固定化耐辐射奇球菌对铀的吸附性能及减量化研究∗

摘要

Sodium alginate(SA)immobilized live Deinococcus radiodurans beads were used to investigate the ad-sorption and elution for uranium as well as the volume reduction by ashing and the chemical speciation of urani-um in ashing.Results showed that the rate of adsorption would reach above 9 5% when the addition of SA im-mobilized D.radiodurans was 25 g/L,temperature was 25 ℃,pH was 3.5,and the initial uranium concentra-tion of 50 mg/L.The maximum adsorption capacity of 103.82 mg/g (dry weight)when the initial uranium con-centration of 100 mg/L.It could also be repeatedly used in multiple adsorption-desorption cycles that treatment by HCl adsorption capacity maintained after three cycles.The volume reduction results showed the SA immobi-lized D.radiodurans beads had a great weight reduction ratio by ashing process,which could reach about 254.4 times.The ashes were testing by SEM,EDS and XRD,It’s crystalline material,including CaCO3 ,Ca(UO2 ) (PO4 ).3 H2 O and (Ca,U)(PO4).2 H2 O.Showed that uranium mainly combined with the phosphorus which in immobilized D.radiodurans cells and form clusters flocculent substance,after ashing it formation of crystal-line phosphate of uranium.%研究采用海藻酸钠(SA)为固定化载体包埋固定活体耐辐射奇球菌(Deinococcus radiodurans ),旨在探讨固定化活体耐辐射奇球菌颗粒对铀的吸附性能、减量化效果及减量后灰分中铀的赋存形态.结果表明,25℃、pH 值＝3．5、投加量25 g/L、初始铀浓度为50 mg/L时,1 h左右可达吸附平衡,吸附率达95％以上,吸附过程符合准二级动力学方程.当初始铀浓度为100 mg/L时,最大吸附量达103．82 mg/g(DW).通过 HCl 解吸复吸3次仍可保持与原有的吸附量相当的水平；固定化颗粒经灰化处理后有较好的减量化效果,湿重和干重减重比分别为17．56和254．37.灰化前后经SEM-EDS、XRD分析,表明铀主要与固定化耐辐射奇球菌细胞中的磷结合成团簇的絮状物质,灰化后结晶成铀的磷酸盐,灰分主要成分为 CaCO3、Ca(UO2)(PO4).3 H2 O 和(Ca,U)(PO4).2 H2 O.