| Polyvinylidene fluoride (PVDF) has been a kind of membrane material with excellent characteristics. However, the application of PVDF membrane is limited in the field of biochemistry, environment, wastewater purification and so on, due to its low surface energy and hydrophobicity. The hydrophobic PVDF membrane is susceptible to the fouling of organic matters and lead to a low water flux. A method of blending modification was mentioned to improve the hydrophilicity of PVDF membrane, and it would endow PVDF membrane with a novel ability of removing heavy metal cations from the wastewater.The concentration of each component in PVDF blending modification cast was optimized by the orthogonality experiment, and the influences of them on the property of PAA/PVDF blending modification membrane were studied. Differential scanning calorimetry (DSC), thermogravimetry (TG), X-ray diffraction measurement (XRD), Fourier transform infrared ray (FTIR), X-ray photoelectron spectroscopy (XPS) and Scanning electron microscopy (SEM) were employed to investigate PAA/PVDF blending modification membrane. The hydrophilicity of PAA/PVDF blending modification membranes was tested and compared with the original one. The adsorption conditions of Cu(II) cation onto the PAA/PVDF blending membrane have been studied. The different variables affecting the sorption capacity of the blending membrane, such as pH of the solution, adsorption time, initial metal ion concentration and the temperature have been investigated. The adsorption/desorption property of the PVDF blending membrane was also studied.The result of the experiment indicated that when the dosage of PVDF, Acrylic acid(AA), Acrylamide(AM), and Benzoyl Peroxide(BPO) were 120g/L, 100ml/L, 10g/L and 6g/L, the prepared blending membrane has a good property. The water take up of the blending membrane is up to 295%, and its strength and adsorption capacity reaches to 102.83g/cm2 and 2.564×10-2mg/cm2, respectively. FTIR and XPS measurements clearly show that the the carboxylic acid functional group was blended to the PVDF membrane successfully. In addition, the results of XRD measurement indicated that the PAA/PVDF membrane has crystal structure, and the XRD pattern of the PAA/PVDF menbrane is dominated by that of the corresponding PVDF structure. It can be seen from TG-DSC characterization, the blending membrane keeps a good thermal stability.The sorption data have been analyzed and fitted well to the linearized adsorption isotherm of the Langmuir isotherms models, and the pseudo-second-order kinetics model represents a better fit to the batch sorption kinetics. The results of D-R isotherms analysis show that the adsorption mechanism is assumed to be an ion exchange between cupric ion and the carboxylic acid functional group of the PAA/PVDF blending membrane. Thermodynamic parametersΔH°,ΔG°andΔS°were also calculated.ΔH°>0,ΔG°<0 andΔS°>0 indicate that the adsorption of Cu(II) cation by the PAA/PVDF blending membrane is a spontaneous and endothermic process. The adsorption/desorption property of the blending membrane is fine too, which indicates that the membrane can be resued. The PAA/PVDF blending membrane would be a good adsorbent material for the heavy metal cations removal, and it should be significant for the removal and recovery of the heavy metal cations from the wastewater.
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