Eco-friendly chitosan/quartzite composite as adsorbent for dye removal

Abstract

In this study, a novel composite chitosan/quartzite, prepared from the combination of industrial wastes, was applied to remove Reactive Black 5 (RB5) dye from aqueous solutions. The use of quartzite powder waste combined with chitosan in the development of new products was reported for the first time and consists of a strategy that will not only reduce the amount of the wastes, but also provide added value to these materials. The composite was characterized by FTIR, SEM, EDS, XRD, TGA and pHPZC techniques, which attested the success of the adsorbent synthesis. The effects of contact time, pH, temperature, and initial concentration were evaluated for RB5 removal. The kinetic models of pseudo-second order and Weber and Morris showed the best fit to experimental data, indicating that the dye-adsorbent interactions and the intraparticle diffusion are the controlling mechanisms for RB5 adsorption on quartzite/chitosan composite. Sips and Liu isotherm models described equilibrium results, with a maximum removal capacity for RB5 of 171.50 mg g−1, at 55 °C. Thermodynamic analysis indicated that the adsorption process is endothermic, showing greater spontaneity at high temperatures. Therefore, the results demonstrate that quartzite/chitosan composite has potential to be used as an effective, sustainable, and low-cost adsorbent for the decontamination of effluents containing RB5.