Highly selective and effective copper removal from wastewater by magnetic precipitation separation

The presence of heavy metals in wastewater poses a substantial threat to both public health and the environment. However, the selective removal and separation of heavy metal ions at ultra-low concentrations from wastewater remains a considerable challenge. In this paper, we innovatively proposed a magnetic precipitation separation method to remove Cu (II) from wastewater using Fe 3 O 4 nanoparticles and Na 2 S. In this process, the Cu (II) was reduced to CuS by Na 2 S, which then rapidly aggregated with Fe 3 O 4 nanoparticles to form Fe 3 O 4 -CuS nanoclusters. SEM, DLS, XRD, VSM and XPS studies demonstrated that the removal of Cu (II) was related to the formation of Fe 3 O 4 -CuS nanoclusters. The results indicated that the removal efficiency of Cu (II) from wastewater could reach 99.75 % within 30 s. In contrast, the removal efficiencies of Co (II), Ni (II), and Zn (II) were 7.64 %, 6.14 %, and 8.41 %, respectively. In addition, the Fe 3 O 4 nanoparticles were easily regenerated from Fe 3 O 4 -CuS nanoclusters using ultrasound, maintaining 98 % removal efficiency of Cu (II) after six consecutive cycles. These results suggested that this method held great potential for the removal of heavy metals from wastewater.