Introduction
Graphitic carbon nitride (gCN) exhibits a unique combination of visible-light responsiveness, suitable band structure, chemical stability, and low cost, making it a highly promising photocatalyst. In photocatalysis, one of the major challenges lies in the difficult separation of the photocatalyst from the reaction medium and its reuse over multiple cycles. This problem can be addressed by immobilizing gCN onto solid support. Therefore, developing reliable immobilization strategies is essential to ensure the long-term stability, reusability, and ecological safety of gCN-based photocatalysts. One of the solutions presented in this research involve the formation of carboxymethylcellulose/gCN (CMC/g-C₃N₄) beads supported by metal ions.
Methods
Beads were synthesized from urea-derived gCN, CMC, CuSO₄ and FeCl₃. The preparation involved the dropwise addition of CMC solution (1 and 2wt%) into a 10wt% aqueous solution of Fe3⁺ or Cu²⁺ ions with dispersed gCN. The resulting beads were characterized by FTIR spectroscopy and compression testing. Stability and reusability of obtained beads as photocatalyst carriers were evaluated and compared through three successive photodegradation cycles using azo-dye Acid Orange 7 as model compound.
Results
In this study, CMC/gCN beads were designed and fabricated. CMC served as a supporting anionic polymer matrix, capable of reacting with cationic crosslinkers such as Cu²⁺ and Fe³⁺ through its –COOH groups, thereby promoting the formation of a dense and stable network with enhanced mechanical strength. The successful formation of the composite structures was confirmed by FTIR analysis, while compression testing and photocatalytic evaluation demonstrated superior durability and efficiency of the beads crosslinked with Cu²⁺-ions.
Conclusion
The study provides insights into how the choice of metal ion crosslinker and synthesis strategy affects the physicochemical properties, structural integrity, and photocatalytic efficiency of the beads. These findings highlight the potential of synthesized beads for their use in sustainable and efficient wastewater treatment.
