.sds / Nc <sub> 5 </ Sub> H <sub> 11 </ Sub> Oh / Nc <sub> 7 </ Sub> H <sub> 16 </ Sub> / H <sub> 2 </ Sub O Microemulsion Interface Property

At the weight ratio of n-C5HnOH/ H2O = 1/1. when the total concentration of SDS (SDSt%) is less than 6%, the ternary mixture of sodium dodecyl sulfate (SDSyn-C5H11OH/H2O is the coexistence of two immiscible microemulsions. Surfactant molecules are adsorbed at the oil-water interface, while assemble into micelles in the bulk solution to form O/W, W/O and BI microemulsions. When SDSt% is less than 3%, with the increase of SDSt%, the SDS concentration in both phases increases, and that of the lower phase (O/W) increases faster, the SDS density at the interface increases, too, which results in the increase of the interfacial potential AE, the capacitanceand the differential capacitance in both the upper phase (W/O) (Co, Cod) and the lower phase (O/W) (Cw, Cwd) and the interfacial capacitance (Ci). and the decrease of the upper phase resistivity p0, the lower phase resistivity pw, and the interfacial resistivity PJ. Due to the relatively faster increase of SDS concentration at the lower phase, the lower phase (O/W) capacitance (Cw) and differenitial capacitance (CWd) are higher than their counterparts in the upper phase (W/O). After SDSt% reaches 3%, the increase of SDS concentration at the upper phase, the composition of which is still in the W/O region, slows down, while the SDS concentration increases at almost the same rate in the lower phase, the composition of which is in the bicontinuous (BI) region. The SDS density at the interface increases slower, and so do the interfacial potential AE, the upper phase capacitance Co and differentia] capacitance Cod. and the interfacial capacitance Ci. The dropping velocity of ρo, ρw, and p, slows down, while Cw and Cwd keep going up at a relatively high rate.In the SDS/n-C5H11OH/n-C7H16/H2O system, with the addition of oil (n-C7H16), the regions in the phase diagram grows from two-dimentional into three-dimentional, the area of O/W region shrinks, and the bicontinuous region becomes narrower. Whenthe total n-C7H16 concentration [(n-C7H16)t%] exceeds 7%, the bicontinuous region breaks away from the W/O region, but it is still linked with the O/W region.At the weight ratio of SDS/n-C5HnOH/H2O System = 5.0/47.5/47.5, the structure of the upper phase of the SDS/n-C5H11OH/n-C7H16/H2O system is W/O, while the structure of the lower phase is bicontinuous. When the (n-C7H16)t% is less than 1%, with the increase of the (n-CyH16)t%, the upper phase (W/O) capacitance (Co, Cod) drops, the lower phase (BI) capacitance (CBI, CBId) rises; at the same time, decrease the W/O-BI interfacial potential AE, interfacial capacitance Ci, and the interfacial charge-transfer current ict. After the (n-C7H16)t% reaches 1%, with the increase of the (n-C7Hi6)t%, AE, Ci, and ict demonstrate no significant change. The results above indicate that the addition of small amount of n-C7Hi6 into the system drives SDS from W/O phase to bicontinuous phase through the W/O-BI interface; when the (n-C7Hi6)t% is greater than 1%, the changing rate of all the electrochemical properties for the upper, phase, the lower phase and the interface slows down, so does the interfacial tension.At the weight ratio of SDS/n-C5H11OH/H2O = 2.0/49.0/49.0, the structure of the upper phase is W/O, while that of the lower phase is O/W. When the (n-C7H16)t% is less than 2%, with the increase of the (n-C7H16)t%, the SDS concentration at the upper phase (W/O) increases, while that of the lower phase (O/W) decreases, the W/O-OW interfacial potencial, interfacial capacitance, interfacial charge-transfer current all increase. After the (n-C7H16)t% reaches 2%, the SDS concentration in both the upper phase and the lower phase changes insignificantly. The existence of n-C7Hi6 has no pronounced effect on the oxidation process of SDS in the lower phase (O/W). The interfacial electrochemical properties change slower. The results above indicate that the addition of small amount (<2%) of n-C7H16 facilitates the transfer of SDS from the lower phase (O/W) to the upper phase (W/O). After the (n-C7H16)t% reaches 2%, the transfer dwindles a...