Faculty Publications
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Item Synthesis, characterization & impedance studies of some new nano filtration membranes(Trans Tech Publications Ltd ttp@transtec.ch, 2010) Padaki, M.; Hegde, C.; Isloor, A.M.In the recent years membrane technology has gained significant attention from polymer chemists all around the world due to their attractive features such as efficiency, low costs, low energy costs and as effective solutions to longstanding problems in the chemical industries. Membrane technologies have been widely applied in the separation of liquids and even gases. Many separation problems can be solved economically by nanofiltration alone or in combination with other separation processes. This study aimed to synthesize polysulfone based nanofiltration membranes using DIPS (diffusion induced phase separation) technique. Newly synthesized polymer membranes were subjected to Infra red spectral and water uptake studies. Membranes were also characterized using electrochemical spectroscopy for their proton conducting property. Their surface morphology is visualized by SEM. © (2010) Trans Tech Publications.Item Synthesis, characterization and desalination study of composite NF membranes of novel Poly[(4-aminophenyl)sulfonyl]butanediamide (PASB) and methyalated Poly[(4-aminophenyl)sulfonyl]butanediamide (mPASB) with Polysulfone (PSf)(2013) Padaki, M.; Isloor, A.M.; Kumar, R.; A.F., A.F.; Matsuura, T.In the present investigation, Poly [(4-aminophenyl)sulfonyl]butanediamide (PASB) and methylated Poly[(4-aminophenyl)sulfonyl] butanediamide (mPASB) polymers were synthesized, using succinyl chloride and substituted 4-amino-1-benzenesulphonamide. Polysulfone composite membranes were prepared by blending these novel polymers by Diffusion Induced Phase Separation (DIPS) method. The performance of the membrane was studied in terms of salt rejection, water flux and molecular weight cutoff. The prepared membranes were hydrophilic in nature, which was confirmed by water uptake studies and contact angle measurement. All the membranes showed 1000. Da molecular weight cutoff. A maximum NaCl rejection of 52% was observed in some of the membranes. The effect of feed NaCl concentration on the NaCl rejection was also studied. The resistance of the membranes in a wide pH range was studied by water uptake measurement. Antifouling properties of the membranes were also performed using Bovine Serum Albumin (BSA) solution. © 2012 Elsevier B.V.Item 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.Item Phase demixing studies in aqueous two-phase system with polyethylene Glycol (PEG) and sodium citrate(2013) Nagaraja, V.H.; Iyyaswami, I.The kinetics of phase demixing in an aqueous two-phase system (ATPS) consisting of PEG/sodium citrate, with various PEG molecular weights (2000, 4000, and 6000) was investigated at 25°C. The rate of demixing of the phases (top/bottom) is essential to scale up the aqueous two-phase extraction (ATPE) process. The individual phase physical properties like density, viscosity, and interfacial tension are highly dynamic with the phase composition, and are responsible for the demixing of phases. Hence, in the present study, the variation of physical properties with phase compositions in terms of tie line length (TLL) was considered for the analysis of the rate of demixing of phases. The effect of the volume ratio of the phases (top/bottom) on the kinetics of phase separation also studied since the dispersed phase holdup in the mixture influences the rate of demixing. The higher TLL with a salt-rich phase as continuous phase showed higher reduction in demixing time when than low TLL at the volume ratio of <1. Based on the analysis, empirical correlations were proposed for top and bottom phase demixing rate in terms of Morton's number, volume ratio, and TLL. The coefficients and constants from the literature and the present correlations were estimated through regression analysis. The developed correlation predicted the demixing rate with lower AARD (±7%) for both the phases. The proposed correlation was accurate and simple in predicting the demixing rate of PEG/sodium citrate ATPS at 25°C. © 2013 Copyright Taylor and Francis Group, LLC.Item Influence of organically modified clay mineral on domain structure and properties of segmented thermoplastic polyurethane elastomer(2014) Anandhan, S.; Lee, H.S.Segmented polyether-urethane/organically modified montmorillonite (O-MMT) nanocomposites were synthesized with poly(tetramethylene glycol) (PTMG), 4,4?