R. Ravi

Bio: R. Ravi is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Hard spheres & Transesterification. The author has an hindex of 10, co-authored 26 publications receiving 363 citations. Previous affiliations of R. Ravi include Purdue University & Indian Institutes of Technology.

Kinetic study of the base-catalyzed transesterification of monoglycerides from pongamia oil

Abstract: The kinetics of the transeterification of vegetable oil is known to follow a three-step reaction mechanism. The third step involves the transesterification of MG. In this study, the transesterification of MG obtained from crude Pongamia oil was achieved with methanol in the presence of KOH as the catalyst. A MG/methanol ratio of 1∶10 was used at different temperatures (30, 45, 55, and 60°C). 1H NMR was used to monitor the progress of transesterification. The study revealed that the kinetics of this reaction followed a reversible second-order model, with a good fit obtained for all temperatures except 30°C. This result is explained as arising out of the importance of transport effects at low temperatures. The forward rate constant increased with an increase in temperature, whereas the reverse rate constant showed a decreasing trend, suggesting that the proposed reverse reaction was not an elementary step.

Kinetics of base-catalyzed transesterification of triglycerides from Pongamia oil

Abstract: The kinetics of transesterification of Pongamia oil using methanol at 60°C were studied. The forward as well as the reverse rate constants of all three steps involved in the transesterification of Pongamia oil are reported for the first time. Among the forward rate constants, the one governing the conversion of TG to DG was the highest and the one for DG to MG was the lowest. A distinct feature of the present work is the direct estimation of the equilibrium constants of all three steps by measuring the concentrations of TG, DG, and MG at very long reaction times. This reduced the number of parameters to be, determined from the kinetic data by one-half, thereby leading to more accurate estimation of the rate constants. The equilibrium constant of the final step involving the conversion of MG to methyl ester and glycerol was at least an order of magnitude greater than that of the first two reaction steps. A detailed comparison was made with kinetic parameters reported in literature. The trend in the relative magnitudes of the rate constants appears to be unique to Pongamia oil.

Kinetic Studies of Base-Catalyzed Transesterification Reactions of Non-edible Oils To Prepare Biodiesel: The Effect of Co-solvent and Temperature

Abstract: The non-edible oils of mahua and jatropha were transesterified using methanol and 1 wt % KOH as the catalyst. The effect of co-solvent and the kinetic study of the transesterification of mahua oil is being reported here for the first time. Kinetics, modeled as a single-step reaction, revealed that the order of the reaction is 2 with respect to the triglyceride concentration and 1 with respect to the methanol concentration in both oils. In the presence of co-solvent, tetrahydrofuran (THF), methanolysis of mahua oil resulted in the increase of the rate constants from 0.08 to 1.17 L2 mol–2 min–1 at 28 °C and from 0.43 to 3.18 L2 mol–2 min–1 at 45 °C. The corresponding values for jatropha oil were found to be 0.50 and 2.76 L2 mol–2 min–1 at 28 °C and 1.26 and 4.56 L2 mol–2 min–1 at 45 °C.

Characterization of solvent clusters in a supercritical Lennard‐Jones fluid

Abstract: We have developed a new methodology for characterizing the solvent cluster structures which occur in a pure supercritical fluid in its compressible regime. This methodology takes advantage of the time scale separation which exists between collective‐cluster and individual‐solvent–atom motions in order to classify atoms according to their ‘‘instantaneous’’ local environments. The resultant picture is of a fluid having density inhomogeneities on a mesoscopic length scale—i.e., clusters and cavities. Calculation of partial radial distribution functions shows that atoms residing in different density domains have very different equilibrium structural properties, information which is not available from the usual total radial distribution function. For example, for a 2‐dimensional Lennard‐Jones fluid at a reduced temperature Tr=1.06 the nearest neighbor coordination number in a high density domain is 4.2, whereas in a low density domain it is only 1.0. We have also found that, for such clustering fluids that in ...

Biodiesel production from non-edible plant oils

Abstract: Because of biodegradability and nontoxicity biodiesel has become more attractive as alternative fuel. Biodiesel is produced mainly from vegetable oils by transesterification of triacylglycerols. From economic and social reasons, edible oils should be replaced by lower-cost and reliable feedstocks for biodiesel production such as non-edible plant oils. This paper reviews various methods for biodiesel production from common non-edible oils employing alcoholysis reactions. The aim of this paper is to present the possibilities of the use of non-edible oils into biodiesel production, to consider the various methods for treatment of non-edible oils and to emphasize the influence of the operating and reaction conditions on the process rate and the ester yield. The special attention is paid to the possibilities of optimization, kinetics and improvement of biodiesel production from non-edible oils.

Physical properties of ionic liquids consisting of the 1-butyl-3-methylimidazolium cation with various anions and the bis(trifluoromethylsulfonyl)imide anion with various cations.

Abstract: Physical properties of 4 room-temperature ionic liquids consisting of the 1-butyl-3-methylimidazolium cation with various perfluorinated anions and the bis(trifluoromethylsulfonyl)imide (Tf2N-) anion with 12 pyrrolidinium-, ammonium-, and hydroxyl-containing cations are reported. Electronic structure methods are used to calculate properties related to the size, shape, and dipole moment of individual ions. Experimental measurements of phase-transition temperatures, densities, refractive indices, surface tensions, solvatochromic polarities based on absorption of Nile Red, 19F chemical shifts of the Tf2N- anion, temperature-dependent viscosities, conductivities, and cation diffusion coefficients are reported. Correlations among the measured quantities as well as the use of surface tension and molar volume for estimating Hildebrand solubility parameters of ionic liquids are also discussed.