Options
Ramesh L. Gardas
Loading...
Preferred name
Ramesh L. Gardas
Official Name
Ramesh L. Gardas
Alternative Name
Gardas, Ramesh
Gardas, Ramesh L.
Gardas, R. L.
Main Affiliation
Email
ORCID
Scopus Author ID
Researcher ID
Google Scholar ID
176 results
Now showing 1 - 10 of 176
- PublicationApparent molar properties of benzyldimethylammonium based protic ionic liquids in water and ethanol at different temperatures(05-01-2015)
;Keshapolla, Dasthaiah ;Singh, Vickramjeet ;Gupta, AkashThe apparent molar volumes, Vϕ and apparent molar isentropic compressibilities, Ks,ϕ of three benzyldimethylammonium based protic ionic liquids, namely, benzyldimethylammonium acetate (BDMAA), benzyldimethylammonium propionate (BDMAP), and benzyldimethylammonium hexanoate (BDMAH) in water and ethanol have been determined at T=(293.15, 298.15, 303.15, 308.15, 313.15 and 318.15)K and at ambient pressure from density, ρ and speed of sound, u measurements. The Redlich-Mayer type of equation has been used to calculate the apparent molar volume, Vϕ∞ and apparent molar isentropic compressibility, Kϕ∞ at infinite dilution, and the corresponding empirical parameters (Sv, Bv, Sk and Bk). The negative magnitude of limiting volumetric slopes, Sv versus m1/2 for (BDMAA+ethanol) binary solutions, suggests that BDMAA-ethanol interactions are strong. Further, the change in thermodynamic properties of binary solutions in relation to the alternation in the anionic structural constitution of protic ionic liquids has also been evaluated. - PublicationEffect of various substituents on benzene ring and their impact on volumetric, acoustic and transport properties of binary liquid mixtures with dimethylacetamide(05-07-2015)
;Syamala, V. ;Venkatramana, L. ;Narasimha Rao, C. ;Sivakumar, K. ;Venkateswarlu, P.Excess volume (VE), excess isentropic compressibility (κES) and deviation in viscosity (δη) were studied for eight binary systems of dimethylacetamide (DMA) with 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,2,4-trichlorobenzene, o-chlorotoluene, m-chlorotoluene, p-chlorotoluene, o-nitrotoluene and m-nitrotoluene in the entire composition range at 303.15K and atmospheric pressure. Excess volume data for the studied mixtures were measured directly using a single composition loading type dilatometer and compared with predictive expressions proposed by Redlich-Kister and Hwang. Moreover, the VE data in the present investigation were analyzed by using Prigogine-Flory-Patterson (PFP) theory. The speed of sound data was measured with a single crystal interferometer at a frequency of 3MHz and data were analyzed in terms of free length theory (FLT) and collision factor theory (CFT). Experimental viscosity data were measured by a suspended Ubbelohode-type viscometer, which in turn used to calculate deviation in viscosity and interaction parameters for various models such as Gruenberg-Nissan, Tamura and Kurata and Hind et al. The experimental data were discussed on the basis of intermolecular interactions between unlike molecules. - PublicationImpact of silver sulfide on rheology and streaming electrification of mineral oil and mixed fluid(01-09-2022)
;Amalanathan, A. J.; ;Sarkar, Bhaswati; ;Harid, N.Griffiths, H.This study reports the effect of adding silver sulfide to mineral oil and mixed fluid on their static electrification and visco-elastic properties. The flow electrification studies indicate an increase in streaming current for higher silver sulfide concentration with the hysteresis pattern indicating a higher current during the decrement of disc velocity. The transition from loss modulus to storage modulus was visible in the mixed fluid compared to mineral oil. Further, the effect of silver sulfide has reduced the storage modulus with frequency sweep and temperature sweep testing on both mineral oil and mixed fluid. - PublicationInfluence of N-1 alkyl substituent on apparent molar properties of 1,2,4-triazolium based ionic liquids in aqueous solutions(01-01-2018)
