岩溶地下河系统石灰石对BTEX的吸附动力学和热力学  

Adsorption kinetics and thermodynamics of BTEX by limestone collected from a karst underground river system

作　　者：陈余道[1,2] 宋晓薇[1,2] 蒋亚萍[1,2] 程亚平[1,2] 

机构地区：[1]桂林理工大学 [2]广西矿冶与环境科学实验中心,广西桂林541004

出　　处：《地学前缘》2014年第4期180-185,共6页Earth Science Frontiers

基　　金：国家自然科学基金项目(41172229);国家科技支撑项目(2012BAC16B02)

摘　　要：石油类单环芳香烃BTEX是岩溶地下水中常见的有机污染物,但有关BTEX与石灰石的吸附研究报道很少。文中利用静态吸附实验,研究了桂林寨底地下河系统石灰石含水介质对汽油组分BTEX化合物的吸附动力学和吸附热力学。结果表明：（1）石灰石含水介质对BTEX具有明显的吸附性,BTEX实验吸附容量介于0.004~0.061mg/g,大小顺序为甲苯〉苯〉间对二甲苯〉邻二甲苯〉乙苯,其动力学过程适合用假二级动力学模型描述,表明乙苯和二甲苯的吸附速率明显高于甲苯和苯,模型预测的BTEX吸附容量介于0.005~0.067mg/g,大小顺序与实验结果一致。（2）BTEX在石灰石含水介质中的吸附热力学符合Freundlich模型及其特例Linear模型,Freundlich常数介于0.076 4~0.189 3[mg/g][L/mg]1/n,1/n介于0.943 4~0.970 1,BTEX分配系数为0.002 3~0.021 2L/g。BTEX吸附能力顺序为间对二甲苯〉乙苯〉邻二甲苯〉甲苯〉苯。然而,石灰石与BTEX之间的吸附等温线不适合用Langmuir模型描述。这项研究能够为深入探讨BTEX在西南岩溶地下水中的迁移与归宿机制提供科学依据。Petroleum mono-aromatic hydrocarbons including benzene,toluene,ethylbenzene and xylene isomer（often referred to as BTEX）are common organic pollutants in karst groundwater.However,the study of the adsorption of BTEX by limestone material is seldom reported.In this paper,the kinetics and thermodynamics of BTEX adsorbed by limestone within aqueous solution are studied via static experiments.The BTEX compounds used were made from saturated gasoline solution,and the limestone materials were collected from the Zhaidi Karst Underground River System in Guilin City of China.The results showed that the adsorption of BTEX on limestone was obvious.The adsorption capacity of BTEX varied from 0.004mg/g to 0.061mg/g with the order of toluenebenzenem,p-xyleneethylbenzeneo-xylene.The pseudo-second order kinetic model was very suitable for the adsorption kinetics of BTEX,which indicated that the adsorption rates of both ethylbenzene and xylene were faster than that of toluene or benzene.Based on the kinetic model,the adsorption capacities of BTEX were also calculated,which ranged from 0.005to 0.067mg/g.In adsorption thermodynamics,the Freundlich model as well as its special Linear model could be well fitted for the adsorption isotherms of BTEX.However,the Langmuir model is not suitable in the study.Based on the thermodynamic models,the adsorption abilities of BTEX varied from strong to weak in the order of m,p-xylene〉ethylbenzene〉o-xylene〉toluene〉benzene.The distribution coefficients of BTEX were obtained,ranging from 0.0023to 0.0212L/g.The study can provide the scientific basis for further study of the fate and transport of BTEX in karst groundwater in the southwestern area of China.

关 键 词：石灰石 单环芳香烃(BTEX) 含水介质 吸附动力学 吸附等温线 

分 类 号：P641.134[天文地球—地质矿产勘探] X131.2[天文地球—地质学]