Table 1 The sequential extraction method (5).
From: Nano silica-mediated stabilization of heavy metals in contaminated soils
Fraction | Form | Extractant | pH | Temperature (°C) | Time (h) | String |
|---|---|---|---|---|---|---|
F1 | Exchangeable (EX) | \({1\text{M MgCl}}_{2}\) | 7 | 25 | 1 | Continuous |
F2 | Bound to Carbonate (CAR) | \({\text{Ch}}_{3}\text{COONa}\) \(+{\text{CH}}_{3}\text{COOH}\) | 5 | 25 | 5 | Continuous |
F3 | Bound to Fe–Mn Oxyhydroxides (OX) | \({0.04\text{ M NH}}_{2}-\text{HCl}\)+\({25\text{\% CH}}_{3}\text{COOH}\) | – | 96 | 6 | Periodical |
F4 | Bound to Organic matter (OM) | \(30\text{\% }{\text{H}}_{2}{\text{O}}_{2}\) \(+\) \({0.02\text{ M HNO}}_{3}\) | 2 | 85 | 2 | Periodical |
\({30\text{ \% H}}_{2}{\text{O}}_{2}\)+\({\text{HNO}}_{3}\) | 85 | 3 | Periodical | |||
\({2\text{ M CH}}_{3}{\text{COONH}}_{4}+ {20\text{ \% HNO}}_{3}\) | 25 | 0.5 | Continuous | |||
F5 | Residual (RES) | \({4\text{ M HNO}}_{3}\) \(+\) 36% HCl | – | 96 | 0.5 | Continuous |
