Synthesis and characterization of magnetic bio-adsorbent developed from Aegle marmelos leaves for removal of As(V) from aqueous solutions

Abstract

A novel magnetic bio-adsorbent was prepared from the leaves of Aegle marmelos tree (Indian bael) and Fe₂O₃ nanoparticles. The AMP@Fe₂O₃ nanocomposite (Aegle marmelos leaf powder) was synthesized by pyrolysis process and applied for As(V) removal through batch adsorption process. The synthesized AMP@Fe₂O₃ nanocomposite was analyzed by several instrumental techniques like XRD, FESEM, TEM, HRTEM, FTIR, BET, and VSM studies. Maximum amount of As(V) was removed at pH 3, contact time of 250 min, adsorbent dose of 0.1 g/L, and initial concentration of 0.5 mg/L at room temperature. The model study revealed that the pseudo-second-order kinetics and Langmuir isotherm models were best fitted with the experimental data. The nanocomposite showed a maximum adsorption capacity of 69.65 mg/g. The endothermic nature of the adsorption process was ascertained from the thermodynamics studies. The zeta potential and FTIR analysis before and after adsorption demonstrated two types of adsorption mechanism. The first one was the electrostatic attraction between negatively charged As(V) ions (H₂AsO₄⁻) and protonated −OH group present on the Fe₂O₃ surface and the second one was ligand exchange between the surface hydroxyl groups and As(V) ions. The AMP@Fe₂O₃ nanocomposite was desorbed with 0.5 M NaOH solutions and also used up to four cycles without any major decrease in removal efficiency. Thus, AMP@Fe₂O₃ nanocomposite can be applied as a potential adsorbent for As(V) removal from wastewater.

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