A strategy of heterogeneous polyurethane-based sponge for water purification: Combination of superhydrophobicity and photocatalysis to conduct oil/water separation and dyes degradation

The diffusion of stubborn oils and organic pigments has become a severe environmental pollution problem. Promisingly, the combination of superhydrophobicity and photocatalysis is expected to provide an efficient, economical and simple solution. In this paper, a kind of superhydrophobic and super-lipophilicity polyurethane (PU)-based sponge was reported by a strategy of undergoing ferric tetroxide loading (Fe₃O₄@PU), polydopamine fixation (PDA-Fe₃O₄@PU), octadecylamine grafting (ODA-Fe₃O₄@PU) and molybdenum disulfide loading (MoS₂-ODA-Fe₃O₄@PU) successively. The results show that the MoS₂-ODA-Fe₃O₄@PU sponge exhibits outstanding superhydrophobicity (with maximum water contact angle of 161.64°), excellent oil absorption capacity (60-109 wt/wt), robust stability in extreme environments and great oil/water separation ability. In addition, the MoS₂-loaded sponge demonstrates desirable outcomes in decomposing methyl orange and methylene blue under light source, and a dual-functional purification system with a heterogeneous polyurethane-based sponge (the upper part is MoS₂-ODA-Fe₃O₄@PU and the bottom part is MoS₂@PU) endowed with superhydrophobicity and photocatalysis can purify water by separating oils and decomposing methylene blue simultaneously.