Effect of freeze-thaw frequency plus rainfall on As and Sb metal(loid)s leaching from the solidified/stabilized soil remediated with Fe-based composite agent

• Published in: The Science of the total environment Vol. 926; p. 171844
• Main Authors: Xue, Ruiyuan, Wang, Kun, Wang, Yipeng, Jiang, Miao, Zhao, Qingliang, Jiang, Junqiu
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.05.2024
• Subjects: adsorption; Antimony; Arsenic; calcium; environment; Ferrous sulfate; fly ash; Freeze-thaw; freeze-thaw cycles; heavy metals; Hydrus-1d; lignosulfonates; Long-term rainfall; rain; remediation; soil; soil stabilization; solidification; Antimony; Hydrus-1d; Ferrous sulfate; Arsenic; Freeze-thaw; Long-term rainfall
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.171844

The composite agent of ferrous sulfate, fly ash, and calcium lignosulfonate (FFC) can remediate the soil contaminated by As and Sb under cyclic freeze-thaw (F-T) via stabilization/solidification (S/S). However, the impact of high-frequency F-T cycles on the leaching behavior and migration of As and Sb in FFC-treated soils remains unclear. Here the leaching concentrations, heavy metal speciation (Wenzel's method), and Hydrus-1d simulations were investigated. The results showed that FFC effectively maintained the long-term S/S efficiency of arsenic remediation subject to an extended rainfall and freeze-thaw cycles, and stabilized the easily mobile form of As. The short-term S/S effect on Sb in the remediated soils suffering from F-T cycles was demonstrated in the presence of FFC. In a 20-year span, the mobility of Sb was affected by the number of F-T cycles (FT60 > FT20 > FT40 > FT0) in soil with a depth of 100 cm. As leaching progressed, FFC slowed the upward proportion of adsorbed As fractions but converted parts of the residual Sb to the form of crystalline Fe/Al (hydro) oxide. Moreover, the adsorption rate and capacity of As also preceded that of Sb. Long-term curative effects of FFC could be observed for As, but further development of agents capable of remedying Sb under cyclic F-T and long-term rainfall was needed. The predictive results on the migration and leaching behavior of heavy metals in S/S remediated soils may provide new insight into the long-term assessment of S/S under natural conditions. [Display omitted] •Ferrous sulfate, fly ash, and calcium lignosulfonate (FFC) were used for S/S.•Most adverse effect was simulated by freeze-thaw (F-T) cycles plus heavy rainfall.•FFC prevented As from migrating under high-frequency F-T and rainfall.•Sb migration was affected by F-T (FT60 > FT20 > FT40 > FT0) after remediation.•Susceptible forms of As and Sb kept growing during long-term rainfall.