Bacterial attachment to RO membranes surface-modified by concentration-polarization-enhanced graft polymerization

Concentration polarization-enhanced radical graft polymerization, a facile surface modification technique, was examined as an approach to reduce bacterial deposition onto RO membranes and thus contribute to mitigation of biofouling. For this purpose an RO membrane ESPA-1 was surface-grafted with a zwitterionic and negatively and positively charged monomers. The low monomer concentrations and low degrees of grafting employed in modifications moderately reduced flux (by 20-40%) and did not affect salt rejection, yet produced substantial changes in surface chemistry, charge and hydrophilicity. The propensity to bacterial attachment of original and modified membranes was assessed using bacterial deposition tests carried out in a parallel plate flow setup using a fluorescent strain of Pseudomonas fluorescens. Compared to unmodified ESPA-1 the deposition (mass transfer) coefficient was significantly increased for modification with the positively charged monomer. On the other hand, a substantial reduction in bacterial deposition rates was observed for membranes modified with zwitterionic monomer and, still more, with very hydrophilic negatively charged monomers. This trend is well explained by the effects of surface charge (as measured by ζ-potential) and hydrophilicity (contact angle). It also well correlated with force distance measurements by AFM using surrogate spherical probes with a negative surface charge mimicking the bacterial surface. The positively charged surface showed a strong hysteresis with a large adhesion force, which was weaker for unmodified ESPA-1 and still weaker for zwitterionic surface, while negatively charged surface showed a long-range repulsion and negligible hysteresis. These results demonstrate the potential of using the proposed surface- modification approach for varying surface characteristics, charge and hydrophilicity, and thus minimizing bacterial deposition and potentially reducing propensity biofouling.     

壳聚糖基纳米纤维载药体系及其缓释行为

为研制具有缓释效果的抗菌材料,以壳聚糖(CS)、聚乙烯醇(PVA)为原料,采用静电纺丝技术制备CS/PVA 复合纳米纤维膜并负载环丙沙星;探究纺丝体系、纺丝工艺对纤维膜微观形貌、接触角、化学结构的影响,分析药物体外释放行为及载药前后试样的抗菌性。结果表明：PVA 的加入提高了CS 的可纺性;改善了纤维膜的亲水性;当纺丝电压为24 kV、CS 和PVA 质量比为1：1. 5 时,纤维膜成网均匀,形貌良好;载药纳米纤维膜具有相对较低的药物释放速率,可有效避免药物突释,且药物释放速率随纤维膜中环丙沙星质量分数的增大而增大;载药CS/PVA 纳米纤维膜对金黄色葡萄球菌具有优良的抗菌性。     

可吸附铜离子丙纶非织造布的改性制备

利用等离子体对惰性丙纶非织造布进行修饰处理,在织物表面引入羧基和羟基极性反应位点。通过接触角测试和显微镜观察确认了改性织物的亲水性和形貌,然后将自制的羧甲基壳聚糖与乙二胺四乙酸在使用缩合剂N,N-二环已基碳酰亚胺的条件下接枝处理织物。研究了等离子体处理时间、吸附时间对铜离子吸附性能的影响。结果表明,低温等离子处理后,织物的亲水性得到了明显改善,织物的接枝率随等离子体处理时间的延长而增大,铜离子吸附能力与吸附时间呈正相关关系。     

改性聚偏氟乙烯中空纤维分离膜的研制

本实验采用干-湿相转化法制备聚偏氟乙烯（PVDF）中空纤维血液分离膜,通过在铸膜液中引入聚乙烯醇(PVA)与戊二醛反应交联物,改善膜材料的亲水性。研究了PVDF浓度、PEG含量等对膜性能的影响。结果表明,改性聚偏氟乙烯(PVDF)血液分离膜的亲水性明显提高,接触角从70.2。降至54.5。,水通量从85.4L/(h.m2)-1提高到189.4L/(h.m2)-1,蛋白吸附性量则从92mg/m2降至27mg/m2,有较好的化学稳定性。随着PVDF浓度的增加,膜的拉伸性能增强,破裂压增大,水通量和膜分离孔径减小;随着PEG含量的提高,膜的机械性能变化不大,水通量明显提高。     

