Preparation and application synthesis of magnetic nanocomposite using waste toner for the removal of Cr(vi)

Abstract

In this study, a novel magnetic nanocomposite was prepared using waste toner (WT) through high temperature decomposition, and calcination was conducted in different atmospheres (air, ammonia, and vacuum). WT calcined in ammonia (WT(NH₃)), and it was then utilized as an efficient absorbent for the reduction of Cr(VI) in aqueous solutions; a batch experiment with different conditions was performed to investigate its Cr(VI) removal ability. The effects of two pH-regulating acid (HCl and H₂SO₄) treatments were also studied. It was found that WT(NH₃) could remove about 99% Cr(VI) at pH 2 under H₂SO₄ treatment. The XRD and TEM results coupled with VSM results confirmed that WT(NH₃) is an Fe₃O₄/Fe₂N nanohybrid, which possesses excellent water-dispersibility and remarkable magnetic properties. XPS analysis showed the presence of Cr(VI) and Cr(III) on the surface of WT(NH₃), which indicated that Cr(VI) was reduced to Cr(III). Furthermore, H₂SO₄ regulation also promoted the reduction of Cr(VI) by WT(NH₃), and this reduction was higher than that obtained by HCl regulation.