Millicent U. Ibezim-Ezeani.et.al. Int. Journal of Engineering Research and Application www.ijera.com ISSN : 2248-9622, Vol. 7, Issue 3, ( Part -1) March 2017, pp.46-52 www.ijera.com DOI: 10.9790/9622- 0703014652 46 | Page Diffusion Dynamics of Metal Ions Uptake at the Carboxylated- Epichlorohydrin Red Onion Skin Extract Resin – Aqueous Interface Millicent U. Ibezim-Ezeani*, Onyewuchi Akaranta** *(Department of Department of Pure and Industrial Chemistry, University of Port Harcourt, P.M.B. 5323, Choba, Port Harcourt, Nigeria. ** (Department of Department of Pure and Industrial Chemistry, University of Port Harcourt, P.M.B. 5323, Choba, Port Harcourt, Nigeria. ABSTRACT Investigation into the diffusion dynamics of Mn 2+ , Fe 2+ and Pb 2+ ions uptake from aqueous solution by chemically modified red onion skin extract was carried out. The polyhydroxylic extract of red onion skin was utilized in the synthesis of carboxylated-epichlorohydrin red onion skin extract resin (CERR). The fourier transform infrared spectra of red onion skin extract and CERR exhibited variations in bond interactions which was ascribed to the structural modification of the extract to yield CERR. Predictions of the mechanism of diffusion dynamics were carried out by applying the data resolved from the fractional attainment of equilibrium at varied times into the Vermeulen diffusion models within the temperature range of 29 to 70°C. The predominance of film diffusion mechanism was established from the smaller values of its diffusion coefficients as compared to those of particle diffusion. The film diffusion coefficient values were lowest at 29°C, indicating the most probable temperature condition for optimum exchange result with the CERR. Deductions from utilizing the Arrhenius type temperature dependence equation gave negative values of activation energy (-7.223 kJ/mol for Mn 2+ , -6.898 kJ/mol for Fe 2+ and -13.957 kJ/mol for Pb 2+ ions); which suggests that increase in temperature from 29 to 70°C, lowered the rate of the exchange reaction. Keywords: Diffusion dynamics, ion exchange resin, metal ions, red onion skin, Vermeulen diffusion models I. INTRODUCTION Diffusion is the spontaneous migration of particulate matter due to spatial gradient in concentration. The direction of the random motion of the diffusing species is down its gradient in a bid to adjust the imbalance in particle density. Thus, for a particular medium, the rate at which substances diffuse in or out of the system and its surrounding is dependent on the variability of parameters like concentration, pressure, temperature and density with change in distance and time. The dominance of diffusion and its principles have gained impetus in many technologies associated with separation, purification, redox reaction, ionic conductivity, solubility, catalysis, recrystallization, water softening, substitution, demineralization, corrosion and so on. This paper presents the diffusion dynamics of Fe 2+ , Mn 2+ and Pb 2+ ions exchange at the CERR – aqueous interface. Ion exchange is based on the principle of diffusion and is the stoichiometric chemical reaction in which the interchange of equivalent ions at the phase boundary is reversible [1]. Diffusion dynamics of ion exchange describes the gradient in chemical kinetics of the interchange of equivalent ions between the exchanging and exchangeable species at a given condition with time until the process attains the state of no net transfer of mass and energy at the interface. In a given system, the steps that determine the diffusion dynamics of ion exchange process are the: (i) Migration of exchanging ions through the bulk solution to the boundary film surrounding the surface of the resin particles. (ii) Migration of exchanging ions from the boundary through the layer of film to the resin particles surface (film diffusion). (iii) Migration of exchanging ions from the resin surface to the intra-particle active sites (particle diffusion). (iv) Interchange of equivalent ions between the exchanging and the exchangeable species at the active internal surfaces of the resin particles (ion exchange). (v) Outward migration of exchanged ions from the particle interior to the surface of the resin particles (particle diffusion). (vi) Outward migration of exchanged ions from the resin surface to the boundary film surrounding the particles (film diffusion). (vii) Migration of exchanged ions from the boundary film into the bulk solution. RESEARCH ARTICLE OPEN ACCESS