添加剂用量对聚醚砜涂层熔喷布结构及性能影响研究

为提高聚醚砜(PES)熔喷非织造布的亲水性能,采用聚环氧乙烷(PEO)和甲基丙烯酸甲酯(HEMA)与铸膜液共混的方式,通过相转化法及刮覆涂层的方法制备聚醚砜涂层熔喷布。对PES涂层熔喷布亲水性能,过滤性能以及孔径大小进行测试分析,并通过扫描电镜观察PES涂层熔喷布的微观结构。结果表明,PES涂层熔喷非织造布的接触角、水通量、孔隙率、平均孔径、截留率、微观形貌等各项性能均随着PEO质量分数的增加有明显提升,而随着HEMA质量分数的增加先是提高后因为HEMA质量分数增加使得铸膜液黏度增加各项性能有所下降。在铸膜液中添加PEO可以提高过滤膜的亲水性能,当PEO的质量分数大于8%,其接触角在60.89°,截留率达到90.1%以上,有较好的过滤性能;而在铸膜液中添加HEMA的过滤膜在HEMA质量分数为8%的时候,接触角最小为62.31°,有最佳的亲水性能。     

紫外光固化技术对聚丙烯非织造布的亲水改性

为扩大聚丙烯非织造布在水处理领域的应用,采用丙烯酸树脂为预聚物,聚乙二醇（400）二丙烯酸酯（PEG（400）DA）为亲水单体,1?羟基环己基苯甲酮（184）为光引发剂,乙酸乙酯为溶剂,通过紫外光（UV）引发自由基聚合法进行聚丙烯（PP）非织造布的亲水改性。分别研究了预聚物、亲水单体和光引发剂的质量分数对改性ＰＰ非织造布亲水性能的影响。结果表明,当丙烯酸树脂、PEG（400）DA 和184 的质量分数分别为7%、13%、1% 时,改性ＰＰ 非织造布亲水性达到最佳,且具有良好的亲水持久性。扫描电子显微镜（SEM）测试结果显示,亲水改性剂牢固地包覆在PP纤维表面。亲水改性的PP非织造布具有较好的抗污染性能和耐酸碱性能。     

壳聚糖改性化学纤维的新方法及其微观分析

用H2CO3溶解壳聚糖凝胶后以物理涂覆的形式包裹在化学纤维表面的方法将疏水性的化学纤维改性成亲水性纤维,增强了化学纤维的可抄造性。结果表明,该方法切实可行,通过显微镜和SEM照片对涂覆壳聚糖前后的维纶纤维进行微观分析,发现在化学纤维表面形成的壳聚糖膜薄而均匀,同时增加了化学纤维的表面粗糙度,涂覆效果较好;通过接触角的变化说明纤维的亲水性得到改善;该方法还具有无残留物和对环境友好的优点。     

天然高分子对化学纤维涂覆改性的新方法

介绍了采用天然高分子对化学纤维进行涂覆，从而改善化学纤维亲水性的方法。主要包括壳聚糖和海藻酸盐的溶胶一凝胶法。壳聚糖和海藻酸盐分子链上都含有大量的羟基等亲水性基团，利用它们的溶解性质可将其均匀地涂覆在化学纤维表面，从而对化学纤维进行亲水化改性。     

常压辉光放电引发聚乙烯纤维接枝丙烯酸

为提高聚乙烯(PE)纤维表面的亲水性,先在常压下用氦气辉光放电处理纤维,再接枝丙烯酸。对不同放电处理工作参数下PE纤维表面的接触角和接枝率变化进行规律性和原理分析。用IR和SEM、EDS分析处理前后PE纤维表面形态变化。实验结果表明:不同辉光放电处理工作参数下PE纤维表面接枝丙烯酸(AA)后使材料的接触角和接枝率呈现不同的规律性变化;经等离子体处理后接枝AA,在PE纤维表面成功引入了极性基团,显著提高了其亲水性。     

模板法制备防污自洁PVDF膜

以二甲基甲酰胺(DMF)为溶剂溶解聚偏氟乙烯(PVDF)粉末,制成涂层胶,并采用不同表面粗糙度的模板对其进行涂层,制备防污自洁PVDF膜。研究了表面粗糙结构和表面能对PVDF膜疏水性能的影响。结果表明,PVDF膜的接触角随表面凸体直径和表面能的减小而增大;滚动角随表面能的减小而减小,与表面粗糙结构无关。采用预涂含氟疏水试剂、表面凸体直径为8.5μm的模板,制得的PVDF膜的接触角为172°、滚动角为2°;采用表面凸体直径为8.5μm的模板,掺杂含氟树脂的PVDF膜的接触角为168°、滚动角为1°,具有优良的防污自洁性能。     

Polyelectrolyte and silver nanoparticle modification of microfiltration membranes to mitigate organic and bacterial fouling

