Browsing by Author "Manivannan, R."

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Azadirachta indica leaves extract as inhibitor for microbial corrosion of copper by Arthrobacter sulfureus in neutral pH conditions-A remedy to blue green water problem
(2016) Swaroop, B.S.; Victoria, S.N.; Manivannan, R.
Copper corrosion by the action of aerobic A. sulfureus in neutral medium was investigated. The bacteria form biofilm and colonize on the copper metal surface resulting in corrosion leading to blue green colour water. A. indica (neem) leaf extract was found to be effective in inhibiting the growth of the bacteria and thus help in preventing the corrosion. The copper coupons immersed for different durations in media with and without neem leaf extract were tested for their weight loss to study the corrosion rate. The copper biocorrosion was also investigated using electrochemical impedance spectroscopy and potentiodynamic polarization studies. The morphology of the films formed on the metal surface in different media at different immersion times were studied using scanning electron microscopy. 2016 Taiwan Institute of Chemical Engineers.
Characterization of Rapid Foam Castings Produced by Different Mold Making Processes
(Springer Nature, 2020) Bhagchandani, R.K.; Ghodke, R.; Manivannan, R.; Negi, S.; Kapil, S.; Karunakaran, K.P.
Rapid casting gives the opportunity to develop a new casting in days, not in weeks or months. Evaporative Pattern Casting (EPC) process gives flexibility to produce complex geometries by integrating several parts in single casting. The lead-time and cost involved in designing and fabricating the metal tooling for Expanded Polystyrene (EPS) pattern making can be overcome by using the Segmented Object Manufacturing (SOM) machine. This hybrid system of pattern making is explored with all sub-systems and a complicated EPS pattern is produced by this Rapid Prototyping system. Conventional EPC process is more complicated due to coating development, vacuum assisted metal pouring and vibration system for filling the cavities by unbounded sand. In the present work, different mold-making processes are explored to avoid complications of conventional process. The Green sand, No-bake sand, and Plaster of Paris molds are prepared using Rapid Prototyped EPS pattern to produce the castings. The castings are characterized by comparing the surface roughness, dimensional accuracy, hardness, and surface morphology. © 2020, Springer Nature Singapore Pte Ltd.
Psidium guajava leaf extract as green corrosion inhibitor for mild steel in phosphoric acid
(2015) Noyel, Victoria, S.; Prasad, R.; Manivannan, R.
The adsorption and corrosion inhibition property of the alcoholic Psidium guajava (guava) leaf extract on mild steel in 1M phosphoric acid medium was investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The studies showed that the inhibition efficiency increases with inhibitor concentration upto 800 ppm and decreases slightly at 1200 ppm. The adsorption obeys both the Langmuir and the Temkin adsorption isotherm equations. The kinetic and thermodynamic parameters were calculated and discussed. The adsorption was found to follow a comprehensive type adsorption dominated by chemisorption. Potentiodynamic polarization studies showed that the inhibitor acted as a mixed-type inhibitor. 2015 The Authors.
Simple one-pot sonochemical synthesis of copper sulphide nanoparticles for solar cell applications
(2019) Singh, A.; Manivannan, R.; Noyel, Victoria, S.
Copper sulphide nanoparticles for solar cell applications were synthesized by a single step sonochemical method using copper acetate and thiourea as precursors. The effects of sonication time, ultrasonic bath temperature and annealing temperature on particle properties were studied. Synthesized particles were characterized using scanning electron microscope, transmission electron microscope, X-ray diffraction spectrophotometer and UV visible spectrophotometer. The particles were found to be a mixture of chalcocite, covellite and djurleite. The optical band gap of the particles was found to be in the range of 1.6 2.1 eV. Heat treatment of the particles was found to give rise to needle shaped particles while a bath temperature of 55 C yielded few nanoplates. 2015 The Authors
Studies on corrosion inhibitory action of ocimum sanctum (Tulsi) leaves extract in mild steel corrosion induced by desulfovibrio desulfuricans
(2018) Chaithra, S.; Gupta, A.; Manivannan, R.; Victoria, S.N.
Studies on the effect of Ocimum sanctum (Tulsi) leaves extract as corrosion inhibitor for mild steel corrosion caused by Desulfovibrio desulfuricans has been carried out. The extract provides 74% inhibition efficiency and is effective up to two weeks. Potentiodynamic polarization studies show the occurrence of pitting corrosion. The electrochemical impedance spectroscopy studies reveal that the nature of the biofilm formed changes continuously. The scanning electron microscopy studies on samples immersed for different durations indicate two layers of different morphologies formed at the end of third and fourth weeks in the uninhibited sample. Energy dispersive x-ray diffraction studies show an increase in sulfide content in uninhibited sample indicating formation of corrosion products. 2019, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.
Visible range photocatalysts for solid phase photocatalytic degradation of polyethylene and polyvinyl chloride
(2017) Gupta, A.; Lakshmi, Y.N.; Manivannan, R.; Noyel, Victoria, S.
Solid phase photocatalytic degradation of polyethylene (PE) and polyvinyl chloride (PVC) with various photocatalysts such as ceria annealed at 350�C and 850�C, zinc oxide annealed at 250�C, copper sulfide and titania particles was studied under different light sources. Except titania, all the other photocatalysts performed reasonably well both in the visible and ultra-violet (UV) radiations. Ceria annealed at 850�C showed degradation efficiencies higher than 70% for PVC in the fluorescent and solar radiation. Ceria annealed at 350�C showed degradation efficiencies higher than 75% for polyethylene in fluorescent, solar and UV radiation. The Fourier transform infrared spectroscopy studies show the presence of adsorbed carbon dioxide on the degraded polymer-photocatalyst composite films. The UV-visible spectroscopic studies show that the ceria, zinc oxide and copper sulfide photocatalysts are active in the visible spectrum resulting in enhanced degradation efficiency in fluorescent and solar radiation.