The PFOTES-CGF shows a good performance in oil–water separation by simple filtration. When the mixture consisted of an equal volume of water and kerosene (dyed with Sudan III) was poured into the filter paper covered with PFOTES-CGF, the above kerosene can get through and dropped into the below beaker, while the water was totally retained on the filter paper (Fig. 4d). After oil–water separation, the water can be collected from the filter paper without the residue of red-colored oil (Fig. 4e), while Sudan III-dyed kerosene was firstly absorbed by the fiber and then dropped into the below beaker.