Biogenic silver and iron oxide nanoparticles from beech steaming condensate for antimicrobial activity and methylene blue removal

Abstract

This study reports a biogenic and eco-friendly approach for the synthesis of silver (BSCAgNPs) and iron oxide nanoparticles (BSCFeNPs) using Oriental beech (Fagus orientalis L.) steaming condensate (BSC) as a dual reducing and stabilizing matrix, enabling the valorization of an underutilized wood-industry by-product. Transmission electron microscopy revealed distinct nanostructures, with BSCAgNPs ranging from 11 to 38 nm and highly uniform ultrasmall BSCFeNPs of 3 to 6 nm, while Fourier transform infrared spectroscopy (FTIR) and EDX analyses revealed changes in BSC-derived functional groups associated with NP formation, while EDX confirmed the elemental presence of Ag and Fe in the respective samples (Ag 60.26% and Fe 68.12%). Relative to the raw condensate, NP formation resulted in a marked enhancement of functional performance, reflecting effective surface functionalization by bioactive constituents. BSCAgNPs exhibited pronounced antimicrobial activity, particularly against Gram-negative bacteria, with minimum inhibitory concentration (MIC) values as low as 0.04 mg/mL for Escherichia coli and Bacillus cereus, supporting their potential relevance to biodeterioration control. In parallel, both NP systems demonstrated efficient removal of methylene blue from aqueous media, with both PFO and PSO models providing good empirical descriptions of the kinetic data and the PSO model showing a slightly better fit (R² > 0.99), with Langmuir-derived Qmax estimates of 84.4 mg/g for BSCAgNPs and 55.4 mg/g for BSCFeNPs at the lowest tested adsorbent dosage of 1 mg/mL. The functional differences observed after NP formation were accompanied by changes in redox-related properties and surface-associated functional groups. Overall, these findings demonstrate that beech wood steaming condensate can be transformed into a functional biogenic nanoplatform that combines antimicrobial efficacy with dye-removal capability, providing a sustainable proof-of-concept platform with potential relevance to biodeterioration control and environmental remediation.