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

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(NH)), 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 HSO) treatments were also studied. It was found that WT(NH) could remove about 99% Cr(vi) at pH 2 under HSO treatment. The XRD and TEM results coupled with VSM results confirmed that WT(NH) is an FeO/FeN 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(NH), which indicated that Cr(vi) was reduced to Cr(iii). Furthermore, HSO regulation also promoted the reduction of Cr(vi) by WT(NH), and this reduction was higher than that obtained by HCl regulation.