Masoumeh Zakeri

Improved Methanol Barrier Property of Nafion Hybrid Membrane by Incorporating Nanofibrous Interlayer Self-Immobilized with High Level of Phosphotungstic Acid

High level of phosphotungstic acid (PWA) was self-immobilized on electrospun nylon nanofiberous sheet to fabricate highly selective methanol barrier layer for sandwich structured proton conducting membranes. Simple tuning for the assembly conditions of central layer and thickness of outer Nafion layers allowed obtaining different composite membranes with superior methanol barrier properties (namely, P=3.59×10(-8) cm2 s(-1)) coupled with proton conductivities reaching 58.6 mS cm(-1) at 30 °C. Comparable activation energy for proton transport and more than 20 times higher selectivity than Nafion 115 confirm the effectiveness of the central layer and resulting membranes for application in direct methanol fuel cells (DMFCs). When tested in DMFC single cell, the performance of hybrid membrane was far better than Nafion 115 especially at higher methanol concentrations.

Clean and Efficient Synthesis of Polyhydroquinoline Derivatives Under Solvent-Free Conditions Catalyzed by Morpholine

A series of 1,4-dihydropyridines was obtained via a sequential Hantzsch condensation under solvent-free conditions catalyzed by morpholine in a one-pot reaction.

Synthesis of pyrano[2,3-c]pyrazoles by ionic liquids under green and eco-safe conditions

Optimization of a green approach to the synthesis of pyrano[2,3-c]pyrazoles based on the one-pot, four-component condensation via a domino Knoevenagel/Michael/cyclization sequence was investigated. This method involved the evaluation of the activity of several ionic liquids (ILs) in various solvents. This one-pot, four-component reaction revealed simplicity, higher yield and lower toxicity advantages over a corresponding three-component method. The effect of reaction parameters including the type and amount of catalyst, type of solvent, reaction temperature and time were studied with respect to yield of pyrano[2,3-c]pyrazoles. Catalyst recyclability and time-saving aspects of the reaction suggest that this method presents real alternatives over conventional reaction protocols.

Phase separated nanofibrous anion exchange membranes with polycationic side chains

Anion exchange membranes (AEMs) have gained significant interest in electrochemical energy devices with a unique set of benefits. However, none of the commercial AEMs behave ideally under alkaline operation conditions and developing appropriate membranes is one of the major hurdles to the durability and performance of anion exchange membrane fuel cells. Here we demonstrate a simple and efficient strategy of using nanofibrous materials, activated by radiation and functionalized with ionic groups to fabricate highly durable and conductive membranes with polycationic side chains. Two series of AEMs were prepared by radiation induced emulsion grafting of vinylbenzyl chloride onto syndiotactic polypropylene and nylon-66 nanofibrous sheets followed by crosslinking and introducing quaternary ammonium groups. A strong correlation was found between the choice of nanofibrous substrate as well as crosslinking degrees with water uptake, ion conductivity and stability of the membranes. A well-developed phase separated morphology was confirmed and the membranes with ion exchange capacities of 1.6–2.1 mmol g−1 showed high ionic conductivity, low methanol permeability and excellent alkaline stability. A hydroxide ion conductivity as high as 132 mS cm−1 was achieved at 80 °C and it was exceptionally retained at up to 90% after evaluation by accelerated degradation testing in 1 M NaOH at 80 °C for 672 h. A Pt-catalyzed fuel cell using these nanofibrous composite membranes showed a peak power density of above 120 mW cm−2 at 80 °C under 90% relative humidity. This strategy and observed properties pave the way for highly conductive and durable ion conducting membranes with tunable characteristics.

Environmentally benign and highly regioselective ring opening of epoxides accelerated by ultrasound irradiation

ABSTRACT Regioselective ring opening of aliphatic and aromatic epoxides with nitrogen heterocycles such as indoles and imidazoles was accelerated using an ultrasonic technique as a green approach. An optimized procedure with the catalyst of choice, MCM-41, represents a real alternative to the conventional reaction protocols owing to the catalyst recyclability, simplicity, green conditions and time-saving aspects. GRAPHICAL ABSTRACT

Composite membranes based on heteropolyacids and their applications in fuel cells

Heteropolyacids (HPAs) are a class of inorganic materials that have been widely used as additives to enhance the performance of fuel cell membranes, recently. This chapter covers the use of HPAs in the preparation of proton exchange membranes (PEM) for polymer electrolyte membrane fuel cells (PEMFCs). The fundamental aspects of HPAs and their corresponding salts in addition to various structural configurations such as Keggin, Wells–Dawson, and Lacunar are discussed. The use of HPAs for preparation of membranes for high-temperature PEMFC and direct methanol fuel cell (DMFC) based on the immobilization on various substrates including perfluorinated sulfonic acids (PFSAs), aromatic hydrocarbons, poly(vinyl alcohol) (PVA), and polybenzimidazole (PBI) are reviewed. The research challenges that need to be addressed to bring the new composite membranes to practical application are also discussed.

Preparation of alkaline polymer catalyst by radiation induced grafting for transesterification of triacetin under neural network optimized conditions

ABSTRACT A simple and flexible method was used to develop new alkaline polymer catalyst through radiation induced grafting of glycidylmethacrylate (GMA) onto polyethylene/polypropylene (PE/PP) nonwoven sheet followed by amination reaction and alkalisation. The chemical structure and morphology of catalyst was evaluated by Fourier transform-infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermal gravimetric analyzer (TGA). The catalyst was examined for the transesterification of triacetin/methanol mixtures in a batch mode and the obtained methyl ester was detected by GC-MS. In order to optimize the reaction parameters towards getting the higher yield, an artificial neural network (ANN) was used to develop a non-linear model correlating the four independent reaction parameters including catalyst dosage, triacetin/methanol molar ratio, reaction time and temperature. The maximum conversion obtained via the simulated annealing (SA) algorithm was 86.2% at the optimal conditions of 5.01 wt% catalyst dosage, triacetin/methanol 1:12 molar ratio, 8 h reaction time and 62.8°C temperature. Upon using these optimal conditions in the experimental reaction, the conversion of as high as 85% was achieved. These results suggest that the simply modified low cost PE/PP fibrous sheet has a potential to catalyze biodiesel production. Moreover, the combined ANN-SA modelling method is highly effective in predicting the conversion of transesterification reaction and optimizing its parameters.