Dynamics Modelling of Multicomponent Metal Ions Removal onto Low-Cost Buckwheat Hulls

The adsorption process from water solutions containing a ternary system of Cu(II), Zn(II) and Ni(II) ions onto buckwheat hulls as a biosorbent was considered in this study. The sorption capacity of the ions was determined in sorption equilibrium batch experiments, and they were 15.13, 5.60 and 5.87 mg/g, respectively. Pseudo-second-order sorption kinetics corresponding to the mechanism of metal ions was assumed. A new method for modelling sorption in a packed column was presented. A system of partial differential equations describing the mass balance, due to the assumption of a properly defined variable, was transformed into a system of ordinary nonlinear equations, which enabled the identification of object parameters: effective diffusion and kinetic coefficients. The sorption capacity of the sorbent, sorption isotherms and kinetic equations were used in dynamics modelling.