Abstract
The work described in this thesis consists of investigations into the sorptive behaviour of magnetite and of zirconia in some dilute aqueous electrolyte solutions. Total sorption at the interfaces Fe[3]O[4]/NaCl, Fe[3]O[4]/NaNO[3], Fe[3]O[4]/Na2SO[4] Fe[3]O[4]/Na[2]HPO[4], Fe[3]O[4]/K[2]CrO[4], ZrO[2]/NaCl, ZrO[2]/HCl and ZrO[2]/HNO[3, has been measured by conductimetric determination of concentration loss from solution when equilibrated with a quantity of the finely divided adsorbent. A potentiometric technique has been devised and used, in conjunction with conductimetric measurements, to determine the extent of sorption of each ionic species from solutions containing three ions. This technique has been used to measure total sorption at the interfaces ZrO[2]/(HCl + HNO[3]) and ZrO[2]/(HCl + NaCl) and to study the phenomena occurring at the Fe[3]O[4]/HCl interface, in which latter case ferrous ions are released into solution. Micro-electrophoretic studies at the ZrO[2]/HCl, ZrO[2]/HNO[3] and ZrO[2]/NaCl interfaces have been made. Electrokinetic potentials and charges in these systems have hence been determined. The phenomena occurring at the metal oxide/solution interfaces studied have been interpreted in terms of ion exchange and physical sorption processes Exchange reactions between ions from solution and amphoteric surface hydroxyl groups have been postulated. Total sorption data have been compared with data obtained, both previously and in the present work, from electrokinetic studies. It is shown that conclusions drawn, regarding adsorb ability of ions at these interfaces, from electrokinetic studies, must be regarded with caution unless direct measurements of total sorption are also available.