摘要
以甘蔗渣为原料,采用微波辅助磷酸活化法制备了同时富含中孔结构和含氧酸官能团的生物质炭,以氮气吸附、红外光谱FT-IR等技术对炭样品表面物化性质进行了表征,通过静态实验法测定了生物质炭对水中亚甲基蓝的吸附特性,分析了溶液pH、初始浓度、温度对吸附的影响,研究了不同pH下蔗渣生物质炭对亚甲基蓝的吸附行为,并从热力学及动力学角度探讨了生物质炭对亚甲基蓝的吸附机理。结果表明,不同制备参数下生物质炭的得率均大于39.2%,但表面物化性质因参数变化有较大差异。在浸渍比1∶1,烘干时间10 h,活化功率900 W,活化时间22 min的条件下,制得的生物质炭的比表面积为1 021 m2/g,亚甲基蓝值超过国家一级品标准1.70倍,表面富含微中孔结构和羟基、羰基、羧基等酸性官能团,中孔约占总孔的40%。静态吸附实验表明,溶液初始浓度对吸附有较大的影响,吸附量随初始浓度的增加,pH的升高及温度的上升而增大,Freundlich方程、Redlich-Peterson方程与Temkin方程能较好地描述等温吸附行为;吸附动力学结果表明,数据符合Elovich方程,吸附行为更倾向于化学吸附;热力学研究表明,吸附吉布斯自由能(ΔG0)<0,吸附标准焓变(ΔH0)>70 kJ/mol,说明该吸附为自发的吸热反应,且化学反应在吸附过程中发挥了重要作用。
Mesoporous biomass-based activated carbons containing acidic groups were prepared with bagasse as raw materials by microwave assisted H3PO4 activation. The surface properties of the carbons were characterized with nitrogen adsorption and infrared spectroscopy（ FTIR）. Main pore characteristics of activated carbons were analyzed by BET equation,Horvath-Kawazoe BET method and H-K method. The adsorption characteristic of methylene blue on the carbons was investigated by conducting a series of batch adsorption experiments. The influences of solution pH value,initial concentration and temperature were investigated. The adsorption behavior of methylene blue on the carbons under different pH was studied. The adsorption mechanism was discussed from kinetics and thermodynamic point of view. The results show that the yield under various conditions is all above 39. 2%,but the surface properties vary from different preparation conditions. Under the conditions of impregnation ratio of 1∶ 1,drying time of 10 h,activation power at 900 W and activation time of 22 min,the BET surface area of prepared activated carbon reached 1 021 m2/ g,when its mesoporous volume and methylene blue value adsorption were 40% of total pore volume and 1. 70 times of the national 1st standard sample of activated carbon,respectively. The nitrogen adsorption shows that the activated carbons were rich in microporous and mesoporous. The FTIR experiment shows that the surfaces of activated carbons were dominated by acidic functional groups such as hydroxy,carbonyl and carboxyl. The adsorption experiments show that the adsorption depended on the initial concentration. The adsorption amount increased with the increase of solution pH value,initial concentration and temperature. The Freundlich,Redlich-Peterson and Temkin isotherm was found to fit experimental data well. The Elovich model describes the adsorption kinetics most effectively,indicating that the adsorption was mainly dominated by chemical adsorption. The negative change in free energy（ ΔG0） and high value of the adsorption enthalpy ΔH0（ 70 kJ/mol） indicated that the adsorption was a spontaneous and endothermic process. Chemical reaction was involved and played an important role in the methylene blue adsorption on the carbon.
出处
《环境工程学报》
CAS
CSCD
北大核心
2014年第3期909-916,共8页
Chinese Journal of Environmental Engineering
基金
国家自然科学基金资助项目(51102136)
国家大学生创新创业训练计划项目(121030779)
关键词
中孔
亚甲基蓝
吸附
热力学
动力学
mesoporous
methylene blue
adsorption
thermodynamics
kinetics
作者简介
作暑简夼：贾佳祺（1991-），女，本科生，主要从事农业废弃物材料的开发以及水体污染物治理研究工作。E-mail：1553961515@qq．com
通讯联系人，E-mail：kqlee@njau.edu.cn
