Efficient photodecolorization of Congo red by CaMgO₂@g-C₃N₄ nanocomposite

Artificial dyes resist conventional oxidation and reduction processes. The current study aims to investigate the utilization of ultrasonically prepared CaMgO₂@g-C₃N₄ nanocomposite for Congo red dye decolorization. The XRD analysis reveals the formation of a multiphase composite containing Ca and Mg oxides alongside g-C₃N₄. The coupling of MgO and CaO to g-C3N4 nanosheets is confirmed by TEM/EDX and XPS analysis. The nanocomposite manifests a high photocatalytic degradation of Congo red dye in an aqueous solution (99 mg/g) with an insignificant retention rate (∼ 5%) by virtue of its large surface area (73 m2/g), low band gap energy (2.85 eV) as well as the photogenerated holes, electrons, and hydroxyl radical involvement. The dye photodecolorization displays a rate constant of 0.07092 min⁻¹ and a decolorization rate of 99%. Furthermore, the photodegradation kinetics fits well with the pseudo-first-order model, and mechanistic modeling suggests a Z-scheme mechanism. This research highlights the powerful catalytic effect of CaMgO2@g-C3N4 for synthetic dyes’ decolorization.