Table 1 The content of ash, surface charge, acid buffering capacity, and cation exchange capacity of the presoaked and raw WWS
Sample | Soaking reagent | Concentration (mmol/L) | Ash (%) | SCa (mv) | CECb (cmol/kg) | ABCc (mmol/pH-kg) |
|---|---|---|---|---|---|---|
Raw WWS | No soaking | – | 30.5 ± 0.8 | − 25.9 ± 1.1 | 140.2 ± 1.8 | 226.3 ± 1.2 |
H2O | – | 25.2 ± 1.5 | − 24.1 ± 1.3 | 133.7 ± 2.5 | 201.4 ± 3.7 | |
H+ | 30 | 26.8 ± 1.1 | − 22.2 ± 0.3 | 116.3 ± 1.8 | 146.7 ± 3.2 | |
K+ | 30 | 24.9 ± 1.3 | − 23.5 ± 0.5 | 122.6 ± 2.5 | 168.9 ± 3.5 | |
Na+ | 30 | 27.5 ± 0.7 | − 24.7 ± 0.2 | 118.9 ± 1.4 | 150.7 ± 2.6 | |
Ca2+ | 30 | 23.3 ± 0.5 | − 16.3 ± 0.4 | 135.6 ± 4.6 | 179.9 ± 2.1 | |
Mg2+ | 30 | 24.8 ± 1.2 | − 18.5 ± 1.3 | 109.2 ± 0.9 | 147.3 ± 4.1 | |
Zn2+ | 30 | 26.3 ± 0.4 | − 17.6 ± 2.1 | 96.5 ± 1.3 | 140.6 ± 1.5 | |
Fe2+ | 30 | 25.7 ± 0.2 | − 10.5 ± 0.3 | 80.8 ± 1.1 | 94.3 ± 2.2 | |
Fe2+ | 10 | 23.1 ± 0.1 | − 14.7 ± 0.5 | 97.4 ± 2.8 | 133.9 ± 1.6 | |
20 | 26.3 ± 0.3 | − 13.2 ± 0.1 | 90.5 ± 3.2 | 119.3 ± 2.3 | ||
30 | 25.8 ± 0.7 | − 11.1 ± 0.0 | 81.6 ± 1.4 | 95.6 ± 1.9 | ||
60 | 24.5 ± 1.1 | − 10.8 ± 0.8 | 74.3 ± 4.2 | 89.5 ± 2.6 | ||
120 | 24.3 ± 0.3 | − 4.7 ± 0.2 | 72.4 ± 1.7 | 79.3 ± 1.0 |