Ca(2,2'-Bipyridine)_3~(2+)-Intercalated Montmorillonite: An Application as Potentiometric Sensor

摘要

This article involves the use of [Ca(2,2'-bipyridine)_3]~(2+)-intercalated montmorillonite as a potentiometric sensor to measure anions in aqueous solution. The [Ca(2,2'-bipyridine)_3]~(2+)-intercalated montmorillonite was prepared by modification of an in situ solid-solid reaction, between natural Ca(II)-montmorillonite and 2,2'-bipyridine at a molar ratio 1:3. The formation of [Ca(2,2'-bipyridine)_3]~(2+)- in the interlayer space of montmorillonite was confirmed by powder X-ray diffraction (XRD) and the existence of 2,2'-bipyridine was confirmed by the C:N ratio of the product compared with that of the 2,2'-bipyridine molecule. The potentiometric sensor was constructed by mixing [Ca(2,2'-bipyridine)_3]~(2+)-intercalated montmorillonite with artificial graphite, polytetrafluoroethylene (PTFE) and carboxymethylcellulose (CMC) in an appropriate ratio. It was found that the sensor had higher sensitivity to S~(2-) rather than other anions, graphs of log[S~(2-)] vs voltage (mv) gave a slope 30.0 which was closed to theoretical value, 29.5. Activity of the [Ca(2,2'-bipyridine)_3]~(2+) sensor was verified by using sensor made from Ca(II)-montmorillonite as a reference. Reproducibility and precision of the electrode were also determined.