Papers by Padmavathi Rajangam
Waste water from industrial areas contains many toxic heavy metal ions, which are carcinogenic an... more Waste water from industrial areas contains many toxic heavy metal ions, which are carcinogenic and need to be removed before water recycling. In this study, complexation microfiltration technique was used to separate the metal ions. Initially, known concentrations of metal ions were complexed with polyethylene glycol (PEG) and polyacrylic acid (PAA). Polymer enhanced microfiltration process has been investigated for removal of toxic heavy metals such as Ni 2+ , Cu 2+ and Cr 6+ from synthetic waste water solutions. The concentration of metal ions in the sample water was analyzed by UV-Vis spectrophotometer. The effects of pH and polymer/metal ratio using two different membranes such as nylon and cellulose nitrate (CN) were investigated. The membranes were characterized by FTIR to identify the functional groups present in the membrane matrix and SEM analysis used to find the pore size and the metal deposition present over the membrane. Among the various combinations, PAA as the comple...
Waste water from industrial areas contains many toxic heavy metal ions, which are carcinogenic an... more Waste water from industrial areas contains many toxic heavy metal ions, which are carcinogenic and need to be removed before water recycling. In this study, complexation microfiltration technique was used to separate the metal ions. Initially, known concentrations of metal ions were complexed with polyethylene glycol (PEG) and polyacrylic acid (PAA). Polymer enhanced microfiltration process has been investigated for removal of toxic heavy metals such as Ni2+, Cu2+ and Cr6+ from synthetic waste water solutions. The concentration of metal ions in the sample water was analyzed by UV–Vis spectrophotometer. The effects of pH and polymer/metal ratio using two different membranes such as nylon and cellulose nitrate (CN) were investigated. The membranes were characterized by FTIR to identify the functional groups present in the membrane matrix and SEM analysis used to find the pore size and the metal deposition present over the membrane. Among the various combinations, PAA as the complexing...
Journal of Porous Materials, 2015
Commercially available multiwalled carbon nanotubes (MWCNTs) were functionalized using a mixture ... more Commercially available multiwalled carbon nanotubes (MWCNTs) were functionalized using a mixture of HNO 3 and H 2 SO 4 in refluxing condition under three different reaction times (1, 3, and 5 h). The Pt loaded on functionalized MWCNTs (f-MWCNTs) (Pt/1f, 3f & 5f-MWCNTs) were prepared by reducing chloroplatinic acid and for comparison Pt loaded on pristine MWCNTs (Pt/MWCNTs) was also prepared. The size of Pt nanoparticles was determined using X-ray diffraction method. The uniform dispersion of the Pt catalyst on CNTs was confirmed by HRSEM and HRTEM. Surface area and pore size were calculated by Brunauer Emmett Teller analysis method. Five membrane electrode assembly sets were prepared (Pt/MWCNTs, Pt/1f, 3f, 5f-MWCNTs and commercial Pt/C) and tested in the fuel cell assembly. The first four were prepared using SPEEK membrane as electrolyte with the synthesized Pt/f-MWCNTs catalysts and the fifth one was prepared using commercial Nafion-117 electrolyte and Pt/C electrode for comparison.
Journal of Biomaterials and Tissue Engineering, 2012
ABSTRACT Chlorotrimethyl silane (CTMS) was used to couple nano hydroxyapatite with chitosan/polya... more ABSTRACT Chlorotrimethyl silane (CTMS) was used to couple nano hydroxyapatite with chitosan/polyacrylamide blend matrix to form the composite (Cs/PAAm/nHA). The interaction of CTMS with chitosan and hydroxyapatite resulted in the formation of inter-chain bridges and pores while at the same time altered hydrophilicity and water retention capacity of the composites. The tensile strength studies showed that CTMS marginally improved the percentage of elongation. In vitro drug loading and release studies performed using the drug acetaminophen revealed that the CTMS concentration had a pronounced influence the amount of drug loaded as well as the release profile of the composites. The in vitro cytotoxicity study performed using NIH 3T3 cells by MTT method showed that the cell viability increased with increase in the concentration of CTMS. The results suggested that, the amount of CTMS incorporated into Cs/PAAm/nHA composite can be varied to attain the desired rate of degradation of the composite and the extent of drug release.
Ionics, 2013
Fuel cell represents a new energy conversion device, which promises to provide clean source of po... more Fuel cell represents a new energy conversion device, which promises to provide clean source of power. Fuel cell [particularly proton exchange membrane fuel cell and direct methanol fuel cell (DMFC)] is a promising candidate for transportation and portable power source applications. In DMFC, there is a problem of methanol crossover. In order to reduce such a problem, there has been an intensive research activity in the modification of Nafion. In the present investigation, self-assembled membranes were fabricated with sulfonated polyether ether ketone as the core part of the membrane. Aminated polysulfone and sulfonated polysulfone were used as the layers in order to prevent the crossover of methanol. The assembled membranes were characterized by ion exchange capacity, water and methanol absorption, and durability. The methanol permeability and selectivity ratio proved a strong influence on DMFC application. Scanning electron microscopy proved smooth surface, which established strong cohesive force for the polymer chains. Among the synthesized self-assembled membranes, the membrane with two bilayers was the best in terms of power density in DMFC. The membrane electrode assembly with two bilayers showed higher performance (~61.05 mW/cm 2) than sulfonated poly(ether ether ketone) and Nafion in DMFC.
