Lamellar inorganic ion exchangers. Proton–copper(II) ion exchange in γ-titanium bis(hydrogenphosphate)
Abstract
The behaviour of γ-Ti(HPO4)2·2H2O in the exchange of Cu2+ has been studied. Exchange isotherms and pH curves were obtained at 25.0,40.0, and 55.0 (±0.1)°C. Half-exchanged phases TiHCu0.5(PO4)2·2.5H2O (interlayer distance 12.4 Å), TiHCu0.5(PO4)2·H2O (10.7 Å), and TiHCu0.5(PO4)2(9.4 Å) were detected. The crystalline solid phases were examined by X-ray diffraction. The free energy, enthalpy, and entropy of the exchange reaction are reported.