number of mass-transfer units

Mass-transfer coefficients in an ion exchanger A bed of ion-exchange beads 1.5 mm in diameter is used to deionize water at 293 K with a superficial velocity of 0.6 cds. The feed concentration is 0.02 M NaC1, and the resin has an equilibrium capacity of 2.4 eq/L of resin bed. The porosity of the 2-m-depth bed is 0.35. For monovalent ions, the effective diffusivity in the pores of the resin is about one-tenth of the normal liquid diffusivity (McCabe et al., 2005). Calculate the volumetric overall mass-transfer coefficient, Kca, and the number of mass-transfer units, N. Use equation (1 – 133) to calculate the diffusivity of NaCl in water.