Synthesis and Characterization of CuO-Loaded Activated Carbon Derived from Cashew Nut Shells for Methylene Blue Removal

Abstract

In this study, a copper oxide-loaded activated carbon (AC–CuO) nanocomposite was synthesized using cashew nut shells as a low-cost carbon precursor for the photocatalytic degradation of methylene blue (MB). The prepared nanocomposite was characterized using XRD, FTIR, HRTEM, BET, zeta potential, TGA, and UV–Visible spectroscopy. XRD confirmed the crystalline nature of CuO with an average crystallite size of approximately 16 nm. HRTEM revealed well-dispersed CuO nanoparticles with distinct lattice fringes, confirming their nanoscale crystalline structure. BET analysis indicated a porous structure with a high surface area, while zeta potential measurements showed a negative surface charge favorable for interaction with MB molecules. The AC–CuOnanocomposite achieved 91% degradation of MB within 90 minand followed pseudo-first-order kinetics with a high correlation coefficient (R² = 0.993). Furthermore, it retained 90% degradation efficiency after five successive cycles, demonstrating good stability and reusability. The results indicate that the cashew nut shell-derived AC–CuO nanocomposite is a promising material for the photocatalytic treatment of dye-contaminated wastewater.