The use of activated carbon derived from spent coffee grounds as a reusable, sustainable, and effective solution for the removal of butylparaben from water

Abstract BACKGROUND Parabens, including butylparaben (BP), are widely used as antimicrobial preservatives in food, cosmetics, and pharmaceuticals, yet are poorly removed by conventional water treatment processes and pose potential risks to aquatic life and human health. This study evaluates activated carbon produced from coffee grounds and chemically activated with ZnCl₂ (ACZnCl₂, 564.4 m 2 ·g −1 ) as a sustainable adsorbent for BP removal from water. RESULTS Using 5 g·L −1 of ACZnCl₂ at pH 7, the highest removal efficiency (77.6 ± 0.4%) occurred at the lowest BP concentration (30 μg·L −1 ), with removal efficiency dropping to 20.0 ± 0.6% when BP concentration increases to 300 μg·L −1 . While most studies examine high BP concentrations (10–200 mg·L −1 ), this work demonstrates effective removal at environmentally relevant trace levels. Equilibrium was reached within 100 min, and adsorption kinetics behavior were well described by PFO and PSO models ( R 2 = 0.998). Equilibrium data fit the Langmuir isotherm ( R 2 = 0.996), indicating monolayer adsorption. Thermodynamic parameters confirmed a spontaneous (Δ G ≤ 0) and exothermic (Δ H ≤ 0) adsorption process. Aspen Adsorption® simulations validated the system, predicting 100% theoretical removal. ACZnCl₂ maintained removal efficiency above 92% after six ethanol regeneration cycles. Allium cepa assays confirmed the elimination of cytotoxicity and genotoxicity in treated effluent. CONCLUSION The study shows that a 0.001 m‐high adsorption column can treat water containing 600 μg·L −1 BP at a flow rate of 5 × 10 −7 m 3 ·s −1 , highlighting ACZnCl₂ as a sustainable and scalable option with strong potential for practical water‐treatment applications. © 2026 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).