氨基改性MCM-48对水溶液中Pd^2+的吸附

Adsorption of palladium( Ⅱ ) from aqueous solution by amino-functionalized MCM-48

采用3毫丙基三乙氧基硅烷对MCM48进行改性,制备出氨基改性介孔硅材料WH_2-MCM-48,通过X射线衍射(XRD)、透射电镜(TEM)、红外光谱(FMR)和N2吸附脱附(BET)对WH_2-MCM-48进行表征,并探讨了WH_2-MCM-48对水溶液中Pd^(2+)的吸附性能。实验考察了初始pH、吸附时间、初始浓度、温度等因素对Pd^(2+)吸附的影响,并讨论了吸附动力学和热力学特征。结果表明:在pH为4~5范围内,吸附效果最好在150 min内达到吸附平衡。吸附动力学符合拟二级动カ学方程,Langmuir等温吸附方程能较好地描述WH_2-MCM-48对Pd^(2+)的吸附特性30℃静态吸附容量为59.67 mg·g^(-1);热力学分析结果表明AH_2-MCM-48对Pd^(2+)的吸附是自发、吸热反应。吸附观附实验表明,0.1 mol·L^(-1)HCl+5%硫脲对Pd^(2+)的洗脱效果好。

MCM-48 functionalized with 3-aminopropyltriethoxysilane（NH2-MCM-48） was synthesized and characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）,nitrogen adsorption-desorption,and Fourier Transform infrared spectrometry（FT-IR）.Its application for Pd^2＋ adsorption from aqueous solution was investigated.The effect of such parameters as solution pH,contact time and temperature,and initial concentration were studied.The results revealed that the optimum adsorption pH of NH2-MCM-48 for Pd^2＋ was from 4to 5,and the adsorption equilibrium was reached within 150 min.The adsorption kinetics indicated that the adsorption process followed a pseudo-second-order model.The adsorption isotherm of Pd^2＋ onto NH2-MCM-48 was well described by the Langmuir equation,and the highest loading capacity was 59.67 mg·g^-1 at 30℃.The thermodynamic parameters indicated that Pd^2＋ adsorption onto NH2-MCM-48 was spontaneous and endothermic.Moreover,NH2-MCM-48 was successfully regenerated using 0.1 mol·L ^-1 HCl with 5%thiourea.