مدل طراحی تغییر یافته برای جذب رنگ بر روی ذغال سنگ

For over 20 years, peat has been recognized as a potential biosorbent for the treatment of wastewaters. Several studies have been reported in the literature including its use in cleaning oil spills1, the removal of heavy metals from wastewaters2, the removal of herbicides3, the treatment of slaughterhouse wastewaters, septic tank effiuents and dairy wastes4. The ability of peat to remove several dyes from aqueous effiuent was reported some time ago5. Further studies on single component adsorption of basic and acid dyes were carried out to study equilibrium isotherms6, diffusion based mass transport processes for batch and fixed bed systems7. Carbon has been used for acid dyes in fixed beds8. However, in these previous studies, conventional simplifi ed design methods—namely, bed depth service time (BDST) and empty bed residence time (EBRT) models—were applied to the experimental breakthrough curve data but failed to correlate these data due to the non-linearity of the BDST versus bed height data obtained. In the present paper new modifications have been developed based on an expression, Nt/N0 = 1 – exp(– a*sqrt(t)), where Nt, N0, a, t represent the bedcapacity at service time t, the saturated bed capacity found in isotherm experiments, a rate constant and the service time of the bed respectively. The expression correlates the residence time in the adsorption bed with the time dependent fraction degree of saturation of the bed. It enables modified BDST and EBRT models to be applied and correlate the experimental data very accurately. This model is particularly suited to predicting the performance of fixed bed adsorbers, when the system requires a long time to reach equilibrium or when several fixed bed adsorbers are used in series.