Jing C, Landsberger S, Li Y L
Nuclear Engineering Teaching Lab, University of Texas at Austin, 10,100 Burnet Road, Austin, TX 78712, USA; School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, Hubei 430074, China.
Nuclear Engineering Teaching Lab, University of Texas at Austin, 10,100 Burnet Road, Austin, TX 78712, USA; Enviroklean Product Development Inc., 9227 Thomasville Dr. Houston, TX 77064, USA.
J Environ Radioact. 2017 Sep;175-176:1-6. doi: 10.1016/j.jenvrad.2017.04.003. Epub 2017 Apr 11.
In this study, nanoscale zero valent iron I-NZVI was investigated as a remediation strategy for uranium contaminated groundwater from the former Cimarron Fuel Fabrication Site in Oklahoma, USA. The 1 L batch-treatment system was applied in the study. The result shows that 99.9% of uranium in groundwater was removed by I-NZVI within 2 h. Uranium concentration in the groundwater stayed around 27 μg/L, and there was no sign of uranium release into groundwater after seven days of reaction time. Meanwhile the release of iron was significantly decreased compared to NZVI which can reduce the treatment impact on the water environment. To study the influence of background pH of the treatment system on removal efficiency of uranium, the groundwater was adjusted from pH 2-10 before the addition of I-NZVI. The pH of the groundwater was from 2.1 to 10.7 after treatment. The removal efficiency of uranium achieved a maximum in neutral pH of groundwater. The desorption of uranium on the residual solid phase after treatment was investigated in order to discuss the stability of uranium on residual solids. After 2 h of leaching, 0.07% of the total uranium on residual solid phase was leached out in a HNO leaching solution with a pH of 4.03. The concentration of uranium in the acid leachate was under 3.2 μg/L which is below the EPA's maximum contaminant level of 30 μg/L. Otherwise, the concentration of uranium was negligible in distilled water leaching solution (pH = 6.44) and NaOH leaching solution (pH = 8.52). A desorption study shows that an acceptable amount of uranium on the residuals can be released into water system under strong acid conditions in short terms. For long term disposal management of the residual solids, the leachate needs to be monitored and treated before discharge into a hazardous landfill or the water system. For the first time, I-NZVI was applied for the treatment of uranium contaminated groundwater. These results provide proof that I-NZVI has improved performance compared to NZVI and is a promising technology for the restoration of complex uranium contaminated water resources.
在本研究中，对纳米零价铁I-NZVI作为美国俄克拉荷马州前西马龙燃料制造场地铀污染地下水的修复策略进行了研究。研究采用了1升批量处理系统。结果表明，I-NZVI在2小时内去除了地下水中99.9%的铀。地下水中的铀浓度保持在27μg/L左右，反应7天后没有铀释放到地下水中的迹象。同时，与NZVI相比，铁的释放量显著降低，这可以减少对水环境的处理影响。为了研究处理系统的背景pH值对铀去除效率的影响，在添加I-NZVI之前将地下水的pH值调节至2-10。处理后地下水的pH值为2.1至10.7。铀的去除效率在地下水的中性pH值时达到最大值。为了讨论铀在残留固体上的稳定性，对处理后残留固相上铀的解吸进行了研究。在pH为4.03的HNO浸出溶液中浸出2小时后，残留固相上总铀的0.07%被浸出。酸性浸出液中铀的浓度低于3.2μg/L，低于美国环保署规定的30μg/L的最大污染物水平。否则，在蒸馏水浸出溶液（pH = 6.44）和NaOH浸出溶液（pH = 8.52）中铀的浓度可以忽略不计。解吸研究表明，在短期内，在强酸条件下，残留固体上可接受量的铀会释放到水系统中。对于残留固体的长期处置管理，在排放到危险垃圾填埋场或水系统之前，需要对渗滤液进行监测和处理。I-NZVI首次应用于铀污染地下水的处理。这些结果证明，与NZVI相比，I-NZVI具有更好的性能，是修复复杂铀污染水资源的一项有前景的技术。
