Faculty Publications

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Author: search.filters.author.Isloor, A.M.Subject: search.filters.subject.Scanning electron microscopy

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    New polypropylene supported chitosan NF-membrane for desalination application
    (2011) Padaki, M.; Isloor, A.M.; Fernandes, J.; Prabhu, K.N.
    In the present study, a new NF membrane was prepared by coating chitosan on polypropylene fiber support, by the dissolution of chitosan in 2% acetic acid solution. The resulting membrane was characterized by thermo gravimetric analysis, water absorption, contact angle measurement and scanning electron microscopy. Prepared membrane showed two Tg peaks, one at ~90 °C that was due to chitosan and the other peak at ~170 °C that was corresponding to the supporting polypropylene membrane. The membrane showed a low swelling ratio at pH 7, 9, and 11 as compared with pH 5. The performance of the membrane was assessed out using dead end cell. Water flux was studied at different pressures. The salt rejection study was done using NaCl solution and the effect of pH on performance of the membrane was also examined. Newly prepared membrane showed improved water flux, and % of rejection is highest in acidic pH and lowest in basic pH. Hydrulic permeability coefficient and the dielectric constant confirms that the prepared membrane is nanofiltration membrane. © 2011 Elsevier B.V.
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    Synthesis and characterization of schiff base metal complexes and reactivity studies with malemide epoxy resin
    (Korean Chemical Society sunlee@kcsnet.or.kr, 2012) Lakshmi, B.; Shivananda, K.N.; Prakash, G.A.; Isloor, A.M.; Mahendra, K.N.
    A novel malemide epoxy containing Co(II), Ni(II) and Cu(II) ions have been synthesized by curing malemide epoxy resin (MIEB-13) and Co(II), Ni(II) and Cu(II) complexes of macrocyclic bis-hydrazone Schiff base. The Schiff base was synthesized by reacting 1,4-dicarbnyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol. The Schiff base and its Co(II), Ni(II) and Cu(II) complexes have been characterized by elemental analyses, spectral (IR, 1H NMR, UV-vis., FAB mass, ESR), thermal and magnetic data. The curing reaction of maleimide epoxy compound with metal complexes was studied as curing agents. The stability of cured samples was studied by thermo-gravimetric analyses and which have excellent chemical (acid/alkali/solvent) and water absorption resistance. Further, the scanning electron microscopy (SEM) and definitional scanning colorimetric (DSC) techniques were confirmed the phase homogeneity of the cured systems.
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    Enhanced hydrophilicity and salt rejection study of graphene oxide-polysulfone mixed matrix membrane
    (2013) Ganesh, B.M.; Isloor, A.M.; A.F., A.F.
    Graphene oxide (GO) dispersed polysulfone (PSf) mixed matrix membranes were prepared by wet phase inversion method. The morphology of membranes was studied using scanning electron microscope (SEM) images. The variation in hydrophilicity was studied by measuring surface wettability and water swelling experiments. The performance of membranes in terms of pure water flux and salt rejection was studied. SEM images depict enhanced macrovoids, while the contact angle data reveals that, GO incorporated membrane surface is moderately hydrophilic. Membranes exhibited improved salt rejection after GO doping. Membrane with 2000ppm GO loading has exhibited maximum of 72% Na2SO4 rejection at 4bar applied pressure. The salt rejection seems to depend on pH of the feed solution and it has been witnessed that the salt rejection showed an increasing trend with increase in the pH. © 2012 Elsevier B.V.
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    Modification of PSf/PIAM membrane for improved desalination applications using Chitosan coagulation media
    (2013) Kumar, R.; A.F., A.F.; Kassim, M.A.; Isloor, A.M.
