Kinetics and Thermodynamics of Alkaline Earth and Heavy Metal Ion Exchange under Particle Diffusion Controlled Phenomenon Using Polyaniline-Sn(IV)iodophosphate Nanocomposite
journal contributionposted on 14.08.2014 by Md. Dilwar Alam Khan, Arshia Akhtar, Syed Ashfaq Nabi
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The polyaniline-Sn(IV)iodophosphate nanocomposite (PANI-SnIP) has been synthesized, and its various kinetic and thermodynamic parameters for alkaline earth and heavy metal ion exchange were evaluated. Above 0.03 M solution of metal ions, the particle diffusion controlled phenomenon is found to be predominant (R2 > 0.98). The kinetic and thermodynamic parameters like diffusion coefficient (Do), energy of activation (Ea), enthalpy of activation (ΔH*), entropy of activation (ΔS*), and free energy of activation (ΔG*) were evaluated under particle diffusion controlled phenomenon. The fractional attainment of equilibrium was faster at an elevated temperature, and the rate of exchange is predominated by Hg(II) ions in the case of multicomponent systems. The positive values of the standard enthalpy change (ΔH*) indicate the endothermic nature of the ion exchange process. The ion exchange follows an associative mechanism as indicated by ΔS* < −130 J mol–1 K–1. The comparatively fast kinetics of ion exchange by the nanocomposite depicts its applicability for environmental remediation.