Aqueous Phase Monomer Research Articles

Continuous preparation of polyHIPE monoliths from ionomer-stabilized high internal phase emulsions (HIPEs) for efficient recovery of spilled oils

We present a facile and continuous approach to prepare polyHIPE monoliths for efficient reclamation of spilled oils. The polyHIPE monoliths were produced from a light induced polymerization of an ionomer, namely sulfonated polystyrene stabilized high internal phase emulsions (SPS-HIPEs). The SPS-HIPEs consisted of seawater as the dispersed aqueous phase and inexpensive monomers such as butyl acrylate and tetraethyl orthosilicate (TEOS) as the continuous phase. Sulfonated polystyrene was from used foams, realizing a sustainable transformation of waste polystyrene. PolyHIPE monoliths from SPS-HIPEs (SPS-polyHIPEs) reached a high gel fraction of 93% with exposure to UV light for only 5min, providing a possibility to produce them continuously. SPS-polyHIPEs are much greener in comparison to those from surfactant- or particles-stabilized HIPEs, and no purification is required prior to use. SPS-polyHIPE monoliths exhibit interconnected macro-porous structures, and the sizes of pores as well as pore throats can be controlled simply by the volume fraction of the dispersed phase. These monoliths are hydrophobic with a water contact angle over 140°. Excellent performances have been verified for oil spill reclamation, including high absorption capacity to a series of organic solvents or oils, high absorption rate of reaching saturated absorption in 3–5min, a high recovery rate over 85% and a high reusability over 20 times. A continuous process has been illustrated using SPS-polyHIPEs as absorbents for oil spill recovery.

Theoretical Study of Reactions between Oxygen-Centered Radicals (•OH and SO4•-) and Vinyl Monomers in Aqueous Phase

Theoretical Study of Reactions between Oxygen-Centered Radicals (^•OH and SO₄^•-) and Vinyl Monomers in Aqueous Phase

Thin-film-composite hollow-fiber membranes for water vapor separation

Polyethersulfone (PES) hollow fiber membranes were prepared using the phase inversion technique. The surface of the PES hollow fiber membranes consisted of thin film composite polymer membranes. These membranes were prepared by interfacial polymerization using four different aqueous phase monomers: 1,3-benzenedithiol (BDT), m-phenylenediamine (MPD), 1,3,5-benzenetrithol (BTT), and piperazine (PIP). The organic phase monomer, trimesoyl chloride (TMC), was used to produce the covalent organic polymers. Different types of aqueous monomers (with a number of reactive groups) and their structures were optimized to achieve maximum gas permeation efficiency and water vapor/N2 selectivity. All prepared membranes were fully characterized using different analytical techniques. Among all of the prepared thin film composite (TFC) membranes the one prepared with the 1,3-benzenedithiol monomer (TFC-HF-1) exhibited superior results as water vapor permeance 2054 GPU, and the water vapor/N2 selectivity 119. The prepared membrane substrates and TFC membranes were characterized by chemical structure, morphology and separation performance. Overall, the membranes exhibited good performance over the entire investigated range of operating conditions.

Development of carboxylated TiO2 incorporated thin film nanocomposite hollow fiber membranes for flue gas dehydration

In this work, thin film nanocomposite (TFN) membranes for water vapor removal have been fabricated by incorporation of carboxylated TiO2 nanoparticles in the polyamide membrane matrix. Surface of pure TiO2 was modified to introduce functional groups on the TiO2 surface and increase the hydrophilicity of the nanoparticles. Modified nanoparticles were then homogeneously dispersed in the aqueous phase monomer (3, 5-diaminobenzoic acid) and reacted with trimesoyl chloride (TMC) to form a thin film nanocomposite membrane (TFN) on top of the polysulfone hollow fiber membrane (HFM) substrate. The carboxylation of TiO2 was confirmed by FTIR spectra. Intrinsic properties of the TFN were analyzed by ATR-FTIR, scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle. Introduction of carboxylated TiO2 caused a more dense and cross-linked polyamide layer due to its high binding affinity with the polyamide layer, which was also confirmed by SEM analysis. Furthermore, the addition of modified nanoparticles also increased the hydrophilicity of the TFN membrane due to excess carboxylic groups. Water vapor permeance and selectivity drastically improved due to the increased water vapor permeation paths provided by the modified nanoparticles. A maximum water vapor permeance and selectivity of 1340 GPU and 486 respectively, were obtained at optimum conditions. In addition, effect of reaction time and monomer concentration have also been studied and correlated.

