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Papers by Arto Pihlajamäki

Research paper thumbnail of Characterization of ultrafiltration membranes by simultaneous streaming potential and flux measurements

Journal of membrane science, 1994

Research paper thumbnail of Effect of Precipitation Temperature on the Properties of Cellulose Ultrafiltration Membranes Prepared via Immersion Precipitation with Ionic Liquid as Solvent

Membranes

Supported cellulose ultrafiltration membranes are cast from a cellulose-ionic liquid solution by ... more Supported cellulose ultrafiltration membranes are cast from a cellulose-ionic liquid solution by the immersion precipitation technique. The effects of coagulation bath temperature and polymer concentration in the casting solution on the membrane morphology, wettability, pure water flux, molecular weight cut-off, and fouling resistance are studied. Scanning electron microscopy, contact angle measurements, atomic force microscopy, and filtration experiments are carried out in order to characterise the obtained ultrafiltration cellulose membranes. The results show the effect of coagulation bath temperature and polymer concentration on the surface morphology and properties of cellulose ultrafiltration membranes. Optimisation of the two parameters leads to the creation of dense membranes with good pure water fluxes and proven fouling resistance towards humic acid water solutions.

Research paper thumbnail of Effect of pH on hydrophilicity and charge and their effect on the filtration efficiency of NF membranes at different pH

Journal of Membrane Science, 2006

In this work the effect of pH on membrane structure, its permeability and retention was studied. ... more In this work the effect of pH on membrane structure, its permeability and retention was studied. In addition, we studied whether the possible changes in the membrane properties due to the pH change are reversible. This is important for understanding the performance of nanofiltration membranes at different conditions and for the selection of cleaning processes. Moreover, the results facilitate the choice of membrane for specific applications.Several commercial NF membranes were studied at different pH values. Their retention and flux were explained by the charge and the hydrophilic characteristics of the membranes. The filtrations were made with uncharged sugar and salt solutions.The lower the membrane contact angle (i.e., a more hydrophilic membrane) the higher was the change in apparent zeta potential when pH was increased from 4 to 7. As a result, the retention of ions with more hydrophilic membranes changed more than hydrophobic ones when the pH was increased in the feed solution. However, some membranes retained ions well at high pH although their apparent zeta potential or hydrophilicity was relatively low. These membranes had charge inside the pores and it was not detected by streaming potential measurement along the surface or by measuring the contact angle of the surface. Thus, the apparent zeta potential of the exterior membrane surface did not sufficiently describe the ionic transport through the membrane. In addition, some membranes became significantly more open at high pH (i.e., flux increased). This was explained by the chemical nature of the polymer chains in the membrane skin layer, i.e., dissociating groups in the polymer made the surface more hydrophilic and looser when charges of the polymer chains started to repel each other at elevated pH. Generally, the retention of uncharged glucose decreased more at high pH than the salt retention. The changes in permeabilities and retentions were found to be mostly reversible in the pH range studied (very slowly in some cases, however).

Research paper thumbnail of Determining the zeta-potential of ceramic microfiltration membranes using the electroviscous effect

Journal of Membrane Science, 1998

The possibility of measuring the zeta-potentials of porous membranes using the electroviscous eff... more The possibility of measuring the zeta-potentials of porous membranes using the electroviscous effect was investigated. The zeta-potential of Membralox 1 ceramic micro®ltration membranes was determined both with the newly developed electroviscous technique and by streaming potential measurements. It was found that the electroviscous technique provided a simple means of obtaining accurate values of zeta-potential, especially for higher zeta-potentials. The streaming potential measurements were found to be more suitable for the determination of the iso-electric point, i.e. the pH at which the zetapotential is zero.

Research paper thumbnail of Preparation and characterization of PES and PSU membrane humidifiers

Journal of Membrane Science, 2011

Polysulfone (PSU) and polyethersulfone (PES) porous membranes; and mixed polymer with nanoparticl... more Polysulfone (PSU) and polyethersulfone (PES) porous membranes; and mixed polymer with nanoparticles TiO2, were prepared for air humidification. The mechanical properties and morphology of these membranes were studied by Tensile tester and SEM/EDX. The ...

Research paper thumbnail of The influence of hydrophobicity, roughness and charge upon ultrafiltration membranes for black tea liquor clarification

Journal of Membrane Science, 2008

... The influence of hydrophobicity, roughness and charge upon ultrafiltration membranes for blac... more ... The influence of hydrophobicity, roughness and charge upon ultrafiltration membranes for black tea liquor clarification. ... 2. Experimental. 2.1. Black tea. Soluble spray driedblack tea powder was supplied by Unilever R&D, Colworth. ...

