Smart carbon foams with switchable wettability for fast oil recovery

The adsorption and recovery of crude-oil from oily water using oil-selective adsorbents is a highly promising solution for the increasing worldwide oil pollution, but remain a challenge. Herein, we reported a carbon foam (CF) with switchable wettability as smart materials for fast oil adsorption and recovery. By grafting poly(4-vinylpyridine) (P4VP) onto the surface of CF, the obtained smart foam presented a pH responsiveness and could change superhydrophilic and superhydrophobic surface according to the pH value. Thus, the smart responsive carbon foam could fast adsorb the oil in neutral solution (pH = 7) with high oil adsorption capacity of 62–120 g g −1 and desorb all the adsorbed oil in acidic solution (pH = 1) within 1.5 min. In addition, only 3% loss was observed for oil (chloroform) adsorption and recovery after successive reuses of up to 15 cycles, which demonstrated great recyclability of the materials.