Chitosan nanoparticles on a natural zeolite as an efficient adsorbent for Congo red

Congo red is a toxic synthetic dye that cannot be readily degraded by conventional methods, thus posing a risk to the environment. The increased use of this dye is mainly due to developments in the textile industry. A possible way to reduce the Congo-red waste is by performing the adsorption processes; therefore, in this study, we used a natural zeolite from Bayah and modified it using chitosan nanoparticles (Na-zeolite@chitosan) to increase its adsorption capacity. The obtained Na-zeolite@chitosan material, which was able to efficiently adsorb Congo red, was further characterized by ultraviolet−visible (UV−Vis) and Fouriertransform infrared (FTIR) spectroscopy as well as by transmission electron microscopy (TEM). A maximum of 98.019% of the Congo red was adsorbed at a concentration of 800 ppm and a pH of 5 for 60 min (the adsorption capacity was 0.00428 mmol/g). Our results exhibit that Congo red adsorption on Na-zeolite@chitosan follows the Freundlich adsorption isotherm and can be described using a pseudo-second-order kinetic model. (paper)