A holistic approach in harnessing impregnated olive stone based activated carbon for Rhodamine B dye removal

• Published in: Separation science and technology Vol. 60; no. 9-10; pp. 1113 - 1128
• Main Authors: Hendekci, Mert Can, Ova Ozcan, Duygu, Ovez, Bikem
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 03.07.2025; Taylor & Francis Ltd
• Subjects: Activated carbon; Adsorption; adsorption modeling; Aqueous solutions; Carbon; Color removal; Dyes; olive stone; Response Surface Methodology; Rhodamine; Rhodamine B dye; Stone; Zinc chloride
• ISSN: 0149-6395; 1520-5754
• DOI: 10.1080/01496395.2025.2483758

This study explored the adsorption performances of ZnCl 2 , KOH and H 3 PO 4 impregnated activated carbons derived from olive stones for Rhodamine B dye removal from aqueous solutions. The equilibrium time and initial dye concentration were 6 h, and 200 mg L −1 , respectively with ZnCl 2 exhibiting the highest adsorption capacity (190.67 mg g −1 ), followed by KOH (118.26 mg g −1 ), H 3 PO 4 (49.81 mg g −1 ), and crude olive stones (21.57 mg g −1 ), compared to the commercial powdered activated carbon (254.30 mg g −1 ). ZnCl 2 impregnated activated carbon (ZOSAC) demonstrated enhanced removal as the adsorbent amount increased and background ions facilitated adsorption. Pseudo-second order model (R 2  = 0.99) best represented the experimetal data among kinetic models. Redlich-Peterson (R 2 > 0.98) model was the most suitable equilibrium model for all ACs. Increasing the temperature from 30°C to 50°C enhanced adsorption capacity. Adsorption was determined to be endothermic (∆H° = 14.91 kJ mol −1 ) and thermodynamically favorable (∆G°<0) for ZOSAC. At the end of the fifth adsorption/desorption cycle, the removal efficiency was 94% and the optimal conditions were 45°C and 252 mg L −1 . ZOSAC emerged as the most efficient and reusable activated carbon for Rhodamine B removal.