Production of activated carbon from date palm stones by hydrothermal carbonization and microwave assisted KOH/NaOH mixture activation for dye adsorption

Saud S Aloud; Hattan A Alharbi; Bassim H Hameed; John P Giesy; Saad S Almady; Khaled D Alotaibi

doi:10.1038/s41598-023-45864-z

Production of activated carbon from date palm stones by hydrothermal carbonization and microwave assisted KOH/NaOH mixture activation for dye adsorption

Sci Rep. 2023 Nov 4;13(1):19064. doi: 10.1038/s41598-023-45864-z.

Authors

Saud S Aloud¹, Hattan A Alharbi², Bassim H Hameed³, John P Giesy^{4

5

6}, Saad S Almady⁷, Khaled D Alotaibi⁸

Affiliations

¹ Department of Soil Science, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, 11451, Riyadh, Saudi Arabia.
² Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, 11451, Riyadh, Saudi Arabia.
³ Department of Chemical Engineering, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar.
⁴ Department of Biomedical Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, SK, S7N 5B3, Canada.
⁵ Department of Integrative Biology, Michigan State University, East Lansing, MI, 48824, USA.
⁶ Department of Environmental Sciences, Baylor University, Waco, TX, 76798, USA.
⁷ Agricultural Engineering Department, College of Food and Agriculture Sciences, King Saud University, 11451, Riyadh, Saudi Arabia.
⁸ Department of Soil Science, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, 11451, Riyadh, Saudi Arabia. khalotaibi@ksu.edu.sa.

Abstract

Date palm stones are regarded as possible alternatives to activated carbon (AC) precursors with high potential for various environmental applications. In this research study, date palm stones derived activated carbon (DPSAC) was used as adsorbent for removing toxic remazol brilliant blue R (RBBR). The synthesis of DPSAC involved a chemical treatment using KOH and NaOH (1:1). Characterization of DPSAC revealed that it exhibited a BET surface area of 715.30 m²/g, Langmuir surface area of 1061.93 m²/g, total pore volume of 0.39 cm³/g, and average pore diameter of 2.15 nm. Adsorption uptake of RBBR increased (from 24.54 to 248.54 mg/g), whereas the removal percentage decreased (from 98.16 to 82.85%) when the initial RBBR concentration increased (from 25 to 300 mg/L). The adsorption process performed best under acidic conditions (pH 3), with an RBBR uptake of 98.33 mg/g. Because of the high R² values (0.9906 and 0.9779) and low average errors (6.24 and 13.95%), this adsorption process followed the Freundlich isotherm and pseudo-first-order (PFO) models, respectively. The Langmuir adsorption capacity (Q_m) was 319.63 mg/g. Thermodynamic parameters were - 11.34 kJ/mol for ∆H° (exothermic in nature), 0.05 kJ/mol K for ∆S° (increasing randomness level at solid-liquid interface), - 27.37 kJ/mol for ∆G° (spontaneous), and 6.84 kJ/mol for E_a (controlled by physisorption).