3.3 Demulsification process
To investigate the demulsification process, the demulsification was recorded by an inverted microscope. As presented in Fig. 4a , a lot of floccules formed as soon as contacting with the emulsion. And the rounded edge of emulsion drop was replaced by the irregular margin of large floccules. The coalescence for emulsions could occur with different patterns, such as two points coalescence liking the cell fusion (Fig. 4b ), three points blend (Fig. 4c ) and multi-point incorporation (Fig. 4d ). Finally, the coalesced emulsion drops would crack as shown in the Fig. 4e , releasing the oleic acid. The oleic acid surrounded the MIL-100(Fe), forming the floccules and floating on the water as showed in Fig. 2a .