INFLUENCE OF pH ON METHYLENE BLUE SORPTION KINETICS FROM AQUEOUS SOLUTIONS USING ORANGE PEELS AS A LOW-COST SORBENT

In the present work, the effect of initial pH of methylene blue solution on the kinetics of dye sorption from synthetic aqueous solution by a natural waste material namely: orange peels, was studied. Kinetic data were measured in batch conditions. Methylene blue uptake was time contact and solution initial pH dependent. Maximum dye sorption was found to occur at initial pH 9. Two simplified kinetic models including a first-order rate equation and a pseudo second-order rate equation were selected to describe the dye sorption kinetics. The process followed a pseudo second – order rate kinetics. A multiple-stage diffusion of methylene blue onto orange peel particles was observed indicating that intraparticle diffusion was not a fully operative mechanism for this systems and reflects some degree of boundary layer control. The desorption of methylene blue from dye-laden-orange peels was performed to an extent of 84 % by a distilled water which solution initial dye was adjusted to 2.