污水治理中PVDF改性膜的应用研究

利用氢氧化钾(KOH)/甲醇(CH₃OH)、KOH/高锰酸钾(KMnO₄)、KOH/KMnO₄/四丁基溴化铵(TBAB)对聚偏氟乙烯(PVDF)膜的疏水性进行化学改性,并将PVDF改性膜应用在污水处理过程中,对其处理能力和抗污染能力进行分析。     

MOF-199@GO改性PVDF荷电纳滤膜的制备及其性能

采用原位生长法制备了MOF-199@氧化石墨烯（GO）纳米复合材料,并对聚偏氟乙烯（PVDF）支撑膜进行表面改性,以克服PVDF膜表面疏水性。通过界面聚合反应,制备了基于MOF-199@GO改性PVDF的聚酰胺复合荷电纳滤膜。采用XRD、SEM、TEM、AFM和zeta电位等手段表征了MOF-199@GO复合材料及MOF-199@GO改性PVDF聚酰胺复合纳滤膜的结构及微观形貌,并测试了MOF-199@GO改性PVDF聚酰胺复合纳滤膜的脱盐性能。结果表明：通过MOF-199@GO复合材料对PVDF支撑膜的表面改性,有效克服了PVDF支撑膜的疏水性,实现了表面聚酰胺薄层的均匀连续生长,荷电纳滤膜表面荷负电性能显著增强,其中经MOF-199@GO充分改性的复合荷电纳滤膜表现出优异的脱盐性能,对MgSO₄、Na₂SO₄、NaCl和MgCl₂四种盐的截留率分别达到了93.56%、93.04%、87.48%和87.11%。     

纳滤膜物化特征对膜分离及膜污染影响研究

针对纳滤膜孔径、孔隙率、粗糙度、表面电荷、亲疏水性等自身物化特征对膜分离特征及膜污染的影响作了综述,同时阐述了纳滤过程中,操作条件、溶液物化特征、膜污染等因素对膜物化特征的影响,对提高纳滤膜性能,进行合理的膜改性,减轻膜污染具有重要意义.     

亲水改性PVDF膜材料及其膜生物反应器应用

膜生物反应器（MBR）技术中最常用的膜材料是聚偏氟乙烯（PVDF）,然而由于PVDF膜的疏水性,使其在用于MBR的运行过程中存在易污染、通量低等缺陷,因此对PVDF膜材料进行亲水改性是近年来国内外研究的热点。本文首先介绍了PVDF膜材料典型的表面涂覆改性和表面化学接枝改性这两种亲水改性方法,然后概述了随着纳米科学技术的兴起,采用无机纳米材料如碳材料氧化石墨烯（GO）、无机抑菌材料纳米银粒子及二氧化钛纳米颗粒等进行功能化复合制备PVDF膜材料等亲水改性方法。研究进展表明,新型亲水改性PVDF膜材料不仅在MBR污/废水处理中优势明显,而且在可再生生物能源生产等可持续发展领域极具潜力。     

酸化高锰酸钾溶液处理的氯丁橡胶表面的粘合性能研究

采用硫酸酸化高锰酸钾(KMnO₄)溶液(H⁺/KMnO₄溶液)对氯丁橡胶(CR)(硫化胶)进行表面改性处理,研究KMnO₄质量分数、pH值和温度对CR表面的性质、化学组成、粗糙度以及CR表面与阻燃涂层的粘合性能的影响。结果表明：H⁺/KMnO₄溶液处理的CR表面粗糙且生成大量含氧基团,CR表面与阻燃涂层的粘合性能提高;H⁺/KMnO₄溶液对CR表面处理的最佳条件为KMnO₄质量分数5%,pH值1.44,温度60℃。     

Influences of Sealing Process upon Corrosion Resistance of Anodic Oxidation Film on AI Alloy

在得出铝合金硼酸-硫酸阳极氧化膜、硝酸铈-高锰酸钾封闭工艺配方的基础上,微小变动封闭液中高锰酸钾的含量,通过封闭前后试样的质量变化、点滴试验、无硝酸预浸的磷-铬酸质量损失试验评定出高锰酸钾的最佳含量.分析了氧化膜封闭前后的表面形貌、探讨了氧化膜封闭后的耐腐蚀性能.结果表明,氧化膜经过稀土封闭后表面生成一层均匀、致密的钝化膜,使试样的耐腐蚀性能得到了提高.     

