Experimental and DFT investigation of surface degradation of polyvinylidene fluoride membrane in alkaline solution

Zhao, Xiaodan; Song, Lina; Fu, Jie; Tang, Pei Song; Liu, Feng

doi:10.1016/j.susc.2011.02.022

Cited by 49 publications

(30 citation statements)

References 26 publications

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“…Hydroxyl groups were partially incorporated into N117 thermolysis products, contributing to their structural diversity. In a previous study, hydroxyl groups were also observed in PVDF membranes treated with alkaline solutions42.…”

Section: Discussionmentioning

confidence: 81%

Characterization of the thermolysis products of Nafion membrane: A potential source of perfluorinated compounds in the environment

Feng

Wei

et al. 2015

Sci Rep

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The thermal decomposition of Nafion N117 membrane, a typical perfluorosulfonic acid membrane that is widely used in various chemical technologies, was investigated in this study. Structural identification of thermolysis products in water and methanol was performed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS). The fluoride release was studied using an ion-chromatography system, and the membrane thermal stability was characterized by thermogravimetric analysis. Notably, several types of perfluorinated compounds (PFCs) including perfluorocarboxylic acids were detected and identified. Based on these data, a thermolysis mechanism was proposed involving cleavage of both the polymer backbone and its side chains by attack of radical species. This is the first systematic report on the thermolysis products of Nafion by simulating its high-temperature operation and disposal process via incineration. The results of this study indicate that Nafion is a potential environmental source of PFCs, which have attracted growing interest and concern in recent years. Additionally, this study provides an analytical justification of the LC/ESI-MS/MS method for characterizing the degradation products of polymer electrolyte membranes. These identifications can substantially facilitate an understanding of their decomposition mechanisms and offer insight into the proper utilization and effective management on these membranes.

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Section: Discussionmentioning

confidence: 81%

Characterization of the thermolysis products of Nafion membrane: A potential source of perfluorinated compounds in the environment

Feng

Wei

et al. 2015

Sci Rep

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“…It was observed that a small peak at 1650 cm À 1 (assigned for carbon-carbon double bond) appeared for membranes that were cleaned using 0.1 M of either NaOH or NaOCl for a lapse of 40 and 60 min, and membranes that were cleaned with 0.01 M for 60 min. The appearance of carbon-carbon double bond denoted the occurrence of dehydrofluorination reaction on the cleaned membrane surface (Rabuni et al, 2013;Zhao et al, 2011). Although the peak signal was relatively low, its appearance signifies that there was an alteration in chemical composition when membranes were cleaned using the chemicals.…”

Section: Ftir Analysismentioning

confidence: 99%

Impact of in situ physical and chemical cleaning on PVDF membrane properties and performances

Rabuni

Sulaiman

Aroua

et al. 2015

Chemical Engineering Science

118

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The effect of cleaning process at mild conditions towards PVDF membrane stability is investigated. Two commonly used cleaning agents (NaOH and NaOCl) were found to reduce PVDF membrane stability. The protein retention performance of membrane is reduced subsequent to membrane cleaning process. The stability of PVDF membrane was affected even at a chemical concentration of 0.01 M. a b s t r a c tAppropriate selection of cleaning agent is an important factor to achieve a better cleaning efficiency and this topic has become an ongoing discussion. This work assesses the impacts of sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl) aqueous solution towards polyvinylidene fluoride (PVDF) stability at the typical concentrations used in membrane cleaning. The cleaned membranes were characterised using field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), pure water flux measurement, contact angle, protein retention and tensile testing. Membrane cleaned at elevated temperature and higher concentration presented a higher water flux than the virgin membrane which can be a worrying sign of alteration in membrane properties. The FTIR spectra indicated that the alteration in chemical composition of the membrane causes a reduction in the degree of hydrophilicity. The mechanical properties of the membrane were compromised based on the declination of tensile strength. The findings from this work suggest that the usage of NaOCl as compared to NaOH causes a more detrimental effect towards the stability of the PVDF membrane.

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“…Several researchers have reported the vulnerability of PVDF membrane towards alkaline environments, though their main intention is to study the degradation mechanism [25][26][27][28]. In our recent study, we too showed that the effects of alkaline environment towards PVDF membrane properties could be observed upon exposure to a mild condition [21].…”

Section: Introductionmentioning

confidence: 62%

“…It has been proposed that the degradation mechanism is mainly caused by the dehydrofluorination process, which leads to the formation of carbon-carbon double bond and the incorporation of oxygen-contained group to the polymer. This mechanism has been discussed thoroughly elsewhere [25,26]. These double bonds are inclined to be chemically attacked by NaOH and NaOCl.…”

Section: Assessment Of Pvdf Membrane Degradationmentioning

confidence: 96%

“…Nevertheless, earlier studies were mainly focused on the degradation mechanism of alkaline attack towards PVDF membrane; therefore, extreme treatment conditions were applied (i.e. relatively high concentrations, temperature or with the presence of catalyst) [25][26][27][28]. PVDF membrane exposed to NaOH solution is known to endure degradation, due to chemical attack by hydroxide ions.…”

Section: Assessment Of Pvdf Membrane Degradationmentioning

confidence: 99%

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A systematic assessment method for the investigation of the PVDF membrane stability

Rabuni

Sulaiman

Hashim

2015

Desalination and Water Treatment

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This article reports the systematic assessment method for membrane stability using a hydrophilic polyvinylidene fluoride (PVDF) membrane. In this study, bovine serum albumin, fouled PVDF flat-sheet membranes were cleaned with sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl). The effects of repeated chemical cleaning on membrane water flux recovery and the PVDF membrane intrinsic properties were investigated. The virgin and cleaned membranes were characterised by water flux measurement, field emission scanning electron microscopy, tensile test, Fourier transform infrared, contact angle measurement and protein rejection performance. As expected, higher cleaning efficiency was achieved when using higher concentration and extended cleaning time with NaOCl showing better performance compared to NaOH. It was found that the use of chemical cleaning agent for fouling control has an impact on membrane integrity and shortens their lifespan. Their declining functionality is normally associated with ageing; a term meant to describe changes in physical parameters and a declined stability.

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Experimental and DFT investigation of surface degradation of polyvinylidene fluoride membrane in alkaline solution

Cited by 49 publications

References 26 publications

Characterization of the thermolysis products of Nafion membrane: A potential source of perfluorinated compounds in the environment

Characterization of the thermolysis products of Nafion membrane: A potential source of perfluorinated compounds in the environment

Impact of in situ physical and chemical cleaning on PVDF membrane properties and performances

A systematic assessment method for the investigation of the PVDF membrane stability

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