纳米TiO2复配添加剂对PVDF中空纤维膜结构和性能的影响

该文将纳米二氧化钛（TiO2）粒子与高分子致孔剂、非溶剂、表面活性剂和无机盐4类制膜添加剂复配处理,采用浸没沉淀相转化法制备聚偏氟乙烯（PVDF）-TiO2复合中空纤维膜。通过扫描电子显微镜、X射线衍射、能谱、拉伸试验、接触角测定和截留试验分别对复合膜的微观孔结构、晶相结构、Ti元素分布、机械性能、亲水性、过滤性能和抗污染性能进行了表征,讨论了纳米TiO2粒子对PVDF膜结构和性能的影响。结果表明通过改变复配添加剂中TiO2粒子的含量,可以有效调控复合膜的结构和性能。当复配添加剂中w（TiO2）为2％（占PVDF固含量的质量分数埘％）时,纯水通量由216L／m^2·h提高至402L／m^2·h,牛血清蛋白截留率由95％降低至90％,复合膜整体性能较为优异。     

γ-Al2O3/TiO2混合纳米粒子改性PVDF超滤膜

为提高聚偏氟乙烯（PVDF）膜的亲水性和强度,将纳米二氧化钛（TiO2）溶胶和纳米氧化铝（γ-Al2O3）按不同比例与聚偏氟乙烯共混,采用相转化法制得共混超滤膜。考察了不同比例的混合纳米粒子对PVDF超滤膜的纯水通量、截留率、力学性能等的影响。并利用扫描电子显微镜（SEM）观察了膜的表面和内部微观结构,红外光谱分析（FTIR）和X射线衍射仪（XRD）考察纳米粒子在PVDF基体中的存在状态,通过对复合膜进行拉力测试研究混合纳米粒子对膜力学性能的影响,并使用接触角测量仪测定膜表面和水之间的接触角来定量分析比较膜表面的亲水性。结果表明,γ-Al2O3/TiO2混合比为1∶2时,膜的性能达到最优,孔隙率为74%,水通量为120 L/（m2.h）,截留率为93%,拉力最大负荷为35 N,拉伸应变为22%。     

TiO_2溶胶改性PVDF超滤膜的制备与性能研究

利用溶胶-凝胶法制备二氧化钛(TiO2)溶胶并添加到铸膜液中,应用非溶剂致相法制备聚偏氟乙烯(PVDF)成品膜。系统研究了溶胶态TiO2、无机态Ti O2以及无机态TiO2/分散剂体系对TiO2/PVDF杂化膜的表面形貌、热稳定性、纯水接触角的影响。结果表明,溶胶态TiO2在铸膜液中分散良好,制取所得成品膜具有优良的综合性能,溶胶态TiO2的加入使得膜的接触角明显降低,孔隙率和平均孔径增大。     

混合添加剂对TiO2/PVDF平板超滤膜性能和结构的影响

研究了不同比例的混合添加剂PEG600-LiCl、丙酮-LiCl、丙三醇-LiCl和PVP-LiCl对TiO2/PVDF平板超滤膜性能和结构的影响,并利用扫描电子显微镜( SEM)和接触角测量仪表征了复合膜的结构.结果表明,PEG600-LiCl、丙酮-LiCl、丙三醇-LiCl和PVP-LiCl 4种混合添加剂均可以改善膜性能,其中PEG600-LiCl、丙三醇-LiCl、PVP-LiCl3种混合添加剂加到铸膜液中,明显改善了PVDF膜表面的亲水性,可以将膜表面接触角降低至55°.当PVP与LiCl的质量比为1∶2时,膜的性能达到最优,孔隙率为82.5％,平均孔径为0.1 μm,水通量为100.5 L·m-2·h-1,截留率为95.4％.     

APTES-SiO2-TiO2/PVDF膜的制备及在有机废水处理中的应用

实验利用浸没沉淀相转化技术成功制备出用于处理有机废水的APTES-SiO2-TiO2/PVDF复合膜.测试结果表明,当APTES-SiO2/TiO2添加量10％时,制备的复合膜孔隙率相较于纯PVDF膜有明显提高,纯水通量达69.81L/m2·h,对有机废水的截留率由纯PVDF膜的27.32％提升至89.32％.制备出的...     

