Abstract
In this work, a fundamental investigation on the removal of methylene blue from aqueous solutions by wheat bran is conducted in batch conditions. Removal kinetic data are determined, and the effects of different experimental parameters, such as wheat bran mass, initial concentration of methylene blue, agitation speed, solution pH, particle size, temperature, and ionic strength on the kinetics of methylene blue removal are investigated. The cationic dye recovery increases with an increase of sorbent mass, solution pH, and temperature. Methylene blue removal decreases with an increase of initial concentration, particle size, and ionic strength. The agitation speed showed a limited influence on the removal kinetics. Modeling of kinetic results shows that sorption process is best described by the pseudo- second order model, with determination coefficients higher than 0.996 under all experimental conditions. The applicability of both internal and external diffusion models shows that liquid-film and particle diffusion are effective sorption mechanisms. The activation energy of sorption calculated using the pseudo- second order rate constants is found to be 13.41 kJ mol(-1) from an Arrhenius plot. The low value of the activation energy indicates that sorption is an activated and physical process. Thus, wheat bran, a low cost and easily available biomaterial, can be efficiently used as an excellent sorbent for the removal of dyes from wastewater. It can be safely concluded that wheat bran is much economical, effectual, viable, and can be an alternative to more costly adsorbents.