Two Birds with One Stone: A Dual-Functional Washing Fluid for Shoreline Oil Spill Response

The gigantic petroleum exploration and production are threatening the lives and well-being of people and other species. Pizeocatalysis is a bridge to transfer ceaseless mechanical energy to chemical energy and thus triggers redox reactions. In this study, piezoelectric MoS2 was used as a surface-washing fluid to physically and chemically decontaminate oiled sands. The MoS2 displayed single- and few-layer structures, which were conducive to piezocatalysis. The addition of MoS2 could decrease the interfacial tension, thereby facilitating oil removal. The oil removal efficiency varied under different environmental conditions. Quenching experiments with different scavengers and electron paramagnetic resonance (EPR) spectra showed the existence of reactive oxygen species (ROS) including O-1(2), O-center dot(2)-, and (OH)-O-center dot. It was found that shaking was a necessary initiator to trigger piezocatalysis and singlet oxygen (O-1(2)) was the dominant ROS. The MoS2 fluid exhibited good stability, maintaining high removal efficiency after five reuse cycles. Notably, results indicated that high-molecular-weight hydrocarbons were degraded into lower-molecular-weight ones, indicating the existence of chemical oxidation pathways in oil removal. This study provides a facile self-powered piezocatalytic surface-washing process by harnessing natural energy from water agitation to clean up oiled sands.