Post-Supercritical CO2 Extraction Biowastes as Sustainable Low-Cost Adsorbents for Malachite Green Removal: Pistachio Shell, Cranberry, and Grape Seed
Esil Mulazimoglu, Caner Guven, Nergiz Kanmaz, Batuhan Yardimci
article (Uluslararası, Hakemli) | Yazar(lar): Esil Mulazimoglu, Caner Guven, Nergiz Kanmaz, Batuhan Yardimci | Yıl: 2026 | Dergi/Kurum: CHEMISTRYSELECT | İndeks: WOS.SCI | DOI: 10.1002/slct.73621 | Anahtar Kelimeler: adsorption, malachite green, supercritical extraction waste, sustainable adsorbent — Özet: Pistachio ex
Pistachio external shell (PES), cranberry (CB), and grape seed (GS) biowastes, recovered after supercritical CO2 (SC-CO2) extraction, were evaluated as low-cost and sustainable adsorbents for the removal of malachite green (MG) from aqueous solutions. The characterization by SEM, FT-IR, and BET confirmed their lignocellulosic structure, and specific surface areas of 21.88 (PES), 22.73 (CB), and 1.42 m2 g-1 (GS). Batch adsorption experiments investigated the initial dye concentration (25-250 mg L-1), pH (2-10), contact time (30-375 min), and temperature (25 degrees C-45 degrees C). Equilibrium data showed excellent agreement with the Langmuir isotherm model (R 2 = 0.95-0.99), indicating monolayer adsorption. The maximum adsorption capacities were 121.67, 142.99, and 116.77 mg g-1 for PES, CB, and GS, respectively. PES and CB attained equilibrium within 90 min (pseudo-first and pseudo-second-order models), whereas GS required 300 min (Elovich model). According to the thermodynamic analysis, PES and CB were endothermic (Delta H degrees = +8.61 and +69.54 kJ mol- 1), whereas GS was exothermic (Delta H degrees = -13.79 kJ mol- 1). The predominant adsorption mechanism was identified as electrostatic interaction, supplemented by hydrogen bonding and pi-pi stacking. Results demonstrate that SC-CO2 extraction of biowastes, without chemical activation, possesses considerable potential for sustainable dye removal.