Browsing by Author "Shetty K, V.S."

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Biocorrosion Behavior of Epoxy-Based Multilayer Nanocomposite Coatings
(Springer Science and Business Media Deutschland GmbH, 2023) Shetty, P.; Arya, S.B.; Shetty K, V.S.
Marine structures are prone to biocorrosion, so developing a suitable coating system to combat corrosion is essential. The present work is focused on the development of a multilayered epoxy-based nanocomposite (NC) coating system reinforced with ZnO filler in the first layer coat (NC1), ZnO and Cu2O in the second layer (NC2), and the third layer consisting of a varying percentage of TiO2 with 5 wt%, 10 wt%, and 15 wt% of TiO2 designated as NC3, NC4, and NC5, respectively, as top coat on the bare steel. Brush coating was employed to fabricate the coatings. Surface morphology and mechanical properties, wettability, corrosion, and biocorrosion behavior of the bare steel and coated substrates were examined. Mechanical properties such as linear scratch hardness and posi adhesion test values of the coatings were found to be in the order NC1 < NC2 < NC3 < NC4 < NC5. The NC3-coating system comprising three layers of coating reinforced with 5 wt% TiO2 imparting hydrophobicity offered maximum resistance to microbial adhesion with 93% and 91% reduction in corrosion rate than the bare metal in natural and artificial seawater, respectively, after the 7th day of immersion. The bacterial and fungal cell counts in the biofilm after the 7th day of immersion were reduced by four and three orders of magnitude, respectively, in the nanocomposite against the bare substrate providing good biofouling resistance. NC3 coating also prevented the release of metal ions into the seawater and acted as a barrier for the leaching of metals from the coating underneath, thus, proving to be safe for the marine environment. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
Mixing and solid-liquid mass transfer characteristics in a three phase pulsed plate column with packed bed of solids in interplate spaces-a novel aerobic immobilized cell bioreactor
(2011) Shetty K, V.S.; Srinikethan, G.
Background: The pulsed plate column (PPC) with packed bed of solids in the interplate spaces finds use as a three phase aerobic bioreactor and is a potential heterogeneous catalytic reactor. Good knowledge of the extent of mixing in the liquid phase and solid-liquid mass transfer coefficient are essential for modeling, design and optimization of these columns. The present work aims at the study of liquid phase mixing and solid-liquid mass transfer characteristics in a three phase PPC. Results: Residence time distribution studies were performed. Dispersion number was found to increase with increase in liquid superficial velocities, frequency of pulsation, amplitude of pulsation and the vibrational velocities. Increase in frequency and amplitude of pulsation, and hence increase in vibrational velocity, resulted in increase of the solid-liquid mass transfer coefficient. Conclusions: The mixing behaviour in this contactor approximated a mixed flow behaviour. The three phase PPC was found to outperform many other kinds of three phase contactors in terms of solid liquid mass transfer characteristics. Empirical correlations developed can be used for the determination of solid-liquid mass transfer coefficients for three phase PPC and hence can facilitate the design, scale-up and modeling of these columns, when used as chemical or biochemical reactors. © 2011 Society of Chemical Industry.
Modelling and simulation of steady-state phenol degradation in a pulsed plate bioreactor with immobilised cells of Nocardia hydrocarbonoxydans
(2011) Shetty K, V.S.; Verma, D.K.; Srinikethan, G.
A novel bioreactor called pulsed plate bioreactor (PPBR) with cell immobilised glass particles in the interplate spaces was used for continuous aerobic biodegradation of phenol present in wastewater. A mathematical model consisting of mass balance equations and accounting for simultaneous external film mass transfer, internal diffusion and reaction is presented to describe the steady-state degradation of phenol by Nocardia hydrocarbonoxydans (Nch.) in this bioreactor. The growth of Nch. on phenol was found to follow Haldane substrate inhibition model. The biokinetic parameters at a temperature of 30 ± 1 °C and pH at 7.0 ± 0.1 are ? m = 0.5397 h -1, K S = 6.445 mg/L and K I = 855.7 mg/L. The mathematical model was able to predict the reactor performance, with a maximum error of 2% between the predicted and experimental percentage degradations of phenol. The biofilm internal diffusion rate was found to be the slowest step in biodegradation of phenol in a PPBR. © 2010 Springer-Verlag.