改性斜发沸石对水中Sr(Ⅱ)的吸附作用  

Modified clinoptilolite adsorption of Sr(Ⅱ) in aqueous solutions

作　　者：罗群 蒋定文 侯登勇 陈伟[1] 胡秀婷 何颖[1] LUO Qun;JIANG Dingwen;HOU Dengyong;CHEN Wei;HU Xiuting;HE Ying(Department of Protection Medicine, Naval Characteristic Medical Center, The Second Military Medical University,Shanghai 200433, China)

机构地区：[1]第二军医大学海军特色医学中心防护医学研究室

出　　处：《辐射研究与辐射工艺学报》2019年第3期14-21,共8页Journal of Radiation Research and Radiation Processing

基　　金：上海市自然科学基金(16ZR1414200)资助~~

摘　　要：自然斜发沸石经高温和化学方法改性后应用于水中Sr^2+的吸附和去除。通过测定放射性核素的吸附容量,选择最优改性方法。采用扫描电镜(SEM)和X射线衍射(XRD)等方法,对改性斜发沸石的晶体结构、微观形态和化学组成等进行了鉴定和检测。研究了在不同吸附温度、吸附时间、核素初始浓度等试验条件下,改性斜发沸石对Sr^2+的吸附过程。结果表明,采用高温+NaOH+NaCl法改性的斜发沸石对Sr^2+的吸附容量最高,达到了79.386mg/g。应用Langmuir方程和Freundlich方程对等温吸附数据进行拟合发现,等温吸附曲线更符合Langmuir方程。Lagergren一级速率方程、Lagergren二级速率方程以及Elovich方程对改性斜发沸石吸附金属核素的动力学吸附过程拟合结果表明,金属核素在改性斜发沸石上的吸附更加符合准二级反应动力学模型,其吸附过程为化学过程。改性斜发沸石对Sr^2+离子吸附过程的焓变ΔH0及熵变ΔS0值为正,吸附过程为吸热过程,当初始离子浓度较高时,ΔG0值为正,并随着初始浓度的降低而降低,随着温度的升高而降低;当初始离子浓度较低时,ΔG0值为负,表明吸附过程为自发的,ΔG0的绝对值随着温度的升高而升高。A natural clinoptilolite was modified using high temperature and chemical agents for adsorption of Sr2+ from aqueous solutions. The adsorption capacity was determined to select the optimum modification method. The adsorption capacities of Sr^2+ were as high as 79.386 mg/g when the natural clinoptilolite was modified using high temperature, NaOH, and NaCl sequentially. Scanning electron microscopy and X-ray diffraction were used to characterize the produced zeolite and identify the crystal structure, morphology, and elemental composition of the samples. The removal and adsorption processes of Sr^2+ using the modified clinoptilolite were performed under various experimental conditions by varying the temperature, initial concentration, and contact time. Adsorption isotherm models (Langmuir and Freundlich) were applied and equilibrium adsorption data were better fitted to the Langmuir isotherm. The reaction kinetic data were studied by Lagergren first and second order models as well as the Elovich particle diffusion kinetic model. The adsorption kinetics were accurately described by the Lagergren second order model and the rate-controlling step was determined to be chemical adsorption. The thermodynamic parameters of ΔH0 and ΔS0 were positive, indicating that the adsorption of Sr^2+ onto the modified clinoptilolite zeolite was an endothermic process. The value of ΔG0 was negative at low initial concentrations, indicating that the adsorption process was spontaneous and the absolute value of ΔG0 increased with an increase in temperature. The value of ΔG0 was positive at high initial concentrations and decreased with an increase in temperature and a decrease in initial concentration.

关 键 词：斜发沸石 吸附 Sr(Ⅱ) 吸附等温线 吸附动力学 吸附热力学 

分 类 号：TQ424.3[化学工程]