ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2019
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IF 7.149
Qing Xia,Liping Qiu,Shuili Yu,Haijun Yang,Lei Li,Yubing Ye,Zhengyang Gu,Liumo Ren,Guicai Liu
The aging effects of sodium hydroxide (NaOH) on ion-exchange membranes were systematically studied, including the membrane properties, desalination performance, and fouling behaviors. After aging in NaOH solution, there were minor changes in the cation-exchange membrane (CEM) properties; however, functional groups (i.e., quaternary amines) on the anion-exchange membranes (AEMs) were converted into benzylic alcohol, alkene, and tertiary amines, respectively, by nucleophilic substitution, Hofmann elimination, and ylide formation. These degradations rendered decreased ion-exchange capacity (IEC), increased electrical resistance, lost hydrophilicity, and weakened mechanical strength. Moreover, severe deteriorations of desalination performance were observed due to the little ion-exchange ability of the degraded AEMs. The desalination rates were restored after cultivating the aged AEMs in acid solution, mainly because the tertiary amines transformed from the hydroxide form (OH-form) to the ionic chlorine form (Cl-form). The restored desalination rates indicated that the main degradation products were tertiary amines. In addition, the antifouling performance decreased in the order of aged OH-form > aged Cl-form > original AEMs due to the reduction of foulant–membrane intermolecular interactions after aging in NaOH solution. The results contribute to establishing a more comprehensive understanding of the effects of alkaline cleaning on IEMs and provide new insights into cleaning-process optimization and membrane modification.
研究领域:
环境科学
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材料科学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2020
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IF 7.489
Ming-Ming Zhu,Yu Fang,Yan-Chen Chen,Yu-Qing Lei,Li-Feng Fang,Bao-Ku Zhu,Hideto Matsuyama
To overcome the organic-/bio- fouling of the membrane, a dual-functional ultrafiltration membrane containing quaternary ammonium and zwitterionic polymers via quaternization and surface radical polymerization was designed, and its antifouling and antibacterial behavior was studied. In this work, poly(vinylidene fluoride)/poly(methyl methacrylate- co -dimethylamino-2-ethyl methacrylate) (PVDF/P(MMA- co -DMAEMA)) blend membrane was quaternized by p -chloromethyl styrene ( p -CMS), and the double bonds were introduced onto the membrane surface, which further participated in the polymerization of zwitterionic monomers on the membrane surface. The results indicated that the resultant membrane exhibited obviously improved hydrophilicity and weak positive charge (isoelectric point, 7.49). The membrane presented higher flux recovery ratio and lower protein adhesion compared with the pure PVDF membrane. Meanwhile, the membrane showed high-efficiency broad-spectrum antibacterial performance, that is, the bacteria killing efficiency of S. aureus and E. coli reached 98.2% and 97.0%, respectively. Moreover, the membrane effectively inhibited bacterial adhesion, which is important for the long-term antibacterial properties of membrane. This antifouling and antibacterial PVDF membrane may have potential in the long-term filtration process, especially when dealing with microbiologically contaminated water.
研究领域:
材料科学
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环境工程
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生物医学工程
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DOI
高影响因子
Membranes
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2022
·Vol. 12
·期 10
·965
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IF 4.562
Muqiao Han,Qi Han,Shanwei Wu,Hu Xiao,Lei Zhang,Yibo Lin,Fangang Meng,Shanshan Zhao
Sodium hypochlorite (NaOCl) is a commonly used cleaning agent for recovering membrane performance in membrane technologies. A thorough understanding of the impacts of NaOCl exposure on membrane properties and fouling behavior is important for optimizing chemical cleaning process and extending membrane lifespan. In this study, three commercial polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membranes (SMM-1010, MEMCOR®CS II and ZeeWeed 500) were used to systematically explore the effects of NaOCl dose and solution pH (8 and 10) on membrane properties. The results showed that membrane pores increased with exposure time prolonging, and more pores were observed at pH 8 aging condition. The amide group in the Fourier transformation infrared spectra was disappeared, while the carboxylic acid and succinimide groups were formed at pH 10 and pH 8 conditions, respectively. The hydrophilicity and pure water permeability (PWP) of SMM-1010 and MEMCOR®CS II membranes had insignificant changes during NaOCl aging process, whereas the hydrophilicity of ZeeWeed 500 membrane slightly decreased and its PWP increased by 1.4-fold. The antifouling properties of NaOCl-aged SMM-1010 and MEMCOR®CS II membranes were slightly improved, whereas the NaOCl-aged ZeeWeed 500 membrane showed severer flux decline with humic acid filtration. Our findings could provide guidance for practical chemical cleaning process optimization.Keywords:NaOCl cleaning;PVDF hollow fiber membrane;physicochemical properties;membrane fouling behavior
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2019
