Acknowledgments:
Funding for this research was provided by the National Natural Science
Foundation of China (51678043; 51878035).
Abstract: The deposition characteristics of lead ions
(Pb2+) in the presence of silicon powders (SPs) were
investigated in water seepage in a long one-dimensional sand column
experiment. The injected SPs possess a very wide particle-size
distribution (PSD). The concentrations of deposited
Pb2+ and SPs and the migration distance along the
water flow direction were measured by sampling. The PSDs of the
deposited SPs in different sections were obtained by laser diffraction
after transport test completion, and microstructure photos were also
acquired through metallographic microscopy. Test results show that the
presence of SPs may promote or inhibit Pb2+ migration,
which is closely related to the concentration of injected
Pb2+, particle size and concentration of injected SPs,
seepage velocity, and change in the absolute zeta potential in the
surface charge. Larger SPs are first deposited within a relatively short
distance from the injection surface of the sand column compared with
smaller SPs. The median diameter of the deposited SPs near the injection
end is larger than that of the injected SPs and gradually decreases with
increasing distance, which represents a clear particle-separation
characteristic due to the flowing water.
Keywords: heavy metal; silicon powder;
metallographic microscopy; particle-size distribution; migration
distance