微生物矿化法固结模拟放射性核素锶的研究

Study on simulated radionuclide strontium mineralized by bacteria

采用微生物矿化法将游离态Sr2+固结为稳定的不可溶的碳酸盐形态,为放射性核素锶的处理提供参考。选取碳酸盐矿化菌进行培养,利用其酶化作用分解尿素,产生CO32-,与溶液中Sr2+结合生成不可溶性碳酸盐。通过微生物矿化试验,分析了p H值、温度、接种量、培养时间、Sr2+及尿素浓度等因素对Sr2+固结率的影响,并采用EDS、XRD、SEM、FT-IR等检测手段对矿化产物的物相和形貌等进行了分析。结果表明:矿化产物为大小不均近球形Sr CO3晶体,相互团聚,且细菌在沉淀生成过程中起到了重要作用;当Sr2+浓度为0.02 mol/L、尿素为20 g/L、接种量体积分数为6.0%、p H值为8.0时,在30℃培养48 h时,微生物矿化对Sr2+固结率可达98.5%左右。

Sr2 +was transformed into insoluble state to provide a reference method for dealing with radionuclide strontium. Bacillus pasteurii was cultivated with medium containing urea. Enzyme of urease was produced and urea was discomposed to CO32-,which could put soluble Sr2 +into insoluble carbonate. The particle size and morphology of the solidifying product was characterized by energy dispersive spectroscopy( EDS),X-ray diffraction( XRD) and scanning electronic microscope( SEM).Factors such as p H,temperature,inoculum concentration,incubation time,concentration of Sr2 +and urea on solidifying rate of Sr2 +was studied. It showed that the solidifying product was composed of aggregative globular Sr CO3 crystals in unequal size. The bacillus played an important role in the precipitating process. Cultivating 48 h at 30 ℃,the solidifying rate reached a peak as about 98. 5%when the concentration of Sr2 +and urea,inoculum concentration and p H was 0. 02 mol / L,20 g / L,6. 0% and p H 8. 0 respectively.