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IF 5.107
Meng He,Honghong Sun,Haixiang Sun,Xiujie Yang,Peng Li,Q. Jason Niu
Conventional nanofiltration membrane fabrication generally includes the usage of toxic organic solvent that poses threats to the environment and public health. Herein, we explored preparing nanofiltration membrane through a non-organic solvent method utilizing the highly reactive natural product, tannic acid (TA), along with cyclohexane-1,4-diamine (CHD). Fabrication process was carried out through sequential immersion of a polyethersulfone (PES) support in two aqueous monomer phases. The absence of a solvent interface facilitated the diffusion and mixing of the two monomers, and the highly reactive quinone derivative of TA enabled the rapid film formation via Michael addition and Schiff base formation. Membrane performance was optimized through investigation of fabrication parameters. The TA-CHD membrane exhibited a negatively charged surface, with a molecular weight cut-off (MWCO) of 600 Da. The membrane prepared at optimal conditions showed approximate 97% and 50.7% rejections towards Na 2 SO 4 and NaCl, with a water flux at approximate 35 L m −2 h −1 (10 bar). Fouling behaviour of the TA-CHD membrane was studied and a chemical cleaning test under two extreme pH was performed to demonstrate the chemical stability. The proposed non-organic solvent method here provides an eco-friendly way to utilize the potential of polyphenol natural products in water purification membrane preparation.
研究领域:
环境科学
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材料科学
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水处理
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产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Guijing Chen,Songzhe Li,Xifan Li,Xin Li,Baicang Liu
The collection and reuse of roof rainwater can alleviate water shortage for daily life. In this study, polyvinylidene fluoride hollow fiber membranes tuned with three multi-walled carbon nanotubes (pure MWCNTs, MWCNTs-COOH, and MWCNTs-OH) were prepared using a non-solvent induced phase separation method for gravity-driven membrane filtration to purify roof rainwater. The results showed that the MWCNTs were distributed on the membrane surface and throughout the porous structure of the cross-section, which changed the pore structure parameters and hydrophilicity. The pure water flux of the MWCNTs tuned membranes increased by 152.5 % at 1.0 bar, and the rejection rates of humic acid and bovine serum albumin increased from 97.4 % and 75.7 % to 98.9 % and 96.3 %, respectively. The extended Derjaguin, Landau, Verwey, and Overbeek (xDLVO) theory states that the presence of MWCNTs leads to changes in the physicochemical properties of the membrane surface, resulting in membranes with different anti-fouling behaviors. A gravity-driven membrane filtration test was continuously operated for 100 days, and all membranes removed 25.0–26.7 %, 49.5–53.0 %, and 89.0–93.3 % of total dissolved solids, dissolved organic carbon, and turbidity from roof rainwater, respectively. However, the pure MWCNTs modified membrane with relatively hydrophobic properties showed a 12.4 % increase in flux over the unmodified membrane. Importantly, the presence of the MWCNTs in the membrane changed the microbial diversity in the biofilter cake layer.
研究领域:
环境工程
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水处理
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纳米技术
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膜科学
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产品关联
DOI
高影响因子
WATER RESEARCH
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2021
·
IF 11.236
Yuefei Song,Xifan Li,Yongxin Wang,Saifei Ma,Tiemei Li,Xiaomei Chen,Yajuan Li,Kai Jiang
Rare information is available on fouling behavior of customized nanofiltration (NF) membrane evoked by pharmaceutically active compounds (PhACs) under real multiple influent matrices pretreated by ultrafiltration module beforehand. To this end, a novel tight NF membrane with excellent perm-selectivity and antiadhesion was fabricated and used to assess its separation performance/mechanism and fouling behavior to a broad range of small molecular PhACs in the context. The adsorption ratio results revealed that the affinities between five selected PhACs and the customized nanocomposite membrane surface were all much weaker (below 5.5%) than the solute-solute interacting forces (between 23.6 and 83.2%), whether for natural or synthetic complex micropollutants. The predominant membrane fouling could be interpreted by the incomplete blocking model in the permeation of both influent conditions. For neat nanocomposite membrane, the order of critical factors important on separation mechanism was electrostatic effect, adsorption and steric hindrance. The fouling layer seemed to act as a secondary separating layer for those negatively charged or hydrophilic PhACs, but showed the cake enhanced concentration polarization effect for the neutral and hydrophobic ones. This study provides valuable insights for defining PhACs fate and NF membrane fouling behavior to fit increasingly stringent criteria for wastewater treatment.
研究领域:
环境科学
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化学工程
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水处理
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膜技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）