丝瓜络纤维对PVDF超滤膜结构和性能的影响

以天然高聚物丝瓜络纤维作为亲水化改性剂,制备了不同丝瓜络纤维含量的亲水化超滤膜,对比分析PVDF基膜和改性膜过滤腐殖酸和海藻酸钠2种典型污染物配制的模拟废水时通量变化规律;考察了不同丝瓜络纤维含量对改性膜孔隙率、亲疏水性、纯水通量、截留率和抗污染性能的影响,利用扫描电镜(SEM)观察了膜微形貌结构。结果表明,丝瓜络纤维的质量分数为1.2%时,滤膜亲水性改善,PVDF质量分数分别为14%和16%的纯水通量较基膜分别提高3倍和3.5倍,截留率均保持93%以上,膜物理清洗后通量恢复率最高达94.2%。过滤模拟废水时,改性膜比通量衰减幅度较小,膜稳态通量高,抗污染性能好。     

高锰酸钾预氧化对混凝-超滤去除天然水体中腐殖酸的影响研究

采用高锰酸钾预氧化-混凝-超滤组合工艺去除天然水体中的腐殖酸,考察了水中腐殖酸的质量浓度分别为2.4、4.3、7.6 mg/L时,高锰酸钾投加量对各工艺出水水质和超滤膜污染的影响。结果表明,高锰酸钾预氧化可以有效提高组合工艺的出水水质。其中,预氧化、混凝和超滤过程分别对天然有机物、腐殖酸和大分子物质具有良好的去除效果。另外,控制高锰酸钾投加量在0.2~1 mg/L可显著减缓膜污染。即使当进水中腐殖酸的质量浓度达到7.6mg/L的条件下,膜比通量在1 h内始终维持在0.95~0.97。     

PVDF膜的亲水改性及其抗污染性能的研究新进展

PVDF膜由于其较强的疏水性能,在水处理应用中需要较强的驱动力,使得运行费用增加;同时膜的疏水性也会导致膜污染、膜堵塞,从而造成膜水通量的降低。因此,针对此问题,提出了PVDF膜的改性,通过对PVDF膜进行改性来提高它的亲水性能从而改善膜的性能。介绍了近年来PVDF膜亲水改性的研究新进展,PVDF膜的改性主要有表面改性和共混改性,表面改性主要有表面接枝与表面涂覆,共混改性主要的共混物质有亲水聚合物、无机纳米粒子以及碳基纳米材料等。研究发现,通过改性后的PVDF膜亲水性能、抗污染性能以及膜的机械性能都有所提高。这为解决PVDF膜的污染问题提供了一种实际可行的方法,并通过提高其亲水性而降低了运行成本。     

MOFs对PVDF膜亲水改性的研究进展

由于聚偏氟乙烯(PVDF)具有优异的力学性能和化学性能所以经常用作水处理膜材料,但PVDF膜表面能低,本身疏水性较强,从而导致膜易被污染、堵塞使得膜水通量降低。因此,对PVDF膜亲水改性尤为重要。综述了不同系列的亲水性金属有机骨架(MOFs)复合材料对PVDF膜亲水改性的最新研究进展。     

Effects of pre-oxidant (KMnO4) on structure and performance of PVDF and PES membranes

