Kinetic studies on hydrated solid transform of cetylpyridinium chloride in aqueous solution.
Kinetic studies on hydrated solid transform of cetylpyridinium chloride in aqueous solution.
复制标题
DOI：
10.1021/jp901048q
复制
发表时间：
2009-06
期刊：
影响因子：
--
通讯作者：
S. Sasaki
中科院分区：
文献类型：
--
作者：
S. Sasaki
研究了十六烷基氯化吡啶(CPC)水溶液中水化固体形成和熔融转变的动力学。降温后CPC溶液的电导率变化表现出较长的水化固体形成诱导期t(Ind)。根据上清液在沉淀固体上的电导率，得到了作为温度函数的溶解度。在过饱和度为16以下时，溶液中固相生成的t(Ind)约为1 000 000 S，而搅拌溶液中的t(Ind)小于静置溶液中未搅拌时的1/10。在搅拌溶液中形成稳定固体的近似关系式为t(Ind)=A(K)(Ln S)(-3)。胶束溶液的A(K)值是单体溶液的2400倍。通过对亚稳固体悬浮液在3℃下保温一定时间的差示扫描量热法，根据稳定固体的熔化热容与总熔化热容的比值，得到了从亚稳固体到稳定固体的转变分数r(稳定)。在对亚稳态固体悬浮液施加剪切时，r(稳定)的变化率约为无剪切情况下的20倍。实验表明，溶液中的剪切作用加速了CPC稳定固体的形成。
Kinetic studies were performed on the transitions of hydrated solid formation and melt in an aqueous cetylpyridinium chloride (CPC) solution. The electric conductivity change of the CPC solution exhibited a long induction period, t(ind), for the formation of a hydrated solid after dropping the temperature. The solubility was obtained as a function of temperature from the conductivity of the supernatant over the precipitated solid. The t(ind) for the solid formation in the solution at a degree of supersaturation, S, below 16 was about 1 000 000 s. The t(ind) in the stirring solution, however, was less than 1/10 of that in the standing solution without stirring. The approximated relation of t(ind) = A(k)(ln S)(-3) was found for the formation of stable solid in the stirred solution. The A(k) values obtained for the micelle solutions were 2400 times greater than those obtained for the monomer solutions. The transition fraction from the metastable solid to the stable solid, r(stable), was obtained from the melting enthalpy ratio of the stable solid to the total melting enthalpy given by differential scanning calorimetry of the metastable solid suspension incubated at 3 degrees C for a given time. The changing rate of r(Stable) observed in applying the shear to the metastable solid suspension was about 20 times the rate in the shear-free case. The present experiments demonstrate that the shear in the solution accelerates the formation of a stable solid of CPC.