Key Laboratory of Plant-Soil Interactions, Ministry of Education, Key Laboratory of Arable Land Conservation (North China), Ministry of Agriculture, College of Resources and Environment, China Agricultural University, Beijing, 100193, China.
Key Laboratory of Plant-Soil Interactions, Ministry of Education, Key Laboratory of Arable Land Conservation (North China), Ministry of Agriculture, College of Resources and Environment, China Agricultural University, Beijing, 100193, China.
Environ Pollut. 2018 May;236:168-176. doi: 10.1016/j.envpol.2018.01.026.
Fate and transport of graphene oxide (GO) have received much attention recently with the increase of GO applications. This study investigated the effect of salt concentration on the transport and retention behavior of GO particles in heterogeneous saturated porous media. Transport experiments were conducted in NaCl solutions with three concentrations (1, 20, and 50 mM) using six structurally packed columns (two homogeneous and four heterogeneous) which were made of fine and coarse grains. The results showed that GO particles had high mobility in all the homogeneous and heterogeneous columns when solution ionic strength (IS) was low. When IS was high, GO particles showed distinct transport ability in six structurally heterogeneous porous media. In homogeneous columns, decreasing ionic strength and increasing grain size increased the mobility of GO. For the column containing coarse-grained channel, the preferential flow path resulted in an early breakthrough of GO, and further larger contact area between coarse and fine grains caused a lower breakthrough peak and a stronger tailing at different IS. In the layered column, there was significant GO retention at coarse-fine grain interface where water flowed from coarse grain to fine grain. Our results indicated that the fate and transport of GO particles in the natural heterogeneous porous media was highly related to the coupled effect of medium structure and salt solution concentration.
近年来，随着 GO 应用的增加，GO 的命运和迁移受到了广泛关注。本研究考察了盐浓度对 GO 颗粒在非均相饱和多孔介质中迁移和滞留行为的影响。使用由细粒和粗粒组成的六个结构填充柱（两个同质柱和四个非同质柱），在三种浓度（1、20 和 50mM）的 NaCl 溶液中进行了迁移实验。结果表明，当溶液离子强度（IS）较低时，GO 颗粒在所有同质和非同质柱中均具有较高的迁移能力。当 IS 较高时，GO 颗粒在六个结构非均相多孔介质中表现出明显的迁移能力。在同质柱中，降低离子强度和增大粒径会增加 GO 的迁移性。对于含有粗粒通道的柱，优先流路径导致 GO 的早期突破，并且在不同 IS 下，粗粒和细粒之间更大的接触面积导致更低的突破峰值和更强的拖尾。在层状柱中，在水流从粗粒到细粒的粗-细粒界面处存在显著的 GO 滞留。我们的结果表明，GO 颗粒在自然非均相多孔介质中的命运和迁移与介质结构和盐溶液浓度的耦合效应密切相关。
