Activated Composite Membranes Research Articles

Osmium Nanoparticles-Polypropylene Hollow Fiber Membranes Applied in Redox Processes.

Composite membranes play a very important role in the separation, concentration, and purification processes, but especially in membrane reactors and membrane bioreactors. The development of composite membranes has gained momentum especially through the involvement of various nanoparticles, polymeric, oxide, or metal, that have contributed to increasing their reactivity and selectivity. This paper presents the preparation and characterization of an active metal nanoparticle-support polymer type composite membrane, based on osmium nanoparticles obtained in situ on a polypropylene hollow fiber membrane. Osmium nanoparticles are generated from a solution of osmium tetroxide in tert-butyl alcohol by reduction with molecular hydrogen in a contactor with a polypropylene membrane. The composite osmium-polypropylene hollow fiber obtained membranes (Os-PPM) were characterized from the morphological and structural points of view: scanning electron microscopy (SEM), high resolution SEM (HR-SEM), energy dispersive spectroscopy analysis (EDAX), X-ray diffraction analysis (XRD), Fourier transform Infrared (FTIR) spectroscopy, thermal gravimetric analysis, and differential scanning calorimetry (TGA, DSC). The process performance was tested in a redox process of p-nitrophenol and 10-undecylenic (10-undecenoic) acid, as a target substance of biological or biomedical interest, in solutions of lower aliphatic alcohols in a membrane contactor with a prepared composite membrane. The characteristics of osmium nanoparticles-polypropylene hollow fiber membranes open the way to biological and biotechnological applications. These membranes do not contaminate the working environment, operate at relatively low temperatures, provide a large contact area between reactants, allow successive oxidation and reduction operations in the same module, and help to recover the reaction mass by ultrafiltration. The results obtained show that the osmium-polypropylene composite membrane allows the reduction of p-nitrophenol or the oxidation of 10-undecylenic acid, the conversion depending on the concentration in the lower aliphatic alcohol, the nature of the lower aliphatic alcohol, and the oxidant or reducing flow through the membrane contactor.

Hierarchical poly(vinylidene fluoride)/active carbon composite membrane with self-confining functional carbon nanotube layer for intractable wastewater remediation

The efficient removal of trace micro pollutants and heavy metals from wastewater has been deemed as major challenge in the field of water treatment. Membrane composites have shown promises for the removal of these contaminants via green chemistry principles (i.e. membrane filtration). However, membrane composites normally lack appropriate surface porosity which hinders their performance, and it oftentimes causes membrane fouling. In this work, in order to ensure simultaneous removal of trace micro pollutants and heavy metals, a multi-functional active carbon inlayed poly(vinylidene fluoride) (PVDF) composite membrane with antifouling surface of polyacryloyl hydrazide (PAH)-grafted-carbon nanotubes (CNTs) layer is fabricated for the cross-flowing separation of oil/water emulsion, and heavy metals removal. The as-prepared PVDF-membrane composite with highly porous structure is integrated with powdered activated carbon (PAC) inlayed via the delayed liquid-liquid de-mixing process. The system shows high dynamic adsorption capacity towards the removal of toxic micro pollutants such as nitro-phenol, sulfamerazine and bisphenol A. In addition, micro/nano-hierarchical surface is constructed on the PVDF membrane via phase inversion. This enables successful anchorage of PAH-grafted-CNTs as antifouling layer on the surface of the PVDF-membrane. The reductive hydrophilic PAH brush on CNTs adsorbs different kinds of trace heavy metals (i.e. Cu2+, Ni+, and Cr3+) through reduction process. The PAH-grafted-CNTs also endows the composite membrane with excellent antifouling towards proteins.

