pH值、相比、温度和金属离子对LIX984界面吸附性能的影响

Interfacial Adsorption Properties of LIX984 with Different pH Values,Phase Ratios,Temperatures and Metal Ions

为探究萃取剂LIX984的界面吸附性能,利用滴体积法研究了水相pH值、相比(O/A)、温度以及几种金属离子对LIX984/DT100-H_2O体系界面性质的影响,计算了界面特性吸附参数C_(min)和A_I,C_(min)为萃取剂分子在液-液界面饱和时,有机相中的最低浓度,其值越大,界面活性越小,AI表示萃取剂分子在界面上的表观横截面积,即每个分子在界面上占有的平均面积,其值越大,分子有序性越低。实验表明,在pH=1.5~3.0范围内随着水相pH值升高Cmin减小,pH=3.0时萃取剂分子界面活性最好;pH=2.0时AI最小,萃取剂分子的界面排列最有序。在相比(O/A)1∶5~5∶1范围内,Cmin随相比的增加先增大后减小,AI随相比的增加先降低后升高,即O/A=1∶1时LIX984界面活性最差但在界面上的排列最有序。温度由20℃升高至40℃时,Cmin几乎不变,在20~40℃间对LIX984界面活性影响不大;AI随温度的升高而增大,20℃时萃取剂分子在界面上排列最有序。水相中Fe^(2+),Al^(3+),Mg^(2+)含量为0.5~6.0 g·L^(-1),Ca^(2+)含量为0.1~0.5 g·L^(-1)时,这几种金属离子的引入使Cmin降低而AI增加,其中Ca^(2+)影响最大。

In order to investigate the interfacial adsorption properties of LIX984,the influences of pH values of aqueous phase,phase ratio（ O/A）,temperature and metal ions on the interfacial properties of LIX984/DT100-H2O were studied by drop volume method. The adsorption parameters such as Cminand AIwere calculated. Cminwas the lowest concentration of extractant molecules in the organic phase when the extractant molecules adsorbed at the liquid-liquid interface were saturated. The greater the Cminwas,the smaller the interfacial activity was. AIwas the average area per molecule at the interface. The greater the AIwas,the lower the ordering was. The experimental results showed that Cmindecreased with pH values increasing from 1. 5 to 3. 0. The interfacial activity of extractant was the highest at pH = 3. 0. While AIwas the smallest at pH = 2. 0 and the extractant molecules were arranged most orderly at the interface.Cminvalue increased first and then decreased,while AIdecreased first and then increased in the O/A range of 1∶ 5 5∶ 1. The interface of LIX984 was most inactive,and the extractant molecules arranged most orderly at the interface at O/A of 1∶ 1. Cminwas almost constant with the temperature increasing from 20 to 40 ℃,indicating that the temperature had little effect on interface activity of LIX984.Nevertheless,AIincreased with the increase of temperature,and the extractant moleculars were most ordered at 20 ℃. Cmindecreased and AIincreased when the concentration of Fe2＋,Al3＋,Mg2＋ ranged from 0. 5 to 6. 0 g·L-1 and Ca2＋ from 0. 1 to 0. 5 g·L-1,and Ca2＋ was the most influential.