Table 1.
Assignment of vibrational modes of chemical species of oxalate from ATR-FTIR spectra shown in Figs 4 and 5.
| [ʋs(C=O)] | [ʋaC=O)] | [ʋs(C-O)] + [ʋ(C-C)] | [ʋaC-O)] | ref. | |
|---|---|---|---|---|---|
| Experimental observations | |||||
| C2O42−, pH 7.0 | — | — | 1570 | 1308 | this study |
| C2O42−, pH 4.5 | — | — | 1570 | 1308 | this study |
| C2O42−, pH 2.0 | 1733 | 1617 | — | 1233 | this study |
| Ox-Fe (1:1), pH 2.0 | 1708 | 1677 | 1389 | 1260 | this study |
| Ox-Fe (1:2), pH 2.0 | 1708 | 1689 | 1389 | 1255 | this study |
| Oxalate + ferrihydrite | 1708 | 1680 | 1412 | 1276 | this study |
| Theoretical calculation | |||||
| Oxalate + ferrihydriteMNMD | 1680 | 1597 | 1383 | 1239 | 51 |
| Oxalate + ferrihydriteBNBD | 1683 | 1570 | 1443 | 1305 | 51 |
| Oxalate + ferrihydriteMNBD | 1687 | 1674 | 1399 | 1280 | 51 |
Mononuclear monodentate (MNMD); binuclear bidentate (BNBD); mononuclear bidentate (MNBD).