Abstract  This study investigates the feasibility of using a two-stage process combining a photochemical oxidation process (UV/H2O2) and a biological fluidized-bed system to treat dilute-organic wastewater discharged from semiconductor manufacturing facilities.. This combined process has the merits of decomposing recalcitrant organic chemicals into intermediate products more amenable to biodegradation, thereby achieving high degree of mineralization of organic compounds that are otherwise toxic to aerobic biodegradation. Six organic solvents, including propylene glycol methyl ether acetate, ethyl lactate, tetramethylammonium hydroxide, 1-methyl-2-pyrrolidone, isopropanol, and phenol, were evaluated due to their common applications in various wafer fabrication processes. The optimal operating conditions (H2O2 dosage, pH, exposure time) for the first-stage UV/H2O2 were determined for each chemical, and a nominal condition was selected for the ensuing biodegradation experiments. GC/MS analyses demonstrated that UV/H2O2 indeed decomposed the chemicals into smaller fragments that could be effectively mineralized by aerobic biodegradation. Excellent reduction efficiencies (>95%) in both TOC and compound concentration were achieved for all compounds except for NMP, whose stable ring structure was refractory to both low-dosage UV/H2O2 oxidation and biodegradation. No significant difference in reduction efficiencies was observed between treatment of the compounds as individual components and as a mixture, suggesting the favorable applicability of the proposed technology.

Abstract  Cellulose triacetate (CTA) membranes for forward osmosis (FO) were fabricated in this study. The fundamental engineering and science of CTA membrane formation were explored by casting the membranes from different solvent systems and characterizing the membranes' morphology using advanced tools such as positron annihilation spectroscopy (PAS). N-Methyl-2-pyrrolidone (NMP) and dioxane were used as the solvents for CTA in the membrane fabrication process. It was found that the choice of solvents for membrane fabrication significantly affects the morphology of as-cast membranes and their FO performance. The CTA membrane cast using NMP as the main solvent has shown poor NaCl rejection but high water flux, whereas the CTA membrane cast using dioxane as the main solvent has excellent NaCl rejection but low water flux. SEM and PAS data reveal that the sublayer of CTA membranes cast from dioxane has a close-cell and much denser structure compared to that cast from NMP. As a result, the former has a significantly lower water flux than the latter in the FO process (5 vs. 27 LMH) using a 2 M NaCl draw solution. Surprisingly, with the addition of acetic acid into the dioxane/acetone solvent system, the resulting membrane has a significantly more porous and open-cell sublayer structure. In addition to the pore forming ability of acetic acid, FTIR spectra confirm the formation of acetic acid/dioxane complexes in the casting solution. Thus, as validated by PAS spectra, the free volume of the active layer of the resultant CTA membranes increases after the addition of acetic acid into the dioxane/acetone casting solution and the water flux increases to 23 LMH using a 2 M NaCl draw solution. Molecular simulations were also conducted to examine CTA polymeric chains in different solvent systems and to witness different CTA chain behaviors in these solvents that leads to significant differences in the as-cast membranes' morphology. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Graphene composites were prepared by hydrothermal method using titanium dioxide (TiO2) adsorbed graphene oxide (GO) sheets as precursors. Free-standing hybrid films for lithium-ion batteries were prepared by adding TiO2/graphene composites to the polyvinylidene fluoride (PVdF)/N-methyl-2-pyrrolidone (NMP) solution, followed by a solvent evaporation technique. These films were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and various electrochemical techniques. Flexible films show an excellent cycling performance, which was attributed to the interconnected graphene conducting network, which depressed the increasing of electric resistance during the cycling. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Polyethersulfone (PES) hollow fiber membranes for kidney dialysis application were prepared by the dry-jet wet-spinning method. A dual-coagulation bath technology was first time employed for fabricating the kidney dialysis membranes with a tight inner skin and loose outer supporting layer structure. A weak coagulant isopropanol (IPA) was served as the first external coagulation bath, while water as the second bath. Experiments demonstrate their advantages of better controlling both inner and outer skin morphology. The as-spun fibers have a higher mean effective pore size (mu(p)), pure water permeation flux (PWP) and molecular weight cut-off (MWCO) with an increase in N-methyl-2-pyrrolidone (NMP) percentage in bore fluid (i.e., internal coagulant). After being treated in 8000 ppm NaOCl solution for 1 day, fibers show larger pore sizes and porosity in both inner and outer surfaces, and thinner inner and outer layers than their as-spun counterparts. Among them, the bleached fibers spun with 50 wt.% NMP in bore fluid have the MWCO (43 kDa) and PWP (40 x 10(-5) L m(-2) Pa-1 h(-1)) suitable for kidney dialysis application. Based on SEM observations and solute rejection performance, the further heat treated fibers in an aqueous solution is found to be an effective way to fine tune membranes morphology and MWCO for kidney dialysis application. The solute rejection performance data of the hollow fiber membranes spun with 55 wt.% NMP in bore fluid after heat treated at 90 degrees C in water for 2 It were found to be very appropriate for the kidney dialysis application. (c) 2007 Elsevier B.V. All rights reserved.