PVDF/PEI-EDA亲疏水复合膜的制备及其抗污染性能

为解决疏水性污染物对膜的污染问题,利用静电纺丝的方法制备了具有抗污染性能的聚偏氟乙烯/聚醚酰亚胺-乙二胺(PVDF/PEI-EDA)亲疏水复合膜,对其进行了表征;以含疏水性污染物(油污)的Na Cl水溶液作为进料溶液进行了直接接触式膜蒸馏脱盐和抗污染实验,并与商业的PVDF疏水膜进行了对比。结果表明,复合膜厚度为340μm,平均孔径0.677μm,孔隙率72.4%;膜表面呈纳米纤维状,具有明显的酰胺基团,膜表面在空气中水接触角为5.6°,在水相中的油接触角为143°。复合膜蒸馏运行稳定,脱盐、抗污染膜蒸馏平均通量分别为5.5、4 kg/(m~2·h),可以有效的防止疏水性污染物(油污)的污染。而商业的PVDF疏水膜膜蒸馏过程不能维持稳定运行。     

无纺布支撑PVDF纳米纤维疏水膜的制备及其性能研究

以N,N-二甲基甲酰胺和丙酮为混合溶剂,采用静电纺丝法制备了基于不同无纺布支撑的聚偏氟乙烯(PVDF)纳米纤维疏水膜,考察了不同无纺布支撑材料对膜结构与膜性能的影响;利用扫描电子显微镜、接触角测量及膜蒸馏脱盐实验等对纳米纤维膜的结构及性能进行了表征。结果表明,以不同无纺布为支撑材料的电纺纳米纤维膜具有良好的疏水性,接触角最高可高达149.5°;复合膜整体孔隙率最高为79.8%,纳米纤维分离功能层的孔隙率最高可达92.6%;纳米纤维膜平均孔径随着静电纺丝时间的延长而降低,膜平均孔径在1.25~2.02μm,尽管膜孔径分布情况各不相同,但复合膜的盐截留率均能达到99.99%以上。以质量浓度35 g/L的NaCl溶液为进料液进行直接接触式膜蒸馏脱盐实验,在疏水膜两侧温差为60℃条件下膜通量最高可达48.84 kg/(m~2·h)。     

高性能PVDF/SiO_2@HPA复合膜在全钒液流电池中的应用

以聚偏氟乙烯(PVDF)多孔膜为基质,采用原位凝胶溶胶合成二氧化硅负载磷钨酸(Si O2@HPA)纳米粒子的方法对多孔膜进行修饰。分别用扫描电子显微镜、电化学工作站、充放电测试仪等仪器对膜的结构、电化学性能进行表征。结果表明:与空白的PVDF相比,经过纳米粒子修饰的复合膜的钒离子选择性得到明显提高。在不同的电流密度下,修饰后的复合膜的充放电效率都高于未修饰PVDF多孔膜,并且在40m A·cm-2的电流密度下,复合膜的能量效率提高了17.6%。在80 m A·cm-2的电流密度下,用PVDF/Si O2@HPA组装的电池在100圈的循环测试中保持较好的稳定性。     

纳米改性膜生物反应器处理生活污水的试验研究

对聚偏氟乙烯(PVDF)微滤膜进行共混改性,制备了3组不同纳米TiO2质量分数的膜组件。通过对膜的微观结构、接触角、孔隙率、平均孔径和水通量等参数进行表征,及放置膜生物反应器内处理生活污水的小试试验研究,对比了3组的出水水质、膜通量和通量恢复率。结果表明:3个膜组件的出水水质均能达到《城市污水再生利用城市杂用水水质标准》(GB/T 18920—2002)的要求,纳米TiO2改善了PVDF中空纤维膜的亲水性,提高了其抗污染能力,有利于延迟膜的清洗周期。     

PVDF／多巴胺改性二氧化钛复合膜光阻隔性研究

制备了表面包覆聚多巴胺层的二氧化钛(TiO2@PDA)复合粒子,并采用溶液刮涂法制备了聚偏氟乙烯(PVDF)／TiO2和PVDF／TiO2@PDA复合膜。利用傅立叶变换红外光谱仪、X射线光电子能谱仪、透射电子显微镜表征了复合粒子的结构,利用紫外–可见光分光光度计、对比率仪表征了复合膜的紫外–可见光阻隔性。结果表明, PVDF／TiO2复合膜对紫外光具有优异的阻隔性,但对可见光的阻隔性(即不透明度)随TiO2含量增加而先增加后不变,PVDF／TiO2@PDA复合膜的不透明度则随TiO2@PDA含量的增加而单调增大。当薄膜厚度为20μm,TiO2体积分数为10％时,PVDF／TiO2复合膜对比率(CR)值为92.8％,小于完全不透明临界值98％,而PVDF／TiO2@PDA (多巴胺处理20 min)复合膜CR值为98.39％。一定TiO2浓度下,随着多巴胺处理TiO2时间的增大,复合膜达到完全不透明所需的薄膜厚度逐渐减小。     

