共存有机酸对MA-DTPA/PVDF螯合膜吸附Ni(Ⅱ)的影响

Influences of coexistent organic acids on Ni(Ⅱ) adsorption onto MA-DTPA/PVDF chelating membrane

采用物理共混/相转移技术,制备了三聚氰胺-二乙烯三五乙酸/聚偏氟乙烯(MA-DTPA/PVDF)螯合膜,开展了其吸附Ni(Ⅱ)的研究,评价了乳酸、柠檬酸、丁二酸对螯合膜吸附性能的影响。实验结果表明,共存有机酸的影响顺序为乳酸<丁二酸<柠檬酸,共存有机酸没有改变螯合膜吸附本质。吸附动力学过程符合准二级动力学模型,等温吸附过程符合Langmiur方程,D-R拟合结果表明吸附过程为离子交换反应。热力学参数0<0、0<0、0>0,表明该吸附为自发的放热过程。

With the combined techniques of solution blending and phase inversion,the melamine-diethylenetriaminepentaacetic acid/polyvinylidene fluoride（MA-DTPA/PVDF） chelating membrane is prepared for the adsorption of Ni（Ⅱ）.The effects of lactic acid,succinic acid and citric acid on the Ni（Ⅱ） uptake of the membrane are investigated.The results indicate that the coexistent organic acids interfere with the Ni（Ⅱ） adsorption in the order of lactic acid succinic acid citric acid.However,the adsorption nature of the membrane does not change due to the presence of the organic acids.The batch adsorption results show that the adsorption kinetics fit well to Lagergren second-order equation and the isotherms can be well described by Langmuir model.D-R plots indicate the ion exchange mechanism of the adsorption process.The thermodynamic parameters,,,demonstrate the spontaneous and exothermic nature of adsorption.