Equilibrium and continuous flow studies on the sorption of Congo Red using ethylenediamine modified rice hulls

The effectiveness of using ethylenediamine rice hulls (EDA-RH) to remove Congo Red (CR) from synthetic dye solution was carried out in batch and column experiments under various experimental conditions. Surface morphology analysis was carried out also using atomic force microscopy (AFM). The experimental data obtained at different initial dye concentrations fitted well to pseudo-second order kinetic model. Application of Langmuir isotherm indicated that maximum sorption capacity of EDA-RH for CR was enhanced by 2-fold as compared to natural rice hulls. Column studies revealed that the breakthrough curves of CR followed the typical S shape of packed-bed systems and it was bed-depth and influent-concentration dependent. The BDST model was used to predict the bed-depth service time data at different bed depths. A plot of BDST at 50% breakthrough yielded a straight line that, however, does not pass through the origin.