Membrane fouling remains one of the most problematic issues surrounding membrane use in water and wastewater treatment applications. Organic and biological fouling contribute to irreversible fouling and flux decline in these processes. The aim of this study was to reduce both organic and biological fouling by modifying the surface of commercially available poly(ether sulfone) (PES) membranes using the polyelectrolyte multilayer modification method with poly(styrenesulfonate) (PSS), poly(diallyldimethylammonium chloride) (PDADMAC), and silver nanoparticles (nanoAg) integrated onto the surface as stable, thin (15 nm) films. PSS increases the hydrophilicity of the membrane and increases the negative surface charge, while integration of nanoAg into the top PSS layer imparts biocidal characteristics to the modified surface. Fouling was simulated by filtering aqueous solutions of humic acid (5 and 20 mg L(-1)), a suspension of Escherichia coli (10(6) colony-forming units (CFU) mL(-1)), and a mixture of both foulants through unmodified and modified PES membranes under batch conditions. Filtration and cleaning studies confirmed that the modification significantly reduced organic and biological fouling.     

新型阻燃亲水聚酯纤维的制备及其性能

由于聚酯纤维回潮率低,染色性差,易积聚静电,易起球,易燃烧,使得其应用受限。为了提高聚酯纤维的亲水性和阻燃性能,采用PTA、EG并添加第三单体（SIPE）、第四单体（PEG）和第五单体(亲水剂)进行共聚反应制备高亲水聚酯切片。通过亲水聚酯切片和含共聚阻燃剂（CEPPA 2-羧乙基苯基次膦酸）的阻燃母粒共混熔融纺丝的方法制备具有阻燃功能和高亲水功能的聚酯纤维,并对其阻燃性能和亲水性能进行测试。分析结果表明经改性后的聚酯切片热稳定性能与PET相比变化不大,表面接触角小于65°,极限氧指数大于30%,得到的亲水阻燃聚酯的亲水性、热稳定性及阻燃性能良好。     

等离子体诱导丙烯酸接枝改性聚丙烯熔喷非织造材料

为提高聚丙烯（PP）熔喷非织造材料表面的亲水性,针对PP表面化学惰性较大的缺点,通过氩气等离子体处理材料表面,然后进行丙烯酸接枝改性,获得了亲水性良好的PP熔喷材料。研究了不同气氛、处理电压和时间对等离子体处理的影响。同时,研究了接枝温度、时间和单体质量分数对丙烯酸接枝处理的影响。采用接触角测量仪、扫描电子显微镜和傅里叶红外光谱仪分别测试了等离子体和接枝处理前后材料亲水性变化、表面形貌及基团的变化。结果表明：在氩气等离子体处理电压为150 V、处理时间为180 s的条件下处理后,当接枝时间为90 min、接枝温度60 ℃、丙烯酸单体质量分数为60%时,样品接触角从140°下降至32°,材料表面亲水性最好。     

国内PVA薄膜材料改性研究进展

聚乙烯醇(PVA)是一种性能优异、用途广泛的薄膜材料,在水溶性及可降解性等方面具有独特优点。文章对PVA的优点、特性作了简要介绍。PVA分子链上含有大量羟基,亲水性较高,在湿度较大的情况下,其阻隔性会急剧下降;PVA熔融温度和分解温度十分相近,给热塑加工带来了困难;PVA是一种可完全降解的高分子聚合物,但其薄膜生物降解周期较长;PVA用作制备亲水膜的材料,但PVA膜纯水渗透量高,其在湿态的稳定性和力学性能不佳。因此,需要对PVA进行不同的改性才能使其达到优良的性能。从PVA的耐水性和水溶性改性、热塑性加工的改性、生物降解性的改性和PVA膜渗透和稳定性改性等4方面对PVA薄膜用材料改性研究方面的进展进行了综述。     

壳聚糖对革兰氏阴性菌抑菌机理的初步研究

体外抑菌法研究壳聚糖对绿脓杆菌、奇异变形杆菌和大肠杆菌的抑菌性能。同时,对细菌表面的亲水性和负电荷进行研究,以阐述革兰氏阴性菌表面性质与壳聚糖对其抑菌性能之间的关系。以大肠杆菌作为代表性菌株,考察了壳聚糖对革兰氏阴性菌的抑菌机理。通过测定菌液中加入疏水性荧光探剂1-N-苯萘胺(NPN)后荧光强度的改变,考察壳聚糖对外膜渗透性的影响。此外,采用红外吸收光谱(FT-IR),对壳聚糖和大肠杆菌的作用产物进行表征。结果表明：革兰氏阴性菌表面的亲水性越好,所带的负电荷越多,壳聚糖表现出较好的抑菌性能;壳聚糖可增加细胞外膜的渗透性,壳聚糖与细胞膜间发生静电作用而使细胞膜破坏,最终导致菌体的死亡。     

缩水甘油改性pADM的亲水性与吸湿动力学研究

采用缩水甘油(Glycido1)对脱细胞猪真皮基质(pADM)进行改性,通过对改性前后材料的接触角和吸湿动力学的研究,探寻改性前后材料亲水性能的变化.研究结果表明:pADM经缩水甘油改性后,材料的接触角降低.材料的吸湿动力学特征符合二级吸附动力学方程,表明吸湿过程属于多分子层吸附;且平衡吸附量随着改性剂用量的增加而提高...     

