Effect of Mg ions on competitive metal ions adsorption/desorption on magnesium ferrite: Mechanism, reusability and stability studies.

The adsorption behavior of magnesium ferrite in single- and multicomponent metal ions solutions in the presence of Mg ions were studied. A dramatic decrease in the adsorption capacity of magnesium ferrite towards Mn, Co, and Ni ions for comparison study of single- and multicomponent solutions was established. The affinity of the sorbent in accordance with the maximum sorption capacities increases in the following order Cu > Co > Ni > Mn. High efficiency of magnesium ferrite regeneration (~100%) with aqueous solutions of magnesium chloride in the concentration range of 0.001-0.1 M was shown. The low degree of toxic metal ions desorption combined with XRD, IR spectroscopy, and EDX analysis data indicate the key role of Mg ion adsorption in the magnesium ferrite adsorbent regeneration. The positive effect of the introduction of Mg ions into multicomponent solutions on metal ions adsorption was established, which is accompanied by an increase in the maximum sorption capacity for all metal ions and especially significant increase in the selectivity towards Cu ions (2.41 mmol/g). The stability of the crystal structure of magnesium ferrite and a low degree of Mg and Fe ions leaching during multiple cycles of adsorption and regeneration of the adsorbent were observed.