Evaluation of activated composite membranes for the facilitated transport of phenol

Abstract In this work the results on the first use of an activated composite membrane (ACM) containing Cyanex 923 for the extraction and transport of phenol are presented. A new dense layer-ACM configuration constituted by piperazine showed better stability than that prepared with 1,3-phenylenediamine. The effects of several parameters on the transport of phenol such as feed phase pH, carrier concentration and stripping phase composition were evaluated. The performance of the membrane was also evaluated during continuous additions of phenol and for a long period of time, observing the same rate of extraction and reextraction. Moreover, phenol transport was evaluated starting from synthetic wastewater of resin production plants type. The results exhibit the potential use of ACMs in the elimination and transport of organic species, even when analyte is initially found in complex solutions.

Development of stable and active PVA‐PSSA/SA‐PVA catalytic composite membrane for esterification enhancement

ABSTRACTAn active and stable catalytic composite membrane (CCM), poly(vinyl alcohol)–poly(styrene sulfonic acid)/sodium alginate–poly(vinyl alcohol) (PVA‐PSSA/SA‐PVA), was prepared to enhance the esterification of ethanol and propionic acid. The morphologies and crystal structures of the CCMs were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray diffraction. The effects of catalytic layer thickness, mass ratio of PVA to PSSA, concentration of catalytic layer solution, ratio of reaction volume to membrane area, and molar ratio of propionic acid to ethanol were discussed. The pervaporation results showed that the flux of CCM increased from 118 to 320 g m−2 h−1 compared with the SA‐PVA membrane because of the close affinity and low resistance of PSSA to water. After crosslinking with 3‐aminopropylmethyldiethoxysilane, the CCMs had good catalytic activities. The acid conversion reached 92.8% at 75 °C in 12 h, and the stabilization of the CCM was greatly improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46514.

Active Polymeric Composite Membranes for Localized Actuation and Sensing in Microtransfer Printing

Soft locally active structures are becoming increasingly important in a number of applications, from microfluidic systems to soft robotics. In this paper, we develop an active polymeric composite membrane for use as an active stamp in the microtransfer printing process. The membrane is a composite of multiple layers: 1) a soft polydimethylsiloxane layer for transfer printing; 2) a lead zirconate titanate (PbZr0.52Ti0.48O3) layer for actuation; 3) metal layers for strain sensing and interconnects; and 4) patterned photopolymer (SU-8) layers for selectively tuning the compliance in the membrane and for handling. A novel and scalable fabrication approach that uses photolithography and microtransfer printing is developed for heterogeneously integrating the different materials into a functional structure. Approaches to designing and characterizing these active membranes are also discussed. Finally, the use of such membranes as stamps in the microtransfer printing process is demonstrated. By distributing actuation closer to critical regions of the tool, adaptability to local conditions for increased robustness and greater process flexibility is achieved. [2014-0211]

Earliest Results in the Use of Activated Composite Membranes for the Transport of Silver Ions from Aqueous Solutions

This paper presents the results concerning the first use of activated composite membranes (ACMs) for the facilitated transport of silver ions containing di-(2-ethylhexyl)-dithiophosphoric acid (DTPA) as the carrier. DTPA was immobilized by interfacial polymerization in a dense layer that was deposited in a porous layer, which was prepared on a nonwoven fabric support by phase inversion. The influence of fundamental parameters affecting the transport of silver ion as the carrier concentration in the membrane phase and stripping agent variation of the stripping solution have been studied. In the optimal conditions, the amount of silver transported across the ACMs was greater than 50%, whereas if the content of the carrier is modified, more than the 90% of the initial silver is removed from the feed phase.

Studies on Transport of Vanadium (V) and Nickel (II) from Wastewater Using Activated Composite Membranes