The structure and performance of membrane materials are very important to the efficient and stable operation in membrane drinking water purification technology. Potassium permanganate (KMnO₄), which can change the characteristics of organic matters and control membrane surface fouling, has been widely used as pre-oxidant in the front of membrane drinking water process. This study investigates the evolution of membrane surface structure and performance when polyvinylidene fluoride (PVDF) and polyethersulfone (PES) were exposed to 10, 100 and 1000 mg·L^-1 KMnO₄ solution for 6 and 12 d, respectively. The aged membrane physicochemical characteristics such as membrane surface morphology, chemical composition, hydrophilicity, porosity and zeta potential were evaluated by modern analytical and testing instruments. The anti-fouling property of membrane surface was also investigated by the filtration-backwash experiment. The results indicated that the different concentrations and exposure time of KMnO₄ led to a different variation on PVDF and PES membrane surface structure and performance, which could further affect the membrane separation performance and the membrane fouling behaviors. The membrane surface pore size and porosity increased due to the dislodgment and degradation of membrane additive (PVP), which improved membrane permeability and enhanced the adsorption and deposition of pollutants in the membrane pores. With the increase of exposure time, the membrane surface pore size and porosity reduced for the reactions of chain scission and crosslinking on membrane materials, and the backwashing efficiency declined, leading to a more serious irreversible fouling. Compared with PVDF membranes, the formation of sulfonic group for PES membranes increased the negative charge on membrane surface due to the oxidation of KMnO₄. The present study provides some new insights for the regulation of the pre-oxidant dose and the selection of the membrane materials in KMnO₄ pre-oxidation combined with membrane filtration system.     

Preparation and properties of MOF-199@GO modified PVDF charged composite nanofiltration membrane

As novel functional materials, metal-organic framework (MOF) and graphene oxide (GO) have received great attentions in recent years. In this work, MOF@GO nanocomposite (MOF-199@GO) is prepared by an in-situ growth method. A novel and highly efficient nanofiltration (NF) membrane can be facilely fabricated via surface decoration of MOF-199@GO onto poly(vinylidene fluoride) (PVDF) substrate before interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) in order to overcome the hydrophobicity of PVDF membrane. The structure and morphology of MOF-199@GO and MOF-199@GO modified PVDF polyamide composite membrane are characterized by XRD, SEM, TEM, AFM and zeta potential. MOF-199@GO modified PVDF composite NF membrane which possesses dense and uniform polyamide thin-layer exhibits higher negative surface potential (up to ~37 mV) at pH 9.5. The performance of MOF-199@GO modified PVDF polyamide composite NF membrane has been investigated by determination of pure water flux and salt rejection. The prepared NF membrane MG3 exhibited highly efficient rejection of MgSO₄, Na₂SO₄, NaCl and MgCl₂, which are 93.56%, 93.04%, 87.48% and 87.11%, respectively. This work provides a worthy reference for designing highly efficient NF membranes modified by MOF and relevant materials.     

Improving the charged and antifouling properties of PVDF ultrafiltration membranes by blending with polymerized ionic liquid copolymer P(MMA‐b‐MEBIm‐Br)

This study describes the fabrication and properties of poly(vinylidene fluoride) (PVDF) filtration membranes modified by blending with ionic liquid block copolymer P(MMA‐b‐MEBIm‐Br), which is synthesized via reversible addition‐fragmentation chain transfer polymerization method. The attenuated total reflectance‐Fourier transform infrared spectroscopy and X‐ray photoelectron analyses reveal that the ionic liquid block copolymers are immobilized on PVDF membrane surface. The modified PVDF membrane exhibits excellent charged and antifouling properties because of the charged and hydrophilic properties of the copolymer. Scanning electron microscopy and atomic force microscopy also indicate the morphological characteristics of the membrane and demonstrate that the surface porous structure becomes denser after adding the copolymer. The data of filtration and the zeta potential of the membranes suggest that the charged properties of the ionic liquid block copolymers are mainly responsible for the improvement of the reversible fouling ratio and the decrease in the total fouling ratio of the membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44751.     

