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  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  The activity coefficients at infinite dilution, gamma(infinity)(13), for 37 solutes: alkalies, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, and water in the ionic liquid 1-butyl-3-methylpyridinium trifluoromethanesulfonate [1,3bmPY][CF(3)SO(3)] were determined by gas-liquid chromatography at the temperatures from (308.15 to 358.15) K. The partial molar excess enthalpies at infinite dilution values Delta H(1)(E,infinity) were calculated from the experimental gamma(infinity)(13) values obtained over the temperature range. The selectivities for the aliphatic/aromatic hydrocarbon separation problem were calculated from gamma(infinity)(13) and compared to the literature values for other ionic liquids, N-methylpyrrolidone and sulfolane.

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  The principal aim of the study was to estimate the level of exposure to organic solvents of graffiti removers, and to identify the chemicals used in different cleaning agents. A secondary objective was to inform about the toxicity of various products and to optimise working procedures.

Exposure to organic solvents was determined by active air sampling and biological monitoring among 38 graffiti removers during an 8-h work shift in the Stockholm underground system. The air samples and biological samples were analysed by gas chromatography. Exposure to organic solvents was also assessed by a questionnaire and interviews.

Solvents identified were N-methylpyrrolidone (NMP), dipropylene glycol monomethyl ether (DPGME), propylene glycol monomethyl ether (PGME), diethylene glycol monoethyl ether (DEGEE), toluene, xylene, pseudocumene, hemimellitine, mesitylene, ethylbenzene, limonene, nonane, decane, undecane, hexandecane and gamma-butyrolactone. The 8-h average exposures [time-weighted average (TWA)] were below 20% of the Swedish permissible exposure limit value (PEL) for all solvents identified. In poorly ventilated spaces, e.g. in elevators etc., the short-term exposures exceeded occasionally the Swedish short-term exposure limit values (STEL). The blood and urine concentrations of NMP and its metabolites were low. Glycol ethers and their metabolites (2-methoxypropionic acid (MPA), ethoxy acetic acid (EAA), butoxy acetic acid (BAA), and 2-(2-methoxyethoxy) acetic acid (MEAA)) were found in low concentrations in urine. There were significant correlation between the concentrations of NMP in air and levels of NMP and its metabolites in blood and urine. The use of personal protective equipment, i.e. gloves and respirators, was generally high.

Many different cleaning agents were used. The average exposure to solvents was low, but some working tasks included relatively high short-term exposure. To prevent adverse health effects, it is important to inform workers about the health risks and to restrict the use of the most toxic chemicals. Furthermore, it is important to develop good working procedures and to encourage the use of personal protection equipment.

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  Nanocrystal ink-coating technique is a low cost, less pollution, and non-vacuum solution based processing to produce CIS absorbing layers for photovoltaics, leading to low fabrication cost and eco-friendly process of solar cells. In this work, highly crystallized chalcopyrite CuInSe2 (CIS) nanocrystals were synthesized by a green and cheap air pressure hot injection method using 1-Methyl-2-pyrrolidinone and glycerol mixed solvent, and copper chloride, indium chloride and selenium dioxide as precursors. The synthesized CIS nanocrystals were used to prepare colloidal nanocrystal inks by dispersing them ultrasonically in absolute alcohol and deposit CIS thin films by dip-coating nanocrystal inks. Basic characterization data of the synthesized CIS nanocrystals and the ink-coated thin films were described by XRD, TEM, FESEM, EDS, UV-vis-NIR, and Hall measurements. (C) 2011 Elsevier B.V. All rights reserved.

Abstract  Hybrid-hollow-fiber membrane bioreactors were developed for the enhanced cometabolic biotransformation of phenol and 4-chlorophenol (4-cp) by Pseudomonas putida ATCC49451. Bioreactor performance was investigated, compared, and analyzed under batch and continuous operating modes. The spinning solutions contained polysulfone (PS), N-methyl-2-pyrrolidone, and various weight ratios of granular activated carbon (GAC) (GAC: PS of 0, 1:4, and 1:2). The bioreactor fabricated with 1:2 GAC hybrid-hollow-fiber membranes demonstrated the best performance for the removal of phenol and 4-cp, both under batch and continuous operations. Under batch operation, 500 mg L-1 phenol and 4-cp were completely removed within 23 h in the bioreactor, compared with 26 and 30 h for the 1:4 GAC and GAC free bioreactors. Sorption, biotransformation, desorption, and bioregeneration were identified as the four steps for substrate removal during batch operation. The 1:2 GAC hollow-fiber membrane bioreactor also manifested superiority over the other two during continuous operation for start up and the transient phase after shock loadings of the feed. 300 mg L-1 phenol and 4-cp were completely removed in the 1:2 GAC hybrid-hollow-fiber membrane bioreactor whereas 4-cp was not completely removed in the other two bioreactors at a feed rate of 30 mL h(-1). From the experimental results, it was inferred that at steady state, biotransformation was achieved through the dynamic equilibrium among sorption, desorption, and biotransformation rates established within the bioreactors.

