Ion Exchange and Sorption Processes as Methods of Synthesis of Double Phosphates and Intercalated Compounds

Abstract

Abstract Traditional methods of obtaining salts by precipitation from solutions, crystallization from melts and solid-state reactions are often ineffective for the synthesis of double phosphates of mono- and polyvalent metals. The reactions of ion exchange or exchanged interaction are not widely used for this purpose. Only soluble acid salts capable of substituting their protons for cations and having sufficient hydrolytical stability are suitable. Their number is quite limited. Among these are: M(HPO4)·H2O, M = Ti, Zr, Hf, Ge, Sn, Pb; UO2HPO4·4H2O, H2MP3 O10 M = Al, Ga, V, Cr, Mn, Fe (TPM-I). A distinctive feature of these compounds is that all of them have two-dimensional lamellar lattice which is capable of reversible changing of crystallographic parameters during the ion exchange process. This proceeds quite easily, since the interaction of protons with the lattice is weak. No cases of effective ion exchange are reported in the solutions of anhydrous phosphates with three-dimensional structure. The an...