-diphenylmethane diisocyanate (MDI), butane diol (BD), and a commercially available clay Cloisite-30B® (O-MMT). The state of dispersion of the clay crystals in the thermoplastic polyurethane elastomer (TPU) matrix was studied by X-ray diffraction and transmission electron microscopy (TEM). The phase-separated morphology of the TPU was revealed by high-resolution TEM (HRTEM) and atomic force microscopy (AFM). O-MMT caused a marginal increase in the glass transition temperature of the soft segments of the TPU and this increase is proportional to the amount of O-MMT in the nanocomposites. Differential scanning calorimetry (DSC) was employed to study the effect of O-MMT on the extent of phase separation in the TPU in these nanocomposites. Thermogravimetric analysis (TGA) results indicate a substantial improvement in the thermal stability of TPU by the addition of O-MMT. Tensile strength and elastic modulus are dramatically decreased by the incorporation of O-MMT into TPU, which is due to the hindrance of the phase-separation process by the exfoliated clay-layered crystals. © The Author(s) 2012 Reprints and permissions:sagepub.co.uk/journalsPermissions.nav.Item Synthesis and characterization of novel sulfanilic acid-polyvinyl chloride-polysulfone blend membranes for metal ion rejection(Royal Society of Chemistry, 2016) Nayak, V.; Jyothi, M.S.; Balakrishna, R.G.; Padaki, M.; Isloor, A.M.Near-complete removal of heavy metals, namely Cd(ii), Cr(vi) and Pb(ii), has been attempted by a membrane purification process using a blend of modified polyvinyl chloride (PVC) and polysulfone (PSf), prepared by the diffusion induced phase separation (DIPS) method. The prepared novel material was characterized by NMR, ATR-IR spectroscopy and DSC. The sulphonyl groups incorporated into PVC enhance the hydrophilicity and are substantiated by water uptake, contact angle (CA) and flux studies. The obtained properties of the blend membrane like increased surface roughness and porosity are observed from AFM and SEM analysis. An enhanced rejection of ?95% which is about 1.15, 1.41 and 1.37 times better than the commercially available NF 270 membrane was observed, for Cd(ii), Cr(vi) and Pb(ii) respectively. The work was further extended to study the antifouling property and the interference of other existing metal ions on the performance. An improved antifouling property with 98.5% rejection for bovine serum albumin (BSA) and a 75.6% flux recovery ratio (FRR) was achieved. The study gains significance in exploring the incorporation of sulphonyl groups in to polymers, to enhance membrane performance. © The Royal Society of Chemistry 2016.Item A Liquid Derivative of Phosphotungstic Acid as Catalyst for Benzyl Alcohol Oxidation in Water: Facile Separation and Stability of Benzaldehyde at Room Temperature†(Wiley-Blackwell, 2017) Bhattacharjee, R.R.; Thangamani, S.; Mal, S.S.Polyetheramines belong to a class of green di-block copolymer with ethylene oxide and propylene oxide moieties along with terminal amine functionality. The polymers are biocompatible and show temperature dependant phase separation properties. Herein, we report the effect of a polyetheramine (Jeffamine®) on the catalytic properties of a well studied polyoxometalate catalysts, phosphotungstic acid (PTA). The catalytic reaction chosen for the test is the hydrogen peroxide-mediated oxidation of benzyl alcohol (BzOH). Modification of PTA with Jeffamine® (PTA-Jeffamine®) resulted in a solvent-less liquid-like material accessible to a wide range of solvents. The PTA-Jeffamine® catalyst was observed to enhance the conversion of BzOH compared to that of pristine PTA and facilitated easy separation of benzaldehyde (BzH) and catalyst from reaction mixture. Stability of synthesized BzH was studied with gas chromatography attached with mass spectrometry (GC-MS). Synthesis of the catalyst is cost-effective and scalable due to easy availability of the individual components and nature of the synthetic protocol. UV-visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM) were used to characterize the catalyst. Surface tension experiment, FE-SEM, ICP-MS and controlled experiments were performed to understand the effect of Jeffamine® in the catalytic process. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimItem Fabrication of novel PPSU/ZSM-5 ultrafiltration hollow fiber membranes for separation of proteins and hazardous reactive dyes(Taiwan Institute of Chemical Engineers, 2018) Nayak, M.C.; Isloor, A.M.; Moslehyani, A.; Ismail, N.; A.F., A.F.Polyphenylsulfone (PPSU) based asymmetric hollow fiber membranes were prepared by the addition of different percentages of ZSM-5 particles by diffusion induced phase separation method. Polyvinylpyrrolidone (PVP) was used as a pore forming agent. The fabricated membranes were characterized by Field Emission scanning electron microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), contact angle, water permeability, water uptake and by porosity measurements. Membranes filtration study was performed using different proteins namely bovine serum albumin (BSA), egg albumin (EA) and hazardous dyes like Reactive black 5 (RB-5), Reactive orange 16 (RO-16) in aqueous solutions. It was found that, addition of ZSM-5 in membrane matrix showed better dye removal capacity because of its hydrophilic and adsorptive nature. The membrane (PZ-3) with higher loading of additive exhibited rejection percentages of 100% for BSA, 95.23% for EA proteins and with reactive dyes 90.81% for RB-5 and 82.84% for RO-16 as compared to the pristine HF membrane. © 2017 Taiwan Institute of Chemical EngineersItem Novel polyphenylsulfone (PPSU)/nano tin oxide (SnO2) mixed matrix ultrafiltration hollow fiber membranes: Fabrication, characterization and toxic dyes removal from aqueous solutions(Elsevier B.V., 2019) Nayak, M.C.; Isloor, A.M.; Siddique, I.; Balakrishna Prabhu, B.; Ismail, N.I.; Asiri, A.M.Novel polyphenylsulfone (PPSU)/nano tin oxide (SnO2) mixed matrix hollow fiber membranes (HFMs) were fabricated by dry-wet spinning via phase separation method. In the current research, reported the contrast between neat PPSU membrane and nanocomposite membranes (PPSU/SnO2), to determine the toxic reactive dyes namely, reactive black-5 (RB-5) and reactive orange-16 (RO-16) removal ability from the aqueous media. Scanning electron microscopy (SEM) was used to observe the HFMs cross-sectional morphological changes and surface roughness parameters of membranes were analyzed using atomic force microscopy (AFM). The surface wettability ability of HFMs was examined with a contact angle, water uptake, and porosity measurements. The cross-flow filter unit was engaged to quantify the water permeability, anti-fouling ability as well as the dye rejection ability of fabricated membranes. With increasing the SnO2 NPs wt% in PPSU polymer matrix the membrane performance was enhanced continuously, it became evident that the incorporated SnO2 NPs plays main role in membrane performance. Added, water-soluble poly (vinylpyrrolidone) (PVP) can also impact the pore morphology in membranes. At the end, PS-3 membrane exhibited lower contact angle (63.7 0), higher water uptake (74.8%), porosity (84.1%), pure water flux 362.9 L/m2 h, and high potential for dyes rejection application, of about >94% for RB-5, and >73% for RO-16 dye, respectively. From the preliminary results, it can be stated that the usage of SnO2 NPs in membrane technology become effective towards wastewater treatment. © 2019 Elsevier B.V.Item PMMA-LZO Composite Dielectric Film with an Improved Energy Storage Density(Springer New York LLC barbara.b.bertram@gsk.com, 2019) Kishor Kumar, M.J.; Kalathi, J.T.Energy storage materials in modern electronic devices and renewable energy systems are inevitable. The incorporation of inorganic fillers into the polymer matrix is a promising option for the advancement of storage materials with high energy density. The agglomeration of inorganic fillers in the polymer matrix and phase separation remain the main obstacles to efficient applications of the composites for energy storage. Here, the primary attention was given to achieve a uniform distribution of high-k LZO (Lanthanum Zirconium Oxide) filler into a PMMA (Polymethylmethacrylate) matrix to enhance the dielectric constant and energy storage density of PMMA while keeping dielectric loss at minimum. We prepared PMMA-LZO composite films with variable LZO content by ultrasound-assisted mixing followed by spin coating the solution on ITO (Indium tin oxide) coated glass. The effect of LZO content on dielectric properties of the LZO-PMMA films was studied. Dielectric constant (k) of PMMA was found to be increased from 3.1 to 15.3 at 15 vol.% LZO loading with a dielectric loss of 0.0582. However, 10 vol.% LZO loaded PMMA showed an improved dielectric constant of 13.4 while the dielectric loss remained the same as that of the neat PMMA. The LZO-PMMA films with 10 vol.% and 15 vol.% of LZO loading exhibited maximum energy density of 5.94 J cm?3 and 6.53 J cm?3, respectively. Overall, the 10 vol.% LZO loading was found to be optimum to achieve a stable film with improved dielectric properties. This work provides a viable approach for the development of flexible, high-energy density materials with a minimum dielectric loss. © 2019, The Minerals, Metals & Materials Society.