聚砜/卟啉功能膜对镉离子的动态富集与检测

Dynamic Preconcentration and Detection of Polysulfone/Porphyrin Functional Membrane for Cadmium Ion

针对水体镉离子(Cd^(2+))的检测需求,将卟啉与膜技术结合制备传感膜,并研究其对Cd^(2+)的动态富集与检测性能。将聚砜(PSF)基膜表面接枝聚对苯乙烯磺酸钠(PNaSS)分子刷,通过静电作用负载光学指示剂5,10,15,20-四(1-甲基-4吡啶基)卟啉(TMPyP),获得聚砜/卟啉功能膜。在动态条件下,由于TMPyP与Cd^(2+)的可逆配位作用,功能膜表现出对水中Cd^(2+)的富集作用,并通过光谱和表观颜色的变化,实现检测功能,同时具有很好的再生能力。研究表明,Cd^(2+)初始溶液浓度越小,流速越小,功能膜吸附检测速率越缓慢;通过控制TMPyP负载量等条件,可实现对超痕量Cd^(2+)的富集与检测;与静态吸附检测过程相比,动态条件更有利于Cd^(2+)的扩散及在膜表面的富集,使功能膜显示出更快的检测速度。

In this paper, the preparation of sensor membrane and preconcentration and detection of cadmium ions （Cd2＋） was implemented by combining porphyrin and membrane technology. The polysulfone/porphyrin functional membrane was prepared by loading 5,10,15,20-tetrakis（4-N-methylpyridyl） porphyrin p-toluenesulfonate （TMPyP） on the surface of polysulfone （PSF） membrane which was modified with poly（sodium p-styrenesulfonate） （PNaSS） brushes. Under the dynamic condition, the functional membrane shows good preconcentration property for Cd2 ＋ due to the coordination interaction between TMPyP and Cd2 ＋ . The spectral and the apparent color changes enable the detection function of the membrane and the reversible coordination endows the membrane with good regeneration ability. Lower initial concentration of Cd2 ＋ solution and lower flow rate lead to lower absorption and detection rate of the functional membrane. The preconcentration and detection for ultratrace Cd2 ＋ can be achieved by controlling the capacity of TMPyP. Compared with the static adsorption, the function membrane shows faster detection for Cd2＋ under the dynamic condition which favor the diffusion and adsorption of Cd2 ＋ on the membrane surface.