Fixed bed studies for the sorption of metal ions onto peat

摘要

In this study,peat has been used as an adsorbent for the removal of heavy metlas in a fixed bed system.Experiments have been performed to investigate the effect of flowrate and bed depth on the peat-metal ion system.A film-poe diffusion modelhas been used to predict the breakthrough behaviour.The three major parameters in the mathematical model are the external mass transfer coefficient,k,the effective pore diffusivity,D_(eff),and the solid-phase loading capacity,q_e.One of the main problems in this type of modelling is the prediction of q_e,particularly for sorbent-solute systems which take a long time to achieve equilibrium saturation.Some researchers have used the equilibrium isotherm capacity,some utilize a fixed fraction of the isotherm capacity and other workers perform the numerical or graphical mass balances at the breakthrough curves,which is time-consuming and tedious.The present method incorporates a novel empirical solution for q_e which is correlated with the service time.Good agreement between the predicted theoretical breakthrough curves and the experimentla results is observed.