Abstract
Arsenic contamination in aquatic resources represents a significant public health and environmental concern, necessitating the development of efficient and low-cost adsorbents. In this study, coal-derived carbon materials were synthesized from Egyptian Maghara coal through surface modification under argon (AC-Ar) and nitrogen (AC-N) atmospheres, followed by chemical oxidation with nitric acid (AC-Oxid). The effects of the modification route on surface morphology, elemental composition, and adsorption performance toward arsenic were investigated. The characterization analyses confirmed the formation of porous structures and successful introduction of O-containing groups upon oxidation. Batch adsorption experiments demonstrated that arsenic removal was pH and time-dependent, with maximum efficiency at pH 2. The superior performance of AC-Oxid across the pH spectrum highlights the effectiveness of nitric acid oxidation in enhancing the chemical affinity and functional reactivity of Maghara coal-based carbon materials toward arsenic species. Adsorption kinetics for all materials were fitted by the pseudo-second order, and intraparticle diffusion analysis indicated that adsorption was governed by multiple rate-controlling steps. Experimental data were well fitted by D-R and Langmuir models, with maximum Langmuir capacities of 84.75, 102.04, and 97.09 mg/g for AC-Ar, AC-N, and AC-Oxid, respectively. The Maghara coal-derived carbon materials showed superior performance, highlighting their potential as a promising adsorbent for arsenic removal from contaminated media.