Abstract  Stable dispersions of reduced graphene oxide (RGO) have been prepared by indole as a previously unreported reducing agent without employing any external stabilizing reagents. The obtained RGO can be individually dispersed in ethanol, N, N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), tetrahydrofuran (THF) and isopropanol. Several analytical techniques including Atomic force microscopy, X-ray diffraction, UV-Vis spectra, Raman spectroscopy and X-ray photoelectron spectroscopy indicate that a significant fraction of the oxygen-containing functional groups are removed, yields a C/O ratio as high as 7.4. The conductivity of RGO is 21.2 S/m and the thickness of RGO increases to 1.7 nm. Furthermore, this new reducing agent is of low toxicity, which makes the reduction much safer than hydrazine and this method is cost-effective to produce single-layered RGO on a large scale.

Abstract  To crystallize selectively forms I and II of clopidogrel hydrogen sulfate (CHS), nucleation behavior and supersaturation level were studied in mixed solvents such as formic acid/isopropanol, N,N-dimethylformamide/isopropanol, and N-methylpyrrolidone/isopropanol. The effect of supersaturation on induction time and nucleation rate was evaluated by comparison between nucleation mechanisms of seeded and unseeded crystallizations. Experimental results indicate that the polymorph obtained by crystallization depends on the type of seed crystals, amount of seed crystals, and seeding point. Homogeneous nucleation was desirable for the formation of form I. Form II corresponds to primary nucleation, i.e., homogeneous and heterogeneous nucleations.

Abstract  The influence of the solvent used for spin-coating on the homogeneity of poly(N-vinylcarbazole) (PVK) films is investigated. Homogenous films are obtained only by the use of toluene, solution in tetrahydrofuran (THF) and chloroform results in radially oriented inhomogeneities and films prepared by use of N-methylpyrrolidone and dimethylacetamide show particle formation during spin-coating. Layered nano-composite thin films are prepared by spin-coating a PVK film on top of a nano-structured titanium dioxide ( TiO2) layer. The TiO2 thin films are prepared by a sol-gel process using an amphiphilic copolymer as structure-directing agent. Structural characterisation of the TiO2 :PVK nano-composite films is done by field emission scanning electron microscopy (FESEM) and grazing-incidence small-angle scattering (GISAXS). Bare TiO2 films are probed for comparison. Light is basically only absorbed in the ultraviolet regime and absorption slightly increases upon addition of PVK, which makes the layered TiO2 :PVK nano-composite thin films good candidates for UV photovoltaic devices. Furthermore, absorption remains stable over a period of several days.