Research paper thumbnail of Comparison of nanofiltration and tight ultrafiltration membranes in the filtration of paper mill process water

Research paper thumbnail of Effect of temperature and membrane pre-treatment by pressure on the filtration properties of nanofiltration membranes

Research paper thumbnail of Physico-chemical characterisations of a UF membrane used in dairy application to estimate chemical efficiency of cleaning

Desalination, 2006

... Murielle Rabiller-Baudrya*, Lydie Paugama, Arto Pihlajamäkib, Marianne Nyströmb aChimie et In... more ... Murielle Rabiller-Baudrya*, Lydie Paugama, Arto Pihlajamäkib, Marianne Nyströmb aChimie et Ingénierie des Procédés, UMR 6226 CNRS “Sciences Chimiques de Rennes” Université Rennes 1– ENSCR, 263 avenue du général Leclerc, Campus Beaulieu Batiment 10 A, CS ...

Research paper thumbnail of Non-enhanced ultrafiltration of iron(III) with commercial ceramic membranes

Journal of Membrane Science, 2009

Membranes are nowadays being developed as a mature technology to deal with polluted waters contai... more Membranes are nowadays being developed as a mature technology to deal with polluted waters containing heavy metals. Nanofiltration membranes have classically been employed for this purpose. However, it was recently shown that a 5 kDa ceramic ultrafiltration membrane could be successfully used to recover iron(III) from aqueous solutions even at acidic pH, although the mechanisms associated with the retention of iron were not clearly established. This paper aims to highlight the phenomena associated with the retention of iron(III) species by commercial ceramic ultrafiltration membranes. The results show that iron(III) retention by ceramic membranes is strongly influenced by the molecular weight cut-off of the membranes and their material, although even 50 kDa molecular weight cut-off membranes are capable to efficiently retain iron species. A retention mechanism based on iron-membrane adsorption seems to be the most likely for explaining iron rejection when using UF membranes. However, charge repulsion phenomena and sieving effects may also contribute to the rejection of iron(III). The occurrence of mononuclear hydrolysed iron species, which can result in the formation of polynuclear species in the neighbourhood of the membrane surface could definitively contribute to the high retention of iron(III) shown by ceramic ultrafiltration membranes.

Research paper thumbnail of Characterization of ultrafiltration membranes by simultaneous streaming potential and flux measurements

Journal of membrane science, 1994

Research paper thumbnail of Effect of Precipitation Temperature on the Properties of Cellulose Ultrafiltration Membranes Prepared via Immersion Precipitation with Ionic Liquid as Solvent

Membranes

Supported cellulose ultrafiltration membranes are cast from a cellulose-ionic liquid solution by ... more Supported cellulose ultrafiltration membranes are cast from a cellulose-ionic liquid solution by the immersion precipitation technique. The effects of coagulation bath temperature and polymer concentration in the casting solution on the membrane morphology, wettability, pure water flux, molecular weight cut-off, and fouling resistance are studied. Scanning electron microscopy, contact angle measurements, atomic force microscopy, and filtration experiments are carried out in order to characterise the obtained ultrafiltration cellulose membranes. The results show the effect of coagulation bath temperature and polymer concentration on the surface morphology and properties of cellulose ultrafiltration membranes. Optimisation of the two parameters leads to the creation of dense membranes with good pure water fluxes and proven fouling resistance towards humic acid water solutions.

Research paper thumbnail of Effect of pH on hydrophilicity and charge and their effect on the filtration efficiency of NF membranes at different pH

Journal of Membrane Science, 2006

In this work the effect of pH on membrane structure, its permeability and retention was studied. ... more In this work the effect of pH on membrane structure, its permeability and retention was studied. In addition, we studied whether the possible changes in the membrane properties due to the pH change are reversible. This is important for understanding the performance of nanofiltration membranes at different conditions and for the selection of cleaning processes. Moreover, the results facilitate the choice of membrane for specific applications.Several commercial NF membranes were studied at different pH values. Their retention and flux were explained by the charge and the hydrophilic characteristics of the membranes. The filtrations were made with uncharged sugar and salt solutions.The lower the membrane contact angle (i.e., a more hydrophilic membrane) the higher was the change in apparent zeta potential when pH was increased from 4 to 7. As a result, the retention of ions with more hydrophilic membranes changed more than hydrophobic ones when the pH was increased in the feed solution. However, some membranes retained ions well at high pH although their apparent zeta potential or hydrophilicity was relatively low. These membranes had charge inside the pores and it was not detected by streaming potential measurement along the surface or by measuring the contact angle of the surface. Thus, the apparent zeta potential of the exterior membrane surface did not sufficiently describe the ionic transport through the membrane. In addition, some membranes became significantly more open at high pH (i.e., flux increased). This was explained by the chemical nature of the polymer chains in the membrane skin layer, i.e., dissociating groups in the polymer made the surface more hydrophilic and looser when charges of the polymer chains started to repel each other at elevated pH. Generally, the retention of uncharged glucose decreased more at high pH than the salt retention. The changes in permeabilities and retentions were found to be mostly reversible in the pH range studied (very slowly in some cases, however).