Studying the role of common membrane surface functionalities on adsorption and cleaning of organic foulants using QCM-D

Adsorption of organic foulants on nanofiltration (NF) and reverse osmosis (RO) membrane surfaces strongly affects subsequent fouling behavior by modifying the membrane surface. In this study, impact on organic foulant adsorption of specific chemistries including those in commercial thin-film composite membranes was investigated using self-assembled monolayers with seven different ending chemical functionalities (-CH(3), -O-phenyl, -NH(2), ethylene-glycol, -COOH, -CONH(2), and -OH). Adsorption and cleaning of protein (bovine serum albumin) and polysaccharide (sodium alginate) model foulants in two solution conditions were measured using quartz crystal microbalance with dissipation monitoring, and were found to strongly depend on surface functionality. Alginate adsorption correlated with surface hydrophobicity as measured by water contact angle in air; however, adsorption of BSA on hydrophilic -COOH, -NH(2), and -CONH(2) surfaces was high and dominated by hydrogen bond formation and electrostatic attraction. Adsorption of both BSA and alginate was the fastest on -COOH, and adsorption on -NH(2) and -CONH(2) was difficult to remove by surfactant cleaning. BSA adsorption kinetics was shown to be markedly faster than that of alginate, suggesting its importance in the formation of the conditioning layer. Surface modification to render -OH or ethylene-glycol functionalities are expected to reduce membrane fouling.     

Cold Plasma Synthesis of Poly(ethylene glycol)-like Layers on Stainless-Steel Surfaces to Reduce Attachment and Biofilm Formation by Listeria monocytogenes

ABSTRACT Poly(ethylene glycol) (PEG)-like structures were generated on stainless steel under di(ethylene glycol) vinyl ether (DiEGVE) radio frequency-plasma environments. Electron spectroscopy for chemical analysis and attenuated total reflectance Fourier transform infrared spectroscopy indicated a PEG-like deposition, which was stable to cleaning, sanitizing, and storage for up to 2 mo. Atomic force microscopy and water contact angle analysis indicated that the modified stainless-steel surfaces were less rough and more hydrophilic than the unmodified surfaces. Listeria monocytogenes attachment and biofilm formation on modified surfaces decreased more than 90% compared with the unmodified stainless steel ( P < 0.01). DiEGVE cold plasma was demonstrated to be a promising technique to reduce bacterial contamination on surfaces encountered in food-processing environments.     

聚丙烯亲水改性纤维的表征

在聚丙烯（PP）中共混少量助剂有效地改进了PP纤维的亲水性。用热失重方法评价了亲水助剂的热稳定性;将改性PP切片或纤维熔融压片后,用接触角评价其亲水性,建立了亲水助剂的筛选评价方法。与纯PP相比,亲水改性PP的流变性能和纺成的纤维的力学性能基本不变,纤维强度大于6.2cN/dtex,接触角降低了48°。DSC和SEM的结果表明,改性PP纤维的熔融行为和结晶度与纯PP纤维相近,亲水助剂在纤维中均匀分散,沿纤维轴方向略被拉伸,宽度约为200nm。     

基于纳滤技术的质检萃取液脱色预处理方法

为提高纺织品及皮革甲醛检测效率和准确性,通过界面聚合法,将采用St?ber方法制备的无机颗粒与聚酰胺复合制备有机-无机杂化纳滤膜,用于纺织品和皮革萃取液脱色预处理。分别采用扫描电子显微镜、X射线光电子能谱仪和接触角仪,对颗粒形貌、纳滤膜表面元素及分离层接触角进行分析;通过纯水通量、无机盐和染料截留等对纳滤膜分离性能进行考察;并分析了纳滤脱色预处理法纺织品和皮革甲醛检测的加标回收率。结果表明:粒径分布均匀的球形二氧化硅及银离子修饰的二氧化硅颗粒成功地负载于亲水性良好的纳滤膜分离层;适量颗粒的添加有利于提高纳滤膜的纯水通量;银离子修饰的二氧化硅颗粒改善了纳滤膜对二价阳离子盐及阳离子染料的截留性能,回收率满足纺织品和皮革甲醛检测的要求。