Table 2.
Dissolution results presented as concentration (mg/L or μg/L) and percent dissolved of nano- and bulk-ZnO and TiO2 samples at low pH (1.5) and neutral pH (pH 7) obtained with the short (2 h) assay (syringe filtration)
| Description | Bulk | Nano | Bulk vs nanob |
|---|---|---|---|
| Neutral pH | |||
| Zn metal | 7.02 ± 0.39 mg/L or 1.33 % | 10.8 ± 0.50 mg/L or 2.05 % (<50 nm) | p < 0.001 |
| ZnO | 4.12 ± 0.21 mg/L or 0.95 % | 7.85 ± 0.27 mg/L or 1.87 % (<100 nm) | p < 0.0001 |
| 8.59 ± 0.45 mg/L or 2.13 % (<50 nm) | p < 0.0001 | ||
| Rutile | 0.146 ± 0.069 μg/L or 0.000048 % | 0.210 ± 0.058 μg/L or 0.000066 % (<100 nm) | p = 0.408 |
| Anatase | 0.190 ± 0.075 μg/L or 0.000059 % | 0.197 ± 0.069 μg/L or 0.000065 % (<25nm) | p = 0.242 |
| Nist 1898a | 0.128 ± 0.040 μg/L or 0.000041 % | ||
| Low pH | |||
| Zn metal | 92.3 ± 21.4 mg/L or 17.5 % | 439.2 ± 24.4 mg/L or 80.8 % (<50 nm) | p < 0.0001 |
| ZnO | 368.7 ± 15.3 mg/L or 88.5 % | 391.3 ± 5.11 mg/L or 97.0 % (<100 nm) | p = 0.0098 |
| 379 ± 5.25 mg/L or 93.6 % (<50 nm) | p = 0.128 | ||
| Rutile | 0.282 ± 0.032 μg/L or 0.000092 % | 0.505 ± 0.059 μg/L or 0.00016 % (<100 nm) | p < 0.0001 |
| Anatase | 58.5 ± 6.08 μg/L or 0.019 % | 69.3 ± 6.44 μg/L or 0.022 % (<25 nm) | p = 0.019 |
| Nist 1898 | 39.1 ± 3.65 μg/L or 0.012 % | ||
Data are presented as mean and standard deviation of five independent replicates
a n = 3; bresults for bulk vs nano are significantly different when p < 0.05