纳米氢氧化镁改性PVDF超滤膜的制备与表征

通过相转化法制备了纳米PVDF/Mg(OH)_2共混超滤膜,研究了负载Mg(OH)_2对PVDF膜结构和性能的影响。以牛血清蛋白(BSA)为模拟污染物进行超滤试验,测试膜的纯水通量和截留率;测定膜表面和水之间的接触角,进而定量分析比较膜表面的亲水性;利用微机电子控制万能试验机测试膜的机械性能;通过扫描电镜(SEM)、原子力显微镜(AFM)、X射线衍射仪(XRD)等方法表征膜表面特征。结果表明,添加纳米Mg(OH)_2的改性膜保持了原有膜的晶型结构,证明纳米Mg(OH)_2与PVDF材料有很好的相容效果。当纳米Mg(OH)_2添加量为0.8%(质量分数)时,改性效果达到最优。此时,接触角从73.1°降至59.6°,纯水通量为333.37 L/(m~2·h),较未改性前提高了126.3%,膜的拉伸最大力为6.8 N,断裂伸长率为16.2%,较未改性膜的机械性能有明显提高,膜的抗污染性也显著提高。

Preparation and characterization of nanomagnesium modified hydroxide PVDF ultra-filtered membrane

The paper is intended to introduce its method for preparing uhrafiltration membrane by blending PVDF with the magnesium hydroxide nano-particles (Mg (OH)2) and analyze the characteristic features of the modified membrane in hoping to improve the performance of the said membrane with the special attention paid to its strong hydrophobicity and likely exposure to being polluted,.For the aforementioned purpose,we have,first of all,added Mg(OH) 2 (dissolved in N,N-dimenthylacetamide solvent) to the PVDF resin (with polyvinyl p yrrolidone additive) in different ratios (0,0.2％,0.4％,0.8％,1％ and 2％,m/m) to form the uniform and transparent cast solution via magnetic stirring in the water basin and,24 hours' quiescence.And,at last,we have analyzed the effect of the loaded nano-magnesium hydroxide on the structure and performance of the membrane by using Bovine serum albumin (BSA) as the typical pollutants for examining the water flux and rejection percentage.As a result,the contact angle of the hybrid membranes has been found by measuring the hydrophobicity changes,whereas the mechanical properties can be identified and determined by the microcomputer-controlled universal electronic material testing machine via the strength variation.What is more,we have also made it clear that the structure,the surface roughness and the surface morphology can all be characterized by the X-ray diffractomer (XRD),the atomic force microscope (AFM) and the scanning electronic microscopy (SEM),correspondingly.And,finally,the experimental results we have gained prove that the optimistic performance of the PVDF/Mg(OH)2 and the hybrid membrane stand at the mass fraction of 0.8％.As compared with the pure PVDF membrane,the contact angle of the PVDF/Mg(OH)2-0.8％ membrane proves to get decreased from 73.1 ° to 59.6° with its pure water flux being only 333.37 L/(m2 · h) at an increasing rate of 126.3％.The crystal morphology of the modified membrane remains constant and all the exhibitive finger holes and spongy pores tend to demonstrate that the nanometer magnesium hydroxide and PVDF enjoy nice compatibility,with their mechanical properties being significantly heightened and their impact resistance and extensibility being greatly ameliorated.What is more,the stain resistance of the modified membrane has also been obviously enhanced.