千屈菜活性炭的制备及其对2，4，6-三氯苯酚吸附性能的研究
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摘要
本研究以草本植物千屈菜为原料,采用H3PO4法制备活性炭。采用比表面积、孔隙结构、红外光谱和Boehm滴定法对制备出的活性炭进行物理结构及表面化学性质表征；并研究其对2,4,6-三氯苯酚的吸附效果,考察了溶液pH值,吸附时间,初始浓度,温度对2,4,6-三氯苯酚吸附效果的影响；通过乙醇溶液对活性炭再生,研究其再生利用率；在此基础上深入分析千屈菜活性炭对2,4,6-三氯苯酚的吸附机理。
经过优化的活性炭制备的最佳工艺条件为：H3PO4溶液质量分数为40%,剂料质量比2：1,浸渍时间12h,升温速度18℃/min,活化温度450℃,活化时间1h。结果表明千屈菜活性炭具有较多的微孔和介孔,比表面积高达1255.75m2/g,孔体积为1.20cm3/g；活性炭表面存在一些官能团,羧基和酚羟基是主要的含氧官能团。吸附实验结果表明,千屈菜活性炭对2,4,6-三氯苯酚吸附效果非常好,实验最佳投加量为0.1g/100ml；在2～4.4的范围内,pH值对吸附过程影响不大,从4.4～12的范围内,吸附量呈逐渐下降的趋势；吸附在开始阶段速度较快,随着时间的推移,逐渐减慢,最后达到吸附平衡,这个过程约为5～6h,吸附动力学过程符合伪二级动力学方程；Temkin等温方程比Freundlich、Langmuir等温方程更适合描述吸附2,4,6-三氯苯酚的热力学特性,吸附是一个放热(△H<0)的过程；吸附机理主要是以物理吸附为主。
吸附饱和的千屈菜活性炭经乙醇溶液再生后,对2,4,6-三氯苯酚仍有很好的吸附效果,与原炭的吸附效果相差很小,具有很好的再生利用性能。
An activated carbon was prepared from the stalk of the scrap aquatic plant loosestrife employing H3PO4 as activator Physical structure and chemical properties were evaluated from specific surface area, pore size distribution, Fourier-transform infrared spectroscopy (FTIR) and Boehm titration. Then, its ability to adsorb 2,4,6-trichlorophenol (2,4,6-TCP) was also appraised. The effects of solution pH, agitation time,2,4,6-TCP initial concentration, and temperature on 2,4,6-TCP adsorption were investigated. The activated carbon was regenered by alcohol to study the recycling rate. On the basis of adsorption properties, adsorptive mechanism was futher discussed.
The optimum conditions for producing the activated carbon were as follows. H3PO4 solution 40 wt.%, loosestrife to H3PO4 2.5:1, Soaking time 12h, heating rate 18℃/min, activation temperature 450℃, activation time 1h. The results of Brunauer-Emmett-Teller surface area and average pore size showed that the activated carbon had 1255.75m2/g of surface area and 1.20cm3/g of total pore volume. The functional groups were formed on the carbon surface, and the carboxyl group and phenolic hydroxyl group were the major oxygen-containing group. The results of adsorption experiment suggested that 2,4,6-TCP could be effectively removed with high adsorption capacities.
The results also showed that the optimum dosage was 0.1g/100ml. The adsorption capacity was not affected by pH from 2～natural value, and at the range of natural～12, the adsorption capacity was decreased. Kinetic researches indicated that the adsorption equilibrium time was obtained about 5～6h. Other kinetic processes were also occurring and contributed to the adsorption properties. Compared.to the Freundlich and Langmuir isotherm model, the Temkin isotherm equation is more appropriate to the adsorption data. The adsorption is considered to be an exothermic (△H<0) process.
Spent activated carbon could be regenerated effectively by alcohol. The regenerated carbon still has greater adsorption capacities, and it is a promising adsorbent for water treatment.
经过优化的活性炭制备的最佳工艺条件为：H3PO4溶液质量分数为40%,剂料质量比2：1,浸渍时间12h,升温速度18℃/min,活化温度450℃,活化时间1h。结果表明千屈菜活性炭具有较多的微孔和介孔,比表面积高达1255.75m2/g,孔体积为1.20cm3/g；活性炭表面存在一些官能团,羧基和酚羟基是主要的含氧官能团。吸附实验结果表明,千屈菜活性炭对2,4,6-三氯苯酚吸附效果非常好,实验最佳投加量为0.1g/100ml；在2～4.4的范围内,pH值对吸附过程影响不大,从4.4～12的范围内,吸附量呈逐渐下降的趋势；吸附在开始阶段速度较快,随着时间的推移,逐渐减慢,最后达到吸附平衡,这个过程约为5～6h,吸附动力学过程符合伪二级动力学方程；Temkin等温方程比Freundlich、Langmuir等温方程更适合描述吸附2,4,6-三氯苯酚的热力学特性,吸附是一个放热(△H<0)的过程；吸附机理主要是以物理吸附为主。
吸附饱和的千屈菜活性炭经乙醇溶液再生后,对2,4,6-三氯苯酚仍有很好的吸附效果,与原炭的吸附效果相差很小,具有很好的再生利用性能。
An activated carbon was prepared from the stalk of the scrap aquatic plant loosestrife employing H3PO4 as activator Physical structure and chemical properties were evaluated from specific surface area, pore size distribution, Fourier-transform infrared spectroscopy (FTIR) and Boehm titration. Then, its ability to adsorb 2,4,6-trichlorophenol (2,4,6-TCP) was also appraised. The effects of solution pH, agitation time,2,4,6-TCP initial concentration, and temperature on 2,4,6-TCP adsorption were investigated. The activated carbon was regenered by alcohol to study the recycling rate. On the basis of adsorption properties, adsorptive mechanism was futher discussed.