;Singh, DharmendraAccurate measurements of volumetric and acoustic properties of aqueous ionic liquid solutions govern a key factor in process design and potential engineering applications. Also, such studies can give an appropriate idea about the nature and extent of intermolecular interactions involved between the solute and solvent in solutions. In this perceptive, the density and speed of sound for aqueous solutions of synthesized 1-alkyl-4-(4-sulfobutyl)-1H-1,2,4-triazol-4-ium trifluoromethanesulfonate based ionic liquids were measured as a function of temperature in the range of 293.15 to 328.15 K at atmospheric pressure. Additionally, effects of N-1 linear or branched alkyl substituent of studied ionic liquids in aqueous solutions on such properties were analyzed. Further, from the experimental data, derived parameters such as apparent molar volume (Vϕ), apparent molar isentropic compression (Ks,ϕ) and limiting apparent molar expansion (Eφ∞) have been evaluated. Moreover, for evaluating the extent of interactions stirring in the solutions, the apparent molar properties at infinite dilution were analyzed through Redlich-Mayer type equations. - PublicationLiquid-liquid extraction(01-01-2023)
;Jisha, K. J. ;Athira, K. K. ;Priyanka, V. P.Separation, purification, and extraction of biomolecules demand paramount importance in life science investigations and application of liquid-liquid extraction (LLE) for this purpose can be considered a benign technique. This chapter deals with various classes of liquid biphasic system (LBS) for the extraction of biomolecules including protein, nucleic acid, natural products, and vitamins. LBS is mainly divided into organic solvent- and water-based systems where the latter is further subdivided into polymer-, surfactants-, ionic liquids-, and deep eutectic solvents-based systems. Most of the systems emerged as a modification to the existing system by mainly compensating for its economic and environmental problems. Common LLE methods such as cloud point titration, extractive fermentation, membrane supported aqueous two-phase system, and aqueous two-phase floatation are discussed briefly. - PublicationElucidation of molecular interactions between a DBU based protic ionic liquid and organic solvents: Thermophysical and computational studies(01-01-2015)
;Singh, Dharmendra ;Singh, Vickramjeet ;Islam, NasarulPrecise determination of thermodynamic properties of binary mixtures containing ionic liquids (ILs), plays an important role in process design and potential engineering applications of these mixtures. Thermodynamic studies can provide an insight into the nature of intermolecular interactions occurring between the solute and solvent in solutions. In this regard, thermodynamic properties of 1,8-diazabicyclo[5.4.0]undec-7-en-8-ium trifluoroacetate [DBUTFA] in two organic solvents viz. N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) have been evaluated at different temperatures (293.15 to 328.15) K. Apparent molar property data were fitted to a Redlich-Mayer type of equation to compute infinite dilution values and empirical parameters. The experimental studies suggest that the nature of the interactions between DBUTFA and organic solvents are influenced by temperature. DBUTFA interacts more strongly with DMF at low temperature (<308.15 K), whereas it interacts more strongly with DMSO at higher temperatures (>308.15 K). Density functional level of theory (DFT) was employed to investigate intra-ionic and inter-ionic interactions between the ions of PIL and organic solvents. The computational results are in good agreement with experimental results. 2016 The Royal Society of Chemistry. - PublicationProtic ionic liquid-assisted cell disruption and lipid extraction from fresh water Chlorella and Chlorococcum microalgae(01-07-2017)
;Shankar, Mukund ;Chhotaray, Pratap K. ;Agrawal, Ayushi; ;Tamilarasan, KrishnamurthiRajesh, MathurProtic ionic liquids (PILs) with their ability to host labile protons and form hydrogen bonds are likely to be efficient catalyst for bioprocessing. This is one of the first reports investigating PIL-assisted microalgal cell disruption and lipid extraction. The applicability of several PILs with butyrolactam, caprolactam, propylammonium and hydroxypropylammonium cations in combination with formate, acetate and hexanoate anions for cell disruption and lipid extraction from fresh water Chlorella and Chlorococcum sp. have been evaluated in this study. The investigations were performed with de-watered wet microalgae under ambient temperatures and hence do not require any energy intensive drying and/or processing steps. The PILs with formate and hexanoate anions when compared with conventional pre-treatment techniques: sonication, microwave and cellulase provided better microalgal cell disruption efficiencies. The FESEM analysis for the Butyrolactam