The effect of plasma treatment of porous polyacrylonitrile membranes is discussed. It is shown th... more The effect of plasma treatment of porous polyacrylonitrile membranes is discussed. It is shown that air plasma increases the surface polarity at low-energy treatment and gradually diminishes it when the energy is increased. When the plasma is set at energies of 12, 30 or 60 W, etching of polymers dominates. Pore diameters of the membranes increase and their distribution functions become broader. When plasma of higher energies (120 or 180 W) is used, the effect of changes of the pore distribution disappears. Membranes modified with plasma of 60, 120 or 180 W do not differ in their porous structure. A simple method of an evaluation of pore diameter distribution function is presented.Der Einfluß von Luftplasma auf poröse Polyacrylnitril-Membranen wird diskutiert. Die Oberflchenpolaritt steigt bei Einwirkung von Luftplasma niedriger Energie und nimmt bei Energieerhöhung schrittweise ab. Bei Plasmaenergien von 12, 30 bzw. 60 W werden die Polymeren vorwiegend getzt, was zu größeren Porend...
Journal of colloid and interface science, Jan 15, 2014
The "capacitive mixing" (CAPMIX) is one of the techniques aimed at the extraction of en... more The "capacitive mixing" (CAPMIX) is one of the techniques aimed at the extraction of energy from the salinity difference between sea and rivers. It is based on the rise of the voltage between two electrodes, taking place when the salt concentration of the solution in which they are dipped is changed. We study the rise of the potential of activated carbon electrodes in NaCl solutions, as a function of their charging state. We evaluate the effect of the modification of the materials obtained by adsorption of charged molecules. We observe a displacement of the potential at which the potential rise vanishes, as predicted by the electric double layer theories. Moreover, we observe a saturation of the potential rise at high charging states, to a value that is nearly independent of the analyzed material. This saturation represents the most relevant element that determines the performances of the CAPMIX cell under study; we attribute it to a kinetic effect.
Arsenic is a very toxic element that must be removed efficiently from aqueous streams. Among the ... more Arsenic is a very toxic element that must be removed efficiently from aqueous streams. Among the most promising techniques used for the removal of arsenic are separation methods using membranes. In this study, a regenerated cellulose ultrafiltration (UF) membrane and a poly(diallyl dimethyl ammonium chloride) P(DADMAC) were coupled and used in combination to remove As(V) from an aqueous solution. The influences of pH, the polymer:As(V) molar ratio, and the presence of interfering ions such as chloride and sulfate were investigated in arsenic removal via the washing method. The efficient retention of arsenic was observed at pH 7 with a 5:1 polymer:As molar ratio and with an efficiency of approximately 85 % at Z = 10 for P(DADMAC). The maximum retention capacity of As(V) was determined by the enrichment method, and the results indicated that 194 mg of As(V) was removed per gram of polymer. Finally, using enrichment and washing methods sequentially, the sorption–desorption process and regeneration of P(DADMAC) were performed successfully.
Chemical Engineering and Processing: Process Intensification, 2015
ABSTRACT Temperature driven membrane thermopervaporation was studied in this work. Impact of vari... more ABSTRACT Temperature driven membrane thermopervaporation was studied in this work. Impact of various experimental conditions (feed temperature - Tf, type of membrane, type of organic solvent in binary aqueous mixture, feed composition) on transport and selectivity in TPV was investigated experimentally. Two commercially available dense PDMS based membranes (Pervatech and Pervap 4060) were utilized during TPV experiments in contact with pure water and binary aqueous mixtures of acetone, butanol and ethanol. Intrinsic properties (permeance and selectivity coefficient) of membranes were determined and discussed. Transport in thermopervaporation increases with an increase of feed temperature (at constant temperature of permeate). During TPV experiments performed with Pervatech in contact with acetone-water system, permeance of acetone increased from 0.12 mol m-2 h-1 kPa-1 at Tf=30oC to 0.24 mol m-2 h-1 kPa-1 at Tf=42oC, whereas permeance of butanol increased from 0.45 mol m-2 h-1 kPa-1 at Tf=30oC to 0.64 mol m-2 h-1 kPa-1 at Tf=41oC. Pervap 4060 membrane showed better properties in thermopervaporative recovery of butanol and ethanol from water than Pervatech membrane. It was also found that the application of stainless steel porous support reduces ethanol and water fluxes, but it does not affect the selectivity up to 3 wt.% of ethanol in feed.
