In the present paper, Graphene Oxide (GO) particles were prepared via Hummer method, and used in synthesis of composite membranes. Polyethersulfone (PES) nanocomposite membranes were synthesized via wet phase inversion technique, and using water as non-solvent. The membrane morphology was investigated using scanning electron microscopy (SEM). Change in the membrane surface hydrophilicity after modification was studied using contact angle measurements. The performance of fabricated PES nanocomposite membranes was measured by evaluating pure water flux, salt rejection, dye retention and heavy metals removal. The results indicated that by increasing the filler percentage up to 5 wt.%, the contact angle between the water droplet and the membrane surface was decreased and the droplet was more dispersed on the membrane surface which implies higher hydrophilicity of the prepared nanocomposite membranes. Moreover, the experimental results corroborated that addition of GO to the membrane significantly improved the pure water flux, salt rejection and heavy metals removal, and can be used as a novel methodology for preparation of high performance membranes in water treatment. Over the last decades, substantial development in chemical industries has eventuated in an increment in the processing speed and a reduction in energy consumption 1. It has been recognized that separation and purification of different materials is one of the most significant techniques in chemical and biochemical engineering which has major contribution to total processing costs 2-6. In order to implement the industrial processes, raw material components must be separated and the obtained products should be purified as well. On the other hand, in the majority of chemical industries, the requirement of separation procedures seems to be unavoidable to efficiently manage the deleterious impressions of greenhouse gases on environment 7-9. In this regard, membranes have been developed for the efficient separation and purification of various types of materials in solid, liquid and gas states. Although the membrane separation procedure is more recent than distillation, adsorption, crystallization and liquid-liquid extraction, significant advancements have been observed in its application over the past two decades due to the efficiency and ease of operation 4,5,10-17. Both polymeric and inorganic membranes have been developed for the purpose of separation and reaction. Polysulfone-based membranes such as Polyethersulfone (PES) are utilized for the fabrication of nanofiltration membranes because of their outstanding mechanical/thermal resistance, chemical compatibility and stability over an extensive range of pH 18. The main disadvantage of the PES membranes is its intrinsic hydrophobic nature. Due to the absorption of organic impurities, these membranes are susceptible to fouling and blockage which leads
The electrochemical performance of the Li/O2 battery under different operation conditions was studied to elucidate the effects of discharge rate, discharge depth and charge taper voltage on the performance and state of charge of the battery. Galvanostatic discharge profiles at various discharge rates showed that the effective capacity of the cell drops with increase in the discharge rate. However the cell's cycleability improved with increase in the discharge rate probably due to the ease of stripping the Li2O2 film formed on the electrode surface reversibly at higher rates, compared with the incomplete removal of discharge products formed within the pores at low discharge rates. The performance of the cell discharged at different cut off voltages showed that decreasing the depth of discharge decreases the rate of capacity fade and improves the cell cycleability. Study of the cell performance at different charge taper voltages showed that the cell capacity increases with charge taper voltage for charge potentials up to 4.45 V. For charge potentials above 4.45 V, the cell performance deteriorates with increasing charge taper voltage significantly, probably due to the decomposition of the electrolyte at higher charge potentials. It is believed that a potential of 4.45 V is the edge of breakdown potential of propylene carbonate based electrolytes.
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