Abstract
The author is deeply grateful for the academic prize awarded from the society of sea water science, Japan. This report is the summary of plenary lecture presented for the prize.
During investigation of some hydroxyapatites [Ca10(PO4)6(OH)2: HAp -Ca10(PO4)4.2(SiO4)1.7(OH)6: SiAp], the author discovered that“Lattice Ca2+ions” of the apatites were selectively ion-exchanged for such notorius cations as Pb2+or Cd2+ions in aqueous solution at room temperature and such interesting ion-exchangers were named as“Lattice Ion Ion-exchanger” by the author. Thus, to selectively separate and uptake small amounts of K+ions from seawater in the presence of a large amount of Na+ions, K+ion memorizing lattice ion ionexchangers have been investigated and Na+form taeniolite (Na+Mg2LiSi4O10·2H2O: Na+T) was found to be a promising inorganic ion-exchanger. Lattice Na+ions of the Na+T were highly selectively ion-exchanged for K+ions in dehydrated state from seawater. Further, SiAp and its extented inorganic ion-exchangers such as hydrotalcite and calcium hydroxide were found to have disinfection effect for Ecoli cells in wastewater. The author hopes that the above inorganic ion-exchangers will be extended to be key materials in environmental and water 21st century.
