Critical flux determination by flux‐stepping

Beier, Søren; Jonsson, Gunnar Eigil

doi:10.1002/aic.12099

Cited by 28 publications

(24 citation statements)

References 18 publications

(37 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A flux stepping method is commonly and conveniently used to determine threshold flux [32]. In the flux stepping method, the permeate flux is increased stepwise, and the TMP at each flux step is recorded [25,29,31]. The average TMP (TMP avg ) or the rate of fouling (d(TMP)/dt) at each flux step is then plotted as a function of flux.…”

Section: Threshold Flux Determinationmentioning

confidence: 99%

“…The threshold flux can also be identified as the flux where d(TMP)/dt increases markedly relative to a regime of low, stable d(TMP)/dt values at lower fluxes [21,25,28,29,31]. This method directly monitors the increase in fouling rate at the threshold flux.…”

Section: Threshold Flux Determinationmentioning

confidence: 99%

“…Membrane operation at zero fouling rate (i.e., below the critical flux) is rarely a realistic possibility [29,31,32]. However, a permeate flux below which the rate of fouling is stable and low, but not zero, is often observed.…”

mentioning

confidence: 99%

“…However, a permeate flux below which the rate of fouling is stable and low, but not zero, is often observed. Recently, Field and Pearce defined this flux, which has been referred to as the critical flux in some earlier studies [25,29,31,33,34], as the "threshold flux" [28]. The threshold flux is the flux that separates the low-fouling, stable operating regime from the high-fouling, unstable operating regime [28].…”

mentioning

confidence: 99%

See 3 more Smart Citations

Effect of polydopamine deposition conditions on polysulfone ultrafiltration membrane properties and threshold flux during oil/water emulsion filtration

Kasemset¹,

He²,

Miller³

et al. 2016

Polymer

View full text Add to dashboard Cite

Surface modification of porous membranes for water filtration has been extensively reported in the literature to improve fouling properties. However, surface modification can significantly change the membrane filtration properties, sometimes resulting in more severe fouling than with the original, unmodified membrane. This study focused on demonstrating surface modification strategies and membrane comparison strategies to better understand the complex, competing phenomena occurring when membranes are surface modified. Polysulfone ultrafiltration membranes were modified with polydopamine (PDA) at different initial dopamine concentrations and deposition times. Membrane properties, including surface hydrophilicity, roughness, and zeta potential, were characterized. PDA coatings significantly increased surface hydrophilicity, but they did not markedly change the surface roughness or zeta potential. The threshold flux during oil/water emulsion filtration was determined and used as a fouling parameter for membranes modified with PDA at various modification conditions. The threshold flux increased when PDA was deposited at low initial dopamine concentrations or short coating times. However, PDA deposition at high initial dopamine concentrations or long coating times decreased the threshold flux, suggesting that a tradeoff exists between increased hydrophilicity and reduced pore size due to surface modification. An increase in membrane surface hydrophilicity was observed at all PDA deposition conditions, which tends to reduce foulant adhesion and increase threshold flux. However, extensive PDA coating significantly decreased membrane pure water permeance, suggesting that some membrane pores may have been narrowed or blocked, increasing local permeate flux through the remaining pores in the PDA-modified membranes. This higher local flux would exacerbate fouling and decrease threshold flux. Comparing unmodified and PDA-modified membranes having similar pure water permeance values, the PDA-modified membranes had higher threshold fluxes than the unmodified membranes.

show abstract

Section: Threshold Flux Determinationmentioning

confidence: 99%

Section: Threshold Flux Determinationmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Effect of polydopamine deposition conditions on polysulfone ultrafiltration membrane properties and threshold flux during oil/water emulsion filtration

Kasemset¹,

He²,

Miller³

et al. 2016

Polymer

View full text Add to dashboard Cite

show abstract

“…The critical flux has usually been measured for MF and UF membranes by the pressure or flux stepping methods where flux is increased step by step and the change in TMP at the same time [33,[36][37][38][39]. The rate of TMP changes as a function of time during filtration can increase remarkably above the critical flux.…”

Section: Critical Fluxmentioning

confidence: 99%

Development of techniques to characterize feed fouling potential for reverse osmosis operations

Taheri¹

View full text Add to dashboard Cite

Several factors affecting conventional fouling indices including SDI, MFI, MFI-UF (under constant pressure and constant flux) were investigated in this chapter. The very non-linear response of SDI to concentration was confirmed whereas the MFI results showed more linear behaviour. Analysis of the MFI-UF for colloidal silica and humic acid showed that the specific cake resistance was highest at low concentration and gradually declined at higher concentrations. For the mixed foulants the presence of modest amounts of humic acid (< 15 mg/L) tended to reduce both MFI-UF and specific resistance below that of the colloidal silica alone (50-150 mg/L). At high concentrations of humic the MFI-UF of the combined foulants exceeded that of silica alone. Over a broad range of NaCl the MFI-UF (constant pressure and constant flux) of the silica was observed to pass through a maximum, and this was explained by changes to particle-particle interactions as salt concentration increased. In contrast with colloidal silica, a maximum of MFI-UF was not observed in the range of NaCl concentration in this study.

show abstract