# Microwave-Assisted Reduction Technology for Recycling of Hematite Nanoparticles from Ferrous Sulfate Residue

## TL;DR

This paper presents a new method to recycle iron from industrial waste using microwave technology to create useful hematite nanoparticles.

## Contribution

The novel contribution is the microwave-assisted reduction technology for synthesizing hematite nanoparticles from ferrous sulfate residue.

## Key findings

- Hematite nanoparticles with an average size of 45 nm were successfully synthesized from ferrous sulfate residue.
- The nanoparticles showed a surface area of ~20.999 m²/g and weak ferromagnetic properties at room temperature.
- The nanoparticles demonstrated potential for applications in electronics, optics, and catalysis due to their light absorption properties.

## Abstract

Accumulation of ferrous sulfate residue (FSR) not only occupies land but also results in environmental pollution and waste of iron resource; thus, recycling of iron from FSR has attracted widespread concern. To this end, this article shows fabrication and system analysis of hematite (HM) nanoparticles from FSR via microwave-assisted reduction technology. Physicochemical properties of HM nanoparticles were investigated by multiple analytical techniques including X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible (UV-Vis) spectrum, vibrating sample magnetometer (VSM), and the Brunauer–Emmett–Teller (BET) method. Analytic results indicated that the special surface area, pore volume, and pore size of HM nanoparticles with the average particle size of 45 nm were evaluated to be ca. 20.999 m2/g, 0.111 cm3/g, and 0.892 nm, respectively. Magnetization curve indicated that saturation magnetization Ms for as-synthesized HM nanoparticles was calculated to be approximately 1.71 emu/g and revealed weakly ferromagnetic features at room temperature. In addition, HM nanoparticles exhibited noticeable light absorption performance for potential applications in many fields such as electronics, optics, and catalysis. Hence, synthesis of HM nanoparticles via microwave-assisted reduction technology provides an effective way for utilizing FSR and easing environmental burden.