H2/CO mixture gas separation using composite hollow fiber membranes prepared by interfacial polymerization method

This paper describes the study on H2/CO mixture gas separation through thin film composite (TFC) membranes prepared by interfacial polymerization method. Composite membranes have been widely applied in gas separation process. Polyethersulfone (PES) hollow fiber membranes (HFMs) are fabricated using dry–wet phase inversion method as high permeability substrates. H2/CO mixture gas selectivity and permeance were studied using different concentrations of aqueous and organic phase monomers. Cross-linked structures of TFC membranes by interfacial polymerization were confirmed and discussed by using the compiled results of characterization, such as ATR-FTIR, FE-SEM, and TEM. The performance of HFM using different monomer concentrations of 1,3-cyclohexanebis methylamine (CHMA) (aqueous phase monomer) and trimesoyl chloride (TMC) (organic phase monomer) towards H2/CO mixture gas selectivity and permeance have been studied, and the effects of operating pressures, retentate flow rates and stage-cuts on separation factor and permeance were also investigated in this work. The monomers concentrations affect the selectivity and permeability in H2/CO mixture gas separation. Experimental results confirmed that increasing of operating pressure and stage-cut led to higher separation factor and showed simulation of module design to consider characteristics of membrane and behaviors for H2/CO mixture gas separation. In this paper, also represent the membrane spinning, polymerization and Membrane process design.

Regulating the aqueous phase monomer balance for flux improvement in polyamide thin film composite membranes

Polyamide thin film composite (PA TFC) membranes are synthesized from interfacial polymerization using two amines in the aqueous phase. The conventional monomer, m-phenelynediamine (MPD), is partially replaced by a linear monomer, 1,3–diamino-2-hydroxypropane (DAHP). The water permeability of the membranes improves by around 22% (to 2.67±0.09Lm−2h−1bar−1) while keeping the same high salt rejection (96–98%) at an optimum DAHP/MPD ratio of 12.8%. While developing the control PA TFC membrane we introduce a washing step and show that the support surface should be free from surface protective coatings to achieve high water flux (2.18±0.08Lm−2h−1bar−1). Incorporating DAHP units into the polyamide network improves the water flux through the membranes fabricated on both original and washed supports. The surface morphologies of polyamide films change significantly with introduction of DAHP, from large ridge-and-valley structure to enlarged nodular structures. High resolution SEM images show an ultrathin polyamide thin film with a thickness that is reduced with addition of DAHP. These influences of DAHP, namely a reduction in the selective layer thickness, an alteration in surface morphology, changes in internal molecular packing and hydrophilicity, are suggested as factors behind the improved water permeability.

Preparation and properties of polyamide/titania composite nanofiltration membrane by interfacial polymerization

The TiO2 sol was added in the polysulfone (PSF) casting membrane solution to prepare polysulfone/titania hybrid membrane in this work. Then the polypiperazine–amide composite nanofiltration (NF) membranes were prepared on PSF/TiO2 hybrid membranes by interfacial polymerization. Piperazine and trimesoyl chloride were used as monomers in aqueous phase and organic phase, respectively. Different preparation conditions affecting the separation performances of NF membrane were discussed, including TiO2 sol concentration, piperazine concentration, trimesoyl chloride concentration, and reaction time. The chemical structure characterizations of polyamide composite membrane were tested by attenuated total reflectance infrared (ATR-IR). The surface images and cross sections were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The addition of TiO2 sol changed the salt rejection slightly, but the water flux was three times than that of the polyamide membrane on the PSF support membrane. The polyamide NF membrane prepared under the optimum condition exhibited Na2SO4 rejection of 96.94% and water flux of 12.84Lm−2h−1. According to the intercepting experiments of polyethylene glycols, the molecular weight cut-off (MWCO) of the resulting membrane was under 600Da.

Adsorption properties of dye imprinted polysiloxane composite microspheres using strong basic anion-exchange resin as matrix

In this study, novel molecularly imprinted polysiloxane composite microspheres (MICS) have been synthesized on the surface of strong basic anion-exchange resin (001 × 7) through a surface molecular imprinting technique by using methyl orange (MO) as the template molecule, ethylenetri(β-methoxy)ethyoxysilane (KH-570) and γ-amidopropyltriethyoxysilane (KH-550) as the functional monomers in aqueous phase. The effects of species of silane, particle sizes, different templates on the adsorption and recognition properties of MICS were investigated. Langmuir adsorption model was employed to describe the isotherms and the maximum adsorption capacity was evaluated. It could be concluded that the adsorption and recognition performances of MICS prepared using two kinds of silane prove superior to those of MICS produced using only one type of silane; the imprinting efficiency of MICS is very high within five minutes and tends to be stable (2.5–2.8) with the time. Adsorption capacity of MO on MO-MICS is higher than that on methyl red imprinted composite microspheres (MR-MICS), indicating that the imprinted microspheres exhibit a certain adsorptive selectivity for the template. The imprinted polysiloxane composite microspheres also show excellent stability in rebinding of the imprint molecules after four adsorption–regeneration cycles.

