Abstract
Olive mill wastewater (OMW) presents a severe environmental challenge in Mediterranean regions due to its high organic load and phytotoxicity, yet it serves as an abundant source of bioactive polyphenols. Herein, we demonstrate a novel, integrated process combining electrochemical pretreatment with microfluidic continuous-flow synthesis to valorize OMW into functional silver nanoparticles (AgNPs) possessing potent anti-diabetic properties. Raw OMW underwent electrochemical clarification using aluminum electrocoagulation, efficiently removing suspended solids (94.2% turbidity reduction) while retaining 86.5% of total phenolic content, predominantly hydroxytyrosol and tyrosol. The polyphenol-rich effluent was directly channelled into a continuous-flow microfluidic reactor as both reducing and capping agent for aqueous silver nitrate (AgNO3). Optimization of flow rates, temperature (60 °C), and residence time (4.2 min) yielded highly monodisperse, spherical AgNPs with a mean hydrodynamic diameter of 18.5 ± 2.3 nm and a zeta potential of -28.4 mV. FTIR spectroscopy confirmed the surface functionalization of AgNPs by phenolic hydroxy groups. In vitro enzymatic assays demonstrated significant anti-diabetic activity, with the synthesized AgNPs inhibiting α-glucosidase and α-amylase with IC50 values of 12.4 ± 0.8 µg/mL and 24.8 ± 1.5 µg/mL, respectively, outperforming standard acarbose. This study highlights a sustainable, circular economy framework that merges electrochemistry, green phytochemical extraction, and continuous nanomaterial manufacturing to convert hazardous agro-industrial waste into high-value biomedical materials.