    Polysulfone (PSf)/poly (isobutylene-alt-maleic anhydride) (PIAM) nanofiltration membranes were modified by changing the coagulation bath with various concentrations of glutaraldehyde cross-linked Chitosan solutions. Further the membranes were treated with 0.1N NaOH solution in order to achieve the hydrolysis of PIAM. The morphological changes of the membranes were determined using scanning electron microscope. The blending of PSf/PIAM membrane, the incorporation of Chitosan (CS) molecules in membrane matrix and the hydrolysis of PIAM in the membrane upon alkali treatment were studied by Attenuated Total Reflectance Infra Red (ATR-IR) spectroscopy. The hydrophilicity of modified membranes was measured using the contact angle analyzer. The pressure and time dependent pure water flux of modified PSf/PIAM/CS membranes were measured and compared with PSf/PIAM membranes (after alkali treatment). The antifouling property of membranes was determined using Bovine Serum Albumin (BSA) protein rejection studies. The modified membranes showed improved hydrophilicity and reduced pore size. The order of rejection of membranes for various electrolytes was Na2SO4>MgSO4>NaCl at minimum pressure of 0.2MPa TMP. The antifouling property of modified membranes increased with an increase in the composition of Chitosan in coagulation bath and membrane M-0.8 showed a maximum fouling resistance ratio of 74%. © 2013 Elsevier B.V.
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    Performance improvement of polysulfone ultrafiltration membrane using N-succinyl chitosan as additive
    (2013) Kumar, R.; Isloor, A.M.; A.F., A.F.; Matsuura, T.
    A water soluble chitosan derivative, N-succinyl chitosan (NSCS), was blended with polysulfone (PSf) in three different compositions to fabricate PSf/NSCS blend membranes. The blending of polymers was confirmed by Attenuated Total Reflectance Infra-Red (ATR-IR) spectroscopy. The membranes were characterized by Scanning Electron Microscopy (SEM) images for their cross-sectional morphology. Pure water flux, water uptake and contact angle of the PSf/NSCS blend membranes were measured and compared with the pristine polysulfone membrane. The PSf/NSCS blend membranes showed enhanced hydrophilicity and permeation fluxes compared to the pristine polysulfone membrane. The membrane antifouling property was determined by filtering the bovine serum albumin (BSA) solution. The maximum flux recovery ratio (FRR) of 70% was observed by the PSf/NSCS blend membrane with 20% NSCS content. The PSf/NSCS membranes with the PSf:NSCS ratios of 80:20 and 90:10 showed nearly the same fluxes as those of polysulfone/polyethylene glycol (PSf/PEG) blend membranes with the same compositions. The hydrophilic derivative of chitosan NSCS acted as an excellent additive in improving PSf ultrafiltration properties. © 2013 Elsevier B.V.
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    Polysulfone-Chitosan blend ultrafiltration membranes: Preparation, characterization, permeation and antifouling properties
    (2013) Kumar, R.; Isloor, A.M.; A.F., A.F.; Abdul Rashid, S.A.; Matsuura, T.
    Biocompatible and naturally occurring chitosan was used as an additive for the preparation of a polysulfone ultrafiltration membrane. Two different compositions of polysulfone in N-methylpyrrolidone (NMP) and chitosan in 1% acetic acid were blended to prepare PSf-CS ultrafiltration membranes by the diffusion induced phase separation (DIPS) method. The proper blending of polysulfone and chitosan in PSf-CS membranes was confirmed by ATR-IR analysis. The surface and cross-sectional morphology of the membranes was studied by scanning electron microscopy (SEM). The membrane hydrophilicity was determined by water uptake and contact angle measurements. The PSf-CS membrane showed an enhanced hydrophilicity compared to a PSf ultrafiltration membrane. The time dependent permeation studies revealed the improved flux of PSf-CS membranes. PSf-CS membranes were subjected to bovine serum albumin (BSA) protein rejection studies. An improved antifouling property was observed for PSf-CS blend membranes as compared to pristine PSf ultrafiltration membranes. Both the permeation and antifouling properties of PSf-CS membranes increased with an increase in chitosan composition. © 2013 The Royal Society of Chemistry.
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    Antifouling and performance enhancement of polysulfone ultrafiltration membranes using CaCO3 nanoparticles
    (2013) Nair, A.K.; Isloor, A.M.; Kumar, R.; A.F., A.F.
    Calcium carbonate nanoparticles were synthesized from calcium nitrate via chemical precipitation method. The nanoparticles were characterized using scanning electron microscope (SEM), Attenuated total reflectance infra red (ATR-IR) spectrum and by X-ray diffraction (XRD). These nanoparticles were used as additive for polysulfone (PSf) ultrafiltration membrane along with polyethylene glycol (PEG) as pore forming agent. The PSf hybrid membranes were characterized by ATR-IR, XRD, and SEM studies. ATR-IR and XRD results indicated the successful incorporation of the nanoparticles in the membranes. Cross sectional images of the membranes along with the elemental mapping of calcium on the membrane surface were assessed using SEM. Hydrophilicity of the membranes was evaluated in terms of contact angle measurements. The permeability of the membranes was determined by measuring the pure water flux (PWF). Membranes were also subjected to antifouling studies using bovine serum albumin (BSA) as the standard protein for rejection. The membranes showed better permeability and antifouling property with the increased addition of CaCO3 nanoparticles. © 2013 Elsevier B.V.
