摘要
【目的】与普通活性炭比较,介孔活性炭具有疏水性好、孔体积大、导电性能好等优势,然而传统制备方法繁杂,原料成本较高。因此,探究新型介孔活性炭制备工艺尤为重要。【方法】以木糖渣为原料,采用NaOH预处理、低温硫酸辅助炭化与磷酸活化相结合的方法制备了高介孔率活性炭。通过单因素实验,分析NaOH预处理时间、浸渍比以及活化温度对活性炭的亚甲基蓝(MB)吸附性能的影响。【结果】研究表明:NaOH预处理脱除木质素促使原料形成孔隙通道,同时使木糖渣纤维发生润胀,有利于活化剂与原料接触,从而获得高介孔率、高比表面积活性炭。当NaOH预处理时间为4 h,磷酸与原料浸渍比4∶1,活化温度500℃,活化时间为1 h所制备的活性炭具有较高的MB吸附值436 mg/g。扫描电镜分析结果表明:样品表面含有丰富的大孔及中孔结构,整体活化充分均匀。氮气物理吸附-脱附分析结果表明:活性炭具有发达的孔隙结构,其比表面积和总孔体积分别高达2 038 m^2/g和2.13 cm^3/g,其中介孔孔容1.56 cm^3/g,介孔率达到73.2%,平均孔径为4.18 nm。【结论】采用适当的NaOH预处理有利于制备孔隙结构优越的活性炭,在重金属离子吸附、有机大分子废水处理以及电子元器件等领域有广泛的应用前景。本研究将为高比表面积介孔活性炭的制备奠定理论基础,并为工业木糖渣的高值化利用提供了一条新途径。
[Objective]Compared with common activated carbon,mesoporous activated carbon has the advantages of good hydrophobic,large pore volume and high conductivity,etc. However,the traditional preparation method is complicated and has higher costs for raw materials. Therefore,it is crucial to explore new mesoporous activated carbon preparation method. [Method] Activated carbon with high mesoporous rate was prepared from corncob residues by NaOH pretreatment,followed by phosphoric acid activation. The influences of NaOH-pretreated time,ratio of H_3PO_4/corncob residues( impregnation ratio) and activation temperature on MB adsorptive property of the activated carbon were investigated through the single factor experiments. [Result] Results indicated that lignin removal from corncob residues by NaOH pretreatment may form pore gallery and swell the fibers,making it easier to contactwith activator. As a consequence,activate carbon with high specific surface area and mesoporous rate was obtained. The best MB adsorption value of 436 mg/g was achieved when corncob was pretreated by NaOH for 4 hours under a impregnation ratio of 4∶ 1,activation temperature at 500 ℃ and activation time for 1 hour. Scanning electron microscopy( SEM) analysis showed that the surface of activated carbon was rich in mesopores and macropores. The developed pore structure and specific surface area were analyzed by N_2 adsorption tests. The surface area,total pore volume and average pore size of activated carbon were 2 038 m^2/g,2. 13 cm^3/g and 4. 18 nm, respectively. Particularly, the mesoporous volume was 1. 56 cm^3/g and the mesoporous rate was 73. 2%. [Conclusion]The above mentioned results indicated that appropriate NaOH pretreatment contributes to the preparation of activated carbon with well-developed mesoporous structure,which has potential application in fields of heavy metal ion adsorption,organic macromolecular wastewater treatment and electronic components preparation,etc. Our work will provide a fundamental research for the efficient preparation of mesoporous activated carbon and promote the highvalue utilization of the corncob residues.
作者
刘鹏鹏
周素坤
王超
游婷婷
许凤
Liu Pengpeng, Zhou Sukun,Wang Chao, You Tingting, Xu Feng(College of Material Science and Technology, Beijing Forestry University, Beijing 100083 ,Chin)
出处
《北京林业大学学报》
CAS
CSCD
北大核心
2018年第3期128-134,共7页
Journal of Beijing Forestry University
基金
教育部中央高校基本科研基金资助项目(2015ZCQ-CL-03)
关键词
木糖渣
介孔
活性炭
吸附
corncob residues
mesoporous
activated carbon
adsorption