Third International Conference on Engineering for Waste and Biomass Valorization, May 2010, Beijing, China. The metals such as vanadium, nickel and iron are identified in the typical crude oils extracted from oil bearing rocks. The produced water contains salts, heavy metals, emulsified oil and other organics after the hot water extraction process (HWEP) of bitumen from oil sands. This is a serious environmental problem waiting for technically and economically feasible solutions. Membrane technologies such as ultra filtration, nanofiltration, and reverse osmosis are widely used in water purification and they are also applied for produced-water (wastewater stream in oil and gas production) purification. This study focuses on the transport of Vanadium (V) and Nickel (II) through activated composite membranes (ACMs) based on carrier Aliquat 336, in cyclohexane and dodecane. Reagents and materials, without further purification, and double distilled water were used. The UV-visible spectrophotometer and Atomic Absorption Spectrometer (FAAS) were utilised for measuring the concentrations of metal ions from aqueous solutions. Optimum conditions for both feed (pH 8) solutions, the influence of hydrodynamic conditions, the concentration of carrier on membrane (0.2, 0.5 and 0.7 M), the influence of aqueous feed acidity (4 < pH < 7), the influence of permeate reagents (NH3, HNO3, and Na2CO3) and the efficiency of separation process were established. The experiments were carried out at 20°C and low concentrations of V (V) and Ni (II), between 5 and 25 ppm, for modelling, as good as possible, one matrix of industrial wastewaters which contain V (V) and Ni (II) after HWEP. The coupled transport of vanadium from aqueous solutions following the reactions: $$ \left( {{\text{R}}_{ 4} {\text{N}}^{ + } {\text{Cl}}^{ - } } \right) \, _{\text{org}} \, + {\text{ VO}}_{ 2} \left( {\text{OH}} \right)_{ 2}^{ - } \rightleftarrows \left( {{\text{R}}_{ 4} {\text{N}}^{ + } {\text{VO}}_{ 2} \left( {\text{OH}} \right)_{ 2}^{ - } } \right)_{\text{org}} + {\text{ Cl}}^{ - } $$ $$ \left( {{\text{R}}_{ 4} {\text{N}}^{ + } {\text{VO}}_{ 2} \left( {\text{OH}} \right)^{ - }_{ 2} } \right)_{\text{org}} + {\text{ 2 OH}}^{ - } \rightleftarrows \left( {{\text{R}}_{ 4} {\text{N}}^{ + } {\text{OH}}^{ - } } \right)_{\text{org}} \, + {\text{VO}}_{ 3} {\text{OH}}^{ 2- } \, + {\text{ H}}_{ 2} {\text{O}} $$ The removal of V (V) and Ni (II) from wastewater samples was found to be governed by the carrier concentration used as well as the conditions of the aqueous feed and permeate solutions. The good efficiency of activated composite membranes separation was observed in case of V (V). The selectivity of Aliquat 336 based ACM toward V (V) and Ni (II) is presented and discussed. Selectivity demonstrated that vanadium ions were removable from mixtures due to the different extraction strength of Aliquat 336. Such selectivity is based on the difference of the dynamic behaviour of the metal ions transport.

Facilitated transport of Cr(VI) through a novel activated composite membrane containing Cyanex 923 as a carrier

This paper describes the facilitated transport of Cr(VI) through a novel Activated Composite Membrane (ACM) containing Cyanex 923 as a carrier. The ACM was prepared by immobilization of the Cyanex 923 on a polysulfone support by means of interfacial polymerisation. The prepared ACM was characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques and contact angle measurements. The effect of feed phase composition, carrier concentration of the casting solution and stripping phase composition on the transport of Cr(VI) was investigated. When the feed phase contained 1 × 10 −3 M Cr(VI) at pH 1.0, 99% of Cr(VI) was transported through the ACM (prepared with 3% carrier solution) by using 1 M NaOH as a stripping phase. Furthermore, Cr(VI) was preferably transported in the presence of various metal ions (i.e., Cr(III), Ni(II), Cu(II), Zn(II), Cd(II), Co(II), etc.) and sulphate and nitrate ions had no negative effect on the transport of Cr(VI). The results also showed that transport efficiency of the ACM was reproducible and it could be efficiently used in the long-term separation processes instead of supported liquid membrane (SLM).