ABSTRACT 75 KHz plasma was used to modify track etched poly(ethylene terephthalate) membranes and... more ABSTRACT 75 KHz plasma was used to modify track etched poly(ethylene terephthalate) membranes and deposit on them flouropolymers. Two fluorine bearing monomers were used: perflourohexane and hexafluorobenzene. The modified surfaces were analyzed by means of attenuated total reflection infra-red spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and wettability. It was detected that hexaflourobenxene deposited to the larger extent than perflourohaxane did. The roughness of surfaces decreased when more fluoropolymer was deposited. The hydrophobic character of surface slightly disappeared during 20-days storage of hexaflourobenzene modified membrane. Perfluorohexane modified membrane did not change its character within 120 days after modification. It was expected that this phenomenon resulted from post-reactions of oxygen with radicals in polymer deposits. The obtained membranes could be used for membrane distillation of juices.
ABSTRACT Results of research on the effectiveness of selected hydrophobic PDMS-based membranes in... more ABSTRACT Results of research on the effectiveness of selected hydrophobic PDMS-based membranes in the pervaporative removal of acetone, butanol and ethanol from binary and quaternary aqueous mixtures are presented. Various investigated PDMS membranes exhibit high selectivity towards butanol. Values of separation factor β in contact with 1 wt.% BuOH are in the range from 27 (Pervatech PDMS 2.0) to 40 (Pervap 1070 PDMS 0.2). Pervatech PDMS 2.0 membrane, showing the highest PSI value, was chosen for experiments with binary and quaternary aqueous mixtures. Simulation of batch pervaporation process showed that during 300 min of the process it is possible to remove over 95% of organics from the feed mixture, containing initially 3 wt.% of ABE mixture and with feed to membrane area ratio of 100 kg m−2. It was also found that a longer batch pervaporation process results in a more diluted permeate. Such phenomenon is caused by the fact that organic fluxes decrease with time whereas water flux is constant during batch process.
In the present study, batch kinetic tests have been performed for boron removal from model soluti... more In the present study, batch kinetic tests have been performed for boron removal from model solutions using boron selective ion exchange resins Diaion CRB 02, Dowex (XUS 43594.00) and Purolite S 108. Several kinetic models have been used to evaluate the sorption kinetics of boron by means of a well mixed stirred system, diffusional models, pseudo‐first‐order, and pseudo‐second‐order kinetic models.
The surface properties of blends of poly(methyl methacrylate) (PMMA) with statistical copolymer o... more The surface properties of blends of poly(methyl methacrylate) (PMMA) with statistical copolymer of styrene and acrylonitrile having 28wt% of acrylonitrile (SAN) have been studied as a function of blend compositions. The surface enrichment of PMMA was shown at all compositions of blends. Presented theoretical calculations well correlate with experimental data. Spinodal decomposition of the PMMA/SAN blend did not result in
The effect of plasma treatment of porous polyacrylonitrile membranes is discussed. It is shown th... more The effect of plasma treatment of porous polyacrylonitrile membranes is discussed. It is shown that air plasma increases the surface polarity at low-energy treatment and gradually diminishes it when the energy is increased. When the plasma is set at energies of 12, 30 or 60 W, etching of polymers dominates. Pore diameters of the membranes increase and their distribution functions become broader. When plasma of higher energies (120 or 180 W) is used, the effect of changes of the pore distribution disappears. Membranes modified with plasma of 60, 120 or 180 W do not differ in their porous structure. A simple method of an evaluation of pore diameter distribution function is presented.Der Einfluß von Luftplasma auf poröse Polyacrylnitril-Membranen wird diskutiert. Die Oberflchenpolaritt steigt bei Einwirkung von Luftplasma niedriger Energie und nimmt bei Energieerhöhung schrittweise ab. Bei Plasmaenergien von 12, 30 bzw. 60 W werden die Polymeren vorwiegend getzt, was zu größeren Porend...
Journal of colloid and interface science, Jan 15, 2014
The "capacitive mixing" (CAPMIX) is one of the techniques aimed at the extraction of en... more The "capacitive mixing" (CAPMIX) is one of the techniques aimed at the extraction of energy from the salinity difference between sea and rivers. It is based on the rise of the voltage between two electrodes, taking place when the salt concentration of the solution in which they are dipped is changed. We study the rise of the potential of activated carbon electrodes in NaCl solutions, as a function of their charging state. We evaluate the effect of the modification of the materials obtained by adsorption of charged molecules. We observe a displacement of the potential at which the potential rise vanishes, as predicted by the electric double layer theories. Moreover, we observe a saturation of the potential rise at high charging states, to a value that is nearly independent of the analyzed material. This saturation represents the most relevant element that determines the performances of the CAPMIX cell under study; we attribute it to a kinetic effect.