Solvent resistant thin film composite nanofiltration membrane: Characterization and permeation study

The present investigation reports the fabrication of thin film composite nanofiltration (TFC-NF) membranes using interfacial polymerization technique for desalination. Ethylene diamine (EDA) and terephthaloyl chloride (TPC) were employed as aqueous and organic phase monomers, respectively to develop polyamide thin layer on the surface of Celgard 2400. The prepared membranes were characterized through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The molecular weight cutoff of TFC-NF membranes was estimated to be below 342Da using dextrose, sucrose and raffinose solutions. A low cost dead end NF Cell was designed and manufactured domestically to conduct permeation experiments. The effect of different reaction conditions including concentration of monomers, residence time in each monomer and curing temperature on the membrane performance (water flux and MgCl2 rejection) was also studied. The water flux was augmented linearly at higher applied pressure while MgCl2 rejection was remained constant. The obtained water flux and MgCl2 rejection were measured 33L/m2h and 90%, respectively at 7bar applied pressure. Beside this, membrane stability was analyzed, which confirmed the excellent constancy of ethanol and n-hexane fluxes even after an extended period. Hagen–Poiseuille equation was applied to estimate the TFC-NF membrane pore size ∼0.45nm.

Interfacially Polymerized Layers for Oxygen Enrichment: A Method to Overcome Robeson’s Upper-Bound Limit

Interfacial polymerization of four aqueous phase monomers, diethylenetriamine (DETA), m-phenylenediamine (mPD), melamine (Mela), and piperazine (PIP), and two organic phase monomers, trimethyl chloride (TMC) and cyanuric chloride (CC), produce a thin-film composite membrane of polymerized polyamide layer capable of O2/N2 separation. To achieve maximum efficiency in gas permeance and O2/N2 permselectivity, the concentrations of monomers, time of interfacial polymerization, number of reactive groups in monomers, and the structure of monomers need to be optimized. By controlling the aqueous/organic monomer ratio between 1.9 and 2.7, we were able to obtain a uniformly interfacial polymerized layer. To achieve a highly cross-linked layer, three reactive groups in both the aqueous and organic phase monomers are required; however, if the monomers were arranged in a planar structure, the likelihood of structural defects also increased. On the contrary, linear polymers are less likely to result in structural defects, and can also produce polymer layers with moderate O2/N2 selectivity. To minimize structural defects while maximizing O2/N2 selectivity, the planar monomer, TMC, containing 3 reactive groups, was reacted with the semirigid monomer, PIP, containing 2 reactive groups to produce a membrane with an adequate gas permeance of 7.72 × 10(-6) cm(3) (STP) s(-1) cm(-2) cm Hg(-1) and a high O2/N2 selectivity of 10.43, allowing us to exceed the upper-bound limit of conventional thin-film composite membranes.

Study on Compositions in Aqueous Phase of Hollow Fiber Composite Nanofiltration Membrane

Hollow fiber composite nanofiltration (NF) membranes were prepared by interfacial polymerization method, with polysulfone (PSF) hollow fiber ultrafiltration membrane as base membrane, piperazine (PIP) as the aqueous phase monomer and trimesoyl chloride (TMC) as the organic phase monomer. The effects of aqueous phase composition on composite NF were discussed. The experimental results show that the optimum compositions in aqueous phase: 1wt% PIP, 0.05wt% MPDA, 1wt% TEA, 3wt% sulfamic acid. The best rejection to MgSO4 was 94.7%, and water flux was 66.1L•m-2•h-1.