Facilitated transport of Cr(III) through polymer inclusion membrane with di(2-ethylhexyl)phosphoric acid (DEHPA)

In this study, transport of Cr(III) through polymer inclusion membrane (PIM) with di(2-ethylhexyl)phosphoric acid (DEHPA) as carrier was reported. First, PIM was characterized by using FTIR and atomic force microscopy (AFM) techniques and contact angle measurements. Then, the effects of Cr(III) (in feed phase), HCl (in stripping phase) and DEHPA (in membrane) concentrations on the transport were investigated. DEHPA concentration varies from 0.25 to 0.5 M and it was determined that the transport of Cr(III) increased with the carrier concentration up to 0.4 M. It was also observed that the transport of Cr(III) through the PIM tended to increase with Cr(III) and HCl concentrations. According to the competitive transport of Cr(III), Cu(II) and Ni(II) through the PIM, the transport selectivity order was found as Cr(III) ≈ Cu(II) > Ni(II). The result from the transport of Cr(III) mixed with Cr(VI) also showed that flux of Cr(III) was not influenced by the presence of Cr(VI) in feed phase and no Cr(VI) transport through the PIM was determined. PIM had lower experimental Cr(III) flux than those of supported liquid membrane (SLM) and activated composite membrane (ACM) under the same experimental conditions. However, long-term stability of PIM and small difference between normalized flux for PIM and experimental SLM flux indicated that PIM could replace SLM for practical applications.

Facilitated transport of Cr(III) through activated composite membrane containing di-(2-ethylhexyl)phosphoric acid (DEHPA) as carrier agent

The facilitated transport of chromium(III) through activated composite membrane (ACM) containing di-(2-ethylhexyl) phosphoric acid (DEHPA) was investigated. DEHPA was immobilised by interfacial polymerisation on polysulfone layer which was deposited on non-woven fabric by using spin coater. Then, ACM was characterised by using scanning electron microscopy (SEM), contact angle measurements and atomic force microscopy (AFM). Initially, batch experiments of liquid–liquid distribution of Cr(III) and the extractant (DEHPA) were carried out to determine the appropriate pH of the feed phase and the results showed that maximum extraction of Cr(III) was achieved at a pH of 4. It was also found that Cr(III) and DEHPA reacted in 1/1 molar ratio. The effects of Cr(III) (in feed phase), HCl (in stripping phase) and DEHPA (in ACM) concentrations were investigated. DEHPA concentration varies from 0.1 to 1.0 M and it was determined that the transport of Cr(III) increased with the carrier concentration up to 0.8 M. It was also observed that the transport of Cr(III) through the ACM tended to increase with Cr(III) and HCl concentrations. The stability of ACM was also confirmed with replicate experiments.

Removal of Cr (VI) from industrial water effluents and surface waters using activated composite membranes

An experimental study for removal of Cr (VI) from industrial water effluents and surface waters using activated composite membranes (ACMs) based on the separation of Cr (VI) species in an ACM separate unit cell is described. Methyltricaprylammonium chloride (Aliquat 336) was used as ‘carrier’ in the activated composite membranes. Atomic Absorption Spectrometer (FAAS) was utilized for measuring the concentrations of metal: in feed solutions, the concentration of metal ranged from 25 to 120 mg L −1 and the pH was higher than 3.00 that decreased the probability that Cr (VI) reduced to Cr (III). Consequently, the effects of the pH and the carrier concentration in the membrane were discussed. The results seemed to prove the efficiency of the activated composite membranes such these: the membrane capacity (mol cm −2), the metal concentration (mg L −1) in feed and permeate solutions and the enrichment factor of Cr (VI) in permeate solutions. After 7 and 25 h of treatment with membrane of polluted water with Cr (VI) the water became unpolluted.

