• journal_title：Clay Minerals
• Contributor：Wei Zhao ; Fan Liu ; Xionghan Feng ; Wenfeng Tan ; Guohong Qiu ; Xiuhua Chen
• Publisher：Mineralogical Society of Great Britain and Ireland
• Date：2012-
• Format：text/html
• Language：en
• Identifier：10.1180/claymin.2012.047.2.04
• journal_abbrev：Clay Minerals
• issn：0009-8558
• volume：47
• issue：2
• firstpage：191
• section：Research Papers

To provide fundamental knowledge for studying the relative content of vacant sites and exploring the mechanism of interaction between Pb²⁺ and birnessite, Fourier transform infrared spectroscopy (FTIR) of birnessites with different Mn average oxidation states (AOS) before and after Pb²⁺ adsorption were investigated. The number of absorption bands of FTIR spectra was determined by using the second derivatives of the original spectra. The band at 899–920 cm^–1 was assigned to the bending vibration of -OH located at vacancies. The bands at 1059–1070, 1115–1124 and 1165–1171 cm^–1 could be attributed to the vibrations of Mn(III)-OH in MnO₆ layers, and the intensities of these bands increased with decreasing Mn AOS. The bands at 990 and 1023–1027 cm^–1 were ascribed to the vibrations of Mn(III)-OH in the interlayers. Mn(III) in MnO₆ layers partially migrated to interlayers during Pb²⁺ adsorption, which led to an increased intensity of the band at 990 cm^–1. The band at 564–567cm^–1 was assigned to the vibration of Mn-O located at vacancies. This band could split by coupling of vibrations due to Pb²⁺ and/or Mn²⁺ adsorbed at vacant sites. The large distance between the band at 610– 626 cm^–1 and that at 638–659 cm^–1 might reflect small Mn(III) ions located in Mn(III)-rich rows.