Effect of ionic strength on methylene blue sorption onto macroporous resins: a comprehensive study

Abstract

In the current study, adsorption behaviors of amberlite XAD-7 and XAD-16 for the removal of methylene blue from its aqueous solutions have been reported with several respects. First, response surface approach (RSA) has been used to identify the optimum conditions (0.21 g resin/10 mL MTB solution under 149 rpm mixing speed of shaking bath) for the best adsorption process of methylene blue (MTB) removal (approximate to 99%). The most significant process parameter was found to be solution volume, followed by resin amount and speed. Effects of fluoride and chloride on the MTB removal have been also investigated. Elevated concentration of ions in MTB solutions gave rise to decline the adsorption capacity regularly, while the adsorption yield enhanced by increase in pH. On the other hand, the concerned adsorption system was a chemisorption process based on the kinetic (pseudo-first order, pseudo-second order, intraparticle diffusion models) and equilibrium (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich isotherm equations) parameters.