Phosphate removal and recovery from water using nanocomposite of immobilized magnetite nanoparticles on cationic polymer

ABSTRACT

A novel nanocomposite (NC) based on magnetite nanoparticles (Fe₃O₄-NPs) immobilized on the surface of a cationic exchange polymer, C100, using a modification of the co-precipitation method was developed to obtain magnetic NCs for phosphate removal and recovery from water. High-resolution transmission electron microscopy-energy-dispersive spectroscopy, scanning electron microscopy , X-ray diffraction, and inductively coupled plasma optical emission spectrometry were used to characterize the NCs. Continuous adsorption process by the so-called breakthrough curves was used to determine the adsorption capacity of the Fe₃O₄-based NC. The adsorption capacity conditions were studied under different conditions (pH, phosphate concentration, and concentration of nanoparticles). The optimum concentration of iron in the NC for phosphate removal was 23.59 mg_Fe/g_NC. The sorption isotherms of this material were performed at pH 5 and 7. Taking into account the real application of this novel material in real water, the experiments were performed at pH 7, achieving an adsorption capacity higher than 4.9 mg_PO4–P/g_NC. Moreover, Freundlich, Langmuir, and a combination of them fit the experimental data and were used for interpreting the influence of pH on the sorption and the adsorption mechanism for this novel material. Furthermore, regeneration and reusability of the NC were tested, obtaining 97.5% recovery of phosphate for the first cycle, and at least seven cycles of adsorption–desorption were carried out with more than 40% of recovery. Thus, this work described a novel magnetic nanoadsorbent with properties for phosphate recovery in wastewater.

GRAPHICAL ABSTRACT

KEYWORDS:

• Magnetite nanoparticles
• polymeric nanocomposite
• adsorption
• phosphate removal
• wastewater

Acknowledgements

One of the authors, Ahmad Abo Markeb is grateful to the Ministry of Higher Education of Egypt for the PhD external mission. The authors would like to extend their gratitude to Purolite for kindly supply the cationic polymer.

Disclosure statement

No potential conflict of interest was reported by the authors.