Magnetic double-core@shell MnO2@NiFe@DE as a multifunctional scavenger for efficient removal of tetracycline, anionic and cationic dyes

Abstract

Design and fabrication of core-shell nanomaterials with excellent properties such as multifunctionality, tunability, and stability for the removal of recalcitrant pollutants from wastewater is highly valued. In this work, magnetic MnO2@NiFe@DE nanocomposites with double-core@shell structures were obtained via a two-step hydrothermal method for efficiently removing tetracycline, anionic and cationic dyes through the synergistic effect of oxidation and adsorption. The novel nanomaterial displayed superior removal of methyl orange, methylene blue, and tetracycline in low pH solutions with 100%, 100%, and 83%, respectively. The effects of solution pH, adsorption time, and contaminant concentration on the performance of the nanocomposite were also investigated, and the pseudo-second-order kinetic model well described the data. Physical adsorption including electrostatic adsorption, anion exchange, and hydrogen bonding are the predominant mechanisms for contaminant removal. The oxidation mechanism is mainly hydroxyl radical action. Through the use of permanent magnets, the recovery process of the adsorbent and the adsorbed dyes and antibiotics is energetically and economically sustainable. This as-synthesized nanocomposite as multifunction material has a high removal rate, low cost, and easy separation, and the applicability in treating the solutions with low pH, which is promised to be an efficient organic wastewater remover in practical applications.