Study On The Stability And Rheological Properties Of Emulsion System By Multiple Light Scattering Technology

The stability of emulsion has been a very basic and important issue in its production and application, which is related to rheology. In the past, rheology properties were mainly measured by mechanical rheometer, and the stability of emulsion was studied by means of macro visual method as phase separation happened. When mechanical rheometer is used for measuring, the mechanical force is acted on the sample, which may damage its original state. The multiple light scatting stability instrument and diffusion wave spectrometer（DWS）, which based on the principle of multiple light scattering, can be used for quantitative characterization of the stability of turbidity system. Through the analysis of the multiple light scattering information, the stability parameter W,the particle size,storage modulus G’and loss modulus G", viscosity η, mean square displacement （MSD） are obtained. The advantage of this technology is that it do not have any damage to the system.Span-80（Sorbitan oleate） and OP-4[Octylphenol polyoxyethylene（4） ether)] are two kinds of oil soluble emulsifiers, which used to be preparation of water in oil（W/O） emulsion liquid membrane system（ELMs）. The ELMs prepared by using Span-80 or OP-4 as emulsifier show different emulsifying performance and stability. In this paper, the multiple light scatting stability instrument and DWS were used to study the stability and rheological properties of two kinds W/O emulsion system, i.e. Span-80/decane/HCl and OP-4/decane/HCl. The influence of temperature, emulsifier concentrations and hydrochloric acid concentrations on the stability and rheological properties of emulsion system was investigated, and the relationship between stability and rheological properties was discussed. The main results are as follows:1. Stability of Span-80/decane/HCl emulsion system. （1） Influence of temperature. With the increased of temperature, the emulsion stability decreased. （2） Influence of Span-80 concentration. With the increased of Span-80 concentration, the emulsion stability increased. （3） Influence of HC1 concentration. With the increased of HC1 concentration, the emulsion stability increased first and decreased afterwards. （4） Influence of extraction reagent. In the present of D2EHPA （Phosphoric acid, bis（2-ethylhexyl） ester） or TBP（Phosphoric acid, tris（1,1-dimethylethyl） ester）, the stability of the emulsion decreased. D2EHPA has more effect on the emulsion stability.2. Rheology of Span-80/decane/HC1 emulsion system. （1） Influence of the temperature. With the increased of temperature, the G’, G" and η are decreased. （2） Influence of Span-80 concentration. When the mass fraction of Span-80 increased, the G’,G" and η decreased.（3） Influence of HC1 concentration. In the range of 0-4 mol·L^-1, when the HC1 concentration is 3 mol·L^-1, the G’, G"and η have the largest values, when the concentration are 0 mol·L^-1 and 4 mol-L^-1, G’, G’’ and η have the minimum valves. MSD showed contrary changes compair to G’, G"and η.3. Stability of OP-4/decane/HCl emulsion system. （1） Influence of temperature. With the increased of temperature, the emulsion stability decreased. （2） With the increased of OP-4 concentration, the emulsion stability increased. （3） With the increased of HC1 concentration, the emulsion stability increased first and decreased afterwards. （4） Influence of extraction reagent. In the present of D2EHPA （Phosphoric acid, bis（2-ethylhexyl） ester） or TBP（Phosphoric acid, tris（1,1-dimethylethyl） ester）, the stability of the emulsion decreased. D2EHPA has more effect on the emulsion stability.4. Rheological properties of OP-4/decane/HCl emulsion system. （1） Influence of temperature. With the increased of temperature, both the G’, G"and η decreased. When the temperature is 50 ℃ and above, with the increase of temperature, the G’and G" increased. （2） Influence of OP-4 concentration. Both of G’and G" and η increased with the increased of OP-4 concentration. （3） Influence of hydrochloric acid concentration. With the increase of hydrochloric acid concentration, both of G’and G" and η are decreased. MSD showed contrary changes compair to G’, G" and η.5. Two emulsion systems in line with rule, that is, the greater the viscoelastic, the greater the stability. The Span-80/decane/HCl emulsion system is small effected by temperature and HCl concentration, on the contrary, OP-4/decane/HCl emulsion system is affected by larger.