固定化硫酸盐还原菌选择性去除U(Ⅵ)的性能

Selective Removal of U(Ⅵ) by Immobilized Sulfate-reducing Bacteria

  • 摘要: 利用聚乙烯醇和海藻酸钠制备了硫酸盐还原菌微球,探讨了Zn2+、Cu2+、乙酸钠、草酸钠和柠檬酸钠对其还原U(Ⅵ)的影响,考察了其选择性去除U(Ⅵ)的工艺。实验结果表明,当Zn2+或Cu2+浓度低于100 mg/L时,U(Ⅵ)还原未受显著影响,但当其增至150 mg/L时,U(Ⅵ)还原被完全抑制。当单齿配体有机物(乙酸钠)存在时,U(Ⅵ)可被彻底还原;而多齿配体有机物(草酸钠和柠檬酸钠)存在时,会延缓甚至完全抑制U(Ⅵ)的还原。对于无机U(Ⅵ)重金属体系,可利用U(Ⅵ)和硫酸盐还原自由能的差异,适当降低COD/SO2-4比值直接选择性去除U(Ⅵ);对于有机U(Ⅵ)重金属体系,可通过多齿配体有机物络合U(Ⅵ),同时利用硫化物选择性沉淀重金属,间接实现U(Ⅵ)的选择性去除。

     

    Abstract: The sulfate-reducing bacteria immobilized in polyvinyl alcohol-sodium alginate beads were prepared. The impacts of Zn2+, Cu2+, acetate, oxalate and citrate on the reduction of U(Ⅵ) were investigated. Furthermore, selective removal of U(Ⅵ) or heavy metals was assessed. The results indicate that the existing of Zn2+ or Cu2+ doesn’t affect U(Ⅵ) removal appreciably when their concentrations are less than 100 mg/L, but they can inhibit U(Ⅵ) removal completely while their concentrations reach 150 mg/L. In the presence of monodentate ligand (acetate), U(Ⅵ) can be removed readily, whereas HQKmultidentate ligands (oxalate and citrate) impose an inhibition on U(Ⅵ) removal. In organic-free wastewater, direct selective removal of U(Ⅵ) can be achieved based on thermodynamic considerations and optimized by appropriately lowering COD/SO2-4. In wastewater containing multidentate organics, U(Ⅵ) can be firstly complexed during precipitation of Zn2+ and Cu2+, and then removed directively after degradation of organic ligands.

     

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