min, and keep it at a constant temperature for 2 h to obtain pre-carbonized material. L2. KOH was mixed with the pre-carbonized material obtained in step L1 at a mass ratio of 2.5:1. The mixture was then added to deionized water and mixed thoroughly. The mass concentration of the pre-carbonized material in the deionized water was 25 mg / mL. The mixture was stirred at 550 rpm for 4.5 h and dried at 110 °C. After drying, the mixture was placed in a tube furnace and heated to 850 °C at a heating rate of 5 °C / min under nitrogen protection at 200 mL / min. The temperature was maintained for 2 h. The mixture was washed with 1 M HCl solution and deionized water until neutral and dried at 110 °C to obtain jujube shell activated carbon. L3. Take the jujube shell activated carbon obtained in step L2 and add it to an 18wt% nitric acid solution. The mass concentration of the jujube shell activated carbon in the nitric acid solution is 25 mg / mL. Reflux at 80℃ for 3.5 h, filter, add the filter cake to distilled water and boil for 12 min, filter, repeat the operation 4 times, and dry at 108℃ to obtain pretreated activated carbon. L4. Disperse the pretreated activated carbon obtained in step L3 in anhydrous ethanol. The mass concentration of the pretreated activated carbon in anhydrous ethanol is 18 mg / mL. Add 3-chloropropyltrimethoxysilane. The volume ratio of 3-chloropropyltrimethoxysilane to pretreated activated carbon is 1.2 mL:1 g. React at 85℃ for 0.5 h. Then add 1 mol / L hydrochloric acid solution. The volume ratio of hydrochloric acid solution to anhydrous ethanol is 1:50. Continue to react for 4.5 h. Cool to room temperature, filter, wash the filter cake with anhydrous ethanol and deionized water, and vacuum dry to obtain chlorinated activated carbon. L5. Melamine (MA) was added to toluene at a mass concentration of 5 mg / mL to obtain a melamine dispersion. The chlorinated activated carbon obtained in step L4 was dispersed in toluene at a mass concentration of 5 mg / mL to obtain a chlorinated activated carbon dispersion. The mass ratio of melamine to chlorinated activated carbon was 1.1:1. The chlorinated activated carbon dispersion was added to the melamine dispersion, and triethylamine was added dropwise with stirring at a mass ratio of 1 g:1.15 mL. The reaction was carried out at 100℃ for 48 h. The mixture was then filtered, the filter cake was washed until neutral, and dried under vacuum to obtain MA-jujube shell activated carbon.
[0037] The preparation method of modified vanillin includes the following steps: V1. Vanillin was dissolved in anhydrous ethanol to obtain a vanillin solution with a concentration of 1 mmol / mL. 1,3-Diaminothiourea was dissolved in anhydrous ethanol to obtain a 1,3-diaminothiourea solution with a concentration of 0.5 mmol / mL. The molar ratio of vanillin to 1,3-diaminothiourea was 2:1. Under nitrogen protection, the vanillin solution was added to the 1,3-diaminothiourea solution, and the mixture was stirred and refluxed at 80°C for 3.5 h. After cooling to room temperature, the mixture was filtered, the filter cake was washed with ethanol, and dried to obtain vanillin-aminothiourea. V2. The vanillin-aminothiourea, epichlorohydrin and tetrabutylammonium bromide obtained in step V1 were mixed and stirred at 85°C for 7 h under N2 atmosphere. After cooling to room temperature, 20 wt% NaOH aqueous solution was added dropwise. The ratio of vanillin-aminothiourea, epichlorohydrin, tetrabutylammonium bromide and NaOH solution was 50 g:240 mL:2.5 g:200 mL. The reaction was continued for 5.5 h. After the reaction was completed, the mixture was washed with saturated sodium chloride solution and deionized water. The organic phase was dried with anhydrous sodium sulfate, and epichlorohydrin was removed by rotary evaporation. The precipitate was precipitated in diethyl ether and dried under vacuum to obtain modified vanillin.
[0038] This embodiment also provides a method for preparing the jujube shell activated carbon adsorbent, including the following steps: S1. Under nitrogen protection, modified vanillin and MA-jujube shell activated carbon were added to DMF and mixed well. The mass concentration of MA-jujube shell activated carbon in DMF was 15 mg / mL. Triethylamine was added, and the ratio of triethylamine to modified vanillin was 0.05 mL: 1 g. The reaction was carried out at 75℃ for 7 h. S2. After the reaction in step S1 is completed, cool to room temperature, filter, wash the filter cake with DMF, anhydrous ethanol and deionized water, and dry under vacuum to obtain jujube shell activated carbon adsorbent.
[0039] The only difference between Comparative Example 1 and Example 1 is that MA-jujube shell activated carbon is used instead of jujube shell activated carbon adsorbent.
[0040] The only difference between Comparative Example 2 and Example 1 is that jujube shell activated carbon is used instead of jujube shell activated carbon adsorbent.
[0041] The only difference between Comparative Example 3 and Example 1 is that chlorinated activated carbon is used instead of jujube shell activated carbon adsorbent.
[0042] Experimental Example 1: Take 50 mL of simulated wastewater sample with an initial lead ion concentration of 100 mg / L, add 20 mg of the regenerable adsorbent from Examples 1-3 and Comparative Examples 1-3, and shake at 180 r / min for 6 h at room temperature. Take the supernatant to determine the lead ion concentration and calculate the adsorption capacity. The results are as follows: Figure 1 As shown.
