物理化学学报 >> 2005, Vol. 21 >> Issue (10): 1169-1173.doi: 10.3866/PKU.WHXB20051022

研究简报 上一篇    下一篇

EXAFS研究不同酸度下Zn2+在水锰矿表面的吸附和沉淀

朱孟强; 潘纲; 李贤良; 刘涛; 杨玉环   

  1. 中国科学院生态环境研究中心环境水质学国家重点实验室, 北京 100085; 中国科学院高能物理研究所同步辐射实验室, 北京 100039
  • 收稿日期:2005-03-03 修回日期:2005-04-19 发布日期:2005-10-15
  • 通讯作者: 潘纲 E-mail:gpan@mail.rcees.ac.cn

EXAFS Study of Zn (II) Adsorption and Precipitation on γ-MnOOH Surface under Different pH Conditions

ZHU Meng-qiang; PAN Gang; LI Xian-liang; LIU Tao; YANG Yu-huan   

  1. State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco- Environmental Sciences, Chinese Academy of Sciences, Beijing 100085; Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039
  • Received:2005-03-03 Revised:2005-04-19 Published:2005-10-15
  • Contact: PAN Gang E-mail:gpan@mail.rcees.ac.cn

摘要: 用EXAFS(extended X-ray absorption fine structure)研究了pH 7.00、7.50、8.00时Zn(II)在水锰矿表面的吸附和沉淀. Zn第一层配位Zn—O距离约为0.202 nm, 不随pH变化, 表明Zn的构型为四面体和八面体的混合物. 在pH 7.00 条件下, Zn—Mn距离约为0.300 nm, Zn主要以双边形式吸附在水锰矿(010)或(110)面. pH 7.50和pH 8.00时, 大部分的Zn在表面形成了结构类似于沉淀样品的多核羟基络合物, 其中0.311 nm Zn—Zn距离对应两个Zn八面体连接, 而0.353 nm Zn—Zn距离对应Zn八面体和Zn四面体连接.

关键词: Zn(II), 吸附, 沉淀, γ-MnOOH, EXAFS

Abstract: Mechanisms of adsorption and precipitation of Zn(II) onγ-MnOOH-water interfaces at pH 7.00, 7.50 and 8.00 were studied using EXAFS (extended X-ray absorption fine structure). The Zn—O distance for adsorbed Zn(II) was 0.202 nm, which did not change when pH increased from 7.00 to 8.00. This result implied that Zn2+ was adsorbed as a mixture of tetrahedron and octahedron. At pH 7.00, Zn2+ was adsorbed on (110) or (001) plane of γ-MnOOH by edge linkage mode, which corresponded a Zn—Mn distance of ~0.300 nm. At pH 7.50 and 8.00, most Zn(II) was precipitated as multinuclear hydroxo-complexes with similar structures where the Zn—Zn distances were 0.353 nm (tetrahedron-octahedron linkage) and 0.311 nm (octahedron-octahedron linkage), respectively.

Key words: Zn(II), Adsorption, Precipitation, γ-MnOOH, EXAFS