3D-Printed SiOC Ceramics Grafted with Chitosan-Graphene Oxide Composite for Enhanced Dye Adsorption

The removal of synthetic dyes from wastewater is a critical challenge in environmental remediation. This study aims to design a novel 3D-printed silicon oxycarbide (SiOC) polymer-derived ceramic (PDC) monolithic support structure, grafted with a chitosan-graphene oxide (GO) composite, to serve as an efficient dye adsorbent. The approach integrates additive manufacturing of SiOC ceramics with surface modification through silane-grafting to enhance adsorption capacity. The optimum parameters for pyrolytic conversion, crosslinking, and grafting mechanisms were thoroughly investigated and confirmed using various characterization techniques, including Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy coupled with energy dispersive X-ray analysis (FE-SEM/EDX), X-ray diffraction (XRD), Raman spectroscopy, and thermogravimetric analysis (TGA). Adsorption studies for methyl orange (MO) dye using an adsorbent with a GO to chitosan mass ratio of 0.1 resulted in a removal efficiency (R%) of 91.16 % and an uptake capacity (q_e​) of 182.33 mg/g under conditions of 30 °C and pH 3.0. In this study, the suitable isotherm model was Harkins-Jura isotherm (R² ∼ 1). The adsorption kinetics were best described by the pseudo-second-order model, indicating that chemisorption on a monolayer was the predominant mechanism. The chitosan-GO composite exhibited strong adsorption properties for MO dye, driven by the synergistic effects of the abundant amino groups on chitosan and the pi-pi stacking interactions provided by graphene oxide. In terms of thermodynamic studies, the reaction is endothermic, and the adsorption process is more spontaneous and favorable at 30 °C compared to elevated temperatures. Additionally, the regeneration studies showed the 3D monolith's durability, with removal efficiency staying above 92 % after five cycles. The surface-grafted PDC monolithic support demonstrated significant mechanical stability and durability, suggesting its potential viability for real-world applications in wastewater treatment.