Free volume and polymeric structure analyses of aromatic polyamide membranes: A molecular simulation and experimental study

Chang, Kai-Shiun; Huang, Yun-Hsuan; Lee, Kueir‐Rarn; Tung, Kuo‐Lun

doi:10.1016/j.memsci.2010.02.076

Cited by 75 publications

(29 citation statements)

References 30 publications

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“…A strategic approach to address this issue is the augmentation of the natural water supply with reclaimed water from treated effluent using advanced water treatment technologies including high-pressure membrane processes such as reverse osmosis (RO) and nanofiltration (NF) (Fujioka et al, 2012;Wintgens et al, 2005). Most commercially available NF and RO membranes for water treatment are polyamide thin-film composite (TFC) and consist of a thin polyamide active skin layer that is responsible for solute separation on top of a porous supporting layer (Chang et al, 2010). Polyamide membranes offer excellent permeate flux, high salt and trace organic rejection, durability and a wide operating pH range, however, they are susceptible to chlorine degradation.…”

Section: Introductionmentioning

confidence: 99%

Effects of hypochlorite exposure on morphology and trace organic contaminant rejection by NF/RO membranes

Simon

Nghiem

2014

Membr. Water Treat.

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The impacts of membrane degradation due to chlorine attack on the rejection of inorganic salts and trace organic contaminants by nanofiltration (NF) and reverse osmosis (RO) membranes were investigated in this study. The rejection of trace contaminants was examined at environmentally relevant concentrations. Changes in the membrane surface morphology were observed as a result of chlorine exposure. A small increase in rejection was consistently observed with all four membranes selected in this study after being exposed to a low concentration of hypochlorite (100 ppm). In contrast, a higher concentration of hypochlorite (i.e., 2000 ppm) could be detrimental to the membrane separation capacity. Membranes with severe chlorine impact showed a considerable decrease in rejection over filtration time, possibly due to rearrangement of the polyamide chains under the influence of chlorine degradation and filtration pressure. The reported results indicate that loose NF membranes are more sensitive to chlorine exposure than RO membranes. The impact of hypochlorite exposure (both positive and negative) on rejection is dependent on the strength of the hypochlorite solution and is more significant for the neutral carbamazepine compound than the negatively charged sulfamethoxazole. AbstractThe impacts of membrane degradation due to chlorine attack on the rejection of inorganic salts and trace organic contaminants by nanofiltration (NF) and reverse osmosis (RO) membranes were investigated in this study. The rejection of trace contaminants was examined at environmentally relevant concentrations.Changes in the membrane surface morphology were observed as a result of chlorine exposure. A small increase in rejection was consistently observed with all four membranes selected in this study after being exposed to a low concentration of hypochlorite (100 ppm). In contrast, a higher concentration of hypochlorite (i.e.: 2000 ppm) could be detrimental to the membrane separation capacity. Membranes with severe chlorine impact showed a considerable decrease in rejection over filtration time, possibly due to rearrangement of the polyamide chains under the influence of chlorine degradation and filtration pressure.The reported results indicate that loose NF membranes are more sensitive to chlorine exposure than RO membranes. The impact of hypochlorite exposure (both positive and negative) on rejection is dependent on the strength of the hypochlorite solution and is more significant for the neutral carbamazepine compound than the negatively charged sulfamethoxazole.

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Section: Introductionmentioning

confidence: 99%

Effects of hypochlorite exposure on morphology and trace organic contaminant rejection by NF/RO membranes

Simon

Nghiem

2014

Membr. Water Treat.

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“…6a and b. The higher slope of displacement in the mean-square displacements diagrams indicates a higher molecular mobility [20,24]. From the mean-square displacements diagram it was found that water exhibited a higher displacement than MMH and UDMH.…”

Section: Binary Mixture Diffusionmentioning

confidence: 96%

“…Data analysis. The mobility of molecules in the polymeric membrane was investigated using mean square displacement (MSD) which can be computed by the following equation [20]. where, r(0) and r i (t) are the initial and final (after time t) position coordinate of atom i, respectively.…”

Section: Permeation Propertiesmentioning

confidence: 99%

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Pervaporation performance of PPO membranes in dehydration of highly hazardous mmh and udmh liquid propellants

Moulik

Kumar

Bohra

et al. 2015

Journal of Hazardous Materials

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“…Wei et al [79] and Zhang et al [80] modified commercial membranes adding 3-allyl-5,5-dimethylhydantoin by a free-radical graft polymerization process, finding, for example, that the chlorinated grafted membranes had remarkable sterilization The correlation between gas and vapor separation characteristics of aromatic polyamides with the bulkiness of the aramids was studied theoretically. Chang et al [76], adopted several simulation techniques, such as molecular dynamics or the Monte Carlo method, to analyze free volume, fractional accessible volume and the size and shape distributions of the free volume, showing that bulky groups in the membranes promote the formation of a continuous and larger free volume. Finally, a correlation between theoretical and experimental data was observed.…”

Section: Scheme 12mentioning

confidence: 99%

Functional Aromatic Polyamides

et al. 2017

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Abstract:We describe herein the state of the art following the last 8 years of research into aromatic polyamides, wholly aromatic polyamides or aramids. These polymers belong to the family of high performance materials because of their exceptional thermal and mechanical behavior. Commercially, they have been transformed into fibers mainly for production of advanced composites, paper, and cut and fire protective garments. Huge research efforts have been carried out to take advantage of the mentioned characteristics in advanced fields related to transport applications, optically active materials, electroactive materials, smart materials, or materials with even better mechanical and thermal behavior.

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Free volume and polymeric structure analyses of aromatic polyamide membranes: A molecular simulation and experimental study

Cited by 75 publications

References 30 publications

Effects of hypochlorite exposure on morphology and trace organic contaminant rejection by NF/RO membranes

Effects of hypochlorite exposure on morphology and trace organic contaminant rejection by NF/RO membranes

Pervaporation performance of PPO membranes in dehydration of highly hazardous mmh and udmh liquid propellants

Functional Aromatic Polyamides

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