Analytical Sciences

Ligand Exchange Reactions of a Monomeric Zirconium Carbonate Complex with Carboxylic Acids Studied by Extended X-ray Absorption Fine Structure, UV Absorption and Raman Spectrophotometry

Fumiyuki TAKASAKI,* Kazuhiko FUJIWARA,** Tomomi KIKUCHI,** Takenori TANNO,*** Yasushi NAKAJIMA,* Yasunori TOYODA,* and Nobuaki OGAWA**

*Daiichi Kigenso Kagaku Kogyo Co. Ltd., 1-6-38 Hirabayashi-minami, Suminoe, Osaka 559-0025, Japan
**Department of Life Science, Graduate School of Engineering and Resource Science, Akita University, 1-1 Tegatagakuen-cho, Akita 010-8502, Japan
***Venture Incubation Center, Akita University, 1-1 Tegatagakuen-cho, Akita 010-8502, Japan

Ligand exchange reactions of a monomeric zirconium carbonate complex with carboxylic acids were studied by means of extended X-ray absorption fine structure (EXAFS), UV absorption spectrophotometry and Raman spectrometry. Three carboxylic acids, gluconic acid, and L-tartaric acid and citric acid, which are mono-, di- and tri-carboxylic acids, respectively, were employed in this study. These three carboxylic acids gave different spectral signatures and concentration dependences, respectively. In the gluconic acid system, the peaks on Fourier transform of EXAFS spectrum and Raman spectrum caused by carbonate ion coordinating to zirconium atom were obviously decreased with increasing gluconic acid concentration compared to the other two carboxylic acid systems. This indicates the high association ability of gluconic acid to zirconium, which was revealed by UV spectrophotometric analysis.

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