Electrical conductivity and cation exchange kinetic studies on poly- o-toluidine Th(IV) phosphate nano-composite cation exchange material

Abstract

An advanced organic–inorganic cation exchange material poly- o-toluidine Th(IV) phosphate nano-composite was synthesized by a modified sol–gel technique by incorporating Th(IV) phosphate precipitate with the matrix of poly- o-toluidine. The material showed good ion-exchange behavior and used successfully in separation of metal ions. The conductivity of the composite was found within the range of 10 −2 to 10 −3 S/cm; measured by 4-in-line-probe dc electrical conductivity measuring technique. The conductivity is at the border of metallic and semiconductor region. Ion-exchange kinetics for few divalent metal ions was evaluated by particle diffusion-controlled ion-exchange phenomenon at four different temperatures. The particle diffusion mechanism is confirmed by the linear τ (dimensionless time parameter) versus t (time) plots. The exchange processes thus controlled by the diffusion within the exchanger particle for the systems studies herein. Some physical parameters like self-diffusion coefficient ( D 0) , energy of activation ( E a) and entropy of activation (Δ S 0) have been evaluated under conditions favoring a particle diffusion-controlled mechanism.