Dynamic sorption of methylene blue by cedar sawdust and crushed brick in fixed bed columns.

The dynamic removal of methylene blue by cedar sawdust and crushed brick was studied in packed bed columns. The values of column parameters were predicted as a function of flow rate and bed height. On evaluating the breakthrough curves, the sorption isotherms of methylene blue onto cedar sawdust and crushed brick in 20 degrees C aqueous solution were experimentally determined in batch conditions. Both the Freundlich and the Langmuir models were found to fit the sorption isotherm data well, but the Langmuir model was better. A series of column tests using cedar sawdust and crushed brick as low-cost sorbents were performed to determine the breakthrough curves with varying bed heights and flow rates. To predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design, five kinetic models; Bohart and Adams, bed depth service time (BDST), Clark, Wolborska, and Yoon and Nelson models were applied to experimental data. All models were found suitable for describing the whole or a definite part of the dynamic behavior of the column with respect to flow rate and bed height, with the exception of Bohart and Adams model. The simulation of the whole breakthrough curve was effective with the Yoon and Nelson and the Clark models, but the breakthrough was best predicted by the Wolborska model.