Crosslinked Chitosan/quarry waste composite beads for adsorption of Reactive Blue dyes

Abstract

The present study aimed to evaluate quarry waste (QW), an industrial by-product rich in silicate and aluminate phases, as a reinforcing filler in a chitosan matrix, and to develop crosslinked chitosan/quarry waste (CS/QW) composite beads for the removal of Reactive Blue 49 (RB 49) and Reactive Blue 222 (RB 222) from aqueous solutions. The prepared composite beads were analyzed using FESEM – EDX, FTIR, XRD, TGA, and DSC techniques. The bead structure exhibited a porous and heterogeneous morphology, which enhanced the accessibility of active sites and facilitated mass transfer during adsorption. Successful formation of CS/QW beads with favorable adsorption properties was achieved. Adsorption behavior was evaluated in batch systems under various operating conditions. Equilibrium data were best described by the Langmuir model, with monolayer capacities of 7.66 mg/g for RB 49 and 6.82 mg/g for RB 222. Kinetic analysis followed a pseudo-second-order model, while thermodynamic results indicated an endothermic process with improved adsorption performance at elevated temperatures. The CS/QW beads retained approximately 48% of their initial adsorption capacity after five regeneration cycles, demonstrating their reusability. Overall, the findings highlight the potential of CS/QW composite beads as cost-effective and sustainable adsorbents for dye-contaminated wastewater treatment.