Faculty Publications
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Item Preparation and characterization of PPEES/chitosan composite nanofiltration membrane(2013) Shenvi, S.S.; Abdul Rashid, S.A.; A.F., A.F.; Kassim, M.A.; Isloor, A.M.Composite membrane having chitosan (CH) as the active layer supported on Poly(1,4-phenylene ether ether sulfone) (PPEES) membrane was synthesized in the current study. The chitosan layer was crosslinked by glutaraldehyde in two different concentrations. The scanning electron microscopic images and hydraulic permeability coefficient revealed the ultrafiltration (UF) nature of the neat PPEES membrane. This was used as a new support material for the casting of chitosan layer in order to get composite membranes. The composite nature of the PPEES/CH membranes was confirmed by FESEM and DSC analysis. The Infrared spectroscopy results confirmed the crosslinking of the chitosan surface by glutaraldehyde (GA). The changes in the hydrophobic nature of the PPEES membrane surface due to deposition of chitosan active layer followed by crosslinking were studied by their contact angle measurement and water flux study. From our studies, PPEES has proved to be a good support membrane for preparation of composite membranes. Increase in GA concentration increased the salt rejection of the membrane up to 34% for NaCl and 53% for MgSO4 on one hand with a simultaneous decrease in the flux values. The hydraulic permeability coefficient values confirmed that the prepared membranes are in nanofiltration range. © 2012 Elsevier B.V.Item 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.Item Effect of acid dopants in biodegradable gel polymer electrolyte and the performance in an electrochemical double layer capacitor(Institute of Physics Publishing custserv@iop.org, 2015) Sudhakar, Y.N.; Muthu, M.; Bhat, D.K.Proton-conducting biodegradable gellan gum gel polymer electrolytes (GPEs) have been prepared using three different dopants, namely ortho-phosphoric (o-H3PO4), sulfuric (H2SO4) and hydrochloric acids (HCl). The GPEs were cross-linked using borax. The polymeric gels were characterized by spectroscopic, thermal, ionic conductivities and dielectric measurements. Proton conductivity was in the range of 5.1 × 10-3 to 3.7 × 10-4 s cm-1 and activation energies were between 0.14 meV and 0.19 meV, at different temperatures. Among the doped acids, the H3PO4 doped GPE exhibited thermal stability at varying temperature. Electrochemical double layer capacitors (EDLCs) were fabricated using activated carbon as electrode material and GPEs. The EDLCs were tested using cyclic voltammetry, ac impedance spectroscopic and galvanostatic charge-discharge techniques. The maximum specific capacitance value was 146 F g-1 at a scan rate of 2 mV s-1. Quite stable values were obtained at a constant current density up to 1000 cycles. © 2015 The Royal Swedish Academy of Sciences.Item Removal of Heavy Metal Ions from Water by Cross-Linked Potato Di-Starch Phosphate Polymer(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2015) Bhat, M.A.; Chisti, H.; Shah, S.A.Potato di-starch phosphate polymer was synthesized by cross-linking potato starch with phosphorus oxy-chloride in basic medium and was then dispersed (0.2-1%) in aqueous solutions of divalent heavy metal ions (Cu2+, Ni2+, Zn2+, and Pb2+), to investigate their removal efficiency by the starch and was found to increase with increase in the polymeric starch content and increase in the heavy metal ion concentration. The removal order was found to be Pb2+ (78.1%) > Cu2+ (58.5%) > Zn2+ (20.5%) > Ni2+ (17.3%) against the constant polymeric starch content. UV-Visible, Fluorescence, FT-IR, SEM, and CHN techniques were used for characterization of different complexes formed. © © Taylor & Francis Group, LLC.Item Preparation and characterization of phosphoric acid-doped hydroxyethyl cellulose electrolyte for use in supercapacitor(SpringerOpen, 2015) Sudhakar, Y.N.; Muthu, M.; Bhat, D.K.A new borax cross-linked biodegradable solid polymer electrolyte based on hydroxyethyl cellulose and phosphoric acid (H3PO4) was prepared. Characterizations of doped and undoped SPE were done using Fourier transform infrared spectroscopic and electrochemical studies. The ionic conductivity