Film-pore diffusion modeling for the adsorption of aqueous dye solution onto acid-treated sugarcane bagasse

The adsorption of methylene blue dye onto acid-treated sugarcane bagasse (ASB) was investigated in batch system. The characterization of ASB was investigated using scanning electron microscopy, X-ray diffractometer and Fourier transform infra-red spectroscopy. The different factors namely adsorbent dosage, solution pH, initial composition of dye solution and temperature on specific dye uptake were examined using ASB in order to evaluate equilibrium kinetic parameters. The suitable variables (dosage = 5 g dm –3 ; initial pH = 6) for the maximum specific uptake of dye onto ASB. The maximum adsorption capacity of 45.4 mg g –1 was obtained at 25°C using ASB. In order to evaluate decay rate and concentration independent mass transfer parameters namely diffusivity and mass transfer co-efficient for adsorption of methylene blue on ASB, the film pore mass transfer model was considered. In this study, external mass transfer co-efficient and pore diffusivity are ranging between 10 –6 and 10 –12 m 2 s –1 , respectively. The rate limiting step for the adsorption of MB on ASB was known to be internal pore diffusion owing to the higher value of Biot number.