Research paper thumbnail of Determining the zeta-potential of ceramic microfiltration membranes using the electroviscous effect

Journal of Membrane Science, 1998

The possibility of measuring the zeta-potentials of porous membranes using the electroviscous eff... more The possibility of measuring the zeta-potentials of porous membranes using the electroviscous effect was investigated. The zeta-potential of Membralox 1 ceramic micro®ltration membranes was determined both with the newly developed electroviscous technique and by streaming potential measurements. It was found that the electroviscous technique provided a simple means of obtaining accurate values of zeta-potential, especially for higher zeta-potentials. The streaming potential measurements were found to be more suitable for the determination of the iso-electric point, i.e. the pH at which the zetapotential is zero.

Research paper thumbnail of Preparation and characterization of PES and PSU membrane humidifiers

Journal of Membrane Science, 2011

Polysulfone (PSU) and polyethersulfone (PES) porous membranes; and mixed polymer with nanoparticl... more Polysulfone (PSU) and polyethersulfone (PES) porous membranes; and mixed polymer with nanoparticles TiO2, were prepared for air humidification. The mechanical properties and morphology of these membranes were studied by Tensile tester and SEM/EDX. The ...

Research paper thumbnail of The influence of hydrophobicity, roughness and charge upon ultrafiltration membranes for black tea liquor clarification

Journal of Membrane Science, 2008

... The influence of hydrophobicity, roughness and charge upon ultrafiltration membranes for blac... more ... The influence of hydrophobicity, roughness and charge upon ultrafiltration membranes for black tea liquor clarification. ... 2. Experimental. 2.1. Black tea. Soluble spray driedblack tea powder was supplied by Unilever R&D, Colworth. ...

Research paper thumbnail of Comparison of nanofiltration and tight ultrafiltration membranes in the filtration of paper mill process water

Research paper thumbnail of Effect of temperature and membrane pre-treatment by pressure on the filtration properties of nanofiltration membranes

Research paper thumbnail of Physico-chemical characterisations of a UF membrane used in dairy application to estimate chemical efficiency of cleaning

Desalination, 2006

... Murielle Rabiller-Baudrya*, Lydie Paugama, Arto Pihlajamäkib, Marianne Nyströmb aChimie et In... more ... Murielle Rabiller-Baudrya*, Lydie Paugama, Arto Pihlajamäkib, Marianne Nyströmb aChimie et Ingénierie des Procédés, UMR 6226 CNRS “Sciences Chimiques de Rennes” Université Rennes 1– ENSCR, 263 avenue du général Leclerc, Campus Beaulieu Batiment 10 A, CS ...

Research paper thumbnail of Non-enhanced ultrafiltration of iron(III) with commercial ceramic membranes

Journal of Membrane Science, 2009

Membranes are nowadays being developed as a mature technology to deal with polluted waters contai... more Membranes are nowadays being developed as a mature technology to deal with polluted waters containing heavy metals. Nanofiltration membranes have classically been employed for this purpose. However, it was recently shown that a 5 kDa ceramic ultrafiltration membrane could be successfully used to recover iron(III) from aqueous solutions even at acidic pH, although the mechanisms associated with the retention of iron were not clearly established. This paper aims to highlight the phenomena associated with the retention of iron(III) species by commercial ceramic ultrafiltration membranes. The results show that iron(III) retention by ceramic membranes is strongly influenced by the molecular weight cut-off of the membranes and their material, although even 50 kDa molecular weight cut-off membranes are capable to efficiently retain iron species. A retention mechanism based on iron-membrane adsorption seems to be the most likely for explaining iron rejection when using UF membranes. However, charge repulsion phenomena and sieving effects may also contribute to the rejection of iron(III). The occurrence of mononuclear hydrolysed iron species, which can result in the formation of polynuclear species in the neighbourhood of the membrane surface could definitively contribute to the high retention of iron(III) shown by ceramic ultrafiltration membranes.