Facilitated transport of metal ions through composite and polymer inclusion membranes

The application of activated composite membranes (ACMs) and polymer inclusion membranes (PIMs) for the transport of Pb(II), Cd(II), and Zn(II) in a continuous extraction–reextraction system using organophosphorous acids as carriers was examined. The ion carriers, DEHPA, Cyanex 301, and Cyanex 302, were incorporated into PIMs composed of cellulose triacetate as a support and o-nitrophenyl pentyl ether as a plasticizer. ACMs were pepared by interfacial polymerization and PIMs by physical immobilization of carrier into plasticized cellulose triacetate. The polyamide top layer of the ACM immobilizes organophosphorous acids by trapping them in the polymer net during the interfacial polymerization process. Transport of Pb(II), Cd(II), and Zn(II) ions through ACM and PIM membranes was determined. Highly selective Pb(II) separation was achieved in the ACM system with Cyanex 301; the transport rate of process, however, was higher for the PIM system. It was found that ACM has much higher stability than PIM. A membrane-based process for Zn(II) or Pb(II) recovery from hydrometallurgical aqueous effluents has been proposed.

Selective transport of platinum(IV) and palladium(II) through hybrid and activated composite membranes containing Aliquat 336

Separation membranes systems for the trans-port of Pt(IV) and Pd(II) from aqueous feedchloride solutions have been developed andcharacterised by using tricaprilylmethylammo-nium chloride, Aliquat 336, as carrier. Thisextracting agent has previously demonstratedits effectiveness to transport Pt(IV) and Pd(II)across SLM [1]. Activated composite membranes (ACM) andhybrid membranes (HM) have been developedwith the main purpose of improving SLMsphysical and chemical properties, to get itsdiffusion facilities but with major chemical andphysical stability. These are metals of high interest due totheir extensive anthropogenic uses such as inautomotive catalysts, as catalysts in thesynthesis of pharmaceuticals as well as injewellery. The large demand of these metalsnext to their high prices has lead to a furtherimpetus for techniques to allow its separationand recovery.

Separation of Zinc and Bismuth by Facilitated Transport through Activated Composite Membranes

This paper reports the results on the further development of activated composite membranes (ACM) containing di‐2‐ethyhexyl‐dithiophosphoric acid (D2EHDTPA) as a carrier. The selectivity and transport properties of D2EHDTPA‐based ACMs towards different metal ions including bismuth and zinc appear to be interconnected with each other. It has been shown that unlike the liquid‐liquid extraction of bismuth, the use of D2EHDTPA‐ACM permits to recover and to concentrate bismuth from a highly saline medium without irreversible destruction of the carrier. The difference in the rates of bismuth and zinc transport through ACMs permits their separation since the former is concentrated in the stripping solution and the latter retains in the feed compartment of the membrane cell.

Atomic force microscopy as a suitable technique for surface characterization of activated composite membranes for metal ion facilitated transport

Activated composite membranes (ACM) have been made based on a polysulfone layer over a non-woven support with a dense layer of aromatic polyamide, and deposited on the polysulfone using interfacial polymerisation by a carrier agent – di(2-ethylhexyl) dithiophosphoric acid – added to the membranes at several concentrations. Two polysulfone supports have been used, one of them commercial (PSf-Com) an other made ad hoc by us (PSf-GTS). The membrane structure has been characterised by both atomic force microscopy (AFM) and scanning electron microscopy (SEM). Firstly, the two polysulfonic bases were studied. The results show that structurally both are quite similar. PSf-Com presents a more regular sponge like structure in the bulk with some macrovoids randomly distributed, with an average size of 25 μm. The results obtained demonstrate that after interfacial polymerisation, some structural defects appear with relatively big valleys and peaks. The roughness has been studied versus the AFM scan size, which allowed the evaluation of the corresponding fractal dimensions. This permitted a detailed comparison and detection of the differences and similarities of the surface structure of all the membranes studied. The membranes made on PSf-GTS, whose surface structure seems to yield a better coverage of polyamide, gave good performances in the extraction of certain heavy metals. After extraction the membranes were analysed by EDS to confirm the permanence of the extractant along with some deposits of salt and extracted ions.