Abstract  Gold nanoparticles were prepared in an aqueous solution and a 50:50 N-methyl-2-pyrrolidone (NMPD)/toluene mixed solvent using o-anisidine as the reducing agent, respectively. The reaction is conducted by choice of the temperature and medium. Transmission electron microscopy (TEM) and LTV-vis absorption spectroscopy measurements show that the size of Au particles is dependent on the synthetic protocols. At the same time, the oxidative polymerization of o-anisidine was achieved. Moreover, the structure of the polymer varied with the preparative conditions. Cross-linked poly(o-anisidine) and poly(o-anisidine) in its doping state (in the form of the emeraldine salt) were obtained, respectively, supported by UV-vis absorption spectra, infrared spectra, and X-ray photoelectron spectroscopy (XPS).

Abstract  La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) hollow fiber membrane precursors were prepared by spinning a starting Suspension containing 68.75 wt % LSCF powders, 6.25 wt % polyethersulfone (PESf), and 25.0 wt % N-methyl-2-pyrrolidinone (NMP) at room temperature using deionized water and tape water as the internal and external coagulants, respectively. High temperature sintering was carried Out in a range of 1200-1500 degrees C to study the influences of the sintering process oil the properties of the LSCF hollow fiber membranes including the microstructure, crystalline phase, mechanical strength, as well as the oxygen permeability. Mechanical strength of the LSCF hollow fibers increased with increasing sintering temperature and reached a maximum of 115 MPa at 1500 degrees C sintering temperature. To obtain gastight LSCF hollow fiber membranes, the sintering temperature must be higher than 1250 degrees C, and the sintering time must be longer than 2 h. However, higher than 1350 degrees C sintering temperature would facilitate the formation of sulfate impurity phases, resulting in noticeable reduction of oxygen permeation flux. The optimum sintering temperature should be around 1300 degrees C, and the sintering time should be within the range of 2-4 h to obtain the gaslight and high flux LSCF hollow fiber membranes.

Abstract  The development of organic devices requires the fabrication of thin films, and inkjet printing has been shown to be a suitable method to reach this goal. This work describes the printing process and characterisation of polyaniline (PANI) printed on bond and photographic papers using a desktop inkjet thermal printer. To enable printing, a solution composed by PANI, n-methyl-2-pyrrolidone, ethylene glycol, alcohol and water must be prepared. PANI is printed on bond and photographic paper and then doping of PANI is performed by hydrochloric acid vapour exposure. Micro-Raman spectroscopy showed that PANI printed on paper keeps its basic characteristics. The results from electrical measurements showed that the surface resistivity of the printed PANI samples decreases by increasing the printing number, i.e. the number of layers that were deposited, and depends slightly on the paper type. A stretched semicircle followed by a linear upward tail, attributed to Warburg impedance combined with other intrinsic mechanisms of PANI on porous media, are always present on the Cole-Cole plots obtained for doped-PANI on bond paper. It was shown that these parameters significantly change with the relative humidity, opening the possibility to apply PANI/paper-based devices as humidity sensors. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  The phase behavior of 1-glyceryl monoleyl ether (GME) in mixtures of water and the solvents 1,5-pentanediol (POL) or N-methyl-2-pyrrolidone (NMP) was investigated by ocular inspection, polarization microscopy, and small-angle X-ray diffraction (SAXD). Phase diagrams were constructed based on analyses of more than 200 samples prepared using the two different solvents at 20 °C. The inverse hexagonal phase formed by GME in excess of water was transformed into the cubic and sponge phase with the increasing amount of each solvent. Particularly POL allowed for the formation of an extended sponge phase area in the phase diagram, comprising up to 70% POL-water mixture. The phase behavior using NMP was found to be similar to the earlier investigated solvent propylene glycol. The extended sponge phase for the POL system was attributed to POLs strong surface/interfacial activity with the potential to stabilize the polar/apolar interface of the sponge phase. The cubic and sponge phases formed using POL were further studied by NMR in order to measure the partitioning of POL between the lipid and aqueous domains of the phases. The domain partition coefficient K (lipid domain/aqueous domain) for POL in cubic and sponge phases was found to be 0.78 ± 0.14 and constant for the two phases.

