Water-soluble Fe3O4nanoparticles with high solubility for removal of heavy-metal ions from waste water

Abstract

In this contribution, we synthesized water-soluble Fe₃O₄ nanoparticles (NPs) with sufficiently high solubility (28 mg mL⁻¹) and stability (at least one month) through a hydrothermal approach, and found that they exhibited excellent removal ability for heavy-metal ions from waste water. For the first time, the water-soluble Fe₃O₄ NPs were used as adsorbents for heavy-metals removal from wastewater. It is noteworthy that the adsorption ability of the water-soluble Fe₃O₄ NPs for Pb²⁺ and Cr⁶⁺ is stronger than water-insoluble Fe₃O₄ NPs. Furthermore, the water-soluble Fe₃O₄ NPs exhibited relatively high saturation magnetization (83.4 emu g⁻¹), which allowed their highly-efficient magnetic separation from wastewater. The most important thing is that the water-soluble magnetite as an adsorbent can directly dissolve in water without the help of mechanical stirring or any extraneous forces, which may solve a key problem for the practical application of magnetic powders in the field of sewage purification. Moreover, the water-soluble Fe₃O₄ NPs show a highly-efficient adsorption capacity for 10 ppm of Pb²⁺ ions solution which can reach 90% within 2 minutes.