Preparation and electrochemical capacitance of hierarchical graphene/polypyrrole/carbon nanotube ternary composites

Abstract In the present work, graphene/polypyrrole/carbon nanotube (GN/PPy/CNT) ternary composites have been fabricated via in situ polymerization method. The negatively charged poly(sodium 4-styrene sulfonate) is used for dispersing GN and CNT in aqueous phase and tethering pyrrole monomer to facilitate the formation of uniform PPy coating. Morphology analysis shows that the stacking of laminated PPy/GN composite is inhibited by introducing one-dimensional CNT to form GN/PPy/CNT composite with three-dimensional hierarchical structure. The prepared GN/PPy/CNT composite with GN:CNT = 8:1 (8GCPPy) exhibits a large surface area of 112 m2 g−1 and meso- and macro-porosity system, which favor the diffusion of the electrolyte ions into the inner region of electrode. The supercapacitive behaviors of the sample electrodes are evaluated with cyclic voltammetry and galvanostatic charge/discharge measurements in 1 M KCl electrolyte. The specific capacitance of 8GCPPy at a current density of 0.2 A g−1 (361 F g−1) is much higher than that of pure PPy (176 F g−1) and binary composites of CNT/PPy (253 F g−1) and GN/PPy (265 F g−1). In addition, owing to the GN and CNT synergistic releasing the intrinsic differential strain of PPy chains during charge/discharge processes, the 8GCPPy composite also shows stable cycling performance (4% capacity loss after 2000 cycles).

Preparation and Characterization of the Tri-Channel Hollow Fiber Charged Mosaic Membrane

Charged mosaic membrane (CMM) has high water flux, low salt retention and high organic rejection. The tri-channel hollow fiber charged-mosaic membrane (CMM) was prepared by interfacial polymerization (IP). The tri-channel polysulfone (PSF) hollow fiber ultrafiltration(UF) membrane was used as the support membrane. Polyethylenimine (PEI), 2, 5-diamino-benzenesulfonic acid (DIA) and basic fuchsin (BF) were used as aqueous phase monomer. Trimesoyl chloride (TMC) was used as organic phase monomer. ATR-IR, scanning electron microscope (SEM) and gas sorption analyzer (GSA) were applied in structural analysis of CMM. The uniform design and SPSS were applied in membrane preparation and data analysis.The polymer ATR-IR spectroscopy shows IP occurrence between aqueous phase monomer and organic phase monomer. Polymer contains both sulfonate group and quaternary ammonium group. It show that the membrane has the feature of CMM. Regression equation was gained, and it shows the CMM retention would enhance with the concentration increase of DIA, PEI and SDS and decrease with concentration decrease of FB in experimental range. The composite layer can be observed from membrane SEM after IP. The CMM retention to NaCl, polyethylene glycol(PEG), Xylenol orange and Methyl chloride is12.4%, 90%, 96%,88% and 88.2% respectively.

Grafting of Oligosaccharides onto Synthetic Polymer Colloids

A new method to form colloidally stable oligosaccharide-grafted synthetic polymer particles has been developed. The oligosaccharides, of weight-average degree of polymerization approximately 38, were obtained by enzymatic debranching of amylopectin. Through the use of a cerium(IV)-based redox initiation process, oligosaccharide chains are grafted onto a synthetic polymer colloid comprising electrostatically stabilized poly(methyl methacrylate) or polystyrene latex particles swollen with methyl methacrylate monomer. Ce(IV) creates a radical species on these oligosaccharides, which then propagates, initially with aqueous-phase monomer, then with the methyl methacrylate monomer inside the particles. Ultracentrifugation, NMR, and total starch analyses together prove that the grafting process has occurred, with at least 7.7 wt % starch grafted and a grafting efficiency of 33%. The surfactant used in latex preparation was removed by dialysis, resulting in particles colloidally stabilized with only linear starch as a steric stabilizer. The debranched starch that comprises these oligosaccharides is found to be a remarkably effective colloidal stabilizer, albeit at low electrolyte concentration, stabilizing particles with very sparse surface coverage.

The measurement of free fatty acid concentration with the fluorescent probe ADIFAB: a practical guide for the use of the ADIFAB probe.

The aqueous phase monomers of fatty acids (FFA) appear in many steps of fat metabolism. Understanding metabolism requires that accurate measurements of FFA levels be determined in enzyme-mediated as well as in membrane and protein binding reactions. Measuring long chain FFA levels with sufficient sensitivity and temporal resolution is now possible using fluorescent probes constructed by ligating fluorescent groups and fatty acid binding proteins. In this paper we provide a practical description of the use of ADIFAB, the acrylodan labeled intestinal fatty acid binding protein. We describe with specific examples how ADIFAB can be used to determine, (1) FFA concentrations in aqueous solutions, (2) binding affinities of fatty acid binding proteins, (3) membrane/water partition coefficients, (4) lipase activities, and (5) serum levels of FFA.