Particles and porous tablets based on Fe^0/ZSM-5 composites prepared by ball-milling for heavy metals removal: Dissolved Fe^(2+), pH, and mechanism

摘要

Novel, low-cost Fe^0/ZSM-5-based particles and porous tablets were prepared by a ballmilling method and used for the removal of Pb^(2+) in solution. Solid-phase characterization by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy(SEMEDS) and transmission electron microscopy(TEM) revealed that the Fe0 microparticles were evenly loaded and tightly immobilized on the surface of ZSM-5 because of the extrusion/welding impact during ball-milling. For different Pb^(2+) concentrations, batch experiments indicated that the removal of Pb^(2+) increased with the decline of dissolved Fe2+and p H value in the solution for particles; opposite results were obtained for the tablets. The differences in the contact between both materials and Pb^(2+) were the main factor controlling Pb^(2+) removal in the solution. Investigation into the effect of initial p H value revealed that high p H reduced the number of electrons released from Fe corrosion. Consequently, low levels of removed Pb^(2+) and dissolved Fe^(2+) were synchronously observed. Also, simulated electroplating wastewater was treated using the prepared particles and porous tablets,and the removal order of Pb^(2+) > Cr^(6+)> Cu^(2+)≈ Cd^(2+) was observed. The Fe^0/ZSM-5 particles and tablets prepared through ball-milling show potential as materials for treatment of Pb^(2+) and other toxic metals.