膜蒸馏用PVDF抗复合污染膜的制备与测试

为提高膜的抗污染能力,对聚偏氟乙烯（PVDF）平板膜进行表面涂覆改性,得到超疏水PVDF平板膜,再将超疏水PVDF平板膜进行表面亲水化改性,制备出超疏水/亲水复合PVDF膜。当PVDF的质量浓度为2%、聚乙二醇（PG）的质量浓度为39%、涂敷液温度为50℃、蒸发时间为10 s、凝固浴温度为60℃时,超疏水PVDF平板膜接触角达到154.8°。表面亲水改性制得的PVDF超疏水/亲水复合膜的接触角为41°。然后研究了超疏水PVDF平板膜和PVDF超疏水/亲水复合膜的抗膜污染性能。结果显示,超疏水PVDF平板膜具有优良的抗无机污染性能和一定的抗有机污染性能;PVDF超疏水/亲水复合膜不仅具有优良的抗无机污染性能,而且其抗复合污染性能尤其是抗有机污染性能得到明显提升,为进一步构建高性能膜蒸馏抗污染膜提出了一个可行的技术方向。     

Dye removal using hydrophobic polyvinylidene fluoride hollow fibre composite membrane by vacuum membrane distillation

Hydrophobic polyvinylidene fluoride (PVDF) hollow fibre composite membranes were prepared by the dilute solution coating process to build a special surface structure that was similar to the dual micro‐nano structure on the lotus leaf. Poly(vinylidene fluoride‐co‐hexafluoropropene) was chosen as the hydrophobic polymer candidate in dilute solution. Membrane morphology and surface hydrophobicity were evaluated by scanning electron microscopy and dynamic water contact angle measurement. The prepared PVDF hollow fibre membranes were employed to separate dyes (Congo Red and Methylene Blue) from water by vacuum membrane distillation. The effects of operational conditions (feed temperature, vacuum pressure and feed flow rate) on the vacuum membrane distillation performance of different PVDF membranes were investigated. The results indicated that the water contact angle values of PVDF composite membrane surfaces improved from 93.6° to 130.8°, which was mainly attributed to the formation of micro‐nano rods. This structure was similar to the dual micro‐nano structure on the lotus leaf. Under test feed temperature, vacuum pressure and feed flow rate conditions, the dye rejection rate of Congo Red and Methylene Blue by the hydrophobic PVDF hollow fibre membrane remained above 99.5% and 99%, which was higher than that of the pristine PVDF membrane (99% and 98%, respectively). In addition, the hydrophobic PVDF hollow fibre composite membrane showed higher permeation flux under different conditions compared with the pristine PVDF membrane, which was attributed to membrane surface hydrophobicity and the electrostatic interactions between dyes and the PVDF membrane surface.     

Preparation of superhydrophobic nanocomposite fiber membranes by electrospinning poly(vinylidene fluoride)/silane coupling agent modified SiO2 nanoparticles

Superhydrophobic nanocomposite fiber membranes were prepared by blend electrospinning of poly(vinylidene fluoride) (PVDF) mixed with silane coupling agent modified SiO₂ nanoparticles. The nanoparticles were prepared by the sol–gel method, and the average particle diameter was measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The effects of the type of silane coupling agent, such as n‐octyltriethoxysilane, vinyltrimethoxysilane (A‐171), and vinyltriethoxysilane (A‐151), and the mass ratio of the modified silica particles and PVDF on the surface wettability of the composite fiber membrane were investigated. The results indicated that the incorporation of silane coupling agent modified silica particles into the PVDF membrane increased the roughness of the surface and formed micro/nano dual‐scale structure compared to the pristine PVDF membrane, which was responsible for the superhydrophobicity and self‐cleaning property of the nanocomposite fiber membranes. The value of water contact angle (CA) increased with the increase of the content of modified SiO₂ nanoparticles in the nanocomposite membrane, ranging from 149.8° to 160.1° as the mass ratio of modified 170 nm SiO₂ with PVDF matrix increased from 0.5:1 to 5:1, indicating the membrane possesses a superhydrophobic surface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44501.     

PVDF-TiO2复合中空纤维膜的制备与表征

将纳米二氧化钛(TiO₂)粒子与4类制膜添加剂复配处理,采用相转化法制备聚偏氟乙烯(PVDF)-TiO₂复合中空纤维膜,讨论了纳米TiO₂粒子对复合膜结构和性能的影响。通过扫描电子显微镜、X射线衍射、能谱分析、热重分析、拉伸试验、接触角测定和超滤实验分别表征了复合膜的微观孔结构、晶相结构和复合均匀性、热稳定性、机械性能、亲水性、超滤性能以及抗污染性能。结果表明：通过添加TiO₂粒子复配添加剂,复合膜的性能得到有效改善。复配添加剂中w(TiO₂)为2%(占PVDF固含量的质量分数)时,纯水通量由348 L/(m²·h)提高至377 L/(m²·h),牛血清蛋白截留率由68%提高至90%,断裂强度和抗污染性能提高,复合膜综合性能优异。     

Hydrophilic Modification of PVDF Microfiltration Membrane with Poly (Ethylene Glycol) Dimethacrylate through Surface Polymerization

