Synthesis of alginate capped aluminum oxide (Al₂O₃) nanocomposite for efficient photocatalytic degradation of methylene blue

Abstract In the presence scenario, dye pollution has become a serious issue in present environment protection which need extensive attention of the scientific community. Methylene blue (MB) has been known for its toxic nature and widely used in various industries. In the present work, we reported the green synthesis of alginate capped alumina (Al 2 O 3 ) nanocomposite (NC). The synthesized Alg@Al 2 O 3 NC have been verified by various sophisticated characterization techniques (XRD, SEM, EDX, UV–vis TEM, FTIR, and XPS). The synthesized Alg@Al 2 O 3 NC have been used as photocatalyst for the degradation of MB dye. Furthermore, photocatalytic activity of the Alg@Al 2 O 3 NC has been studied under ultraviolet (UV) light. The obtained results exhibited excellent photocatalytic properties of the Alg@Al 2 O 3 NC. The effect of photocatalyst doses (0.1–5 g l −1 ), pH −1 (1–10), MB dye concentration (50–120 ppm), and irradiation time (5–135 min) of UV light were also optimized. The highest efficiency of 99.2% has been observed for MB degradation via Alg@Al 2 O 3 NC. The investigations of kinetics demonstrated that the photocatalytic degradation proceeded along a pseudo-first-order pathway in accordance with the Langmuir–Hinshelwood (L-H) kinetic model. The Alg@Al 2 O 3 NC also exhibited excellent reusability for 4 cycles and suggested that Alg@Al 2 O 3 NC can be used for various cycles. In this study, we proposed the cost-effective green synthetic method for the preparation of Alg@Al 2 O 3 NC and its application as photocatalyst for the removal of MB dye under UV light.