The deposition characteristics of coupled lead ions and suspended
silicon powders along the migration distance in water seepage
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.