Abstract  A facile and one-pot method for the synthesis of Pt, Pd, and their alloy nanocrystals along with their exciting electrocatalytic activities toward methanol oxidation have been reported. Unique structures like truncated octahedrons of Pd, Pt, and their alloys like CoPt and PdPt have been synthesized in presence of a reducing solvent like N-methyl pyrrolidone (NMP) and stabilizer like polyvinyl pyrrolidone (PVP). Among these nanocrystals, Pd16Pt84 and Co5Pt95 show tremendous improvement in the electro-oxidation of methanol in acidic media with mass activities of 1790 and 1417 mA/mg(Pt), respectively (with lower onset potential compared to Pt alone), which is believed to be much higher compared to that of previous reports and state-of-art Pt/C and RuPt/C catalysts, indicating a better alloy formation and stable particle-support interactions.

Abstract  Eleven Chinese immature source rock concentrates from the immature oil formations in four different depressions were extracted ultrasonically with a mixture of CS2 and N-methyl-2-pyrrolidinone (CS2/NMP) at room temperature. The samples were also extracted with CHCl3 and a mixture of methanol/acetone/chloroform (MAC) for comparison. The solvent system CS2/NMP is very efficient for the extraction of immature source rock concentrates, giving much higher extraction yields than CHCl3 or MAC. The composition of the extracts using different solvent mixtures is also different. Model compound tests indicate that no chemical reactions have taken place between the NMP and the substrates in the extraction. These results suggest that there are abundant non-covalent bond interactions in the organic matter of the immature source rock concentrates. The fact that CS2/NMP mixed solvent extracts more than MAC and CHCl3 is not only because it can dissolve higher molecular weight fractions, but also because it has stronger ability to disrupt the complex interactions existing between the soluble and insoluble fractions. Biomarker distributions in the saturated hydrocarbon fractions are different for different solvent systems, suggesting that care should be taken when comparing the biomarker parameters in source rocks when using different solvents for extraction. (C) 2000 Elsevier Science Ltd. All rights reserved.

Abstract  Skeletal isomerization of 1-pentene to 2-methyl-1-butene (2M1B) and 2-methyl-2-butene (2M2B) provides the precursors for etherification with methanol to produce tertiary amyl methyl ether ( TAME), an oxygenate fuel additive for octane improvement. Although the technology has been proven commercially, the use of a Fischer-Tropsch (FT)-derived pentene feed has not been examined previously. In this work, the effect of oxygenates present in an FT-derived pentene feed on conversion, selectivity, and the deactivation of a commercial catalyst is described. The results are compared with those obtained with a model feed containing no oxygenates and also with an FT feed from which the oxygenates have been removed. The presence of oxygenates in the feed required a start of run temperature above 320 degrees C to prevent competitive adsorption with the olefins, but these higher temperatures led to rapid catalyst deactivation. Oxygenates could successfully be removed from the FT feed by n-methylpyrolidone wash. This resulted in a longer catalyst cycle length (10-12 months) than in the presence of oxygenates (1-2 months).

Abstract  In this work, the preparation of nanofiltration flat sheet membranes based on polyphenylsulfone (PPSU) was investigated. A synthesis method based on phase inversion with three different compositions of PPSU (17 wt.%, 21 wt.% and 25 wt.%) in dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP) and a mixture of dimethylformamide (DMF) and NMP was employed. Scanning electron microscopy (SEM) was used to investigate the morphological characteristics and the structure of the membranes, which were found to have a typical asymmetric structure with a dense skin top layer and a porous substructure. The pore size was estimated by measuring the permeation rate of N(2) when different pressures are applied, ranging from 15 nm to 40 nm, depending on the manufacturing method. An increasing amount of macro-voids was observed in the membrane substructure when the polymer concentration is decreased. The performance of the prepared membranes has been tested by the measure of methanol permeability and the rejection of a dissolved dye (Rose Bengal). The methanol permeability decreases with increasing polymer concentration while the rejection of Rose Bengal (RB) increases. In addition, the impact of ethyl acetate, n-hexane, toluene, diethyl ether, iso-propanol and acetone on the membranes was investigated by measuring the flux of methanol and rejection of RB before and after solvent exposure. The membranes were visually stable in most of the solvents except acetone and toluene. The performance of the membranes changed dramatically for ethyl acetate and diethyl ether while iso-propanol had a minor effect and complete stability was observed with n-hexane. (C) 2011 Elsevier B.V. All rights reserved.

