Facile synthesis of eco-friendly activated carbon from leaves of sugar beet waste as a superior nonconventional adsorbent for anionic and cationic dyes from aqueous solutions

The current study presents a unique and innovative approach to sustainable activated carbon (AC) synthesis using non-conventional agricultural wastes, leaves of sugar beet (LSB), via a thermo-chemical activation process. This approach not only offers a sustainable solution for LSB elimination, but also provides an eco-friendly alternative to commercially available acti-vated carbon. The thermo-chemical activation process was conducted at various ratios of H3PO4 / LSB (0.5:1, 1:1, 2:1, and 3:1 w/w ratios) at a fixed temperature (550 degrees C/2h). The unique amorphous nature, porous structure, BET surface area (SBET = 700.7 m2/g), and surface chemistry nominated the synthesized AC at 2:1 ratio as a superior adsorbent material for methyl orange, MO, and methy-lene blue, MB, from standard solutions in the batch system at different experimental conditions. Kinetic investigations revealed that the pseudo-second order equation explained the sorption data well. In contrast, intra-particle diffusion was not the only limiting stage in the adsorption of the addressed dyes. Similarly, the linear Langmuir equation described the adsorption data of the inves-tigated dyes better than Freundlich one with maximum removal capacity (qmax) of 185.2 and 140.8 mg/g for MB and MO, orderly. This confirms the homogenous/monolayer nature of the adsorbed ions through isoenergetic active sites upon the AC(2:1) surface. Furthermore, the electro-static attraction was not the only leading mechanism of adsorption of both dyes, but substantial participations by hydrophobic hydrogen-bonding forces may be considered. (c) 2023 Science, Technology & Innovation Funding Authority (STDF). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).