Abstract  Solubilities of SO2 in five selected inexpensive organic solvents with low volatility were measured at temperatures from 303.2 K to 333.2 K and pressures up to 120 kPa. The solvents include sulfolane (SUF), ethylene glycol (EG), propylene carbonate (PC), N-methylimidazole (NMI) and N-methylpyrrolidone (NMP). The obtained results indicated that the solubilities of SO2 in the five organic solvents followed the sequence NMI > NMP > SUF > PC > EG. The absorption isotherms of SO2 in SUF, EG, and PC showed ideal profiles, while those in NMI and NMP showed nonideal types. The Henry's law constants of SO2 in SUF, EG, and PC in terms of molality were calculated by drawing linear fit between SO2 solubilities and SO2 partial pressures. The interactions of SO2 with NMI and NMP were examined through density functional theory (DFT) calculations, and the solvent saute complex formations were illustrated. The experimental solubilities of SO2 in NMI and NMP were successfully correlated by a reaction equilibrium thermodynamic model (RETM) proposed based on the DFT calculations. Subsequently, Henry's law constants, reaction equilibrium constants, and heat of complex formation were also calculated to evaluate the potential of applying these organic solvents in SO2 absorption. The performance of SO2 absorption in these organic solvents were further compared with that in ILs and results illustrated that NMI and NMP were good alternatives to IL for applying in SO2 absorption.

Abstract  (Solid + liquid) equilibria for the binary systems (N-methyl-2-pyrrolidinone + phenol, or 3,5-dimethylphenol) have been determined using a cryometric dynamic method. Congruently melting compounds form with the formulae: C5H9NO center dot C6H5OH, or C5H9NO center dot(C6H5OH)(2), and C5H9NO center dot C8H9OH, or C5H9NO center dot(C8H9OH)(2). Compound formation is attributed to a charge-transfer interaction of N-methyl-2-pyrrolidinone with phenol or 3,5-dimethylphenol, or is attributed to a strong O-(HO)-O-... hydrogen bond between the oxygen atom of N-methyl-2-pyrrolidinone and hydroxyl group of phenol. The larger intermolecular interaction is observed for the (N-methyl-2-pyrrolidinone + phenol) binary mixture, where the melting temperature of the 1:1 congruently melting compound is higher. Experimental solubility results are compared with values calculated by means of the Ott equation using parameters derived from the SLE results. The correlation of the solubility data is obtained with a average root-mean-square deviation in temperature sigma(T) = 0.25 K and sigma(T) = 0.19 K for the systems with phenol or 3,5-dimethylphenol, respectively. (c) 2005 Elsevier B.V All rights reserved.

Abstract  Low-rank coals were extracted with various solvents under ultrasonication at room temperature. In the case of single solvent extraction, N-methyl-2-pyrrolidinone (NMP) gave the highest extraction yield for Loy Yang coal, 14.3 wt % (daf). Among the mixed solvents used in this study, NMP-methanol (8:2) and NMP-water (3:1) mixed solvents gave the high yields, 15.3 and 15.1 wt % (daf), respectively. The NMP-carbon disulfide mixed solvent was not effective, although it gave very high extraction yields for bituminous coals. FT-IR measurements for Loy Yang coal, its extract, and residue showed that they have similar chemical structures. In polar solvents, Loy Yang coal swelled more highly than subbituminous coals, and the highest swelling ratio was also obtained in NMP, indicating high affinity between Loy Yang coal and NMP. The mixture of Loy Yang coal with NMP forms a gel structure at the composition of about 83 wt % NMP and 17 wt % coal.

