pH法测定杨梅单宁临界胶束浓度(CMC)及CMC的影响因素探讨

杨梅单宁(bayberry tannin,BT)的临界胶束浓度(CMC)是杨梅单宁溶液的一个重要物理参数。实验利用pH法测定水溶液中杨梅单宁分子形成胶束形态前后H+浓度的突跃,以pH-CBT做图测定杨梅单宁溶液的CMC值,并且探讨杨梅单宁溶液CMC值的影响因素。结果表明:303.0 K时杨梅单宁的CMC值为1 067.9 mg/L,且该值受溶液温度、无机离子种类与用量的影响;CMC值随温度升高呈现先减小后升高的趋势,313.0 K时降低为1062.0 mg/L;Na+和Ca2+的加入使CMC值降低,且由于Ca2+比Na+所带电荷量更大,造成CMC值更低;303.0 K时加入相同用量(10 mmol/L)的Na+和Ca2+,使杨梅单宁溶液的CMC值分别降低为897.5 mg/L和891.4 mg/L。

Determination of Critical Micelle Concentration of Bayberry Tannin via pH Method and Its Influence Factors

Critical micelle concentration （CMC） was a vital physical character of bayberry tannin （BT）.In this paper, CMC of BT was determined by pH method .The jump of H ＋concentration before and after the formation of BT micelle was investigated to obtain the CMC by plotting a graph of pH against CBT.Furthermore, influence factors of CMC were also investigated.The result showed that CMC of BT was 1067.9mg/L at the temperature of 303.0K, and the CMC was influenced by solution temperature , kind and usage of inorganic ions.Along with the rise of solution temperature , CMC decreased first and then increased .A minimum value of 1062.0mg/L was determined at 313.0K.Meanwhile, CMC also decreased after additions of Na ＋and Ca2＋into BT solution, respectively.And the CMC was 891.4 mg/L after adding Ca2＋which was lower than that of Na ＋for the higher charge of Ca2＋.The CMC of BT was 897.5 mg/L and 891.4 mg/L respectively after adding Na ＋and Ca2＋with the same amount.（10 mmol/L, the temperature of 303.0K）.