Selectivity of polyamide nanofiltration membranes for cations and phosphoric acid

Niewersch, Claudia; Meier, Klaus; Wintgens, Thomas; Melin, Thomas

doi:10.1016/j.desal.2009.09.097

Cited by 37 publications

(25 citation statements)

References 3 publications

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“…1(b)), phosphorus removal also increases with the increase of both feed conductivity and DOC. According to Niewersch et al [24], the feed solution composition influences the retention of each species due to the required electroneutrality that includes all the ions in solution and the building of electric double layers on the membrane surface. Multivalent cations will be retained by membrane and indirectly will increase the total concentration of the anions in feed water (Fig.…”

Section: Phosphorus Removalmentioning

confidence: 99%

Phosphorus recovery from waters using nanofiltration

Santos

Ribeiro

Teixeira

2014

Desalination and Water Treatment

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A B S T R A C TRecovery of phosphorus has been gaining importance due to its natural scarcity and expensive price. In this work, nanofiltration (NF) has been tested as a technology to treat surface waters with phosphorus and simultaneously recover that phosphorus. Two membranes of same material, but different molecular size were tested (NF270 and NF90). Results showed that membrane fluxes were more affected by the presence of salts, natural organic matter, and especially microcystins than phosphorus. In addition, phosphorus removals were very high (>90%) and varied with the membrane type, feed conductivity, and dissolved organic carbon (DOC). The increase in feed conductivity and DOC originated higher phosphorus removals. Furthermore, the presence of microcystins did not affect the high-phosphorus removals. Results show that more than 96% of the total phosphorus mass can be recovered using NF membranes. NF is therefore a technology that should be considered for phosphorus recovery from surface waters.

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Section: Phosphorus Removalmentioning

confidence: 99%

Phosphorus recovery from waters using nanofiltration

Santos

Ribeiro

Teixeira

2014

Desalination and Water Treatment

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“…Similar observations were also reported by Ducom et al (32) in the air-sparged nanofiltration of oil-water macroemulsions. At higher operating pressures, the driving force across the membrane for water transport increases leading to an enhancement of pure water flux (33). This is an indication of the fact that the membrane is quite stable and does not get compacted or stretched at higher pressure.…”

Section: Results and Discussion Effect Of Gas Sparging On Clean Watermentioning

confidence: 96%

“…With increase in operating pressure (at fixed feed concentration), the driving force across the membrane increases, leading to an enhancement of the permeate flux (33). Gas sparging at the gas velocity of 0.8 ms −1 led to some apparently contradictory results.…”

Section: Effect Of Tmp and Feed Concentrationmentioning

confidence: 97%

Mitigation of Flux Decline in the Cross-Flow Nanofiltration of Molasses Wastewater under the Effect of Gas Sparging

Nath¹,

Patel²

2014

Separation Science and Technology

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Gas sparging has been shown to significantly affect the performance of nanofiltration of molasses wastewater using a hydrophilized polyamide membrane (molecular weight cut-off 250) in a flat sheet module. Sparging of nitrogen at two different gas velocities was capable of appreciable alleviation of permeate flux decline over a period of time under the present experimental conditions when compared with the conventional unsparged nanofiltration. Critical flux (J crit ), limiting flux (J lim ), and shear stress number (N s ) were determined at different cross-flow velocities for both the cases in the presence and absence of gas sparging. Increase in N s with increasing cross-flow velocity was more pronounced in presence of gas sparging. Almost 1.5-2 fold increase in N s was observed using cross-flow velocity of 0.8 ms −1 with gas sparging, compared to the case of "no sparging." However, there was no significant improvement of rejection behavior of the solutes in presence of gas sparging. The value of mass transfer coefficient was considerably higher with increasing cross-flow velocity, while gas sparging was on, as against the case of "no sparging." In terms of percentage increase in permeate flux with increase in trans-membrane pressure (TMP), gas sparging could achieve higher enhancement where concentration polarization is expected to be severe, that is, at high TMP and high feed concentrations. Some practical issues and technical limitations of gas sparging are also discussed.

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“…The initial low rate of the flux increase is due to the variation in the trans-membrane pressure and the inlet pressure at lower and higher pressure operation. In the former case, the pressure drop across the membrane and in the system pipe line becomes quite significant in relation to the pressure of operation, compared to the case of higher pressure [18,19].…”

Section: Effect Of Tmpmentioning

confidence: 99%

Performance of polyamide and polyethersulfone membranes in the nanofiltration of reactive dye-salt mixtures on pilot scale

Patel¹,

Nath²

2014

Desalination and Water Treatment

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A B S T R A C TThin film composite polyamide (PA-NF) and polyethersulfone (PES-NF) membranes were used to study their performance towards reclamation of an aqueous solution of reactive red 198 and NaCl in a nanofiltration pilot plant. It was found that there were significant differences between the performance of the two membranes, and that the membrane properties played an important role in the dye removal rate, stable permeate flux, and salt rejection of the membrane. The experimental results showed that both the permeate flux and observed rejection decreased with an increase in dye as well as salt concentration in the feed. The maximum flux obtained with PA-NF membrane at 12.5 mg/l feed concentration was 11.4 Â 10 À6 m 3 /m 2 s, whereas with PES-NF the flux was 5.5 Â 10 À6 m 3 /m 2 s. The flux decline as a function of time for PES-NF membrane was much less compared to PA-NF. The contact angles of PA-NF and PES-NF membranes were found out to be 52 o and 73 o , respectively. Atomic force microscopy images revealed that the PA-NF membrane surface had more roughness than that of PES-NF.

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Selectivity of polyamide nanofiltration membranes for cations and phosphoric acid

Cited by 37 publications

References 3 publications

Phosphorus recovery from waters using nanofiltration

Phosphorus recovery from waters using nanofiltration

Mitigation of Flux Decline in the Cross-Flow Nanofiltration of Molasses Wastewater under the Effect of Gas Sparging

Performance of polyamide and polyethersulfone membranes in the nanofiltration of reactive dye-salt mixtures on pilot scale

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