Heavy-Metal Chelating Properties of Strawberry (Fragaria × Ananassa Duch.) Leaf Extracts

Strawberry (Fragaria × ananassa Duch.) leaves are an agricultural waste that emerges in large quantities after the strawberry harvest. Since strawberry leaves are generally considered agricultural waste, the utilization of this waste biomass or its extracts has attracted great interest as a low-cost and sustainable method for pollution removal. The material for this study consisted of the green leaves collected from strawberry plants (Fragaria × ananassa Duch.) cultivated under greenhouse conditions, immediately following the fruit harvest. The study material was ground following the drying process and prepared as a powdered sample possessing a homogeneous particle size requisite for the analyses. Subsequently, the samples were extracted for a duration of two hours using an ultrasonic bath method with ethanol employed as the solvent. The interaction of strawberry leaf extracts with a series of transition and heavy metals was examined using UV–Vis spectroscopy in order to clarify its binding behavior and selectivity. Concentration-dependent spectral measurements revealed marked perturbations upon metal addition, confirming complex formation. The data indicated that Hg displayed the strongest affinity, with a breakpoint at approximately 0.5 equivalents, consistent with a HgL₂ stoichiometry, whereas Cd and Pb produced clear maxima around 2.0 equivalents, supporting a 2:1 metal-to-ligand binding model. Zn, Cr, and Cu also induced spectral changes but with lower intensity and less well-defined stoichiometries, Cu showing mixed behavior between 1:1 and higher-order species. These results demonstrate that strawberry leaf extracts have a pronounced tendency to coordinate toxic heavy metals, particularly Hg (II), Cd (II), and Pb (II), underlining its potential utility as a selective chelator in environmental monitoring and remediation.