Purification Of Heavy Metals In Water By Adsorption-magnetic Separation Method

The magnetic composite nanomaterials adsorbents treat heavy metals in waste water have been studied in this paper. Adsorption method is an effective way to treat heavy metals, and the key of adsorption is selection of adsorbent. The magnetic composite nanomaterials with magnetic fly-ash hollow cenosphere as core has special core-shell structure and high adsorption properties, which become promising materials in the application of adsorption. They can be separated from waster water effectively by magnetic separation method because of high magnetic, and realize the recycled utilization and purified water quality.In this experiments, the magnetic composite nanomaterials adsorbents doped with Sm, Nd, La were prepared respectively, and analysis them property. In adsorption experiments, with Cr(VI) and Pb(II) as treatment object, the adsorption time, temperature, adsorbents dosage and the pH effect on the adsorption efficiency of adsorbents were investigated, and the optimal adsorption conditions are determined. The adsorption kinetics, isotherms and FTIR analysis were studied to explore the adsorption mechanism. The experiments results show that the magnetic nanomaterials doped with Sm, Nd, La were prepared successfully, which have excellent adsorption effect on Cr(VI) and Pb(II). The three kinds of adsorbents adsorbed Cr(VI) all conform to pseudo-second order and Freundlich isotherm, the adsorbents adsorbed Pb(II) all conform to pseudo-second order, Langmuir and Freundlich isotherm, and the adsorption index all less than 1, which suggest that the adsorption behavior all belongs to monolayer adsorption. The mechanism may include physical adsorption and chemical adsorption: On the one hand, the adsorbentls adsorb Cr(VI) and Pb(II) through electrostatic attraction, on the other hand, the reactions of complexation between the Cr(VI) or Pb(II) and some functional groups on the adsorbents surface, which remove heavy metals.Purification of Cr(VI) and Pb(II) heavy metals in waste water by adsorption-magnetic separation method respectively, after treating, the heavy metals concentrations were far lower than the discharge standard. Desorption of adsorbents, the desorption rate is above 88%, it shows that the prepared adsorbents have a good desorption ability, well stability, which can be repeated use and have a promising application.