Nanofiltration processes applied to the removal of phenyl-ureas in natural waters

Benítez, F. Javier; Acero, Juan L.; Real, Francisco J.; Garcı́a, Carmen

doi:10.1016/j.jhazmat.2008.10.047

Cited by 16 publications

(7 citation statements)

References 24 publications

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“…However, the estradiol steady-state feed and permeate concentrations were very similar for the three pressures used, showing no effect of pressure on the hormone retention. Furthermore, steady-state mass adsorbed was found not to vary with pressure, as obtained in another study [186]. In contrast, distinct differences in hormone retention when subjected to different pressures have been obtained elsewhere [153].…”

Section: Membrane Static Adsorptionsupporting

confidence: 62%

Estrogenic micropollutant adsorption dynamics onto nanofiltration membranes

Semiao

Schäfer

2011

Journal of Membrane Science

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Nanofiltration (NF) can be used in water and wastewater treatment as well as water recycling applications, removing micropollutants such as hormones. Due to their potential health risk it is vital to understand their removal mechanisms by NF membranes aiming at improving and developing more effective and efficient treatment processes. Although NF should be effective and efficient in removing small molecular sized compounds such as hormones, the occurrence of adsorption onto polymeric membranes results in performances difficult to predict and with reduced effectiveness and efficiency. This study aims firstly at defining, understanding and quantifying the relevant filtration operation parameters and, secondly, in identifying the physical mechanisms of momentum and mass transfer controlling the adsorption and transport of hormones onto polymeric NF membranes in cross-flow mode. The hormones estrone (E1) and 17-β-estradiol (E2) were chosen as they have very high endocrine disrupting potency. The NF membranes used and tested were the NF 270, NF 90, BW30, TFC-SR2 and TFC-SR3 since they have a wide span of pore sizes. The first step is to experimentally acquire the knowledge of how fluid flow hydrodynamics and mass transfer close to the membrane affect hormone adsorption. The focus will be particularly on the effect of operating pressure, circulating Reynolds numbers (based on channel height, Re h) and hormone feed concentration. These hydrodynamic parameters play an important role in concentration polarisation development at the membrane surface. A Re h increase from 400 to 1400 for the NF 270 membrane caused the total mass adsorbed of E1 and E2 to decrease from 1.5 to 1.3 ng.cm-2 and 0.7 to 0.5 ng.cm-2 , respectively. In contrast, a pressure increase from 5 to 15 bar yielded an increase in the adsorbed mass of E1 and E2 from 1.0 to 1.8 ng.cm-2 and 0.5 to 0.7 ng.cm-2 , respectively. Moreover, increasing hormone feed concentration caused an increase in the mass adsorbed for both hormones. These observations led to the conclusion that adsorption is governed by the initial concentration at the membrane surface which, in turn, depends on the hormone feed concentration, operating Re h and pressure. Membrane retention, however, depends on the initial polarisation v ACKNOWLEDGEMENTS I would like to thank Professor Andrea Schäfer for giving me the opportunity to do a PhD and the conditions to have the financial support for it. Her support, constructive criticism, ability to make me think and perseverance were essential to the success of this work. The difficult moments also turned out to be helpful and a valuable contribution to my personal and scientific maturity.

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Section: Membrane Static Adsorptionsupporting

confidence: 62%

Estrogenic micropollutant adsorption dynamics onto nanofiltration membranes

Semiao

Schäfer

2011

Journal of Membrane Science

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“…The higher permeability of the semi-aromatic membrane (NF99) can be attributed, as mentioned above, to its less dense and thinner polyamide layer and to the probable presence or more pinholes and local defects. The permeate flux increases linearly with pressure for both membranes, which means that no important fouling or polarization effects are to be expected [42]. The greater increase in permeate flux in the case of the NF99 membrane may also be due to the less dense and thinner polyamide layer of this membrane.…”

Section: Membrane Characterizationmentioning

confidence: 91%

“…Size exclusion and the Donnan effect are the two main mechanisms involved in rejection during nanofiltration and reverse osmosis [42,43]. For the uncharged molecules, such as 4C2MP at pH 8, size exclusion was the dominating factor influencing retention, while for the charged molecules, the Donnan effect resulting from the electrostatic interaction between membrane and charged solutes governed solute transport.…”

Section: Influence Of Pressurementioning

confidence: 99%

Removal of 4-chloro-2-methylphenol from aqueous solutions by nanofiltration and reverse osmosis

Hidalgo

León

Gómez

et al. 2015

Desalination and Water Treatment

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A B S T R A C TChloromethylphenols are typical phenolic pollutants frequently found in wastewater treatment plants and industrial landfill leachates, while pressure-driven membrane processes have been demonstrated to be a practical and competitive alternative for their removal. The performance of two membranes (an NF99 nanofiltration membrane and an RO99 reverse osmosis membrane) for removing 4-chloro-2-methylphenol (4C2MP) from synthetic solutions at different pressures, feed concentrations and feed pH values is compared in this paper using permeate flux and rejection as representative parameters. Higher permeate fluxes were obtained with the NF99 membrane but higher rates of 4C2MP rejection were obtained with the RO99 membrane. There was a substantial increase in 4C2MP rejection as the pH was increased from 8 to 11 in the case of the NF99 membrane. The results are explained by the different chemical structures of the active layers of both membranes.

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“…2b). This can be explained by assuming that an increase in pressure leads to both an increase in the water flux, the permeate becoming more dilute, and to an increase in the fouling layer on the membrane, which partially obstructs the permeation of atrazine and leads to higher R values [30].…”

Section: Influence Of Studied Parameters On Atrazine Rejectionmentioning

confidence: 99%

Atrazine removal from aqueous solutions by nanofiltration

Dalo

Hidalgo

́mez

et al. 2010

Desalination and Water Treatment

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There is an increasing concern about the release of herbicides and other organic compounds to the environment as a result of agricultural activities, due to their high toxicity for living organisms and their difficult to be degraded. Triazines are widely used herbicides that are highly toxic and frequently appear in natural watercourses, atrazine being one of the most commonly detected herbicides in aquatic systems. The atrazine rejection coefficients and the permeate fluxes of different nanofiltration membranes (NF-99, NF-97, Desal-5-DL and Desal-5-DK) for the removal of atrazine from water solutions in different operating conditions (feed atrazine concentration, pressure and pH) are studied in this article. Atrazine rejection was greater with the NF 99 and NF 97 membranes (90-98%), while the DL and DK membranes show much lower rejections (40-50%). The highest permeate fluxes are obtained with NF-99 and DL membranes. Atrazine rejection and permeate flux show no dependence on the atrazine feed concentration, low dependence on pH and a high positive dependence on pressure (especially the permeate flux). The results are explained by taking into account different solute parameters and membrane properties that affect the nanofiltration process.

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Nanofiltration processes applied to the removal of phenyl-ureas in natural waters

Cited by 16 publications

References 24 publications

Estrogenic micropollutant adsorption dynamics onto nanofiltration membranes

Estrogenic micropollutant adsorption dynamics onto nanofiltration membranes

Removal of 4-chloro-2-methylphenol from aqueous solutions by nanofiltration and reverse osmosis

Atrazine removal from aqueous solutions by nanofiltration

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