Photocatalytic degradation of methylene blue using chitosan/NiO nanocomposite: A comprehensive exploration

Abstract

The present research work aims to illustrate the potential power of chitosan nanoparticles and chitosan/nickel oxide (NiO) nanocomposite for the photocatalytic degradation of methylene blue (MB). Initially, chitosan nanoparticles and chitosan/NiO nanocomposite were prepared using ball milling technique, focusing on the theory of top-down preparation. It was observed that, the as-prepared chitosan/NiO nanocomposite exhibited spherical shape with small size. Meanwhile, chitosan nanoparticles were prepared with irregular shape as depicted from TEM analysis. XRD affirmed the pure phase and crystalline structure of chitosan nanoparticles as a result to the observation for two peaks at 11.3o and 20.11o. New characteristic peaks at 35.3o, 38.5o, 49o, and 63o were noticed owing to the presence of NiO blended with chitosan nanoparticles. The estimated values of optical band gap energy for chitosan nanoparticles and chitosan/NiO nanocomposite are (3.6 eV, 3.5 eV), respectively. The photocatalytic degradation of MB dye employing chitosan nanoparticles and chitosan/NiO nanocomposite achieved 21 % and 96.1 %, respectively. The enhancement of photocatalytic efficiency of MB dye was mainly attributed to the potential effect of NiO nanoparticles. The findings also demonstrated that the photocatalytic performance of both chitosan nanoparticles and chitosan/NiO nanocomposite was pH, time, and catalyst doses dependent and obey Langmuir-Hinshelwood model. The photocatalytic activity of chitosan/NiO nanocomposite lost 14.9 % of its performance after first two cycles. Therefore, chitosan/NiO nanocomposite has emerged as a pioneering agent in sustainable water treatment, promising a transformative approach to combat water pollution. This study can guide future research, industry practices, and policy decisions towards a future where water treatment is synonymous with environmental harmony and innovation.