Abstract  Solvent swellings of the raw coals, their extracts and residues, which were obtained by carbon disulfide-N-methyl-2-pyrrolidinone mixed solvent extractions of some bituminous coals at room temperature, were studied. The swelling ratios (Q) of the raw coals were generally lower than those of the corresponding extracts and residues, like the results of Larsen et al. for the swelling of two bituminous raw coals and their residues. Swelling ratios of PS (pyridine-soluble and acetone-insoluble extract fraction), PI (pyridine-insoluble extract fraction), and residue in four solvents were in the order of cyclohexane < methanol < benzene < THF for three bituminous coals. For Illinois No. 6 coal, which has a higher oxygen content than the coals above, swelling ratios in methanol are higher than those in benzene. Large synergistic effect for the swelling ratios of PI in benzene-methanol mixed solvent was observed. These results were discussed from the points of the nature of cross-link bonds and cross-link density of raw coals, extracts and residues.

Abstract  The excess molar volumes, V-m(E), have been calculated from measured values of density over the whole composition range at the temperature 298.15 K and atmospheric pressure for the 11 mixtures {N-methyl-2-pyrrolidone + (methanol or ethanol or propan-1-ol or cyclohexane or cyclooctane or cyclohexene or benzene or 1-hexene or 1-octene or 1-hexyne or 1-octyne)}. The results are discussed in terms of the hydrogen bonding and other intermolecular associations. The experimental results have been correlated and compared with the results from Flory-Benson-Treszczanowicz (FBT) model and the Extended Real Associated Solution (ERAS) theory. (C) 1998 Elsevier Science B.V. All rights reserved.

Abstract  The microporosity and performance of polyetherimide (PEI) membranes produced by the coagulation post-leaching technique were investigated. Computational chemistry and chemical structure principles indicate that a lithium cation solvated in NMP (N-methyl-2-pyrrolidinone) forms a complex with two NMP molecules. This complex was determined to be stable in NMP and isopropanol but not in methanol or water. Increasing the additive (LiNO3) concentration in the casting solution lead to a greater number of micropores in the 0.7-1.2 nm range, while the peak in the micropore distribution remained unchanged at 1.0 nm. Molecular mechanics calculations indicate that the PEI polymer chain can form coils having an inner section of 0.7 nm x 1.0 nm. Micropore measurements and computational chemistry results suggest that the inherent size of the PEI polymer coils remains unchanged on the addition of LiNO3 but the number of polymer coils increases. A linear relation was found to exist between the permeance of the membranes to air and micropore volume. Larger micropores were present at higher LiNO3 concentrations and caused a decline in the actual separation factor for these membranes. (C) 2001 Elsevier Science B.V. All rights, reserved.

Abstract  The solubility of sulpiride in organic solvents of acetone, N-methylpyrrolidone (NMP), ethanol, tetrahydropyran (THF), N,N-dimethylformamide (DMF), and methanol between (278 and 328) K was measured using a laser monitoring observation technique. Results of these measurements were correlated with a semiempirical equation. For the seven solvents studied, the data are fitted well with a semiempirical equation.

