聚偏氟乙烯共混改性膜对Cu2+吸附性能的研究

应用热诱导聚合和相转移技术,制备了具有离子交换性能的聚偏氟乙烯(PVDF)共混改性膜,采用XPS、XRD、SEM和FTIR表征了PVDF改性膜的结构和组成,分析了PVDF共混改性膜对水溶液中Cu²⁺的吸附性能,研究了PVDF共混改性膜对Cu²⁺的吸附热力学和吸附动力学 .结果表明,动力学吸附过程符合准二级动力学方程,等温吸附过程符合Langmuir模型.吸附过程的平均吸附能为8～16　kJ/mol,表明该吸附过程为离子交换反应.热力学参数ΔG⁰<0、ΔH⁰>0、ΔS0>0,证实了吸附过程为自发的吸热过程.PVDF共混改性膜经吸附/脱附4次循环后,对模拟废水中Cu²⁺和城市污水中Cu²⁺的吸附量分别大于0 .025 mg/cm^２和0 .015 mg/cm^２,脱附率超过95%.PVDF共混改性膜具有优良的吸附/脱附性能、良好的稳定性和潜在的应用前景.

Adsorption Characteristics of Cu2+ onto the Polyvinylidene Fluoride Blending Modified Membrane

Using the combination method of thermally induced polymerization technique and phase inversion blending process, a novel polyvinylidene fluoride (PVDF) blending modified membrane with ion-exchanging property, was prepared. The PVDF modified membrane was characterized by XPS, XRD, SEM and FTIR. The adsorption property, adsorption isotherm and batch sorption kinetics of Cu2+ by the PVDF modified membrane were studied. The results indicate that the adsorption processes for Cu2+ are found to follow the pseudo-second-order kinetics equation. And the isotherm of adsorption of Cu2+ by the modified membrane is good agreement with that of Langmuir isotherm model. The values of the mean free energies of the adsorption process are found to be between 8 and 16 kJ/mol, which shows that the adsorption mechanism of the PVDF modified membrane is an ion-exchange process. The value of deltaH0 is > 0, deltaG0 is < 0, and deltaS0 is > 0, which shows that the adsorption of the PVDF modified membrane is a spontaneous and endothermic process. The experimental data also show that the PVDF modified membrane possesses an excellent adsorption/desorption property. The adsorption capacity of Cu2+ onto the modified membrane in the synthesized Cu2+ solution and the sewage water is more than 0.025 mg/cm2 and 0.015 mg/cm2, respectively, and its desorption efficiency is still beyond to 95%, after four adsorption/desorption processes. It can be found that the PVDF modified membrane can be reused almost without any significant loss in the adsorption performance. PVDF modified membrane can be used for the recovery of metal traces and polishing of treated effluents containing heavy metals.