Photo-thermal conversion properties of phosphonium-based ionic liquid, its magnetized and emulsion forms

Abstract

In this work, phosphonium-based ionic liquid (PIL) and its magnetized form (MPIL) were used for heat generation from light. Based on the experimental results, MPIL shows better performance compared to PIL. The MPIL nanofluid was stable even after several consecutive heating/cooling cycles in the closed system. Due to low transparency, the MPIL exhibits the most light-to-heat conversion efficiency on its surface so that the surface temperature respectively reaches 62.5 ℃ and 78.0 ℃ after 60 min simulated light and sunlight irradiation. The photo-thermal conversion ability of the MPIL was examined at various light intensities. Several thermo-physical parameters for PIL and MPIL were calculated and compared, approving the superiority of the MPIL in photo-thermal conversion. To overcome the high cost of large amount of utilized MPIL, which is the drawback of most of ionic liquids, the stable surfactant-free MPIL+Oil emulsion is prepared with a very low amount of MPIL (for the first time), which shows good photo-thermal conversion performance. The outstanding advantages of both MPIL nanofluid and MPIL+Oil emulsion including not using dispersant and high photo-thermal durability/ability make them suitable candidates for practical photo-thermal conversion applications.