膜材料对膜曝气生物膜反应器性能影响的比较

选择聚偏氟乙烯(PVDF)和聚丙烯(PP)中空纤维曝气膜作为膜曝气生物膜反应器(MABR)的膜组件材料,比较两种膜材料由于亲疏水性能、表面形态、生物相容性等性质的差别,对MABR挂膜启动速度、生物附着量、脱氮除碳及膜污染等性能的影响。研究显示,运行末期PVDF和PP膜纤维生物附着量分别为35.62 g·m^-2和30.63 g·m^-2。通过场发射扫描电子显微镜观察两种膜表面生物污染情况,PVDF膜纤维表面呈鱼鳞状结构,有效保护了膜孔不被微生物完全堵塞。在90 d的运行周期内以PVDF为曝气膜材料的MABR获得了90%以上的COD去除率和78%的TN去除率;而以PP为曝气膜的MABR由于运行后期曝气膜纤维污染严重仅得到了76.5%的COD去除率和49.1%的TN去除率。因此,PVDF曝气纤维更适于作膜曝气生物膜反应器的曝气膜。     

Poly(vinylidene fluoride)‐Based Membranes for Microalgae Filtration

Two poly(vinylidene fluoride) (PVDF) membrane modification approaches, i.e., poly(vinylpyrrolidone) (PVP) modification and sulfonation, were applied and investigated to produce a fouling‐resistant membrane for microalgae filtration. Both methods were able to alter the membrane surface to become more hydrophilic. However, clean water permeance increased only for the PVP‐modified membranes, while the sulfonated membranes underwent a significant morphology transformation to a denser membrane and thus lower permeance. Microalgae filtration with PVP‐modified membranes showed less fouling compared to the pristine one, particularly in the beginning of the filtration, indicating that fouling reduction on these membranes mainly occurs in the initial fouling stage. Fouling is also found to be influenced by the microalgae species, possibly due to the different properties of the formed cake layer.     

Ag3PO4改性PVDF超滤膜的结构与性能

将不同量Ag₃PO₄均匀地分散在聚偏氟乙烯(PVDF)铸膜液中, 利用相转化法制备了改性PVDF膜, 通过扫描电镜(SEM)、接触角测定、过滤实验和污染性测试等研究了其微结构、分离性和耐污染性等, 并考察了膜污染后的清洗效果。结果表明, 添加Ag₃PO₄ 的PVDF膜具有不同的微结构与性能, 当添加1% 的Ag₃PO₄时, 膜皮层变薄、微孔数增多, 并呈现出最优化的水通量、亲水性、力学性、抗污染能力和截留率等。采用太阳光-水清洗能使改性膜的通量恢复率达到85%以上。     

自组装法制备PVDF-SiO2/PVSQ超疏水复合膜及膜蒸馏抗污染性能

采用乙烯基三甲氧基硅烷(VTMOS)对SiO₂疏水改性,通过自组装法,将改性SiO₂接枝在商业PVDF(聚偏氟乙烯)膜表面,使其表面达到超疏水。利用场发射电子显微镜、红外光谱仪、接触角测量仪及毛细流孔径分析仪等仪器对改性前后膜的表面形貌、化学组成、接触角及孔径变化等性能参数进行表征。结果表明,VTMOS不仅对SiO₂疏水改性,还通过自身的水解缩聚反应,生成了规整圆球状的聚乙烯基倍半硅氧烷(PVSQ)微粒,纳米级SiO₂分布于微米级PVSQ表面,在改性膜表面构造了多层次微/纳米粗糙表面,在低表面能疏水基团乙烯基和甲氧基的共同作用下,成功实现了超疏水改性,改性膜水接触角达到159.5°,滚动角降至8.1°。以NaCl、HA和CaCl₂混合溶液为进料液,对商业PVDF膜和改性膜进行了长期直接接触式膜蒸馏(DCMD)实验,探究其抗污染性能。结果表明,改性膜适用于长期DCMD实验,并表现出比商业PVDF膜更稳定的通量,截盐率始终大于99.99%,具有良好的稳定性和抗污染性能。     

聚偏氟乙烯-聚酰胺管式复合膜的分离性能研究

以聚偏氟乙烯(PVDF)管式超滤膜为基膜,无水哌嗪(PIP)为水相单体,均苯三甲基酰氯(TMC)为有机相单体,采用界面聚合法制备了不同截留性能的PVDF/聚酰胺(PA)管式复合膜.研究了不同性能管式复合膜的截留分子量、膜表面荷电性测试、对无机盐的截留性能,以及染料废水脱盐的应用.实验结果表明,截留率R(MgSO4)由9...