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Abstract : Scrutinizing the Nanostructural and Nanomechanical Features of Regenerated Cellulose Ultrafiltration Membranes
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Abstract: Ultrafiltration (UF) membranes have been widely used for many separation processes in which high performance is required. Commercial regenerated cellulose UF membranes with variable molecular weight cut-offs were characterized by high performance atomic force microscopy (AFM) using the novel quantitative nanomechanical mapping mode and the versatility of its signal channels towards nanoscale features elucidation of the materials surface. In addition, Raman spectroscopy was applied in order to investigate some possible chemical behavior changes associated with the UF membranes’ cut-offs. Overall, the results showed that the proposed AFM method was reliable to gain qualitative and quantitative data at unprecedented nanoscale resolution and such information can be used to distinguish UF membranes according to their specific molecular weight cut-offs and properties even on situations in which the molecular behavior were not influenced by the UF membrane’ cut-off. This approach can be useful on quality control procedures of researchers and manufacturers producing or modifying these polymeric materials. Keywords: Ultrafiltration membranes, Atomic force microscopy, Quantitative nanomechanical mapping, Raman spectroscopy, Nanostructural properties, Nanomechanical properties, Molecular weight cut-off.Download Full Article |
Abstract : Polychloroprene Rubber/Reduced Graphene Oxide (RGO) Nanomembranes for Pervaporation Separation of Azeotropic Mixtures
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Abstract: Chloroprene rubber is a high performance elastomer with remarkable ageing, heat and oil resistance. A new class of elastomeric nanocomposite was prepared by incorporating reduced graphene oxide (RGO) into chloroprene rubber (CR). RGO is synthesised from natural graphite, through GO route via Hummer’s method. This paper focuses on the influence of reduced graphene oxide on chloroprene rubber based elastomeric composites and their pervaporation separation of azeotropic liquid mixtures. The effect of concentration of RGO on separation factor, pervaporation separation index (PSI) and flux of the membranes were analysed. Chloroprene loaded with 0.9 phr (parts per hundred rubber) RGO shows an improved permeation rate among all other membranes while chloroform/acetone (80/20) azeotropic liquid mixture was used as feed solution. Flux increases with increasing the concentration of filler, reaches an optimum value and then decreases. Interestingly PSI also shows similar trend. Keywords: Pervaporation, graphene oxide, chloroprene rubber, azeotropic liquid mixtures, flux.Download Full Article |
Abstract : Ion Exchange Membranes for Electrodialysis: A Comprehensive Review of Recent Advances
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Abstract: Electrodialysis related processes are effectively applied in desalination of sea and brackish water, waste water treatment, chemical process industry, and food and pharmaceutical industry. In this process, fundamental component is the ion exchange membrane (IEM), which allows the selective transport of ions. The evolvement of an IEM not only makes the process cleaner and energy-efficient but also recovers useful effluents that are now going to wastes. However ion-exchange membranes with better selectivity, less electrical resistance, good chemical, mechanical and thermal stability are appropriate for these processes. For the development of new IEMs, a lot of tactics have been applied in the last two decades. The intention of this paper is to briefly review synthetic aspects in the development of new ion-exchange membranes and their applications for electrodialysis related processes. Keywords: Electrodialysis, ion exchange membrane, anion exchange membrane, cation exchange membrane, bipolar membrane.Download Full Article |
Abstract : Divalent Transition Metals Substituted LaFeO3 Perovskite Catalyst for Nitrous Oxide Decomposition
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Abstract: Divalent transition metals substituted LaFeO3 type perovskite catalysts (LaFe0.95M0.05O3 with M= Cu2+ and Ni2+) were synthesized by hydrothermal method and characterized by using X-ray diffraction (XRD), temperature programmed reduction with H2 (H2-TPR) and N2-physisorption techniques. The catalytic activity of the catalysts was tested for N2O decomposition reaction. Enhancement in the catalytic activity was observed after substitution of Cu and Ni metal ions into LaFeO3 framework. LaFe0.95Ni0.05O3 showed higher catalytic activity than LaFeO3 and LaFe0.95Cu0.05O3 catalysts. The plausible reason for the increased activity is that LaFe0.95Ni0.05O3 sample possessed high oxygen mobility than the other two samples. Keywords: Perovskite, N2O decomposition, Ni and Cu metal ions, XRD, H2-TPR.Download Full Article |
