Effects Of Water-soluble Co-solvent On Properties Of Pickering Emulsions And Study On TMB Oxidation In Pickering System

Hydrophobic silica was used as solid emulsifier to prepare Pickering emulsions,which is the main research content in the paper,and we investigated the effects of watersoluble co-solvent on the properties of Pickering emulsions.At last,the oxidation of TMB by hydrogen peroxide in Pickering emulsion system was also explored.In this experiment,we investigated some parameters,determining the optimal value of these parameters in Pickering emulsions.We selected three aspects to investigate: the content of solid emulsifier,the water/oil ratio and pH value.The experimental results show that the maximum reaction conversion conditions were at 5wt.%-9wt.% particle emulsifier fraction in oil phase,at 1.0-1.6water/oil ration,and at 2.5 pH value.Effects of water-soluble co-solvents(WSCs)on the properties of W/O Pickering emulsions were investigated.Pickering emulsions were prepared in the system of 1,2,4-trimethylbenzene(TMB)/ hydrophobic silica/water with varying concentrations of WSCs(ethanol,acetic acid and glycerin).Mean droplet size distributions of the obtained emulsions were studied to investigate the effect of WSCs types and concentrations.The results demonstrated that mean droplet diameter distributions decreased at first and then increased with increased WSC concentrations,and the emulsions existed the minimum droplet mean diameters at 60% ethanol,40% acetic acid and 80% glycerin concentration in water phase.Moreover,the effect of WSC concentration on the phase inversion locus was further investigated,and the result was similar to the data of droplet mean diameters.At the same time,Infrared Radiation(IR)spectrometer was used to investigate the mechanism and the results show that the WSC attaching on hydrophobic silica changed the wettability of the particles and facilitate the formation and phase inversion of the emulsion.The hydrogen bonds between the co-solvent groups attached on the solid particles make great effect on the droplet size of the emulsion and strengthen the interaction between emulsifiers.Finally,two-phase reaction of TMB oxidation was used to verify the conclusions above,and found water-soluble co-solvent was indeed advantageous to two-phase reactions.Overall,proper WSC is in favor of the stability of Pickering emulsion,which has a great prospect in the area of two-phase reaction.Our findings will offer a novel way to improve the ability of emulsification in Pickering emulsion system without modification of the solid emulsifier.