Eco-friendly ferrocene-functionalized chitosan aerogel for efficient dye degradation and phosphate adsorption from wastewater

Developing highly efficient, biodegradable and eco-friendly adsorbents to remove pollutants from wastewater has been a significant and long-term global challenge. Herein, a novel aerogel (Fc-CS) has been developed through the functionalization of glutaraldehyde-crosslinked chitosan with ferrocene groups. Methylene blue (MB) and eutrophication ions (PO43−) have been chosen as model pollutants to evaluate the adsorption efficiency of Fc-CS aerogel. The results demonstrated that Fc-CS aerogel possessed high specific surface area and good thermal stability. Freundlich model fitting revealed that both PO43− and MB were adsorbed in a multilayered fashion on the Fc-CS aerogel through complex adsorption mechanisms, and pseudo-second-order kinetic model fitting confirmed the involvement of chemical adsorption. Benefiting from the appending of ferrocene groups, Fc-CS aerogel not only showed excellent PO43− adsorption performance, but also provided a Fenton-like active center to catalyze dyes degradation. According to the Langmuir isothermal model, the maximum adsorption capacity for PO43− was approximately 1141 mg·g−1, exceeding those of most previously reported bio-based adsorbents. The addition of H2O2 significantly enhanced the MB removal efficiency of Fc-CS aerogel from 8.20% to 92.79% by triggering a Fenton-like reaction. After five cycles, no significant attenuation in removal efficiency was observed for either MB or PO43−, with or without H2O2. This eco-friendly and recyclable biomaterial could be an attractive candidate for removing MB and PO43− from aquatic systems. The present work provided a feasible pathway to design and develop highly efficient bio-aerogel for wastewater treatment and environmental remediation.