Study On The Phase Behavior Of Hexadecyl Trimethyl Ammonium Bromide Microemulsion

Microemulsion has excellent performances of solubilization and emulsification for organic phase,so it is becoming more and more widely used in the treatment of organic pollutants and oily sludge.It is usually composed of surfactant,oil,water and alcohol,and all these factors affect the phase behavior and solubilization performance of the microemulsion.The influence of different kinds of inorganic salts,salinity and oil/water ratio on phase behavior of hexadecyl trimethyl ammonium bromide microemulsion system was investigated through Winsor phase diagram and?-?fishlike phase diagram.It was found that the type of ion in the inorganic salt and the change of valence show different effects on the phase behavior and the solubilization behavior of the microemulsion system.The counter ion of surfactant plays a main role on microemulsion system,so in cationic surfactant microemulsion system,the higher the valence state and the greater the radius of anion in the salt are,the stronger influence on the phase behavior has.The anion in inorganic salts has singnificant influence on microemulsion solubilization capacity,however,the cation has little influence.It was found that in the optimum Winsor type III microemulsion system,the optimum salinity gradually decreases with the increase of oil and water ratio,while the change of optimum solubilization parameters is not obvious.The law of solubilization behavior of organic mixtures in the CTAB mocroemulsion system was also studied in this work.Binary and quaternary mixtures of n-Hexane,n-heptane,n-octane and n-dodecane with different equivalent alkyl carbon number(EACN)were chosed as the oil phase by adjusting the mole ratio between the hydrocarbons.The relations between the optimum dosage of alcohol(A~*)or optimal solubilization parameter(SP~*)and EACN were investigated.It was found that the A~*vs.EACN and the SP~*vs.EACN relations fit quadratic functions.For a certain surfactant under constant condition,the quadratic functions are the same no matter what kinds of hydrocarbons were used.The n-hexane and n-octane hydrocarbons were used as the oil mixture to prepare the optimum Winsor type III microemulsion.Gas chromatography was used to measure the organics content in the excess oil phase.The partition of organics under different surfactant and NaCl concentrations was studied.The results show that the content is different for organics in the excess oil phases and in the initial organic mixtures,which means that selectivity was occurred during solubilization.Volume ratio of n-hexane to n-octane in the solubilized oil phase increased by 0.1182,0.2590,0.3151,0.3351 times than that in the inintial oil phase at CTAB content of 4.0,5.0,6.0,7.0wt%,that is to say,the microemulsion system preferentially solubilized n-hexane,and the selectivity is more significant with the increase of CTAB content.Volume ratio of n-hexane to n-octane in the solubilized oil phase increased by 0.2590,0.1521,0.2799 and 0.2174 times than that in the inintial oil phase at NaCl content of 3.0,4.0,5.0,6.0wt%.In general,molecules with smaller molecular volume and light polarity are preferentially solubilized.The microemulsion containing n-hexane and n-octane was used to wash the atmospheric residue on cotton.The influence of microemulsion type,washing time and the oil type on the oil removal rate were investigated.The results showed that the oil removal effect when n-hexane used as the oil phase was better than that of n-octane.Washing time of 120min,gave higher washing efficiency when Winsor type III microemulsion was used as the detergent.