of the films increased with increase in acid concentration and the ionic conductivity obtained at 303 K was 4.1 × 10-3 S cm-1. Furthermore, effects of acid concentration on ionic conductivity and activation energy were discussed. Dielectric studies showed long tail-like feature indicating capacitive nature. A supercapacitor was fabricated and its electrochemical characteristics were studied. The supercapacitor showed a fairly good specific capacitance of 83 F g-1 at 2 mV s-1 and galvanostatic charge-discharge studies showed the mirror-like pattern with 98 % columbic efficiency. Cyclic stability was measured up to 2000 cycles. © 2015 The Author(s).Item Enhancement of n-3 polyunsaturated fatty acid glycerides in Sardine oil by a bioimprinted cross-linked Candida rugosa lipase(Elsevier Inc. usjcs@elsevier.com, 2018) Sampath, C.; Belur, P.D.; Iyyaswami, R.Considering the advantages of bioimprinting and carrier free immobilization, cross-linked enzyme aggregates (CLEA) were prepared by using bioimprinted Candida rugosa lipase (CRL) with Bovine serum albumin (BSA), Polyethyleneimine and glutaraldehyde. Effect of various factors such as CRL-Oleic acid ratio, CRL-BSA ratio, CRL- Polyethyleneimine ratio, glutaraldehyde loading, cross-linking time etc., on lipase activity recovery and aggregate yield were studied and optimized. This immobilized lipase (CRL-CLEA) was used for the selective hydrolysis of ester linkages of non-PUFA glycerides, with an aim to concentrate EPA and DHA glycerides in the Sardine oil. Imprinting with oleic acid in the presence of ethanol and Tween 60, and further immobilization with co-aggregates and cross-linking agent showed 10.4 times higher degree of hydrolysis compared to free enzyme. As result, 2.83-fold increase of n-3 PUFA content in deacidified oil was obtained by using CRL-CLEA. The resultant oil had negligible di- and triglycerides content, proving higher efficiency in hydrolysing ester bonds of fatty acids, other than n-3 PUFA. Reusability studies showed CRL-CLEA could be reused up to 5 runs without a substantial reduction in its performance. Improvement in degree of hydrolysis, thermostability, efficiency of hydrolysis and reusability were achieved due to bioimprinting and subsequent immobilization of CRL in the form of CLEA. © 2017 Elsevier Inc.Item Characterization and mechanical properties of sisal fabric reinforced polyvinyl alcohol green composites: Effect of composition and loading direction(Institute of Physics Publishing helen.craven@iop.org, 2019) Nagamadhu, M.; Jeyaraj, P.; Mohan Kumar, G.C.M.This research focuses on microstructure characterization and exploring mechanical properties of sisal fabric reinforced Polyvinyl Alcohol composites using conventional vacuum-assisted pressure compression method. Naturally available sisal fiber is used as reinforcement material in this composite because of its abundant availability in Southern India. The sisal fiber, PVA and its composites were characterized using Fourier Transform Infrared Spectroscopy. Initially, Polyvinyl Alcohol polymer was cross-linked with Glutaraldehyde, and mechanical properties were evaluated. It was observed that 20% Glutaraldehyde and 80% Polyvinyl Alcohol polymer combination yielded best mechanical properties. Further, two plain and one weft rib were considered and their textile properties were characterized. The results revealed that fabric crimp and yarn linear density had significant influence on tensile properties of the fabric. Influence of different fabric properties such as weaving pattern, grams per unit area, and loading direction on mechanical properties of composites were analyzed. The woven fabric having least gram per unit area of sisal resulted in best mechanical properties like tensile, bending, and impact. The weft rib fabric composites in weft direction exhibited best mechanical properties. © 2019 IOP Publishing Ltd.Item Influence of glutaraldehyde on dynamic properties of poly(vinyl alcohol) polymer(ICE Publishing, 2020) Mohan Kumar, G.C.M.; Jeyaraj, J.; Nagamadhu, M.This study investigated the dynamic mechanical properties of poly(vinyl alcohol) (PVA; (CH2CH(OH)) n ) cross-linked with glutaraldehyde (GA; OHC(CH2)3CHO).*The cross-linked polymer was prepared by using a conventional casting technique and then treated with sulfuric acid (H2SO4) for 24 h.