Carbon foams produced from lignin-phenol-formaldehyde resin for oil/water separation

Carbon foams for oil/water separation were synthesized using lignin-phenol-formaldehyde (LPF) resin as the carbon source and polyurethane (PU) foam as the template. Lignin was extracted from sedge grass and was used to replace 25 wt% of the phenol to prepare a LPF resin in an alkaline medium. The carbon foams exhibit unique properties such as open macropores, low bulk density, good water repellency and efficient oil absorption. The absorption capacities of the carbon foams are 12 to 41 times their own weight for a wide range of oils and organic solvents. The foams can be recycled by directly burning the oil within their pores and absorption capacity remains above 83% after 10 absorption test cycles, indicating that the carbon foams are promising oil sorbents with a good recyclability.