[0043] Figure 1 The results showed that the adsorption capacity of the adsorbents in Examples 1-3 for lead ions was significantly higher than that in Comparative Examples 1-3. Specifically, Comparative Example 1 used only MA-jujube shell activated carbon as the adsorbent without grafting modified vanillin, Comparative Example 2 used jujube shell activated carbon as the adsorbent, and Comparative Example 3 used chlorinated activated carbon as the jujube shell activated carbon adsorbent. Comparative Examples 1-3 all significantly reduced the number of groups that can coordinate with heavy metals, resulting in a decrease in the adsorption performance of heavy metal ions.
[0044] Experimental Example 2: After the adsorbent reached adsorption saturation, it was dried and added to a 0.1 mol / L HCl solution. The solution was shaken at 180 r / min for 3 h at room temperature to induce desorption. After drying, the adsorption experiment was repeated. Five cycles of adsorption-desorption tests were performed, and the adsorption capacity retention rate was calculated after each adsorption of lead ions. The results are as follows: Figure 2 As shown.
[0045] Figure 2 The results showed that the adsorbent prepared in Example 1 could maintain an adsorption capacity retention rate of more than 85% after 5 adsorption-desorption cycles. After cycling, the removal rate of Comparative Examples 1-3 was significantly lower than that of Example 1. Comparative Examples 1-3 lacked active sites, and their cycling capacity decreased rapidly and their cycling stability decreased after repeated use.
[0046] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.
Claims
1. A jujube shell activated carbon adsorbent, characterized in that, The raw materials for preparation include the following components in parts by weight: 10-15 parts of MA-jujube shell activated carbon and 5-8 parts of modified vanillin; The preparation method of MA-jujube shell activated carbon includes the following steps: L1. Wash the jujube shells to remove impurities, dry them, and pulverize them to obtain jujube shell powder. Heat the powder to 450-500℃ under a nitrogen atmosphere to obtain pre-carbonized material. L2. Mix KOH with the pre-carbonized material obtained in step L1, add deionized water and mix well, stir, dry, heat to 800-900℃ under nitrogen protection, wash, dry, and obtain jujube shell activated carbon. L3. Take the jujube shell activated carbon obtained in step L2, add it to nitric acid solution, reflux, filter, add the filter cake to distilled water, boil, filter, dry, and obtain pretreated activated carbon; L4. Take the pretreated activated carbon obtained in step L3, disperse it in anhydrous ethanol, add 3-chloropropyltrimethoxysilane, react at 80-90℃, then add 1 mol / L hydrochloric acid solution, continue the reaction, cool, filter, wash the filter cake, dry, and obtain chlorinated activated carbon. L5. Melamine is added to toluene to obtain a melamine dispersion. The chlorinated activated carbon obtained in step L4 is dispersed in toluene to obtain a chlorinated activated carbon dispersion. The chlorinated activated carbon dispersion is added to the melamine dispersion, triethylamine is added dropwise, the reaction is carried out at 100°C, the mixture is filtered, the filter cake is washed and dried to obtain MA-jujube shell activated carbon. The preparation method of modified vanillin includes the following steps: V1. Vanillin was dissolved in anhydrous ethanol to obtain a vanillin solution. 1,3-Diaminothiourea was dissolved in anhydrous ethanol to obtain a 1,3-diaminothiourea solution. Under nitrogen protection, the vanillin solution was added to the 1,3-diaminothiourea solution, stirred and refluxed, cooled, filtered, washed, and dried to obtain vanillin-aminothiourea. V2. Mix the vanillin-aminothiourea, epichlorohydrin and tetrabutylammonium bromide obtained in step V1, stir and react at 80-90℃ under N2 atmosphere, cool, add 20wt% NaOH aqueous solution dropwise, continue the reaction, wash, dry, rotary evaporate, precipitate, dry, and obtain modified vanillin.
2. The jujube shell activated carbon adsorbent according to claim 1, characterized in that, In step L2, the mass ratio of KOH to pre-carbonized material is 2-3:
1.
3. The jujube shell activated carbon adsorbent according to claim 2, characterized in that, In step L4, the ratio of 3-chloropropyltrimethoxysilane to pretreated activated carbon is 1-1.5 mL:1 g.
4. The jujube shell activated carbon adsorbent according to claim 3, characterized in that, In step L4, the volume ratio of the hydrochloric acid solution to anhydrous ethanol is 1:
50.
5. The jujube shell activated carbon adsorbent according to claim 4, characterized in that, In step L5, the mass ratio of melamine to chlorinated activated carbon is 1-1.2:
1.
6. The jujube shell activated carbon adsorbent according to claim 5, characterized in that, In step L5, the ratio of melamine to triethylamine is 1 g: 1.1-1.2 mL.
7. The jujube shell activated carbon adsorbent according to claim 6, characterized in that, In step V1, the molar ratio of vanillin to 1,3-diaminothiourea is 2:
1.
8. The jujube shell activated carbon adsorbent according to claim 7, characterized in that, In step V2, the ratio of vanillin-aminothiourea, epichlorohydrin, tetrabutylammonium bromide, and NaOH solution is 50 g: 200-250 mL: 2-3 g: 200 mL.
9. A method for preparing jujube shell activated carbon adsorbent as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Under nitrogen protection, modified vanillin and MA-jujube shell activated carbon were added to DMF and mixed well. Triethylamine was added and the mixture was reacted at 70-80℃ for 6-8 h. S2. After the reaction in step S1 is completed, cool to room temperature, filter, wash the filter cake with DMF, anhydrous ethanol and deionized water, and dry under vacuum to obtain jujube shell activated carbon adsorbent.