Nanoparticle enhanced evaporation of liquids: A case study of silicone oil and water

Wenbin Zhang,Zexian Cao,Ailing Ji,Rong Shen,Kunquan Lu

doi:10.1063/1.4764294

Abstract

Evaporation is a fundamental physical phenomenon, of which many challenging questions remain unanswered. Enhanced evaporation of liquids in some occasions is of enormous practical significance. Here we report the enhanced evaporation of the nearly permanently stable silicone oil by dispersing with nanopariticles including CaTiO3, anatase and rutile TiO2. An evaporation rate as high as 1.33 mg/h·cm2 was measured in silicone oil when dispersed with 100 nm-sized CaTiO3 particles. Dependence of evaporation rate on the chemistry, size and structure of the particles suggests that some weak absorption sites on the particles half floating on the liquid surface are responsible for the facilitated evaporation of liquid molecules. Enhanced evaporation is also observed for water when dispersed with anatase TiO2 particles. The results can inspire the research of atomistic mechanism for nanoparticle enhanced evaporation and exploration of evaporation control techniques for treatment of oil pollution and restoration of dirty water.

Highlights

Oil pollution has a large devastating impact on the environment
Significantly enhanced evaporation was observed for silicone oil dispersed with CaTiO3 and TiO2 nanoparticles
Our measurement clearly demonstrated that only nanoparticles that half float on the liquid surface and provide some weak adsorption sites, depending on the specific nature of the nanparticles’surface, lead to enhanced evaporation, as verified by the variation of evaporation rate on the size and volume fraction of particles, and differentiated by the anatase and rutile TiO2 phases

Summary

INTRODUCTION

Oil pollution has a large devastating impact on the environment. The oil interacts with the surrounding elements via many physical and chemical processes such as oxidation, spreading, evaporation, dissolution, dispersion and biodegradation, etc.[1]. Lu et al have fabricated several kinds of high yield stress (even over 200 kPa at 5 kV/mm) electrorheological fluids by dispersing TiO2, CaTiO3 and SrTiO3 nanoparticles in silicone oil.[7,8] the implementation of these electrorheological fluids confronts an annoying problem, that is, for some particular combinations of oil and nanoparticle, the oil which is almost permanently stable by itself in the same conditions will disappear very quickly via evaporation.[10] We are led to the question as which features of the nanoparticles have caused the fast evaporation of the liquids The answer to this question is expected to provide clues for the development of strategies and methods for the enhancement or suppress of liquid evaporation, which is of essential importance to, among others, the removal of oil pollution and polluted water, and to ameliorate the quality of draught-prone soils. The results provide rich clues to the research of atomistic mechanism and to the development of liquid treatment techniques

EXPERIMENTAL

RESULTS AND DISCUSSION

CONCLUSIONS