hexanoate (BTH) treated cells show extensive pattern of microalgal cell disruption. The fluorescence imaging analysis coupled with culturing experiments indicates a near-complete disruption and loss in viability of the PIL-treated microalgal cells. The lipid yield from the formate and hexanoate anions-PILs was statistically comparable and/or higher to the Bligh & dyer control method. Among the PILs, BTH recorded 1.86 and 1.72 folds higher lipid yields than the control method with Chlorella and Chlorococcum sp. respectively. The lipids show predominance of C16 and C18 fatty acids similar to lipid profile obtained with the control method. Furthermore, the PILs were also found to have a beneficial role in reducing the chlorophyll pigments in the final lipid product. Overall, the results show PILs with formate and hexanoate anions can be utilized for a relatively energy efficient, one-step cell disruption and lipid extraction process from wet microalgae. - PublicationInvestigation of Anion Structural Effects on Solute-Solvent Interactions of Ionic Liquids with DMF by Volumetric, Acoustic, Viscometric Properties and COSMO-RS Calculations(26-03-2021)
;Losetty, Venkatramana ;Hazarathaiah Yadav, C. ;Devi Wilfred, CeciliaThis study reveals that the effect of anion structures on solvent-solute interactions by analysis of sophisticated thermophysical properties of ionic liquids (ILs) with molecular solvent. Three imidazolium based ILs (1-octyl-3-methylimidazolium) [Omim][NTf2], [Omim][PF6] and [Omim][SCN] were synthesized, characterized and measured the thermophysical properties such as density (ρ) sound speed (u) and viscosity (η) of all ILs with DMF as solvent for binary mixture at various conditions. Furthermore, various derived thermophysical properties (Formula presented.), κs,Φ, (Formula presented.) and ηr, were calculated from experimental data. The type of interactions such as IL-IL or IL-solvent or solvent-solvent are occurred among the component molecules were estimated from the empirical parameters and COSMO−Rs computational study. The obtained results show that the size of anion is governing the volumetric, acoustic and viscometric properties of the studied ILs with DMF. - PublicationExtraction behavior of Am(III) and Eu(III) by tri-n-octylmethylammonium diglycolamate ionic liquid impregnated XAD-7(22-09-2017)
;Dasthaiah, K. ;Selvan, B. Robert ;Suneesh, A. S. ;Venkatesan, K. A. ;Antony, M. P.Aliquat-336-based strongly hydrophobic ionic liquid, tri-n-octylmethylammonium diglycolamate ([A336]+[DGA]−), was prepared and impregnated in Amberlite XAD-7 (abbreviated as [A336]+[DGA]−/XAD-7) for studying the extraction behavior of Am(III) and Eu(III) from nitric acid medium. The distribution ratio of Am(III) and Eu(III) in [A336]+[DGA]−/XAD-7 decreased with an increase in the concentration of nitric acid and the mechanism of trivalent metal ion extraction in the resin phase was elucidated. The uptake of Am(III) and Eu(III) in [A336]+[DGA]−/XAD-7 followed a second order and from the Langmuir adsorption model the apparent europium extraction capacity was determined. The conditions needed for efficient separation of Am(III) from Eu(III) was optimized. - PublicationEffect of chain length of alcohol on thermodynamic properties of their binary mixtures with benzylalcohol(10-04-2014)
;Venkatramana, L. ;Sivakumar, K.; Reddy, K. DayanandaDensities (ρ) of pure liquids and their mixtures have been measured over the entire composition range for the binary mixtures of benzylalcohol with 1-heptanol, 1-octanol, 1-nonanol and 1-decanol at 298.15 K to 313.15 K and at atmospheric pressure by using Rudolph Research Analytical Digital Density Meter (DDM-2911 model). Further, the speed of sound (u) for the above said mixtures were also measured at 303.15 K and 313.15 K. The experimental density data were used to compute excess molar volumes (VE) and compared with predictive expression proposed by Redlich-Kister equation. Excess speed of sound (uE), isentropic compressibility (κS) and excess isentropic compressibilities (κSE) were evaluated from experimental sound velocity and density data. Moreover, the experimental speed of sound data was compared in terms of theoretical models proposed by Schaaff's collision factor theory (CFT) and Jacobson's free length theory (FLT). The experimental results were discussed in terms of intermolecular interactions between component molecules. © 2014 Elsevier B.V.