Glycerol-based modified carbons as adsorbents for efficient and sustainable nitrate removal from wastewater

Nitrate contamination in water bodies poses significant environmental and health concerns, necessitating the development of efficient removal technologies. This study investigates the adsorption behavior of nitrate in synthetic effluents using glycerol-derived activated carbons. The carbons were synthesized via hydrothermal carbonization of glycerol in the presence of sulfuric acid and Fe (III) salt, followed by thermal activation at 515 ​°C under a nitrogen atmosphere. Further functionalization was performed through ammoniation at varying temperatures (400–800 ​°C) to introduce nitrogenous groups. The adsorbents were characterized using Fourier-transform infrared spectroscopy (FTIR), elemental analysis (CHNS), zeta potential, inductively coupled plasma optical emission spectrometry (ICP-OES), nitrogen adsorption/desorption isotherms, and X-ray photoelectron spectroscopy (XPS). Results revealed that ammoniation significantly enhanced the nitrate adsorption capacity, with the best performance observed at 800 ​°C due to the increased surface area. Additionally, nitrogen incorporation at 600 ​°C provoked an enhancement in adsorption capacity. Adsorption kinetics followed the pseudo-second-order model, indicating chemisorption as the dominant mechanism. The Langmuir isotherm best describes nitrate adsorption, suggesting monolayer coverage. The study highlights the potential of modified glycerol-based carbons as sustainable and cost-effective adsorbents for nitrate removal in wastewater treatment. These findings contribute to adsorption-based water purification technologies and support the valorization of glycerol, an abundant biodiesel byproduct, in environmental applications.

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