The hydrophilic modification of poly (vinylidene fluoride) (PVDF) membrane with poly (ethylene glycol) dimethacrylate (PEGDMA) through grafting reaction for antifouling was reported. The influence of PEGDMA content, reaction temperature and time, on the structure, morphology, antifouling, and hydrophilicity of PVDF-g-PEGDMA membrane has been investigated. The PEGDMA monomers that were grafted on the surface of PVDF microfiltration membrane were confirmed by Attenuation total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), and morphology study conducted by SEM revealed the changes before and after modification. The protein adsorption, filtration performance, water content, and dynamic contact angle were used to characterize the antifouling and hydrophilicity of the modified PVDF membranes. Compared with the pristine PVDF membrane, the bovine serum albumin (BSA) adsorption on the PVDF-g-PEGDMA membrane decreased about 80%, and the water contact angle of the membrane dropped to 0°. Besides, the experimental results revealed no significant differences between the membrane samples with respect to pore size.     

催化臭氧分离膜制备及去除腐殖酸机理分析

以微污染水为处理对象,考察了新型催化膜的过滤性能及抗污染行为。实验过程中采用溶胶凝胶法制备纳米TiO2粉体,将不同焙烧温度的纳米TiO2颗粒加入铸膜液中,利用相转换法制备催化膜。采用X射线衍射（XRD）及扫描电子显微镜（SEM）对膜进行表征,对膜的纯水通量、孔隙率、接触角、膜的催化性能及分离特性进行了系统地测定。实验结果表明,金红石型TiO2催化膜对腐殖酸（humic acid,HA）及总有机碳（total organic carbon,TOC）的去除效率分别为70%及65%以上,说明金红石型TiO2催化膜具有较高的污染物去除及抗污染特性。实验结果证实新型多功能膜对于水处理的实际应用具有较大的发展潜力。     

混合溶剂对TiO2/PVDF平板超滤膜性能和结构的影响

采用N,N-二甲基乙酰胺(DMAC)和N-甲基吡咯烷酮(NMP)为混合溶剂制备PVDF超滤膜。考察了不同混合比例的DMAC和NMP对膜性能及膜结构的影响,同时利用扫描电子显微镜(SEM)对膜表面及断面结构进行分析,原子力学显微镜(AFM)对膜表面粗糙度进行了分析,利用接触角测量仪对膜表面接触角进行了测量。结果表明,使用混合溶剂对膜孔径和膜亚层结构影响较大,但混合溶剂对膜孔隙率和接触角基本没有影响。当混合溶剂DMAC/NMP为1:2时,膜性能达到最优,孔隙率为70%,平均孔径为0.24μm,水通量为373 L.m-2.h-1,截留率为88%。     

Preparation and properties of PVDF/PVA hollow fiber membranes

On principle of polymer blend phase separation, PVDF/PVA hollow fiber membranes were prepared using phase inversion method. The membrane morphology and performance varied with the blending ratio. The PVDF/PVA blends showed incompatibility by the results of dynamic mechanical analysis (DMA) and infrared attenuated total reflection (FTIR-ATR) sampling technique. Based on bursting pressure and tensile strengths results, we suggest that the mechanical properties of PVDF/PVA blend membranes are worse than that of PVDF membrane. PVA can improve the hydrophilicity of PVDF/PVA hollow fiber membranes, which could be illuminated by the decrease in contact angle, the increase in equilibrium water content (EWC) and the variety in dynamic moisture regain. The pure water flux increases while the rejection ratio decreases with PVA content increasing. Moreover, PVA can improve the anti-fouling property of PVDF/PVA hollow fiber membranes, which could be illuminated by the result of increase coefficient of resistance.     

超疏水聚偏氟乙烯复合微孔膜的制备及性能

提出了一种超疏水聚偏氟乙烯（PVDF）复合微孔膜的制备方法。以相转化法制备的PVDF膜为基膜,通过恒压过滤将多壁碳纳米管（MWCNTs）沉积到PVDF基膜表面,再经聚二甲基硅氧烷（PDMS）溶液修饰,可制得接触角达162°、滚动角约10°的PVDF复合微孔膜。用原子力显微镜和扫描电镜对膜表面进行结构分析,并测试了膜的接触角、气通量和机械强度等性能,考察了MWCNTs及PDMS浓度对膜结构和性能的影响。研究表明,CNTs在具有微米级粗糙度的基膜上强化了纳米结构,提高了膜的粗糙度,PDMS降低了膜的表面能,二者协同作用使复合膜的接触角大幅提高,滚动角显著下降。与高度疏水的PVDF基膜相比,PVDF复合膜的疏水性大幅提高,断裂伸长率加倍,在模拟海水真空膜蒸馏过程中,保持了较高的传质通量和截留率,具有更好的操作稳定性和抗污染性能。