Structure–performance correlation of polyamide thin film composite membranes: effect of coating conditions on film formation

Rao, A. Prakash; Joshi, Sumit; Trivedi, J.J.; Devmurari, C.V.; Shah, Vatsal

doi:10.1016/s0376-7388(02)00305-8

Cited by 234 publications

(50 citation statements)

References 22 publications

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“…1540 cm -1 decreases in intensity and undergoes a slight hypochromic shift with exposure. The peak at 1487 cm -1 corresponds to a characteristic peak (CH 2 stretch) of polysulfone [52] whereas the peak at 1540 cm -1 corresponds to the C-N stretch of the PA (II) group [18]. It appears that the polysulfone layer of this material is not affected by the chloramine solution as evidenced by the unchanged characteristic peak however a chemical change in the PA structure has occurred as a result of chloramine exposure.…”

Section: Structural Changes Measured By Infrared Spectroscopymentioning

confidence: 90%

Degradation of polyamide reverse osmosis membranes in the presence of chloramine

2011

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Exposure to relatively low concentrations of chlorinated chemicals such as hypochlorite can reduce the performance and ultimately result in the failure of polyamide (PA) reverse osmosis membranes. Whereas the tolerance of PA membranes to chloramine solutions is considerably higher than that of hypochlorite, the presence of some metal ions can potentially catalyze and accelerate degradation reactions. Spectroscopic techniques are commonly used to qualitatively assess the chemical degradation of membranes by observing changes in structural peaks. This paper presents a technique to quantitatively evaluate changes in PA membranes exposed to chloramine by means of a peak ratio derived from a typical amide peak and an invariant peak in the same spectrum. The effect of some common metal ions and combinations of these on the peak ratio parameter derived from a typical amide peak is also reported.

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Section: Structural Changes Measured By Infrared Spectroscopymentioning

confidence: 90%

Degradation of polyamide reverse osmosis membranes in the presence of chloramine

2011

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“…Freger [27] measured the membrane thickness of LPRO and SWRO membranes by transmission electron microscopy and reported that the LPRO membrane have thinner active skin layer than the SWRO membrane, which is consistent with the fact that it is an SWRO membrane with lower permeability and higher sodium ion rejection than the ESPA2 and ESPAB membranes (Table 3). In addition, Prakash et al [30] reported a strong correlation between the effective thickness of active skin layer and pure water permeability of RO membranes. It is also noteworthy that the ESPAB is likely to be a modified version of the ESPA2 (which may explain the same calculated free-volume hole-radii of these two membranes).…”

Section: Pals Analysismentioning

confidence: 99%

Rejection of small and uncharged chemicals of emerging concern by reverse osmosis membranes: The role of free volume space within the active skin layer

Fujioka¹,

Oshima²,

Suzuki³

et al. 2013

Separation and Purification Technology

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Nghiem, L. D. (2013). Rejection of small and uncharged chemicals of emerging concern by reverse osmosis membranes: The role of free volume space within the active skin layer. Separation and Purification Technology, Rejection of small and uncharged chemicals of emerging concern by reverse osmosis membranes: The role of free volume space within the active skin layer AbstractFree-volume hole-radii of the active skin layer of one seawater and two low pressure reverse osmosis (RO) membranes -namely SWC5, ESPAB, and ESPA2 respectively -were evaluated using positron annihilation lifetime spectroscopy (PALS) with a slow positron beam. The results were related to the rejection of boric acid and eight N-nitrosamines to provide insights to the transport of these small solutes through RO membranes. At pH 8 (which is the experimental pH in this study), these solutes are uncharged. PALS analysis showed that the SWC5 has the smallest mean free-volume hole-radius (0.259 nm) among the three RO membranes investigated here. Correspondingly, the SWC5 membrane exhibited the highest rejection of boric acid and all N-nitrosamines. Results reported here also showed that the rejection of these chemicals increased in the order of increasing molecular volume. In addition, the difference in their rejection amongst the three RO membranes investigated here was most apparent for those (i.e., boric acid and N-nitrosodimethylamine (NDMA)) with a small molecular volume. The EPSA2 and ESPAB were determined to have mean freevolume hole-radius of 0.289 nm. However, the ESPAB membrane had lower water permeability and showed considerably higher rejection of boric acid and NDMA than the ESPA2 membrane. These results suggest that in addition to the mean free-volume hole-radius, other membrane parameters and properties such as the freevolume hole-radius distribution and thickness of the active skin layer can also play a role in governing the rejection of small and uncharged solutes by RO membranes. Free-volume hole-radii of the active skin layer of one seawater and two low pressure reverse 441 osmosis (RO) membranes -namely SWC5, ESPAB, and ESPA2 respectively -were 442 evaluated using positron annihilation lifetime spectroscopy (PALS) with a slow positron 443 beam. The results were related to the rejection of boric acid and eight N-nitrosamines to 444 provide insights to the transport of these small solutes through RO membranes. At pH 8 445 (which is the experimental pH in this study), these solutes are uncharged. PALS analysis 446showed that the SWC5 has the smallest mean free-volume hole-radius (0.259 nm) among the 447 three RO membranes investigated here. Correspondingly, the SWC5 membrane exhibited the 448 highest rejection of boric acid and all N-nitrosamines. Results reported here also showed that 449 the rejection of these chemicals increased in the order of increasing molecular volume. In 450 addition, the difference in their rejection amongst the three RO membranes investigated here 451 was most apparent for those (i.e., boric acid and N-nitr...

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“…For having high permeability and selectivity, the barrier layer of TFC membrane should be very thin with a highly crosslinked structure [5][6][7]. Besides, the separation performance of TFC membrane is also known to be influenced by the intrinsic properties of the barrier layer, namely, surface charge, surface morphology, hydrophilicity, chemical functionality and pore size, since they affect the interaction between water and solutes [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…Besides, the separation performance of TFC membrane is also known to be influenced by the intrinsic properties of the barrier layer, namely, surface charge, surface morphology, hydrophilicity, chemical functionality and pore size, since they affect the interaction between water and solutes [8][9][10][11]. In order to achieve the desired properties, numerous studies have already been made by different researchers to optimize the conditions of interfacial polymerization, such as the type of monomer and its concentration, reaction time and curing conditions [7,12,13].…”

Section: Introductionmentioning

confidence: 99%

Study on the thin film composite poly(piperazine-amide) nanofiltration membrane: Impacts of physicochemical properties of substrate on interfacial polymerization formation

et al. 2014

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Structure–performance correlation of polyamide thin film composite membranes: effect of coating conditions on film formation

Cited by 234 publications

References 22 publications

Degradation of polyamide reverse osmosis membranes in the presence of chloramine

Degradation of polyamide reverse osmosis membranes in the presence of chloramine

Rejection of small and uncharged chemicals of emerging concern by reverse osmosis membranes: The role of free volume space within the active skin layer

Study on the thin film composite poly(piperazine-amide) nanofiltration membrane: Impacts of physicochemical properties of substrate on interfacial polymerization formation

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