Yoshimi Seida

Europium-binding abilities of dissolved humic substances isolated from deep groundwater in Horonobe area, Hokkaido, Japan

The binding of europium to dissolved humic substances (HSs), isolated from deep groundwater in the Horonobe area, Hokkaido, Japan, was evaluated by means of a three-dimensional fluorescence quenching technique. The Ryan and Weber model, extended by the charge neutralization model, was applied to the fluorescence quenching profiles to evaluate the conditional binding constants (K) at pH 5.0 and an ionic strength of 0.1. The K values for fulvic (FA) and humic acids (HA) in the Horonobe groundwater were comparable with each other regardless of the position of the fluorescence peaks. As compared with HSs from Lake Biwa, Aldrich, and Dando soil, the K values of the Horonobe groundwater HSs were the smallest, indicating that the Horonobe groundwater HSs have a lower affinity for the binding of europium compared to the HSs from surface environments. In addition, the results of the Aldrich-based comparison indicate that the Horonobe groundwater HSs have a lower binding affinity for trivalent lanthanides/actinides compared with other groundwater HSs obtained from different aquifer. These findings demonstrate that the characteristics and origin of deep groundwater HSs needs to be taken into consideration assessing the effects of HSs on the speciation of radionuclides in deep groundwater in geological disposal systems.

Detection of AU(III) ions using a poly(N,N-dimethylacrylamide)-coated QCM sensor

A polymer-coated quartz crystal microbalance (QCM) sensor has been developed for the detection of Au(III) ions in a HCl aqueous solution. Poly(N,N-dimethylacrylamide) (poly(DMAA)) gel was used as a sensing material. The poly(DMAA) gel adsorbs Au(III) ions in the HCl aqueous solution, whereas it is inactive toward most other metal ions. The equilibrium adsorption of Au(III) ions onto the poly(DMAA) gel can be expressed by the Henry-type isotherm. The oscillation behavior of the poly(DMAA)-coated QCM sensor was investigated, and linear relationships between the resonance frequency shift and the concentration of Au(III) ions were obtained for concentrations of less than 0.032 mol/m(3) (6.3 mg/m(3)) in the single and multicomponent metal systems. The poly(DMAA)-coated QCM sensor detects Au(III) ions successfully with high selectivity and sensitivity even in the presence of other metal ions and organic compounds.

A simple method for the determination of adsorption kinetic parameters using circulating-type shallow bed reactor (CSBR)

aZenkosha Co. Ltd., Tokyo, Japan, email: takashi@zenko.co.jp bDepartment of Safety, Health and Environmental Engineering, Hungkuang University, Taichung 433, Taiwan, Tel. +886 4 26318652; Fax: +886 4 26525245; email: fan@sunrise.hk.edu.tw cNatural Science Laboratory, Toyo University, Tokyo, Japan, email: seida@toyo.jp dDepartment of Applied Chemistry, Meiji University, Kawasaki, Japan, emails: tkino@meiji.ac.jp (T. Kinoshita); egfuruya@meiji.ac.jp (E. Furuya)