Abstract The coupled transport of heavy metals with suspended particles has been a topic of growing interest. The main purpose of this study is to experimentally investigate the seepage transport of heavy metal Pb2+ in the presence of silicon powders (SPs) through a sand column under different seepage velocities (v = 0.087–0.260 cm/s), injection Pb2+ concentrations (CP = 0–800 μg/ml) and SP sizes (D50 = 2.8–25.5 μm), which were likely to be encountered in practical engineering. The sand column was installed in a cylindrical chamber of 300 mm in length and 80 mm in internal diameter. The results clearly show that the increase in acidity results in a reduction of the repulsive interactions between SPs and the matrix, and consequently a decrease in the peak values in breakthrough curves (BTCs), especially for larger-sized SPs. The peak values and recovery rate of Pb2+ are obviously increased and an earlier breakthrough can be observed, due to the higher capacity of SPs with negative charge to adsorb heavy metal pollutants such as Pb2+ with positive charge. The adsorption of Pb2+ on SPs can reduce the repulsive forces between SPs and the matrix, thus resulting in the increase of the deposition possibility of SPs and the decrease of peak value and recovery rate.

中文翻译：

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硅粉存在下重金属Pb2+通过砂柱的渗流传输

摘要 重金属与悬浮颗粒的耦合传输一直是一个越来越受关注的话题。本研究的主要目的是实验研究在硅粉 (SPs) 存在下重金属 Pb2+ 在不同渗流速度 (v = 0.087–0.260 cm/s)、注入 Pb2+ 浓度 (CP = 0–800 μg/ml) 和 SP 大小 (D50 = 2.8–25.5 μm)，这在实际工程中很可能会遇到。砂柱安装在一个长 300 毫米、内径 80 毫米的圆柱形腔室中。结果清楚地表明，酸度的增加导致 SP 与基质之间的排斥相互作用减少，因此穿透曲线 (BTC) 中的峰值降低，尤其是对于较大尺寸的 SP。由于带负电荷的SPs对带正电荷的Pb2+等重金属污染物具有更高的吸附能力，因此Pb2+的峰值和回收率明显增加，并且可以观察到更早的突破。Pb2+在SPs上的吸附可以降低SPs与基体之间的排斥力，从而导致SPs沉积可能性增加，峰值和回收率降低。