Mercury Ions Removal from Aqueous Solution Using an Activated Composite Membrane

This work presents the results concerning the first use of activated composite membranes (ACMs) for the removal of Hg(II) ions from aqueous solution, using as the ligand di-(2-ethylhexyl)dithiophosphoric acid (DTPA). The effects on the removal percentage of Hg(ll) of variables such as pH, the nature of the acid, the concentration of mercury (in the feed solutions), and the ligand content (in the membrane) as well as the total surface membrane area exposed to the Hg(II) aqueous solution were studied. During the course of the removal experiments, the membrane was immersed in the Hg(II) aqueous solution in acid media and samples of the solution were taken at different times to enable monitoring of the mercury concentration changes. Itwasfound that when the ACM was prepared with a 1.0 M DTPA casting solution and the feed solution contained 2.49 x 10(-4) M Hg(II) in HCI 0.1 M the amount of mercury extracted was higher than 93%. Straight forwardly, additional experiments were carried out with the free-DTPA composite membranes to make up a set of control reference points to verify that removal of the investigated heavy metal was a consequence of the presence of the organic ligand; otherwise there was no Hg(II) concentration variation at all.

Activated Composite Membranes Containing the Chiral Carrier N-hexadecyl-l-hydroxyproline. Description of Morphology and Performance

Activated composite membranes (ACMs) containing the chiral carrier N-hexadecyl-l-hydroxyproline have been characterized by scanning electron microscopy (SEM). SEM membrane images have been further ...

Mass transfer determining parameter in facilitated transport through di-(2-ethylhexyl) dithiophosphoric acid activated composite membranes

Activated composite membranes (ACMs) containing di-(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA) as a carrier have been found to facilitate the transport and separation of several cations. This paper describes an approach to the chemical characterisation of the transport phenomena of Zn 2+, Cd 2+, Cu 2+, Ni 2+, Sn 2+ and In 3+ by an ACM. The selectivity of D2EHDTPA based ACM towards different metal ions is presented and discussed focusing in Zn 2+ and Cd 2+ transport and recovery. Selectivity demonstrates that zinc ions are removable from mixtures due to the different extraction strength of D2EHDTPA. Such selectivity is based on the differences of the dynamic behaviour of the metal ions transport. In addition, a correlation of the chemical behaviour of those ACM systems with the corresponding solvent extraction systems has been found.

Facilitated transport of Hg(II) through novel activated composite membranes.

The results presented in this work deal with the prime application of activated composite membranes (ACMs) for the transport of Hg(II) ions in a continuous extraction-re-extraction system using di-(2-ethylhexyl)dithiophosphoric acid (DTPA) as carrier. The effects of variables such as the pH, the nature of the acid and the concentration of the casting solutions on the transport of Hg(II) are also investigated. When the ACM was prepared with a 0.5 M DTPA solution and when the feed solution contained 2.5x10(-4) M Hg(II) in 0.1 M HCl, the amount of mercury extracted was greater than 76%. The re-extracted mercury was subsequently recovered by means of a stripping phase comprising 0.3 M thiourea solution in 2 M H2SO4, yielding 54% of the initial amount of mercury after transport had taken place for 180 min.

Ion-exchange membranes made of semi-interpenetrating polymer networks, used for pervaporation-assisted esterification and ion transport

Ionic membranes were prepared by blending poly(vinyl alcohol) (PVA) with an ionic polymer. Semi-interpenetrating polymer networks (sIPN) in which the crosslinked PVA chains trap the ionic polymer were obtained by using a heat treatment at 180 °C or dibromoethane vapor at 140 °C, respectively, for poly (styrene sulfonic acid) (PSSH), poly (sodium styrene sulfonate) (PSSNa), poly (acrylic acid) (PAA) or poly (dimethyl dimethylene piperidinum chloride) (PDMeDM-PCl) as the ionic polymer. The stability of the sIPN membranes in some liquid media was studied to select the appropriate membranes for the envisaged applications. The thermally crosslinked PVA/PSSH membranes showed an effective catalytic effect on the esterification reaction between n-propanol and propanoic acid. An active composite membrane made of a layer of PVA/PSSH deposited on a dense PVA layer of an industrial dehydration membrane exhibited both high catalytic activity and high selectivity to water in the pervaporation-assisted esterification. The values of the counter-ion transport number indicated that some crosslinked ionic membranes have good ion permselectivity.