Arsenic is a very toxic element that must be removed efficiently from aqueous streams. Among the ... more Arsenic is a very toxic element that must be removed efficiently from aqueous streams. Among the most promising techniques used for the removal of arsenic are separation methods using membranes. In this study, a regenerated cellulose ultrafiltration (UF) membrane and a poly(diallyl dimethyl ammonium chloride) P(DADMAC) were coupled and used in combination to remove As(V) from an aqueous solution. The influences of pH, the polymer:As(V) molar ratio, and the presence of interfering ions such as chloride and sulfate were investigated in arsenic removal via the washing method. The efficient retention of arsenic was observed at pH 7 with a 5:1 polymer:As molar ratio and with an efficiency of approximately 85 % at Z = 10 for P(DADMAC). The maximum retention capacity of As(V) was determined by the enrichment method, and the results indicated that 194 mg of As(V) was removed per gram of polymer. Finally, using enrichment and washing methods sequentially, the sorption–desorption process and regeneration of P(DADMAC) were performed successfully.
Chemical Engineering and Processing: Process Intensification, 2015
ABSTRACT Temperature driven membrane thermopervaporation was studied in this work. Impact of vari... more ABSTRACT Temperature driven membrane thermopervaporation was studied in this work. Impact of various experimental conditions (feed temperature - Tf, type of membrane, type of organic solvent in binary aqueous mixture, feed composition) on transport and selectivity in TPV was investigated experimentally. Two commercially available dense PDMS based membranes (Pervatech and Pervap 4060) were utilized during TPV experiments in contact with pure water and binary aqueous mixtures of acetone, butanol and ethanol. Intrinsic properties (permeance and selectivity coefficient) of membranes were determined and discussed. Transport in thermopervaporation increases with an increase of feed temperature (at constant temperature of permeate). During TPV experiments performed with Pervatech in contact with acetone-water system, permeance of acetone increased from 0.12 mol m-2 h-1 kPa-1 at Tf=30oC to 0.24 mol m-2 h-1 kPa-1 at Tf=42oC, whereas permeance of butanol increased from 0.45 mol m-2 h-1 kPa-1 at Tf=30oC to 0.64 mol m-2 h-1 kPa-1 at Tf=41oC. Pervap 4060 membrane showed better properties in thermopervaporative recovery of butanol and ethanol from water than Pervatech membrane. It was also found that the application of stainless steel porous support reduces ethanol and water fluxes, but it does not affect the selectivity up to 3 wt.% of ethanol in feed.
ABSTRACT 75 KHz plasma was used to modify track etched poly(ethylene terephthalate) membranes and... more ABSTRACT 75 KHz plasma was used to modify track etched poly(ethylene terephthalate) membranes and deposit on them flouropolymers. Two fluorine bearing monomers were used: perflourohexane and hexafluorobenzene. The modified surfaces were analyzed by means of attenuated total reflection infra-red spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and wettability. It was detected that hexaflourobenxene deposited to the larger extent than perflourohaxane did. The roughness of surfaces decreased when more fluoropolymer was deposited. The hydrophobic character of surface slightly disappeared during 20-days storage of hexaflourobenzene modified membrane. Perfluorohexane modified membrane did not change its character within 120 days after modification. It was expected that this phenomenon resulted from post-reactions of oxygen with radicals in polymer deposits. The obtained membranes could be used for membrane distillation of juices.
ABSTRACT Results of research on the effectiveness of selected hydrophobic PDMS-based membranes in... more ABSTRACT Results of research on the effectiveness of selected hydrophobic PDMS-based membranes in the pervaporative removal of acetone, butanol and ethanol from binary and quaternary aqueous mixtures are presented. Various investigated PDMS membranes exhibit high selectivity towards butanol. Values of separation factor β in contact with 1 wt.% BuOH are in the range from 27 (Pervatech PDMS 2.0) to 40 (Pervap 1070 PDMS 0.2). Pervatech PDMS 2.0 membrane, showing the highest PSI value, was chosen for experiments with binary and quaternary aqueous mixtures. Simulation of batch pervaporation process showed that during 300 min of the process it is possible to remove over 95% of organics from the feed mixture, containing initially 3 wt.% of ABE mixture and with feed to membrane area ratio of 100 kg m−2. It was also found that a longer batch pervaporation process results in a more diluted permeate. Such phenomenon is caused by the fact that organic fluxes decrease with time whereas water flux is constant during batch process.
In the present study, batch kinetic tests have been performed for boron removal from model soluti... more In the present study, batch kinetic tests have been performed for boron removal from model solutions using boron selective ion exchange resins Diaion CRB 02, Dowex (XUS 43594.00) and Purolite S 108. Several kinetic models have been used to evaluate the sorption kinetics of boron by means of a well mixed stirred system, diffusional models, pseudo‐first‐order, and pseudo‐second‐order kinetic models.
The surface properties of blends of poly(methyl methacrylate) (PMMA) with statistical copolymer o... more The surface properties of blends of poly(methyl methacrylate) (PMMA) with statistical copolymer of styrene and acrylonitrile having 28wt% of acrylonitrile (SAN) have been studied as a function of blend compositions. The surface enrichment of PMMA was shown at all compositions of blends. Presented theoretical calculations well correlate with experimental data. Spinodal decomposition of the PMMA/SAN blend did not result in
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