The optimum conditions for producing the activated carbon were as follows. H3PO4 solution 40 wt.%, loosestrife to H3PO4 2.5:1, Soaking time 12h, heating rate 18℃/min, activation temperature 450℃, activation time 1h. The results of Brunauer-Emmett-Teller surface area and average pore size showed that the activated carbon had 1255.75m2/g of surface area and 1.20cm3/g of total pore volume. The functional groups were formed on the carbon surface, and the carboxyl group and phenolic hydroxyl group were the major oxygen-containing group. The results of adsorption experiment suggested that 2,4,6-TCP could be effectively removed with high adsorption capacities.
The results also showed that the optimum dosage was 0.1g/100ml. The adsorption capacity was not affected by pH from 2～natural value, and at the range of natural～12, the adsorption capacity was decreased. Kinetic researches indicated that the adsorption equilibrium time was obtained about 5～6h. Other kinetic processes were also occurring and contributed to the adsorption properties. Compared.to the Freundlich and Langmuir isotherm model, the Temkin isotherm equation is more appropriate to the adsorption data. The adsorption is considered to be an exothermic (△H<0) process.
Spent activated carbon could be regenerated effectively by alcohol. The regenerated carbon still has greater adsorption capacities, and it is a promising adsorbent for water treatment.
引文
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[13]孙艳,一次性筷子制备活性炭的研究,生物化工及材料工程研究[J],28(2011)4-11.
[14]梁昕,蒙李燕,陈晓珊,石佳明,蒙冕武,黄颖,磷酸炭化-活化法制备污水厂污泥活性炭工艺[J],化工进展,30(2011)1124-1129.
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[16]王稚真,卢晗锋,张波,陈银飞.水蒸气对改性椰壳活性炭吸附VOCs的影响[J].环境工程学报,4(2010)2566-2570.
[17]董良飞,张廷全,王利平.KDF55/椰壳活性炭/石英砂/沸石联用净化饮用水[J].中国给水排水25(2009)83-85.
[18]代晓东,鲍旭晨,朱勇军,静国光,张坤,改性活性炭去除水中的二甲基亚硝胺[J].炭素技术.29(2010)11-16.
[19]刘娅,董瑞,颜海燕,李江,薄皮核桃壳活性炭处理啤酒工业废水的研究[J].石河子大学学报(自然科学版),29(2011)94-97.
[20]J.N. Sahu, Jyotikusum Achary, B.C. Meikap, Optimization of production conditions for activated carbons from Tamarind wood by zinc chloride using response surface methodology [J]. Biores. Tech.101 (2010) 1974～1982.
[21]A. Zabaniotou, G. Stavropoulos, V. Skoulou, Activated carbon from olive kernels in a two-stage process:Industrial improvement[J], Biores. Tech.99 (2008) 320～326.
[22]程捷,竹活性炭处理六价铬废水的试验研究[J].福建林业科技,33(2006)126-128.
[23]李大伟,朱锡锋,富含中、微孔稻壳活性炭的表征及液相吸附性能[J].中国环境科学,30(2010)1597-1601.
[24]M. Joao, Valente Nabaisa, Pedro Nunesa; Peter J.M. Carrotta, M. Manuela, L. Ribeiro Carrotta, A. Macias Garciab, M.A. Diaz-Diezb, Production of activated carbons from coffee endocarp by CO2 and steam activation [J]. Fuel Proc. T.89 (2008)262～268.
[25]Joao Valente Nabais, Peter Carrott, M.M.L. Ribeiro Carrott, Vania Luz, Angel L. Ortiz, Influence of preparation conditions in the textural and chemical properties of activated carbons from a novel biomass precursor:The coffee endocarp [J] Biores. Tech.99 (2008) 7224～7231.
[26]吴开金,陈涵,林冠烽,油茶壳活性炭的制备工艺研究[J].福建林业科技,38(2011)92-94.
[27]李恒英,李艳,千屈菜的繁殖和应用[J],新农业,5(2011)49.
[28]欧克芳,刘念,谢广林,金晶,园林植物千屈菜的研究与应用[J].辽宁农业科学3(2011)46-48.
[29]康东娟,唐晓龙,易红宏,宁平,叶智青,李凯,超级活性炭的制备和性能研究及应用现状[J].环境科学与技术,34(2011)110-117.
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[31]S.C.R. Santos, V.J.P. Vilar, R.A.R. Boaventura, Waste metal hydroxide sludge as adsorbent for a reactive dye [J]. J. Hazard. Mater.153 (2008) 999～1008.
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