Abstract  The visible-light-responsive photoelectrochemical and photocatalytic properties of nanoparticles of C(60), partially hydrolyzed aluminum phthalocyanine chloride (denoted as AlPc), and a composite of the two are reported. The three types of nanoparticles were obtained through a reprecipitation method from N-methyl-2-pyrrolidone solutions of C(60), aluminum phthalocyanine chloride (AlPcCl), and their mixture, respectively. The nanoparticle composite's ultraviolet-visible absorption, diffuse-reflectance and Fourier transform IR spectra, X-ray diffraction pattern, and scanning electron microscopy image are all similar to the sum of those of the C(60) and AlPc particles, respectively. The nano-ordered composite exhibits p/n junctionlike photoelectrochemical characteristics, which were investigated in comparison with those of vapor-deposited C(60) (n-type), AlPcCl (p-type), C(60)/AlPcCl (n/p), and AlPcCl/C(60) (p/n) electrodes. The nanoparticle composite further shows photocatalytic activity for the decomposition of trimethylamine to carbon dioxide in a suspension system.

Abstract  Microparticles of ampicillin have been precipitated by a supercritical antisolvent process (SAS) using carbon dioxide and N-methylpyrrolidone as the antisolvent and solvent, respectively. The mean particle size (PS) and particle size distribution (PSD) of the processed antibiotic were chosen as responses to evaluate the process performance. The levels for a screening design of experiments were chosen to allow the process to take place in a single supercritical phase. Under these conditions, all of the, experiments led to the successful precipitation of ampicillin. Concentration was a key factor as this had the most marked effect on; both PS and PSD.

Abstract  Research on the dispersion of pristine single-walled carbon nanotubes (SWCNTs) is mostly focused on measuring the dispersion limit in various organic solvents, yet little attention has been paid to the dispersion stability of SWCNTs in viable organic solvents. We have studied SWCNT dispersion stability for mixtures of the organic solvents N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidinone (NMP). Our results show that mixing DMF and NMP can yield dispersion stabilities that are 60-115% greater than the pure solvents with a 50/50 mixture (v/v). SWCNT aggregation is described by a physical model that combines the Maxwell-Boltzmann energy distribution function and DLVO theory for quantitative comparison between solvent systems.

Abstract  An optimised isolation procedure of single-wall carbon nanotubes (SWNTs) from a SWNT soot without using any surfactant is reported. Amorphous carbon and small graphitic particles were washed away with N-methyl-2-pyrrolidone (NMP) and acetone. A large amount of graphite-coated metal particles were removed with the oxidation of the SWNT material with HNO3 (6.5 and 4 M) and by washing the oxidised SWNT material with a mixture of methanol (MeOH) and deionised water. The isolated material was investigated with transmission electron microscopy (TEM) and Raman scattering (647.1 and 532 nm). An elemental analysis of the content of Co and Ni in the SWNT samples isolated at different steps of the isolation procedure was performed. On the basis of the TEM images and elemental analysis it was estimated that the purified material contains more than 75 wt.% of SWNTs. (C) 2002 Elsevier Science Ltd. All rights reserved.

Abstract  Preparation of asymmetric polyetherimide (PEI) hollow fibre membranes with high gas selectivity was studied by introducing volatile organic compounds as additives into the dope solutions. The additives used include methanol, acetone, a mixture of methanol/acetone and tetrahydrofuran (THF). N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc) were used as solvents. The PEI hollow fibre membranes were spun using tap water as the external coagulant and 50 wt.% ethanol aqueous solution as the internal coagulant. The effect of air gap, polymer concentration, solvent and additives on membrane separation properties was investigated. It has been shown that parameters, such as the solvent, additive and air gap affect the dense skin layer formation. Asymmetric PEI hollow fibre membranes with high He/N-2 selectivity can be prepared using volatile non-solvent additives and NMP as the solvent at a suitable length of the air gap. The PEI hollow fibre membrane prepared using THF as the additive shows the poor selectivity. (C) 2002 Published by Elsevier Science B.V.