Rapid removal of cadmium ions using green-synthesized Fe₃O₄ nanoparticles capped with diethyl-4-(4 amino-5-mercapto-4H-1,2,4-triazol-3-yl)phenyl phosphonate

Water-dispersible diethyl-4-(4-amino-5-mercapto-4H-1,2,4-triazol-3-yl)phenyl phosphonate (DEAMTPP)-capped biogenic Fe₃O₄ magnetic nanocomposites (DEAMTPP@Fe₃O₄ MNP) have been successfully synthesized using Ananas comosus peel pulp extract. The size, structure, magnetic properties, and porosity of the prepared DEAMTPP@Fe₃O₄ MNPs were investigated. The concentration- and pH-dependence of Cd(ii)-adsorption properties of the DEAMTPP@Fe₃O₄ MNPs was demonstrated: the adsorption efficiency maximized (96.1%) at pH 6 and at 60 mg L^-1 of Cd(ii) concentration. The maximum Cd(ii) adsorption capacity of the DEAMTPP@Fe₃O₄ MNPs, calculated using a Langmuir isotherm, was 49.1 mg g^-1, amongst the highest values reported for Cd(ii) adsorbents. The ferromagnetic nature of the composite material allows its facile recycling without significant loss of removal efficiency. The excellent adsorption capacity of the nano-adsorbent, together with other advantages like reusability, easy separation, and environmentally-friendly composition, makes it a suitable adsorbent for removal of Cd(ii) ions from environmental and industrial wastes.