The ion exchange kinetics of H + /Ni 2+ on a relatively new hyper-crosslinked styrene-divinylbenzene sulfonated polymer was investigated in order to evaluate the material for removal of nickel ions from wastewaters. The ion exchanger has macro-, meso-and micropores. The ion exchange rate was measured at 298 K in conditions favoring a particle diffusion control using a potentiometric method. The results were modelled with both quasi-homogeneous and bidisperse pore kinetic models. The H + /Ni 2+

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... nterdiffusion coefficients obtained with the different kinetic models were compared and discussed. The evaluated H + and Ni 2+ self-diffusion coefficients at 298 K are 2.37 10-10 and 3.75 10-12 m 2 s-1 , respectively. List of symbols D effective intraparticle diffusivity; self-diffusion coefficient for isotopic exchange; integral interdiffusion coefficient for mutual ion-exchange (m 2 s-1) a D effective macropore diffusivity; macropore self-diffusion coefficient for isotopic exchange; macropore integral interdiffusion coefficient for mutual ion-exchange (m 2 s-1) i D effective micropore diffusivity; micropore self-diffusion coefficient for isotopic exchange; micropore integral interdiffusion coefficient for mutual ion-exchange (m 2 s-1) e e, number of ion equivalents at equilibrium in the resin and solution phases (eq) F fractional attainment of equilibrium (dimensionless) M a∞ macropore uptake at equilibrium (eq/kg) M i∞ micropore uptake at equilibrium (eq/kg) n number of terms in a series pH 0 , pH ∞ , pH t pH of the external solution at t = 0, equilibrium and time t 94 Sorinela Daniela Cantea, Eugen Pincovschi, Ana Maria S. Oancea 0 r mean radius of the resin swollen beads (m) i r microsphere radius (m) S n roots of equation S n cot S n = 1 + S n 2 /3ω t time (s) Greek Symbols 2 2 0 i a i r D r D = α dimensionless rate parameter ∞ ∞ = α β a i M M 3 / dimensionless equilibrium parameter β′ α′, roots of equation 0 3 3 2 = − + ω ω x x 2 0 r t D a = θ dimensionless time 2 0 r t D = τ dimensionless time e e / = ω dimensionless equilibrium parameter