State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences , Beijing 100012, China.
Environ Sci Technol. 2014;48(1):582-90. doi: 10.1021/es4037379. Epub 2013 Dec 20.
Since in situ formation of Mg(OH)2 can efficiently sorb phosphate (PO4) from low concentrations in the environment, a novel dispersed magnesium oxide nanoflake-modified diatomite adsorbent (MOD) was developed for use in restoration of eutrophic lakes by removal of excess PO4. Various adsorption conditions, such as pH, temperature and contact time were investigated. Overall, sorption capacities increased with increasing temperature and contact time, and decreased with increasing pH. Adsorption of PO4 was well described by both the Langmuir isotherm and pseudo second-order models. Theoretical maximum sorption capacity of MOD for PO4 was 44.44-52.08 mg/g at experimental conditions. Characterization of PO4 adsorbed to MOD by use of X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and solid state (31)P nuclear magnetic resonance revealed that electrostatic attraction, surface complexation and chemical conversion in situ were the major forces in adsorption of PO4. Mg(OH)2 formed in situ had a net positive charge on the surface of the MOD that could adsorb PO4(3-) and HPO4(2-) anion to form surface complex and gradually convert to Mg3(PO4)2 and MgHPO4. Efficiency of removal of PO4 was 90% when 300 mg MOD/L was added to eutrophic lake water. Results presented here demonstrated the potential use of the MOD for restoration of eutrophic lakes by removal of excess PO4.
由于 Mg(OH)2 的原位形成可以有效地从环境中的低浓度中吸附磷酸盐 (PO4)，因此开发了一种新型分散氧化镁纳米片修饰的硅藻土吸附剂 (MOD)，用于通过去除过量的 PO4 来修复富营养化湖泊。研究了各种吸附条件，如 pH 值、温度和接触时间。总的来说，吸附容量随着温度和接触时间的增加而增加，随着 pH 值的增加而降低。PO4 的吸附同时符合 Langmuir 等温线和拟二级动力学模型。在实验条件下，MOD 对 PO4 的理论最大吸附容量为 44.44-52.08mg/g。通过 X 射线粉末衍射 (XRD)、X 射线光电子能谱 (XPS) 和固态 (31)P 核磁共振对吸附到 MOD 上的 PO4 的表征表明，静电吸引、表面络合和原位化学转化是吸附 PO4 的主要作用力。MOD 表面原位形成的 Mg(OH)2 带正电荷，能够吸附 PO4(3-)和 HPO4(2-)阴离子形成表面络合物，并逐渐转化为 Mg3(PO4)2 和 MgHPO4。当向富营养化湖水添加 300mg/L 的 MOD 时，PO4 的去除效率达到 90%。结果表明，MOD 具有通过去除过量的 PO4 来修复富营养化湖泊的潜力。
