K KESAVA RAO
Department of Chemical Engineering
Indian Institute of Science
Phone (Off) : +91-80-2293 2341
Phone (Res) : +91-80-2341 2695
Email : kesava at iisc.ac.in
EducationB. Tech, Chemical Engineering, IIT Madras 1977;
M. S., Chemical Engineering, University of Houston 1979;
Ph. D., Chemical Engineering, University of Houston 1982.
Recent Work(a) Water Treatment1. Defluoridation of water
Reject water from a reverse osmosis unit at Yellampalli village and also synthetic water samples were treated using adsorption. Activated alumina (AA) and a hybrid anion exchange resin with zirconia nanoparticles (HAIX-Zr) were used as the adsorbents. The performance of the adsorbents was fairly good for water containing only fluoride or a mixture of ions, and the cost of treated water was in the range Rs. 0.1/L - 0.4/L for AA and Rs. 0.2/L - 1.5/L for HAIX-Zr. However, for reject water, the cost increased significantly, as it was Rs. 1 - 1.5/L for AA and Rs. 11.5/L for HAIX-Zr. Further work is needed to examine how the cost can be reduced. (Joint work with M.V.V. Naga Samrat, J.R. Mudakavi, J. Riotte, and A. SenGupta.)2. Denitrification of water in a microbial fuel cell (MFC)
It was shown for the first time that a consortium of seawater bacteria can be used to reduce nitrate in synthetic water samples in the cathode compartment of a MFC to nitrogen gas. The same consortium of bacteria were used in the anode compartment, along with acetate, peptone, and glucose. The power generated by the cell was higher when the commonly used phosphate buffer was replaced by bicarbonate buffer in the cathode compartment. Surprisingly, high concentrations of ammonium ions were found in both the compartments, but the reasons for this result are not clear. Further, water from the cathode compartment contains bacteria, and hence additional treatment is needed before it can be used for drinking. (Joint work with M.V.V. Naga Samrat, B. Ruggeri, and T. Tommasi.)(b) Granular flowThe lift force on a stationary disc immersed in a rotating granular bed
The discrete element method (DEM) was used to examine this problem. The results suggest that the lift arises because of an asymmetry in the dilation (or decrease in solids fraction) and the velocity field above and below the disc. The occurrence of a lift is demonstrated visually by showing that a disc that is not constrained in the vertical direction rises as the cylinder rotates. (Joint work with B. Debnath and P. Nott.)(c) Thermodynamics
Augmented Gibbs-Tolman model for surface tension: Gibbs modelled the interfacial region of a two-phase system by introducing a dividing surface separating the phases. He chose a particular dividing surface, called the surface of tension, which simplifies the expression for the internal energy and whose tension represents the surface tension sigma of the fluid. By considering expressions for the variation of the pressure in the transition region, Tolman (1948,1949) derived expressions for the sigma and the surface of tension. In the Gibbs-Tolman (GT) model, the unstable region in the pressure-density plane is collapsed onto a surface across which the pressure and density are discontinuous. Thus there is a physical surface of discontinuity separating the vapour and liquid phases and a surface of tension. By proposing simple expressions for the variation of the pressure in the two phases, Tolman derived expressions for sigma and the location of the surface of tension. In the augmented Gibbs-Tolman model (AGT), the same approach is used, except that the pressure variation is augmented by a term involving the spatial gradient of the density, as suggested by Rowlinson and Widom (1982). Using 4 adjustable parameters, it is found that the AGT model correlates data for 152 pure liquids and 57 liquid mixtures with an absolute average deviation in the range of 2 - 3 %. However, one of the length scales in the model turns out to be negative, for reasons that are not clear. (Joint work with S. Tumram and M.S. Ananth.)
Lecture NotesTreatment of drinking waterChemical reaction engineering
Demonstration Experiments (video)Part 1 Part 2 Part 3 Part 4 Part 5 Part 6 Silo music (audio)
MembershipFellow, Indian Academy of Sciences
Samrat, M.V.V.N., Rao, K.K., SenGupta, A.K., Riotte, J., and Mudakavi, J.R., Defluoridation of reject water from a reverse osmosis unit and synthetic water using adsorption, J. Water Process Engineering 23 (2018) 227 - 237. Samrat, M.V.V.N., Rao, K.K., Ruggeri, B., and Tommasi, T., Denitrification of water in a microbial fuel cell (MFC) using seawater bacteria, J. Cleaner Production 178 (2018) 449 - 456. Debnath, B., Rao, K.K., and Nott, P.R., The lift on a disc immersed in a rotating granular bed, AIChE J 63, 5482-5489 (2017) Tumram, S., Rao, K.K., and Ananth, M.S., Augmented Gibbs-Tolman model for surface tension, Langmuir 33, 11687-11697 (2017) Medina, A., Serrano, D.A., Gutierrez, G.J., Rao, K.K., and Vargas, C.A.. (2013). On the mass flow rate from silos with lateral exit holes, Revista Mexicana de Fisica, 59, 287-291. Anjaneyulu, L., Kumar, E.A., Sankannavar, R., and Rao, K.K. (2012). Defluoridation of drinking water and rainwater harvesting using a solar still, Ind.Eng. 51, 8040-8048. Rohit, Kanwar, L., and Rao, K.K., Development of a low-cost portable colorimeter for the estimation of fluoride in drinking water, Sensors and Actuators , B 149, (2010) 245-251. Dhoriyani, M.L., Jonnalagadda, K.K., Kandikatla, R.K., and Rao, K.K., Silo music: sound emission during the flow of granular materials through tubes, Powder Techol. 