Role of reducing agent in extraction of arsenic and heavy metals from soils by use of EDTA

Remediation of sandy soil contaminated by heavy metals with Na2EDTA washing enhanced with organic reducing agents: element distribution and spectroscopic analysis

“…The combination of organic reducing agents with Na 2 EDTA increased the removal efficiencies of arsenic, cadmium, copper and lead from soil. The extent of the increase in removal efficiencies depended on the type of soil, the reducing agent and the metals (Kim et al ., ). The increases in removal efficiencies were 19–31% for arsenic, 6–19% for cadmium, 3–12% for copper and 6–21% for lead in samples compared with washing with Na 2 EDTA only (Figure ).…”

“…A similar pattern was observed by Kim et al . () and Zhang & Tsang (). Meanwhile, competition between cations (such as ferric and calcium ions) in soil might affect removal of the target metals (Di Palma, ) and further research is needed.…”

“…Soil contaminated with heavy metals is a major, worldwide environmental problem as anthropogenic activities intensify (Domínguez et al ., ), which can pose a long‐term risk to biological systems (Kim et al ., ). Chelator‐assisted soil washing has been widely investigated to develop effective soil remediation strategies for contaminated soil (Zhang & Tsang, ; Beiyuan et al ., ).…”

“…Recent studies have recognized that combinations of Na 2 EDTA with reducing agents could be suitable for removing both arsenic and cationic heavy metals simultaneously from contaminated soil (Qiu et al ., ; Kim et al ., ; Kim et al ., ). In general, previous studies focused on improving the efficiency of metal removal and metal redistribution under Na 2 EDTA washing enhanced with reducing agents, such as sodium dithionite, NH 2 OH‐HCl, oxalic acid and ascorbic acid (Houben et al ., ; Im et al ., ; Kim et al ., ). There has been little research, especially by spectroscopic analysis, to investigate surface features of soil and reveal washing mechanisms (Shim et al ., ; Kim et al ., ).…”

Effects of EDTA on adsorption of Cd(II) and Pb(II) by low-permeability soil minerals and on their microscopic characteristics

“…In detail, on the one hand, some EDTA introduced into the HM-SM system could be adsorbed on and cover the surfaces of SMs [33,38]; and this made the surfaces of SMs heterogeneous, blocking some adsorption sites and making them nonuniform [16,27]. On the other hand, EDTA and HM ions were both adsorbates for SMs, and they were interactive via chelation [26,28,[39][40]; and this was accord with the mechanism of the Freundlich isotherm model. Additionally, because the matching ratio between divalent metal ions and EDTA in chelation process was 1:1 (MR = 0.5), which meant a more effective and stable HM-SM-EDTA system, the linear relationship was better when the MR of more points in a certain line was closer to 0.5.…”