*The flexural properties during static and dynamic modes were studied using a three-point bending condition.*The static flexural properties are improved with the addition of 30% GA in PVA, with higher value of strain.*It was observed that the dynamic mechanical properties of PVA improved significantly with an increase in cross-linking percentage.*The storage and loss moduli increased drastically with the addition of the cross-linker up to 20%, and marginal changes occurred with further addition of the cross-linker.*The fracture behavior was transformed from ductile to brittle for more than 20% cross-linker.*Shifting of the rubber region and liquid region with higher temperatures was observed in storage and loss modulus plots.*Improvement in the adhesion factor, cross-linking density and effectiveness was observed for GA up to 25%.*The test duration was estimated using the Williams-Landel-Ferry model for different temperatures.*The major changes were in the modulus in the rubbery plateau region.*The cross-linked polymer had much greater storage and loss moduli, indicating a closer network structure and higher stiffness.* © 2020 ICE Publishing: All rights reserved.Item Integration of Zwitterionic Polymer Nanoparticles in Interfacial Polymerization for Ion Separation(American Chemical Society, 2020) Gnani Peer Mohamed, G.P.S.; Isloor, A.M.; Bavarian, M.; Nejati, S.A thin-film nanocomposite (TFN) membrane was developed by integrating zwitterionic polymeric nanoparticles into the active layer of the membranes. High surface area zwitterionic polymeric nanoparticles (370 m2/g) were developed through distillation-precipitation polymerization (DPP). Sodium 4-vinylbenzenesulfonate (SVBS) was used as the monomer and N,N?-methylenebis(acrylamide) (MBAAm) utilized as the cross-linking agent. l-cysteine (l-Cys) was tethered to these matrices through thiol-ene reaction. The as-synthesized zwitterionic P(MBAAm-co-SVBS)@l-Cys nanoparticles were dispersed into the organic solution of trimesoyl chloride (TMC) to be integrated into the polyamide (PA) selective layer of thin film nanofiltration membranes. The PA layer was synthesized by interfacial polymerization through the reaction of 2% (w/v) of piperazine (PIP) in the aqueous phase and 0.15% (w/v) of the TMC solution. The fabricated TFN membranes exhibited pure water permeability (Jw) of 11.4 L/m2h bar and salt rejection value of 97.6% and 16.9%, for sodium sulfate and sodium chloride, respectively. The fabricated membranes demonstrated metal ion removal efficiencies of 99.48% and 95.67% for Pb2+ and Cd2+ ions, respectively. © © 2020 American Chemical Society.Item Synthesis and detailed characterization of sustainable starch-based bioplastic(John Wiley and Sons Inc, 2022) Chakraborty, I.; Pooja, N.; Banik, S.; Govindaraju, I.; Das, K.; Mal, S.S.; Zhuo, G.-Y.; Rather, M.A.; Mandal, M.; Neog, A.; Biswas, R.; Managuli, V.; Datta, A.; Mahato, K.K.; Mazumder, N.There is an urgent requirement of replacing the environmentally hazardous petroleum-based plastics with sustainable and efficient starch-based bioplastics. Development and detailed characterization of the biodegradable bioplastics from plant-based polysaccharides such as starch is essential to reduce plastic pollution in the environment. In this research, bioplastics were developed from an equivalent blend of starch from two different sources namely rice and potato (1:1, w/w), crosslinked with different concentrations of citric acid (CA). The effect of CA cross-linking of starch-based bioplastics was investigated on its physicochemical and functional properties. The X-ray diffraction (XRD) spectra revealed that the synthesized bioplastics were amorphous in nature with broad diffraction peaks. Further, the peak at 1716 cm−1 in Fourier transform infrared (FTIR) spectra indicated the formation of ester bonds in CA cross-linked bioplastics. Atomic force microscopy (AFM) revealed the surface roughness of the bioplastics decreased with increasing concentration of CA. Mechanical and thermal properties of bioplastics were characterized using universal testing machine, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA), respectively. © 2022 Wiley Periodicals LLC.