Kinetics of adsorptive removal of drimarene brilliant red from aqueous solution using untreated agricultural residues

The potential of untreated banana and orange peels, and rice husk was tested for drimarene brilliant red (DBR) dye removal from aqueous solution. Kinetics was also studied in a batch experiment. Dose of adsorbents varied from 6 to 12 g/L, particle sizes 0.2 and 0.8 mm and contact time 2-32 h. High dose and small particle size favoured DBR removal efficiency significantly. The highest adsorption capacity was shown by rice husk (10 mg/g), then orange peels (9 mg/g) and the lowest by banana peels (4 mg/g). Langmuir isotherm (R/super 2/=0.99) and pseudo-second order model (R/super 2/=0.99) depicted well the equilibrium and best explained the kinetics for rice husk, respectively. Initial adsorption appeared as pore diffusion in all the cases and film diffusion was controlling the rate, later on. Based upon the analytical data, a simple model has been presented that fitted best to describe rice husk adsorption kinetics. (author)