SORPTION OF AQUEOUS TOXIC ANIONS ON
CALCINED Mg/Al LAYERED DOUBLE HYDROXIDE: AN APPROACH TO MECHANISM

Kang, Mun Ja; Rhee, Seog Woo; Hahn, Pil Soo

doi:2003.8.1.22

Environmental Engineering Research 2003;8(1): 22-30. DOI: https://doi.org/10.4491/eer.2003.8.1.022

SORPTION OF AQUEOUS TOXIC ANIONS ON CALCINED Mg/Al LAYERED DOUBLE HYDROXIDE: AN APPROACH TO MECHANISM

Mun Ja Kang¹^†, Seog Woo Rhee², and Pil Soo Hahn¹

¹Radioactive Waste Disposal Team, Korea Atomic Energy Research Institute, Daejeon 305-600, Korea
²Center for Biomedical Engineering, University of California, Irvine, CA 92697, USA

Corresponding Author: Mun Ja Kang ,Tel: +82-42-868-2078, Fax: +82-42-868-8850, Email: munkang@kaeri.re.kr

Received: August 6, 2002; Accepted: November 6, 2002.

ABSTRACT

In order to understand the sorption mechanism of Tc04" and Cr042" on calcined Mg/Al layered double hydroxide (LDH). spectroscopic identifications were performed. Calcined LDH and LDH sorbed with ReCV (Tc04" surrogate) or C1O42' were characterized by the powder X-ray diffraction, 27AI MAS NMR (Magic Angle Spinning Nuclear Magnetic Resonance), and FT-1R spectroscopies. The XRD pattern of LDH(Re04)2 shows the broad 006 reflection of 4.78 A. The NMR and FT-IR spectra reveal that the calcined LDH was reconstructed with intercalating Re04" in the aqueous RetV solution. In the previous study the sorption of Tc04~ and Re04' onto calcined LDH v/as proposed to be an ion-exchange reaction: generation of LDH hydroxide, Mg6Ab(OH)i8, as an intermediate and then replacement of the OH" by Tc04" or Re04" ions. In the present study it was identified by the XRD analysis of reaction solid of Re04" sorption that the LDH hydroxide is produced and exists in the reaction solid along with LDH(Re04);. This demonstrates that LDH hydroxide is the intermediate of the sorption process. In the case of Cr042" sorption on the calcined LDH, the LDH hydroxide is generated together with LDH(Cr04).

Keywords: CrO4^2- | layered double hydroxide | ReO₄^- | sorption | toxic anion