167 (2006) 55-71. Muite, B.K., Quinn, S.F., Sundaresan, S., and Rao, K.K., Silo music and silo quake: granular flow-induced vibration, Powder Technol., 145 (2004) 190-202. Mohan, L.S., Rao, K.K., and Nott, P.R., A frictional Cosserat model for the slow shearing of granular materials, J. Fluid Mech., 457 (2002) 377-409. Mohan, L.S., Nott, P.R. and Rao, K.K., A frictional Cosserat model for the flow of granular materials through a vertical channel, Acta Mechanica, 138 (1999) 75-96. Sen, A., Rao, K.K., Frizzell, M.A. and Rao, G., A low-cost device for the estimation of fluoride in drinking water, Field Anal. Chem. Tech., 2 (1998) 51-58. Mohan, L.S., Nott, P.R. and Rao, K.K., Fully developed flow of coarse granular materials through a vertical channel, Chem. Engng Sci., 52 (1997) 913-933. Jyotsna, R. and Rao, K.K., A frictional-kinetic model for the flow of granular materials through a wedge-shaped hopper, J. Fluid Mech., 346 (1997) 239-270. Basak, T., Rao, K.K. and Bejan, A., A model for heat transfer in a honey bee swarm, Chem. Engng Sci., 51 (1996) 387-400. Raghuram, P.T. and Rao, K.K., Serendipity in the development of demonstration experiments, Physics Education, 31 (1996) 313-320. Prakash, J.R. and Rao, K.K., Steady compressible flow of cohesionless granular materials through a wedge-shaped bunker, J. Fluid Mech., 225 (1991) 21-80. Jyotsna, R. and Rao, K.K., Steady incompressible flow of cohesionless granular materials through a wedge-shaped hopper: frictional-kinetic solution to the smooth wall, radial gravity problem, Chem. Engng Sci., 46 (1991) 1951-1967. Prakash, J.R. and Rao, K.K., Steady compressible flow of granular materials through a wedge-shaped hopper: the smooth wall, radial gravity problem, Chem. Engng Sci., 43 (1988) 479-494. Kaza, K.R., and Sundaresan, S., Non-random distribution of adsorbates on catalytic surfaces: the role of interactions between adsorbates, Chem. Eng. Commun., 35 (1985) 333-355. Sundaresan, S. and Kaza, K.R., Non-random distribution of adsorbates on catalytic surfaces: the role of adsorbate mobilities on reaction rates, Chem. Eng. Commun., 35 (1985) 1-22. Sundaresan, S. and Kaza, K.R., The effect of limited mobilities of adspecies on the rates of desorption and reaction, Surf. Sci., 160 (1985) 103-121. Kaza, K.R. and Jackson, R., Boundary conditions for a granular material flowing out of a hopper or bin, Chem. Engng Sci., 39 (1984) 915-916 (shorter communication). Kaza, K.R. and Jackson, R., The rate of discharge of coarse granular material from wedge-shaped mass flow hoppers, Powder Technol., 33 (1982) 223-237. Kaza, K.R. and Jackson, R., Diffusion and reaction of multicomponent gas mixtures in isothermal porous catalysts, Chem. Engng Sci., 35 (1980) 1179-1187.
Rao, K.K., and Nott, P.R., An Introduction to Granular Flow, Cambridge University Press, New York (2008).
Papers presented at conferences
Rao, K.K., Flow of granular materials through a wedge-shaped hopper, in 'Solid-solid interactions: Proceedings of the First Royal Society-Unilever Indo-UK Forum in Materials Science and Engineering', M.J. Adams, B.J. Briscoe, and S.K. Biswas (eds.), The Royal Society - Imperial College Press, (1996), pp.238-249. Kaza, K.R. and Sundaresan, S., CO oxidatation on Pt(111): The effect of interactions between adsorbates and adsorbate mobility on the reaction rate, in 'Frontiers in Chemical Reaction Engineering', L.K. Doraiswamy and R.A. Mashelkar (eds.), Wiley Eastern (1984), pp. 323-335 (Proc. Intl. Chemical Reaction Engineering Conference, Pune, 1984.) Kaza, K.R. and Jackson, R., A problem in the flow of granular materials, Proc. Ninth U.S. Nat. Congr. Applied Mechanics, Ithaca, (1982). Kaza, K.R., Villadsen, J. and Jackson, R., Intraparticle diffusional effects in the methanation reaction, Chem. Engng Sci., 35 (1980) 17-24. (Proc. Sixth Intl. Symp. Chemical Reaction Engineering, Nice, 1980.)
Rao, K.K., Avoid plastic banners, Curr. Sci. 114 (2018) 943 (correspondence section) Sundaresan, S., Feinberg, M., Rao, K.K., and Nott, P.R., A tribute to professor Roy Jackson: intellectual leader, scholar, mentor, AIChE J. 63 (2017) 5239 - 5249. Shreyas, L., Kanwar, L., and Rao, K.K. (2013). Chemical engineering and the mitigation of fluorosis, Indian Chemical Engineer, 55, 1-12. (Unrefereed text of an invited lecture.) Rao, K.K., Conflict between development and the environment, Curr. Sci. 100 (2011) 281. Rao, K.K., Laboratory notebooks: a cautionary tale, Curr. Sci., 96 (2009) 181-182 (correspondence section). Rao, K.K., Conferences and global warming, Curr. Sci., 94 (2008) 296 (correspondence section). Rao, K. K., Linking the Indian rivers, Curr. Sci., 85 (2003) 565 (correspondence section). Rao, K.K., Review of the book ``Statics and Kinematics of Granular Materials'', by R.M. Nedderman, J. Fluid Mech., 286 (1995) 405. Rao, K.K., Scaling in living systems, Indian Science Cruiser, 5 (1991) 13-19. Rao, K.K., Large granule and slow release urea, report prepared for the Department of Science and Technology, New Delhi, (1987).