Experimental and DFT Studies of Antibiotics Removal Through Activated Carbon: A Step‐by‐Step Adsorption Process at Atomic Level

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Abstract In this paper, starch‐based porous activated carbon adsorbent (KOH@SAC) is prepared, characterized (by BET, SEM, XRD, FTIR and TGA), and assessed for the removal of broad‐spectrum antibiotics, cefotaxime (CEFO), and ceftriaxone (CEFT), from aqueous solutions. The experimentally measured adsorption capacity of KOH@SAC is 333.76907 ± 6.01983 mg g −1 for CEFO and 262.42692 ± 11.252 mg g −1 for CEFT. The negative change in Gibbs free energy with the increase in temperature and positive change in enthalpy, for both antibiotics, reveal spontaneous, and endothermic nature of adsorption. The experimental data follows Langmuir, DR, Freundlich, and Temkin adsorption isotherms. The reaction follows pseudo‐second‐order kinetics and is controlled by film diffusion and Intraparticle diffusion concurrently. Quantum mechanical, Density Functional Theory (DFT) calculations are also carried out to verify the experimental results. These results provide a clear understanding of the step‐by‐step adsorption process at the atomic level. The DFT results revealed that oxygen, sulfur and nitrogen atoms of the CEFO and CEFT are the active sites that lead to its adsorption onto KOH@SAC. The experimental and theoretical results presented in this paper reveal that KOH@SAC is an efficient adsorbent for the removal of hazardous antibiotics from water.

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