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    Preparation and characterization study of PPEES/chitosan composite membrane crosslinked with tripolyphosphate
    (Elsevier, 2014) Shenvi, S.; A.F., A.F.; Isloor, A.M.
    A novel composite membrane was prepared using chitosan (CH) as the active layer supported on a Poly(1,4-phenylene ether ether sulfone) (PPEES) membrane. The chitosan layer was ionically cross linked with sodium tripolyphosphate (TPP). The composite nature of PPEES/CH membranes was confirmed by Scanning Electron Microscopy (SEM). Infrared (IR) spectroscopy results and SEM-EDX analysis confirmed the crosslinking of chitosan surface with TPP. The membranes exhibited higher crosslinking density in acidic media than in basic media. The changes in the hydrophobic nature of PPEES membrane surface due to deposition of chitosan active layer followed by crosslinking were studied by their contact angle measurement, water flux and water uptake studies. The membranes showed rejection up to 55% and 21% towards MgSO4 and NaCl respectively at pH=5 and a flux recovery ratio of 73%. © 2014 Elsevier B.V.
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    Enhanced permeation performance of cellulose acetate ultrafiltration membranes by incorporation of sulfonated poly(1,4-phenylene ether ether sulfone) and poly(styrene- Co -maleic anhydride)
    (American Chemical Society service@acs.org, 2014) Shenvi, S.; A.F., A.F.; Isloor, A.M.
    A cellulose acetate (CA)-based ultrafiltration membrane was prepared by incorporation of mechanically strong, sulfonated poly(1,4-phenylene ether ether sulfone) (SPEES) to which hydrolyzed poly(styrene-co-maleic anhydride) (PSMA) was added as a novel additive. The preparation of SPEES was investigated in detail. SPEES having a degree of sulfonation of 21%, was more suitable for the blend. The chemical constitutions of SPEES, PSMA, and the blend membranes were confirmed by attenuated total reflectance fourier transform infrared spectroscopy. The scanning electron microscopy images revealed finger-like projections in the membrane structure. The performance of the membranes was analyzed on the basis of water content, porosity, flux, and antifouling studies. A membrane comprising 30% SPEES and 2% additive showed superior performance with flux and flux recovery ratio of 228 L/(m2 h) and 91%, respectively. It was concluded that the prepared membranes showed better performance in comparison with neat CA membranes. © 2014 American Chemical Society.
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    Preparation and antifouling properties of PVDF ultrafiltration membranes with polyaniline (PANI) nanofibers and hydrolysed PSMA (H-PSMA) as additives
    (Elsevier, 2014) Pereira, V.R.; Isloor, A.M.; Bhat, K.U.; A.F., A.F.
    Polyaniline (PANI) nanofibers were used as hydrophilic additives to study their effect on the performance of polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes. PVDF UF membranes were prepared by the phase inversion method with hydrolyzed polystyrene-co-maleic anhydride (H-PSMA) and PANI nanofibers as additives. PANI nanofibers were synthesized by rapid mixing reaction and were used as a hydrophilic modifying agent with varying concentrations (0-1.5 wt.%) in the membranes. The synthesized PANI nanofibers were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. Hydrolyzed PSMA was prepared by the hydrolysis of PSMA and was used as a novel pore forming additive. The addition of PANI nanofibers into the membranes increased the membrane hydrophilicity, porosity, water uptake and permeability. The membranes also showed good antifouling nature during BSA (bovine serum albumin) filtration when compared to the pristine membrane without PANI nanofibers. Membrane with 1.0 wt.% PANI content showed highest permeability among the synthesized membranes. The membrane having highest permeability was subjected to heavy metal ion rejection which showed high rejection of 98.52% and 97.38% for heavy metal ions Pb2+ and Cd2+ respectively. © 2014 Elsevier B.V.