Surfactant Cmc And Thermodynamic Properties In Non-aqueous Solvent

Recent years, our country entered the row of the surfactant powerful nation, how to utilize "the industry monosodium glutamate" to promote our country's economic development well is currently the major concerns of the people. For this reason studies the property of surfactant in water only is not enough, we also need to study the property of surfactant in the non-aqueous solution. With the rapid development of biotechnology, the reverse micelle extraction technology applications become wider. In addition, the coating, the paint industry, the micro-emulsion, the rubber group catalysis and so on are involved the surfactant in non-aqueous solution. Thus, property research of surfactant in non-aqueous solution is significant.Critical micelle concentration is the important performance indicators. A lot of effort has been put into research on the micellization process in aqueous solutions. However, such research in nonaqueous solvents has received only limited attention. But studies of the properties of surfactants under different conditions, research on alcohol influence on critical micelle CMC and thermodynamic functions of surfactants in nonaqueous solutions also have some industrial applications. For example, some new highly effective pesticides, such as netenpyrem and thiamethoxam cannot be dissolved in water or apolar solvents. They have to be made as dusting or wettable powders which lowers the killing efficiency and also harms the environment.To avoid these problems, it is better to dissolve these materials in polar solvents, which requires a better understanding of the relationships among surfactant, cosurfactant, and polarsolvent. The research of surfactant in non-aqueous solution provides theoretical foundation. There are important theoretical and broad prospects.In this paper, the CMC is obtained by the microcalorimetric method and the electric conductivity. And the regularity of CMC and thermodynamics are appered. The main contents are as follows:1. Microcalorimetric method1.1 the determination and regularity of CMCThe power-time curves of the micelle formation process were determined for 0.01 mol·L^-1CTAB in DMF or DMA, which contained various concentration alcohol at different temperatures. The CMC values can be obtained according to the corresponding concentration of the lowest point of the power-time curves. The results showed that: Under the condition of identical alcohol concentration, identical carbon number of the alcohol, the CMC values increased with the increment of temperature; under the condition of identical temperature, identical carbon number of the alcohol, the CMC values increased with increasing concentration of alcohol. Under the condition of identical temperature, identical alcohol concentration, the CMC of surfactants decreased with an increase in the carbon number of the alcohol.1.2 Thermodynamic function acquisition and regular discussionThe area of the curve which represents the thermal effect was obtained. The standard enthalpy changes (ΔH_m^θ) of the micellization process of CTAB in DMF or DMA containing different concentrations of alcohols were calculated.ΔG_m^θandΔS_m^θcan also be obtained by thermodynamic theory. The results showed that: Under the condition of identical alcohol concentration, identical carbon number of the alcohol, theΔH_m^θand theΔS_m^θincreased with the increment of temperature, theΔG_m^θdecreased with the increment of temperature; Under the condition of identical temperature, identical carbon number of the alcohol, theΔH_m^θand theΔS_m^θdecreased with increasing concentration of alcohol, theΔG_m^θincreased with increasing concentration of alcohol; Under the condition of identical temperature, identical alcohol concentration, theΔG_m^θ, theΔH_m^θand theΔS_m^θdecreased with an increase in the carbon number of the alcohol.2. Molar electric conductivityThe value ofλwas determined by conductometer instruction manual. The value ofΛ_m was calculated. The CMC was obtained by the curve ofΛ_m-c. theΔH_m^θwas obtained by the van't Hoff equation.TheΔG_m^θand theΔS_m^θwere also obtained by thermodynamic theory.The results showed that: With the increment of temperature, the CMC increased, theΔG_m^θdecreased, the change ofΔH_m^θ,ΔS_m^θwere not too obvious. The CMC, TheΔH_m^θ, TheΔG_m^θand theΔS_m^θwere all decreased with an increase in the carbon number of the surfactant.The innovation of this paperMcrocalorimetric method was used to study the interactivity of surfactants, cosurfactants and solvents in non-aqueous solution. The CMC andΔH_m^θwere determined by power - time curve. TheΔG_m^θandΔS_m^θwere calculated by thermodynamic equations. This is a new method to gain CMC and thermodynamic function.