Mechanism of some alkylammonium-ion exchanges by α-zirconium bis-(monohydrogenorthophosphate) monohydrate

Abstract

Crystalline zirconium phosphate, α-ZrP, has been investigated as an ion exchanger for the systems (NEtH₂+[NEtH₃]⁺)–H⁺, (NEt₂H +[NEt₂H₂]⁺)–H⁺, and (NEt₃+[NEt₃H]⁺)–H⁺ by potentiometric titrations. The exchange process in the case of ethylammonium ions occurs via phase transitions in four equal stages with the formation of pure phases. However, the ion exchange between α-ZrP and diethylammonium ions goes through three equal steps, again with phase transition. Two coexisting phases are observed throughout the exchange process of triethylammonium ions with α-ZrP. The maximum of uptake of ethyl-, diethyl-, and triethyl-ammonium ions is 100, 50, and 25% of the proton-exchange capacity of α-ZrP, respectively. X-Ray diffraction and thermal analysis methods have been used to characterize the products at different steps of the process.