Cation-exchange kinetic studies on poly-o-toluidine Ce(IV) phosphate: a nano-composite and electrical conducting material

An advanced cation-exchange nano-composite poly-o-toluidine Ce(IV) phosphate was synthesized by sol–gel technique by incorporating Ce(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⁻¹; measured by four-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 (∆S°) have been evaluated under conditions favoring a particle diffusion-controlled mechanism.