THE SORPTION OF ANIONIC SPECIES ON HYDROUS TIN DIOXIDE

This paper describes the anion exchange properties of hydrous tin diox ide and of a composite silica-tin dioxide. The anions studied were flu oride, iodide, iodate and antimonate. Some isotherm data have been obt ained and have been correlated with the Langmuir isotherm in which the coefficient in the denominator is negative. Generally speaking the up take of anions drops as the pH of the contacting solution rises. The b alance of evidence would seem to indicate that the process is classica l ion exchange. The extent of the pH range over which this occurs is s urprising and contradicts classical notions of hydrous oxide ion excha nge theory. (C) 1997 Elsevier Science S.A.