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Adoor S.G.,Govindram Seksaria Science College | Bhat S.D.,CSIR - Central Electrochemical Research Institute | Dionysiou D.D.,University of Cincinnati | Nadagouda M.N.,Govindram Seksaria Science College | Aminabhavi T.M.,Govindram Seksaria Science College
RSC Advances | Year: 2014

Composite membranes of sulfonatedpoly(ether ether ketone) (sPEEK) containing nascent and modified silicotungstic acid (STA) nanoparticles were tested for pervaporation (PV) separation of water-isopropanol mixtures. The performance of filler loaded composite membranes was better than that of nascent polymer membranes. The chemically modified STA containing membranes showed improved PV performance compared to those of nascent STA loaded membranes. This effect is attributed to leaching of STA during the PV cycles. The leaching effect was reduced after modification of STA with cesium carbonate. Among all the composite membranes prepared by the solution casting method, the membrane containing 7 wt% modified STA gave the highest PV separation performance compared to those containing 3, 5 and 10 wt% STA. The PV performance of the 7 wt% STA loaded membrane was further tested as a function of feed water composition from 10 to 25 wt% and a temperature range of 30-60 °C. Characterization of the membranes was done by universal testing machine (UTM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The PV results have been explained in terms of sorption-diffusion principles and Arrhenius activation parameters. This journal is © the Partner Organisations 2014.

Adoor S.G.,Govindram Seksaria Science College | Rajineekanth V.,Govindram Seksaria Science College | Nadagouda M.N.,Govindram Seksaria Science College | Chowdoji Rao K.,Sri Krishnadevaraya University | And 2 more authors.
Separation and Purification Technology | Year: 2013

Phosphotungstic acid (PTA) in unmodified and modified form (by ammonium carbonate) was incorporated as filler nanoparticles in different compositions (3%, 5%, 7% and 10%) in sodium alginate (NaAlg) to develop nanocomposite membranes (NCMs) by solution casting method and cross-linked with glutaraldehyde. The performance of these NCMs has been tested over that of pristine NaAlg membrane for dehydration of isopropanol and ethanol via the pervaporation (PV) technique. Membranes were characterized by a variety of techniques. The PV performance was investigated over the feed water composition of 10-30 wt.% and temperature interval of 30-60 C. Improvement in separation performance was observed for the modified membranes than the unmodified membranes, suggesting the importance of chemical modification of PTA nanoparticles to avoid the leaching problem. The NaAlg membrane containing 10 wt.% modified PTA showed the highest PV performance, clearly indicating the effect of adding modified PTA. © 2013 Elsevier B.V. All rights reserved.

Kalagi S.S.,Govindram Seksaria Science College | Dalavi D.S.,Shivaji University | Pawar R.C.,Shivaji University | Tarwal N.L.,Shivaji University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2010

We report the synthesis of structurally and uniformly deposited porous tungsten oxide (WO 3) thin films for the first time by the novel route of polymer assisted deposition (PAD) using ammonium tungstate as a precursor with polyvinyl alcohol (PVA) as an additive. The effect of deposition parameters on the morphological, optical and electrochemical performance of the thin films is investigated. WO 3 thin films were characterized for their structural, morphological, optical and electrochromic properties. XRD result indicates monoclinic phase of WO 2.92. FT-Raman studies show high intensity peaks centered at 997 cm -1and 798 cm -1. SEM results indicate that there is uniform deposition of porous WO 3-PVA agglomerates on the transparent substrates. SEM data show low dense structure of an average grain size of about 1 μm. Electrochromic studies reveal highly reversible and the stable nature of the thin films. Transmission data show an optical modulation density of 46.57% at 630 nm with an excellent reversibility of 89% and an electrochromic coloration efficiency of 36 cm 2/C. © 2009 Elsevier B.V. All rights reserved.

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