In most cases authors are permitted to post their version of the article (e.g. in Word or Tex for... more In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
The transport of hydronium and hydroxide ions through reverse osmosis membranes constitutes a uni... more The transport of hydronium and hydroxide ions through reverse osmosis membranes constitutes a unique case of ionic species characterized by uncommonly high permeabilities. Combined with electromigration, this leads to complex behavior of permeate pH, e.g., negative rejection, as often observed for monovalent ions in nanofiltration of salt mixtures. In this work we employed a rigorous phenomenological approach combined with chemical equilibrium to describe the trans-membrane transport of hydronium and hydroxide ions along with salt transport and calculate the resulting permeate pH. Starting from the Nernst-Planck equation, a full non-linear transport equation was derived, for which an approximate solution was proposed based on the analytical solution previously developed for trace ions in a dominant salt. Using the developed approximate equation, transport coefficients were deduced from experimental results obtained using a spiral wound reverse osmosis module operated under varying p...
Seawater nanofiltration (SWNF) generates a softened permeate stream and a retentate stream in whi... more Seawater nanofiltration (SWNF) generates a softened permeate stream and a retentate stream in which the multivalent ions accumulate, offering opportunities for practical utilization of both streams. This study presents an approach to simulation of SWNF including all major seawater ions (Na+, Cl-, Ca2+, Mg2+, and SO42-) based on the Nernst-Planck equation, and uses it for permeate and retentate streams composition prediction. The number of degrees of freedom in the system was reduced by assuming a very high ionic permeability for Na+, which only weakly affected the other parameters in the system. Two alternatives were examined to analyze the importance of concentration dependence of ion permeabilities: The assumption of constant ion permeabilities resulted in a reasonable fit with experimental data. However, for the permeate composition the overall fit was significantly improved (P<0.0001) when the permeabilities of Ca2+ and Mg2+ were allowed to depend on the ratio of their total ...
As a complementary step towards solving the general event detection problem of water distribution... more As a complementary step towards solving the general event detection problem of water distribution systems, injection of the organophosphate pesticides, chlorpyrifos (CP) and parathion (PA), were simulated at various locations within example networks and hydraulic parameters were calculated over 24-h duration. The uniqueness of this study is that the chemical reactions and byproducts of the contaminants' oxidation were also simulated, as well as other indicative water quality parameters such as alkalinity, acidity, pH and the total concentration of free chlorine species. The information on the change in water quality parameters induced by the contaminant injection may facilitate on-line detection of an actual event involving this specific substance and pave the way to development of a generic methodology for detecting events involving introduction of pesticides into water distribution systems. Simulation of the contaminant injection was performed at several nodes within two diffe...
ABSTRACT The boron isotopic composition of calcium carbonate skeletons is a promising proxy metho... more ABSTRACT The boron isotopic composition of calcium carbonate skeletons is a promising proxy method for reconstructing paleo-ocean pH and atmospheric CO2 from the geological record. Although the boron isotope methodology has been used extensively over the past two decades to determine ancient ocean-pH, the actual value of the boron isotope fractionation factor (εB) between the two main dissolved boron species, 11B(OH)3 and 10B(OH)−4, has remained uncertain. Initially, εB values were theoretically computed from vibrational frequencies of boron species, resulting in a value of ∼19‰. Later, spectrophotometric pH measurements on artificial seawater suggested a higher value of ∼27‰. A few independent theoretical models also pointed to a higher εB value. Here we provide, for the first time, an independent empirical fractionation factor (εB=26.0±1.0‰;25 °C), determined by direct measurements of B(OH)3 in seawater and other solutions. Boric acid was isolated by preferential passage through a reverse osmosis membrane under controlled pH conditions. We further demonstrate that applying the Pitzer ion-interaction approach, combined with ion-pairing calculations, results in a more accurate determination of species distribution in aquatic solutions of different chemical composition, relative to the traditional two-species boron-system approach. We show that using the revised approach reduces both the error in simulating ancient atmospheric CO2 (by up to 21%) and the overall uncertainty of applying boron isotopes for paleo-pH reconstruction. Combined, this revised methodology lays the foundation for a more accurate determination of ocean paleo-pH through time.
