Desorption Kinetics of Heavy-Metal Cations onto Titanium Phosphate

The desorption kinetics of divalent ions (Cu²⁺, Mn²⁺, Co²⁺, Ni²⁺) onto amorphous titanium phosphate is studied. It is established that the desorption of heavy-metal cations onto titanium phosphate is realized by a mixed mechanism: external diffusion and internal diffusion. It is shown from the diffusion coefficients calculated that diffusion in the pores of the sorbent occurs without steric hindrance. For all of the ions studied, a pseudo-second-order model adequately describes the chemical interaction. It is shown that the rate and selectivity of desorption is markedly determined by the effective radius of the hydrated ions.