From Waste to Reuse: The Valorization of Almond Shells ( Prunus dulcis ) as a Sustainable Biosorbent for the Removal and Recovery of Phenolic Compounds in Winery Wastewater

High Resolution Image Download MS PowerPoint Slide Almond shell powder (ASP) derived from Nonpareil (soft-shell) and Peerless (hard-shell) almond varieties was evaluated as a natural bioadsorbent for removing phenolic compounds from model and industrial winery wastewater. Binding kinetics, particle size, mass-to-liquid ratio (m/v), and recovery efficiency were assessed. Nonpareil and Peerless adsorption fit an Elovich kinetic model ( R 2 = 0.986 and 0.982, respectively). Optimal adsorption occurred at a 0.2–0.5 mm particle size and a 1:10 ASP-to-wastewater ratio (m/v), yielding 79.05 ± 0.79% (0.84 ± 0.01 mg g –1 ) total phenolic content. Phenolic recoveries were 70.26 ± 0.18% (0.51 ± 0.01 mg g –1 ) for Nonpareil and 52.36 ± 0.30% (0.44 ± 0.00 mg g –1 ) for Peerless using optimized conditions: 50:50 ethanol/water (v/v) at a 1:25 ASP-to-solvent ratio (m/v). These findings demonstrate that ASP is a viable, low-cost, and sustainable material for phenolic removal from winery wastewater with the added benefit of enabling phenolic compound recovery.