Electrochimica Acta, 2012
Polymer electrolyte membranes used in proton exchange membrane fuel cell (PEMFC) and direct metha... more Polymer electrolyte membranes used in proton exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC) suffer from low dimensional stability. Hence multilayered membranes using sulfonated polysulfone (SPSu) and silica (SiO 2) were fabricated to alter such properties. The introduction of an SiO 2 layer between two layers of SPSu to form the multilayered composite membrane enhanced its dimensional stability, but slightly lowered its proton conductivity when compared to the conventional SPSu/SiO 2 composite membrane. Additionally, higher water absorption, lower methanol permeability and higher flame retardancy were also observed in this newly fabricated multilayered membrane. The performance evaluation of the 2 wt% SiO 2 loaded multilayered membrane in DMFC showed a maximum power density of 86.25 mW cm −2 , which was higher than that obtained for Nafion 117 membrane (52.8 mW cm −2) in the same single cell test assembly. Hence, due to the enhanced dimensional stability, reduced methanol permeability and higher maximum power density, the SPSu/SiO 2 /SPSu multilayered membrane can be a viable and a promising candidate for use as an electrolyte membrane in DMFC applications, when compared to Nafion.
Carbohydrate Research, 2012
Stimuli sensitive biodegradable polymers have important applications in the fields of drug delive... more Stimuli sensitive biodegradable polymers have important applications in the fields of drug delivery and tissue engineering. In this study, biodegradable composite films of chitosan-polyacrylamide-nano hydroxyapatite (Cs-PAAm-nHA) with different concentrations of Chlorotrimethylsilane (CTMS) were fabricated and characterized using Fourier transform infrared (FTIR) spectroscopy. FTIR and XRD results suggested that CTMS functioned to couple nHA with the Cs-PAAm polymer matrix. The swelling study indicated that the formation of numerous CTMS based inter-chain bridges and pores facilitated water absorption and swelling. Hence, incorporation of CTMS into Cs-PAAm-nHA composites not only improved their stability but also controlled the degradation of the composites, which are important for drug delivery applications.
Cases on Green Energy and Sustainable Development, 2020
To reduce reliance on fossil fuels and increase demands for clean energy technology worldwide, th... more To reduce reliance on fossil fuels and increase demands for clean energy technology worldwide, there is currently a growing interest in the use of fuel cells as energy-efficient and environmentally-friendly power generators. With this inevitable depletion, fossil fuels will not be able to respond to energy demand for future. Among all major types of fuel cells, hydrogen fuel cells (HFCs) are in the forefront stage and have gained substantial attention for vehicle and portable applications, which is composed of a cathode, an anode, and a PEM. The heart of the fuel cells is membrane electrode assembly (MEA). An electro-deposition technique for preparing the nano-catalyst layer in PEMFCs has been designed, which may enable an increase in the level of Pt utilization currently achieved in these systems. Functionalization process has been done using a mixture of concentrated nitric acid and sulfuric acid in refluxing condition. The hydrocarbon-based polymer membrane has been used as elect...
Desalination, 2011
The present study focuses the efficiency of an anion exchange polymer for the adsorption of diffe... more The present study focuses the efficiency of an anion exchange polymer for the adsorption of different heavy metal ions from water samples. Solutions with different concentrations of the heavy metals were prepared and the efficiency of the ionomer in separation of the metals was evaluated by adsorption technique. Quaternized poly styrene ethylene butylene poly styrene (QAPSEBS) was used as the ionomer and it was prepared by two step method, viz. chloromethylation and amination. The membrane was prepared by solution casting method using an appropriate solvent. There are various factors affecting the metal ion adsorption on the polymer membrane such as metal ion concentration, pH, treatment time and temperature were studied. From the results obtained, it was found that the percentage adsorption increased with (a) increase in the metal ion concentration, (b) increase in the treatment time up to 2 h after which it levels off, (c) decrease in temperature from 75°C to 35°C. In addition to that, the effect of extent of amination of the polymer membrane was also examined. The polymer membrane was characterized using FT-IR, 1 H-NMR, DSC, TGA, XRD and SEM. The results revealed that the polymer membrane showed high efficiency in adsorption for Cr(VI) ion rather than removal of Cu(II) and Ni(II) ions.
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Papers by Padmavathi Rajangam