Compound MnO₂-Fe₃O₄ Adsorption Of Heavy Metals From Aqueous Solutions And Its Research Of Recycling

Heavy metals pollution was a great threat to public health and the environment, in particular the industrial wastewater, such as electroplating, metallurgy, battery manufacturing, which usually containing high concentrations of heavy metals, and ofen after pretreatment still containing a lower concentration of heavy metals, which limited environmental emissions. However, in this kind of situation a lot of adsorbent not only removal effect was poor, but also because of its low apparent density, particle size small, difficulties exist in the practication of solid-liquid separation, which in turn cause secondary pollution. Therefore this paper put forward to develop a technology and material to remove the heavy metal ions in water, make its can effectively remove heavy metals in water, also can be recycled used repeatedly, and achieves the win-win effect of environment and benefit.In various types of adsorbents, metal oxides with characteristics of hydrolysis had good chemical affinity with heavy metal, among these metal oxides, manganese oxide was stable and had strongest affinity with heavy metal ions; the magnetic Fe₃O₄ not only had good magnetic as well as certain adsorption performance, choose Fe₃O₄ combined with manganese oxide, which made the composite material had good removal efficiency of heavy metals and magnetic separation recycling performance under magnetic field.Composite magnetic material MnO₂-Fe₃O₄ with core-shell structure was prepared by hydrothermal synthesis method; Studied the adsorption removal rate and removal rate of MnO₂-Fe₃O₄; Discussed the influence of surrounding factors on adsorption removal rate, revealed the adsorption mechanism; And gave further investigations of desorption and recycling of this composite material MnO₂-Fe₃O₄.The adsorption interface structure, remove effect of heavy metal and adsorption mechanism were studied by IR, Zeta and ICP. The results showed that: the adsorption process in line with the Langmuir model, heavy metal ions on the surface of MnO₂-Fe₃O₄ was outer complexation reaction; the adsorption removal rate of Cu²⁺、Cd²⁺、Zn²⁺、Pb²⁺ were 99.81%、99.76%、83.25%、98.15% respectively; the maximum adsorption capacity of the MnO₂-Fe₃O₄ towards Cu²⁺、Cd²⁺、Zn²⁺ and Pb²⁺ were 498.575, 439, 416.5,and 490.5mg/g. According to the FTIR analysis and point of zero charge value analysis the adsorption mechanism indicated that heavy metal ions removal by MnO₂-Fe₃O₄ was an ion-exchange process, and the decisive composition was Mn O2 in the process of adsorption; Composite material MnO₂-Fe₃O₄ still had good adsorption efficiency after five times adsorption-desorption when HCl as desorbent, which proved that adsorbent MnO₂-Fe₃O₄ had good regeneration and recycling performance, and the accumulated adsorption quantity of Cu²⁺、Cd²⁺ and Pb²⁺ in the five cycles were more than 2475mg/g respectively, the Zn²⁺ was 2107.5mg/g.