Fig. 7 ATR-IR and XPS for the fresh and used MIL-100(Fe) (a ~c were the results of ATR-IR, d was the result of XPS)
In order to make it clear what happened for the SDS covered on the model emulsion. The component of the SDS solution after interaction with MIL-100(Fe) was detected by ion chromatogram (IC) and liquid chromatogram-mass spectroscopy (LC-MS). The result of IC suggested that the SO32- or SO42- was released from SDS after interaction with MIL-100(Fe) (Fig. 8 ). What’s more, MIL-100(Fe) degraded the SDS obviously according to the results of LC-MS (Fig. S8 ). The hydrogenation peak at m /z =187 verified that the degradation products contained dodecyl alcohol (CH3(CH2)10CH2OH, M=186) (Fig. S9 ), which implied that the group of SO32- instead of SO42-, was prefer to be extracted from SDS when the MIL-100(Fe) interacted with SDS. The dodecyl alcohol could be oxidized into undecyl carboxylic acid (CH3(CH2)10COOH, M=200) with a molecule ion peak at m /z =199 (Fig. S9 ) further. After interaction with SDS, the BTC with a molecule ion peak atm /z =209 (Fig. S10 ) was released from MIL-100(Fe). The components with retention time of 4.6 min (m /z =223) and 5.1 min (m /z =237) were the ester and binary ester of BTC with formulas of C8H5O6CH3and C8H4O6(CH3)2(Fig. S11 and Fig. S12 ). Those esters might be the residues when the MIL-100(Fe) was prepared, because there were absorption band of C-H for CH3 at 2871 cm-1 and 2974 cm-1 and absorption band of C-O-C for esters at 1088 cm-1 in the ATR-IR results of fresh MIL-100(Fe) (Fig. S13 ). The leaching for BTC, C8H5O6CH3and C8H4O6(CH3)2implied that the structure of MIL-100(Fe) was destroyed at some degree, which can cause the changes of absorbance for the carboxylate and -CH3 group as showed in Fig. 7a and7c .