Faculty Publications
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Item Synthesis and desalination performance of Ar+-N+ irradiated polysulfone based new NF membrane(2011) Hegde, C.; Isloor, A.M.; Padaki, M.; Wanichapichart, P.; Liangdeng, Y.In the last few years, membrane technology has gained more attention from polymer chemists throughout the globe. Nowadays, surface modification of membrane is very useful in biotechnology and food science. In the present investigation, we have synthesized polysulfone based composite nanofiltration (NF) membranes, and characterized these membranes by FT-IR, SEM and membrane performance studies. Surface plasma treatment was carried out by irradiation with argon and nitrogen beams in suitable conditions. It was observed that nitrogen beam caused surface roughness that was more severe than the Ar beam. After irradiation, water contact angle was slightly increased. For pure water permeability, flux increased linearly with the operating pressure. However, for the salt solution, the flux was decreased marginally and salt rejection increased after irradiation due to surface modification. The modification effect was characterized in terms of contact angle, AFM employed roughness measurement and dielectric property. It revealed that irradiated NF membranes showed higher salt rejection and lower flux as compared to the nonmodified membranes. Accordingly, the roughness of the membrane surface intensively affected the performance of RO membrane. © 2010 Elsevier B.V.Item Conversion of microfiltration membrane into nanofiltration membrane by vapour phase deposition of aluminium for desalination application(2011) Padaki, M.; Isloor, A.M.; Nagaraja, K.K.; Nagaraja, H.S.; Pattabi, M.Preparation and modification of NF membrane are challenging aspects in research. In the present work, we have synthesised Polysulfone (PSf) microfiltration membrane and reduced the pore size to nano level by physical vapour deposition (PVD) of aluminium metal. Membrane pore size was reduced from micro pore to nano pore, which rejected 42.22% of NaCl from the solution with 164L/m2h. And also water permeation decreases from 1.10324-10-10 to the 9.141-10-12. The SEM and AFM pictures showed the surface modification and metal deposition in the pores. The performance of the membrane was studied by dead end flow cell using 3.5% of NaCl solution, in which PVD membrane showed 42.22% of rejection with 16.4L/m2h flux. Thermal analysis from DSC showed Tg of 265°C. Contact angle measurement, and water uptake were also reported. © 2011 Elsevier B.V.Item Polysulfone/N-phthaloylchitosan novel composite membranes for salt rejection application(2011) Padaki, M.; Isloor, A.M.; Wanichapichart, P.N-phthaloylchitosan (CS) was synthesized by the reaction of chitosan with phthalic anhydride in dimethyl formamide. Different compositions of polysulfone (PSf) and N-phthaloylchitosan were used to prepare novel polysulfone/N-phthaloylchitosan (PSf/CS) composite membranes by phase inversion method. The composition ratios between the former and the latter were 80:20, 85:15, 90:10, and 95:5. Water flux results revealed that, PSf:CS 80:20 membrane is found to have greatest effective pore area while PSf:CS 95:05 membrane has the smallest value. The pore area is found to be larger with the increase in CS composition. In addition, its water swelling property increases with the increase of CS composition. Water flux results are in consistent with dielectric constant value. Use of known molecular weight of polyethylene glycol rejection study, revealed that, PSf:CS 95:05 membrane possessed the smallest pore size among these membranes. In conclusion, change of ratio between PSf and CS, considerably affects membrane pore size and hydrophilicity. For salt filtration, membrane PSf:CS 95:05 showed 93%, 76.11% and 70.12% rejection of MgSO4, Na2SO4, and NaCl, respectively. © 2011 Elsevier B.V.Item 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.Item Preparation and characterization of polysulfone and modified poly isobutylene-alt-maleic anhydride blend NF membrane(2012) Ganesh, B.M.; Isloor, A.M.; Padaki, M.Recently nanofiltration (NF) is gaining more importance for water treatment. It is replacing the conventional method of water treatment due to advantages of NF membranes over RO system. In this work, we are discussing the preparation of NF membrane for desalination of sea water. We herein report the synthesis of polymer, by the reaction of p-amino benzoic acid (PABA) and poly isobutylene-alt-maleic anhydride (PIAM) and its blend membrane preparation with polysulfone (PSf). The new membranes were characterized by SEM images, surface wettability to investigate the hydrophilic nature of the membrane, water swelling, pure water flux, molecular weight cut-off and salt rejection of the membranes. The membranes showed nano size (<50nm) pores in SEM image, and the contact angle data revealed that membrane surface is moderately hydrophilic. Membrane with 70:30 (PSf:modified PIAM) composition has shown good salt rejection of 96% at 200kPa for 3500ppm of NaCl solution with a pure water flux of 38.36Lm -2h -1. © 2011 Elsevier B.V.Item Studies on copper coated polysulfone/modified poly isobutylene alt-maleic anhydride blend membrane and its antibiofouling property(2013) Isloor, A.M.; Ganesh, B.M.; Isloor, S.; A.F., A.F.; Nagaraj, H.S.; Pattabi, M.As nanofiltration is gaining more and more importance in the field of desalination, one has to address the many obstacles in order to achieve effective/efficient filtration. One such issue is biofouling and microbial attack to the membrane. This paper describes about the study on copper coating onto the membrane surface as biofouling protective layer. This is an attempt to come up with a new approach for desalination and an antimicrobial membrane. The work indicates that, the copper coated membrane can resist the possible microbial attack to some extent while maintaining good salt rejection and appreciable flux. SEM and EDX studies had shown the distribution of copper on the membrane surface. The copper coated membrane had shown the maximum salt rejection of about 96% for 3500ppm NaCl solution and also it had shown the pure water flux of 36Lm-2h-1. © 2012 Elsevier B.V.Item 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.Item Permeation, Antifouling and desalination performance of TiO2 nanotube incorporated PSf/CS blend membranes(2013) Kumar, R.; Isloor, A.M.; A.F., A.F.; Abdul Rashid, S.A.; Ahmed, A.A.Polysulfone (PSf) and chitosan (CS) blend membranes were prepared by incorporating titanium dioxide nanotubes (TiO2NT) in different compositions. The proper blending of PSf and CS in the PSf/CS/TiO2 membranes was confirmed by ATR-IR spectroscopy. The influence of nanotubes on morphology of membranes was investigated by Field Emission Scanning Electron Microscopy (FESEM). The effect of nanotubes on hydrophilicity of the membranes was studied by water swelling and contact angle measurements. The distribution of TiO2NT on the membrane surface was determined by Transmission Electron Microscope (TEM) analysis. The permeation property of PSf/CS/TiO2NT membranes was carried out by measuring the time dependent pure water flux (PWF). Bovine serum albumin (BSA) protein rejection studies were performed to know the antifouling properties. The rheological percolation threshold of PSf/CS/TiO2NT solutions was measured by viscosity studies. The nanotubes incorporated PSf/CS membranes showed enhanced permeation and antifouling properties compared to PSf/CS and nascent PSf ultrafiltration membranes. Membranes prepared well above rheological percolation threshold showed drastic reduction in pore size and acted as nanofiltration (NF) membranes. © 2013 Elsevier B.V.Item 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.