Abstract
Mg-Al layered double hydroxides (LDHs) were applied to soils to control phosphorus (P) loss. Column experiments were conducted with soil and LDHs under saturated conditions to investigate the retention and release of P with various LDHs dosages, flow velocity, and pH. The P retention and retardation of P breakthrough in soil with LDHs were enhanced with increasing LDHs dosages and pH as well as with decreasing flow velocity. The retention of P was successfully analyzed using a two kinetic sites model that accounted for irreversible and reversible retentions. Increasing LDHs dosages, decreasing flow velocity, and increasing pH bring greater maximum retained concentration on the solid phases (Smax1, i.e. irreversible retention) for P in LDHs-soil system. For reversible retention, the greater release rate from site 2 (k2d) than first-order retention rate coefficient on site 2 (k2) for most experiments reflects a rapid release process and near equilibrium transport behavior of P in LDHs-soil system. It is worth noting that the change of soil pH (8–5) and Darcy velocity (0.17–0.65 cm min−1) has little influence on the release of P from soil mixing with LDHs. The stability of LDHs in soil increases with greater LDHs dosages, higher pH, and lower velocity.
Published Version
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