Iron oxide nanoparticles from clove and green coffee for antioxidant and antimicrobial activities and analytical application in caffeine removal

This study investigates the green synthesis, characterization, and biological activities of iron oxide nanoparticles (IONPs) synthesized from clove and green coffee extracts. FTIR spectroscopy identified reactive functional sites, including -OH, C=O, and polyphenolics, confirming their role as reducing and stabilizing agents XRD analysis showed amorphous IONPs at ambient temperature and crystalline phases after annealing at 550 °C. SEM imaging revealed pyramidal morphologies for green coffee-derived IONPs and rod-like structures for clove-derived IONPs. Also, nitrogen adsorption and desorption (BET) and X-ray photoelectron spectroscopy were used to gain a thorough grasp of the surface characteristics of the nanoparticles. The Dubinin-Radushkevich isotherm best described caffeine adsorption, confirming physisorption, while the Langmuir model indicated monolayer adsorption with maximum capacities of 596.91 mg/g (clove) and 714.55 mg/g (green coffee). Kinetic studies suggested pseudo-second-order adsorption for green coffee-derived IONPs (R² = 0.96156) and the Elovich model for clove-derived IONPs (R² = 0.98595). Antimicrobial tests showed strong antibacterial activity of clove-derived IONPs against S. aureus and B. cereus, with significant antifungal efficacy against P. reqfortii. Green coffee-derive IONPs exhibited higher DPPH radical scavenging activity (87.03%) than clove-derived IONPs (27.18%). Cytotoxicity assessment on WI-38 human lung fibroblasts revealed concentration-dependent effects, with green coffee-derived IONPs showing higher biocompatibility (CC₅₀ = 564.04 μg/mL) than clove-derived IONPs (CC₅₀ = 398.41 μg/mL). Economic analysis confirmed laboratory-scale production costs of $6.92-7.25/g, with projected 70% reduction at industrial scale through waste valorization and process intensification. These observations demonstrate the applicability of eco-compatible IONPs as antimicrobial and antioxidant agents, offering a sustainable alternative to conventional treatments. Further optimization and clinical validation are recommended.