Applied Research Center, Florida International University, 10555 West Flagler Street, Miami, FL 33174, USA.
Applied Research Center, Florida International University, 10555 West Flagler Street, Miami, FL 33174, USA.
J Environ Manage. 2018 Oct 1;223:108-114. doi: 10.1016/j.jenvman.2018.06.012. Epub 2018 Jun 13.
Temporary base treatment is a potential remediation technique for heavy metals through adsorption, precipitation, and co-precipitation with minerals. Manipulation of pH with ammonia gas injection may be especially useful for vadose zone environments as it does not require addition of liquids that would increase the flux towards groundwater. In this research, we conducted laboratory batch experiments to evaluate the changes in uranium mobility and mineral dissolution with base treatments including sodium hydroxide, ammonium hydroxide, and ammonia gas. Our data show that partitioning of uranium to the solid phase increases by several orders of magnitude following base treatment in the presence of different minerals and natural sediments from the Hanford site. The presence of dissolved calcium and carbonate play an important role in precipitation and co-precipitation of uranium at elevated pH. In addition, significant incongruent dissolution of bulk mineral phases occurs and likely leads to precipitation of secondary mineral phases. These secondary phases may remove uranium via adsorption, precipitation, and co-precipitation processes and may coat uranium phases with low solubility minerals as the pH returns to natural conditions.
暂态碱处理是一种通过吸附、沉淀和矿物共沉淀来去除重金属的潜在修复技术。用氨气调节 pH 值特别适用于非饱和带环境，因为它不需要添加会增加向地下水迁移通量的液体。在这项研究中，我们进行了实验室批量实验，以评估在含有不同矿物和汉福德现场天然沉积物的情况下，用氢氧化钠、氨水和氨气进行碱处理后铀的迁移性和矿物溶解的变化。我们的数据表明，在碱性条件下，铀向固相的分配增加了几个数量级。溶解的钙和碳酸盐的存在对高 pH 值下铀的沉淀和共沉淀起着重要作用。此外，大量矿物相的不相容溶解会导致次生矿物相的沉淀。这些次生相可能通过吸附、沉淀和共沉淀过程去除铀，并可能在 pH 值恢复到自然条件时用低溶解度的矿物覆盖铀相。
