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首页> 外文期刊>RSC Advances >Micellization, surface activities and thermodynamics study of pyridinium-based ionic liquid surfactants in aqueous solution
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Micellization, surface activities and thermodynamics study of pyridinium-based ionic liquid surfactants in aqueous solution

机译：吡啶基离子液体表面活性剂在水溶液中的胶束化，表面活性和热力学研究

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摘要

The micellization and surface activity properties of long-chain pyridinium ionic liquids n -alkyl-3-methylpyridinium bromide ([C _( n ) mpy][Br], n : the carbon numbers of hydrophobic tails, n = 12, 14, 16) in aqueous solution were systematically investigated through electronic conductivity measurement, surface tension, and ultraviolet-absorption spectra. The surface chemical parameters and thermodynamics parameters were obtained. The [C _( n ) mpy][Br] ionic liquids exhibit higher surface activities than conventional surfactants with corresponding alkyl chain lengths. The effects of inorganic salts (LiBr, NaBr, MgBr _(2) ), organic alcohols (C _(2) H _(5) OH, C _(3) H _(7) OH, C _(4) H _(9) OH, C _(5) H _(11) OH) and temperature on the critical micelle concentration (CMC) values of [C _( n ) mpy][Br] aqueous solutions were also investigated. The CMC values remarkably decreased with the addition of inorganic salts. The CMC values increased slightly in the presence of ethanol, but decreased gradually as the chain length of the alcohol increased. The CMC values assumed a trend of decreasing and then increasing with the increase of temperature. The calculation results of thermodynamic parameters show that both adsorption and micellization processes of [C _( n ) mpy][Br] are spontaneous; the enthalpy of [C _(12) mpy][Br] is negative at 293.15 K and becomes negative with temperature increasing. For [C _(14) mpy][Br] and [C _(16) mpy][Br] this transition occurs at 288.15 K and the micellization process is entropy-driven in the investigated temperature range.
机译：长链吡啶鎓离子液体正烷基溴化3-烷基-3-甲基吡啶鎓（[C _（n）mpy] [Br]，n：疏水尾的碳数，n = 12，14，16通过电子电导率测量，表面张力和紫外线吸收光谱系统研究水溶液中的）。获得了表面化学参数和热力学参数。 [C _（n）mpy] [Br]离子液体比具有相应烷基链长的常规表面活性剂具有更高的表面活性。无机盐（LiBr，NaBr，MgBr _（2）），有机醇（C _（2）H _（5）OH，C _（3）H _（7）OH，C _（4）H的影响_（9）OH，C _（5）H _（11）OH）和温度对[C _（n）mpy] [Br]水溶液的临界胶束浓度（CMC）值也进行了研究。添加无机盐后，CMC值显着降低。在乙醇存在下，CMC值略有增加，但随着醇链长度的增加而逐渐降低。 CMC值假定随温度升高先降低后升高的趋势。热力学参数的计算结果表明，[C _（n）mpy] [Br]的吸附和胶束化过程是自发的。 [C _（12）mpy] [Br]的焓在293.15 K时为负，并随温度升高而变为负。对于[C _（14）mpy] [Br]和[C _（16）mpy] [Br]，此转变发生在288.15 K，并且在研究的温度范围内，胶束化过程是熵驱动的。

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