The quality with which water is released from desalination plants is continuously increasing. Sin... more The quality with which water is released from desalination plants is continuously increasing. Since desalination permeates are slightly acidic, contain very low buffering capacity and are very soft, post-treatment is always required. This paper reviews the knowledge accumulated in the last decades on desalination post-treatment processes. It covers fundamental chemistry aspects, required water quality criteria, advantages and disadvantages of currently applied processes, engineering and cost considerations, recent full-scale project experience and up-to-date research trends.►Fundamental chemistry aspects ►Definition of required water quality criteria ►Advantages and disadvantages of currently applied post-treatment processes ►Engineering and cost considerations ►Recent full-scale project experience
In most cases authors are permitted to post their version of the article (e.g. in Word or Tex for... more In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
The transport of hydronium and hydroxide ions through reverse osmosis membranes constitutes a uni... more The transport of hydronium and hydroxide ions through reverse osmosis membranes constitutes a unique case of ionic species characterized by uncommonly high permeabilities. Combined with electromigration, this leads to complex behavior of permeate pH, e.g., negative rejection, as often observed for monovalent ions in nanofiltration of salt mixtures. In this work we employed a rigorous phenomenological approach combined with chemical equilibrium to describe the trans-membrane transport of hydronium and hydroxide ions along with salt transport and calculate the resulting permeate pH. Starting from the Nernst-Planck equation, a full non-linear transport equation was derived, for which an approximate solution was proposed based on the analytical solution previously developed for trace ions in a dominant salt. Using the developed approximate equation, transport coefficients were deduced from experimental results obtained using a spiral wound reverse osmosis module operated under varying p...
Seawater nanofiltration (SWNF) generates a softened permeate stream and a retentate stream in whi... more Seawater nanofiltration (SWNF) generates a softened permeate stream and a retentate stream in which the multivalent ions accumulate, offering opportunities for practical utilization of both streams. This study presents an approach to simulation of SWNF including all major seawater ions (Na+, Cl-, Ca2+, Mg2+, and SO42-) based on the Nernst-Planck equation, and uses it for permeate and retentate streams composition prediction. The number of degrees of freedom in the system was reduced by assuming a very high ionic permeability for Na+, which only weakly affected the other parameters in the system. Two alternatives were examined to analyze the importance of concentration dependence of ion permeabilities: The assumption of constant ion permeabilities resulted in a reasonable fit with experimental data. However, for the permeate composition the overall fit was significantly improved (P<0.0001) when the permeabilities of Ca2+ and Mg2+ were allowed to depend on the ratio of their total ...
As a complementary step towards solving the general event detection problem of water distribution... more As a complementary step towards solving the general event detection problem of water distribution systems, injection of the organophosphate pesticides, chlorpyrifos (CP) and parathion (PA), were simulated at various locations within example networks and hydraulic parameters were calculated over 24-h duration. The uniqueness of this study is that the chemical reactions and byproducts of the contaminants' oxidation were also simulated, as well as other indicative water quality parameters such as alkalinity, acidity, pH and the total concentration of free chlorine species. The information on the change in water quality parameters induced by the contaminant injection may facilitate on-line detection of an actual event involving this specific substance and pave the way to development of a generic methodology for detecting events involving introduction of pesticides into water distribution systems. Simulation of the contaminant injection was performed at several nodes within two diffe...
ABSTRACT The boron isotopic composition of calcium carbonate skeletons is a promising proxy metho... more ABSTRACT The boron isotopic composition of calcium carbonate skeletons is a promising proxy method for reconstructing paleo-ocean pH and atmospheric CO2 from the geological record. Although the boron isotope methodology has been used extensively over the past two decades to determine ancient ocean-pH, the actual value of the boron isotope fractionation factor (εB) between the two main dissolved boron species, 11B(OH)3 and 10B(OH)−4, has remained uncertain. Initially, εB values were theoretically computed from vibrational frequencies of boron species, resulting in a value of ∼19‰. Later, spectrophotometric pH measurements on artificial seawater suggested a higher value of ∼27‰. A few independent theoretical models also pointed to a higher εB value. Here we provide, for the first time, an independent empirical fractionation factor (εB=26.0±1.0‰;25 °C), determined by direct measurements of B(OH)3 in seawater and other solutions. Boric acid was isolated by preferential passage through a reverse osmosis membrane under controlled pH conditions. We further demonstrate that applying the Pitzer ion-interaction approach, combined with ion-pairing calculations, results in a more accurate determination of species distribution in aquatic solutions of different chemical composition, relative to the traditional two-species boron-system approach. We show that using the revised approach reduces both the error in simulating ancient atmospheric CO2 (by up to 21%) and the overall uncertainty of applying boron isotopes for paleo-pH reconstruction. Combined, this revised methodology lays the foundation for a more accurate determination of ocean paleo-pH through time.
The quality with which water is released from desalination plants is continuously increasing. Sin... more The quality with which water is released from desalination plants is continuously increasing. Since desalination permeates are slightly acidic, contain very low buffering capacity and are very soft, post-treatment is always required. This paper reviews the knowledge accumulated in the last decades on desalination post-treatment processes. It covers fundamental chemistry aspects, required water quality criteria, advantages and disadvantages of currently applied processes, engineering and cost considerations, recent full-scale project experience and up-to-date research trends.►Fundamental chemistry aspects ►Definition of required water quality criteria ►Advantages and disadvantages of currently applied post-treatment processes ►Engineering and cost considerations ►Recent full-scale project experience
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