The effect of pH on the removal of anionic dyes from colored textile wastewater using a biosorbent

The effect of pH on equilibrium and kinetics of dye adsorption onto canola hull as a biosorbent was studied. Reactive Red 198 (RR198), Reactive Blue 19 (RB19), Direct Red 79 (DR79), and Direct Red 80 (DR80) were used as model textile dyes. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and UV–vis spectroscopy were used. The presence of functional groups onto canola hull was investigated using FTIR spectroscopy. The pseudo first‐order, pseudo second‐order and intraparticle diffusion kinetics models were examined to evaluate the kinetics data. The Langmuir, Freundlich, and Tempkin adsorption isotherm models were applied to describe the equilibrium isotherms. The FTIR spectrum proved the presence of functional groups such as hydroxyl and amino groups in canola hull surface. The results showed that the adsorption of RR198, RB19, DR79, and DR80 onto canola hull followed Tempkin isotherm. Adsorption kinetic of dyes followed pseudo second‐order kinetics. Desorption tests showed maximum dye releasing of 88% for RR198, 86% for RB19, 91% for DR79, and 95% for DR80 at pH 12. Data showed that canola hull could be used as a novel natural material for the removal of anionic dyes from wastewater. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011