Efficient adsorption of nitroaromatic compounds from reusable hierarchical porous biochar emanates from the Ananas comosus crown and Citrus limetta fibers

Abstract

Waste materials are used to prepare biochar (BCs) by direct pyrolysis method. 4-nitrophenol (4-NP) was efficiently removed (∼99 % and ∼ 97 %) among other nitroaromatic compounds (2,4,6-Trinitrophenol, Picric acid; 4-NP, 3-NP, and 2,4-dinitrophenol, 2,4-DNP) by Ananas comosus biochar (ACBC) and Citrus limetta biochar (MFBC) respectively. The best adsorption occured at pH 5, 10 ppm of concentration of adsorbate, 5 mg of adsorbent dose, 5 mins, and 293 K temperature. The adsorption of 4-NP reaches its equilibrium within 5 min which is extremely rapid. To comprehend the adsorption mechanism, we explored the influence of adsorbent dose, pH, contact time, temperature, and adsorbent concentration was studied. Further, we have explored the kinetics model, isotherm model, and thermodynamics studies. It was also revealed that ACBC and MFBC are showing superb recyclability with high removal efficiency. This investigation provides both opportunities, offering not only positive environmental outcomes but also practical advantages.