Table 2. pH and Concentrations of Species (mmol L−1) Involved in Zn Immobilization in the Samples.
| Biochars | pH* |
CO32− |
Si species |
PO43− |
Ca2+ |
Mg2+ |
||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| B | B + Zn | B | B + Zn | B | B + Zn | B | B + Zn | B | B + Zn | B | B + Zn | |
| PN350 | 8.3 ± 0.1 | 6.7 ± 0.1 | ND | ND | 0.01 ± 0.00 | 0.001 ± 0.000 | 0.03 ± 0.00 | ND | 0.08 ± 0.00 | 0.8 ± 0.2 | 0.07 ± 0.00 | 0.05 ± 0.00 |
| PN550 | 10.0 ± 0.0 | 7.0 ± 0.1 | 0.3 ± 0.3 | ND | 0.05 ± 0.00 | 0.02 ± 0.00 | 0.04 ± 0.00 | ND | 0.10 ± 0.01 | 1.4 ± 0.0 | 0.06 ± 0.00 | 0.09 ± 0.00 |
| WS350 | 9.5 ± 0.0 | 7.1 ± 0.0 | ND | ND | 0.89 ± 0.02 | 0.09 ± 0.00 | 0.06 ± 0.00 | ND | 0.08 ± 0.00 | 0.5 ± 0.1 | 0.09 ± 0.00 | 0.18 ± 0.02 |
| WS550 | 10.4 ± 0.0 | 7.2 ± 0.1 | 1.1 ± 0.0 | ND | 1.95 ± 0.05 | 0.23 ± 0.00 | 0.06 ± 0.00 | ND | 0.11 ± 0.00 | 0.5 ± 0.1 | 0.08 ± 0.00 | 0.17 ± 0.02 |
*As some ions released from biochar may consume released OH− in biochar + water mixture as reaction time increases, the pHs of B and B + Zn were determined at the reaction time of 2 h.