The Synthesis And Adsorption Behavior To Radioactive Ions Of Magnesium Silicate Gels

In this paper, novel magnesium silicate gels （MgO·SiO₂,2MgO·3SiO₂,MgO·2SiO₂and MgO·3SiO₂） were synthesized using sodium silicate and magnesiumsalts as raw materials. The adsorption performantce of the four magnesium silicategels were evaluated by removing the methylene blue in water. At25℃, the saturatedadsorption mounts of the four magnesium silicate gels to methylene blue were351.6,359.6,500.8and508.1mg·g^-1that were much higer than the saturated adsorptionmounts of other adsorbents to methylene blue. In this paper, the new magnesiumsilicate gels have good adsorption performance.The four magnesium silicate gels were characterized by scanning electronmicroscopy and FT-IR spectrometer. Results showed that there was no magnesiumhydroxide absorption peak illustrating that the magnesium was in the form ofmagnesium oxide in magnesium silicate gels. These novel materials contained Mg-Oand Si-Mg-O bonds in460cm^-1, demonstrating that Mg was embedded in Si-Otetrahedral covalent bonds. With the increasing of the SiO₂content, honeycomb porestructure in magnesium silicate gels increased gradually, particle became morewell-distributed, surface became more coarse. Compared the same magnesium silicategels, the surface was rougher and honeycomb pore structure was more developed aftercalcinating.Four novel magnesium silicon gels to radioactive isotope Co²⁺adsorptionexperiments showed that the four novel magnesium silicon gels samples had thelargest adsorption volume to Co²⁺after calcination on500℃. In the range of25℃to45℃, the saturated adsorption mounts of the four magnesium silicate gels to Co²⁺were70～105.5mg·g^-1,131～162.4mg·g^-1,135.5～181.8mg·g^-1and93.8～121.8mg·g^-1. The adsorption process could be described by Langmuir isotherm, in the rangeof25℃to45℃. The saturated adsorption mounts of magnesium silicon gels to Co²⁺were much higer than the saturated adsorption mounts of other adsorbents to Co²⁺, under the same conditions. The four magnesium silicon gels have excellentregeneration performance after adsorption-desorption for four times.MgO·2SiO₂to radioactive isotope of Ni²⁺adsorption performance wasresearched. The results showed that MgO·2SiO₂had the largest adsorption volume toNi²⁺after calcination on550℃. In the range of25℃to45℃, the saturatedadsorption mounts of MgO·2SiO₂to Ni²⁺were107.5,124.1and118.2mg·g^-1,respectively. The adsorption process could be described by Langmuir isotherm andpseudo-second order model, in the range of25℃to45℃. The saturated adsorptionmount of MgO·2SiO₂to Ni²⁺was much higer than the saturated adsorption mounts ofother adsorbents to Ni²⁺, under the same conditions. MgO·2SiO₂has excellentregeneration performance after adsorption-desorption for four times.MgO·2SiO₂to radioactive isotope of Mn²⁺adsorption performance wasresearched. The results showed that MgO·2SiO₂had the largest adsorption volume toMn²⁺after calcination on500℃. In the range of25℃to55℃, the saturatedadsorption mounts of MgO·2SiO₂to Mn²⁺were69.1,95.5,86.5and124.3mg·g^-1,respectively. The adsorption process could be described by Langmuir isotherm andpseudo-second order model, in the range of25℃to55℃. The saturated adsorptionmount of MgO·2SiO₂to Mn²⁺was much higer than the saturated adsorption mountsof other adsorbents to Mn²⁺, under the same conditions. MgO·2SiO₂has excellentregeneration performance after adsorption-desorption for four times.The results showed that novel magnesium silicon gels have good adsorptionand regeneration performances to radioactive ions (Co²⁺, Ni²⁺and Mn²⁺).Consequently, the novel magnesium silicon gels can be used to deal with radioactivewaste water. On one hand, the magnesium resources can be effectively used, on theother, the environment can be protected. Achieve the goal of the win-win situation.