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  Two kinds of pyridine insoluble fractions (PI) of coal extracts with different solubilities in N-methyl-2-pyrrolidinone (NMP) were characterized in this paper. PI-0 was obtained by the pyridine fractionation of Upper Freeport coal extracts with a CS2/NMP mixed solvent (1: 1 by volume), and its solubility in NMP is 53 wt %. While PI-1, which was obtained by the removal of NMP and tetrabutylammoniurn acetate (TBAA) from a PI-0 solution in NMP containing TBAA, was almost completely soluble in NMP. Solid-state (CNMR)-C-13 spectra indicated that the two PIs have the same chemical structure. The viscoelastic properties and methanol adsorption behaviors of the two PIs were measured. The dynamic viscoelasticities of the two PIs are similar, and the elastic modulus (G') of PI-I is lower before the softening temperature than that of PI-0, suggesting that the macromolecular network of Pl-I is looser compared to that of PI-0. The methanol sorption behaviors of PI-0 and PI-I are also similar, and lines curve-fitted with the Langmuir-Henry equation were in agreement with the experimental data, suggesting that the bulk structure of the two PIs is similar. The methanol sorption for PI-1 is larger than that for PI-0. The constants of the Langmuir-Henry equation obtained by successive fitting for the two PIs indicated that the microporosity of PI-I is larger than that of PI-0. The results obtained here suggested that the dissociation of molecular interactions is responsible for the high solubility of PI-1.

Abstract  Microspheres (MCs) of different polymers, such as poly(ether sulfone) (PES), polyetheretherketone with card, with and without pore formers, were prepared by the non-solventinduced phase separation (NIPS) process. The polymers were solubilized in different types of solvents, such as dimethyl formamide (DMF), dimethylsulfoxide (DMSO), N-methylpyrrolidone, and gamma -butyrolactone as a dispersed phase, whereas dodecane, isopropanol, water, and sodium dodecyl sulfate were used as continuous phases. The technique yielded asymmetric and symmetric porous, spongy, or finger-like, spherical MCs having a diameter tailored by the monopore film pore size employed. The influence of polymer and pore former (polyvinylpyrrolidone k17), the continuous phase composition and operating membrane process conditions, and solvent uptake behavior of different solvents are studied in detail. The operative conditions and chemical compositions are correlated with the spherical nature, structural interaction, pore size, porosity, and morphology of the MCs prepared. Ternary phase diagrams were drawn for PES/DMF and PES/DMSO using different alcohols, such as butanol, isopropanol, ethanol, and methanol. BET (BrunauerEmmetTeller) surface analysis also provided information about the surface of MCs. MCs with different diameters and porosities are obtained by controlling the concentration of the dispersed phase polymer concentration, used during the preparation, and diameter of the monopore film. (c) 2012 Wiley Periodicals, Inc. Adv Polym Techn 31: 231241, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21281

Abstract  In the present study, photocatalytic decomposition of N-methyl-2-pyrrolidone (NMP) using light sources of UVA, UVC and UVLED was investigated. The effects of different parameters such as NMP initial concentration, pH value, catalyst loading, inorganic salts and the type of light sources on the reaction rate were evaluated, and optimum conditions were determined. The results of experiments showed that catalyst loading of 0.9 g/1 TiO sub(2) was the optimum and further increase in the TiO sub(2) loading reduced removal efficiency. The highest photodegradation reaction rate was obtained in neutral condition rather than acidic or alkaline condition. Furthermore, the effects of inorganic salts were investigated. Result showed that photocatalytic degradation rate was affected significantly in the presence of bicarbonate and chloride. The experimental data showed that the photocatalytic degradation of NMP can be simulated by using pseudo-first-order reaction rate expression. The apparent rate constant (k sub(obs)) over TiO sub(2) photocatalyst with 254 nm ultraviolet lamp (UVC), 365 nm ultraviolet lamp (UVA), and UVLED were 0.0454, 0.0205 and 0.0125 min super(-1) respectively.

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  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  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  Thermophysical properties of 2-pyrrolidone (PYR), N-methyl-2-pyrrolidone (NMP), and N-cyclohexyl-2-pyrrolidone (CHP) binary and ternary liquid mixtures with methanol are reported at 298.15 K and 0.1 MPa over the full composition range. Excess and mixing properties derived from the experimental ones were correlated using Redlich-Kister (RK) equation, for binary mixtures, and Cibulka (C) equation, for ternary ones. Density Functional Theory (DFT) was also used to analyze structural and energetic features of cyclic lactams in gas phase and methanol solution. Results show the formation of H-bonding and dipolar interactions between cyclic amides and methanol, although these are weakened when a third component is added to the binary mixture, thus decreasing remarkably the values of ternary properties in comparison with binary ones and leading to the weakening of the binary blends' intermolecular interactions.

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  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  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.