A green nanotechnology approach based on coffee waste as a precursor for zero-valent iron in soil decontamination of...

The increasing use of antidepressants has resulted in their widespread occurrence in water bodies and soils. Venlafaxine (Vlx), a widely prescribed antidepressant, is a persistent and non-degradable pollutant frequently detected in rivers, lakes, municipal wastewater, and soils. This study investigates the effectiveness of green nanoscale zero-valent iron (nZVI), synthesized from spent coffee grounds (SCGs), in removing Vlx from both water and soil, building on the established use of nZVIs for contaminant remediation in environmental systems. A Box-Behnken design (BBD) was employed to evaluate the effects of three parameters-Vlx concentration (X₁), nZVI mass (X₂), and water recovery volume (X₃)-on three responses: % Vlx in water fraction (R1), % Vlx subsequently extracted from solid fraction (R2), and % Vlx extracted from water and soil (R3 = R1 + R2). The resulting reduced quadratic models for all responses (with an inverse transformation for R1) were highly significant (p < 0.0001). Additional experiments were conducted, including an assessment of the effect of pH on Vlx removal from water. Experiments performed under the BBD-optimized conditions (X₁ = 2.075 mg/L Vlx, X₂ = 0.269 mg SCG40°C-nZVI, X₃ = 7.186 mL H₂O) with nZVI synthesized from different extracts and biomasses underscored the critical influence of the synthesis method on remediation performance. The greenness of the nZVI synthesis by SCG extracts was also assessed by several green analytical chemistry methods. This work represents the first application of nZVI for remediation of Vlx-contaminated soil, providing novel and valuable insights into their potential for soil decontamination strategies.