KANIKI TUMBA - Academia.edu (original) (raw)
Papers by KANIKI TUMBA
AIChE Journal, 1972
A simple thermodynamic expression determining the infinite dilution activity coefficients from th... more A simple thermodynamic expression determining the infinite dilution activity coefficients from the dew point isobar is presented. A flow method measuring the dew point temperature for ternary and binary isobaric systems is proposed. An analysis determining the infinite diluvion ternary activity coefficients for ethanol-isopropyl alcohol-water system at 1 atm. is illustrated.
Journal of Food Engineering
Optimization studies for the esterification and transesterification of oil extracted from Croton ... more Optimization studies for the esterification and transesterification of oil extracted from Croton gratissimus grains were carried out using the response surface methodology (RMS) that utilizes the central composite design (CCD) and the analysis of variance (ANOVA). A 23 full-factorial rotatable CCD for three independent variables at five levels was developed in each case, giving a total of 20 experiments needed per study. The three design factors chosen for study were the catalyst concentration, methanol-to-oil ratio, and the reaction temperature. The values of the acid value of oil (in esterification) and the percentage FAME yield and FAME purity (in transesterification) were taken as the responses of the designed experiments. In the optimization of the esterification and transesterification processes, the ANOVA showed that both quadratic regression models developed were significant. The optimum operating conditions for the esterification process that could give an optimum acid valu...
Fluid Phase Equilibria, 2016
Abstract The glass transition temperature (Tg) of ionic liquids (ILs) was estimated with a group-... more Abstract The glass transition temperature (Tg) of ionic liquids (ILs) was estimated with a group-interaction contribution method. This temperature is very important for phenomena in polymeric materials, amorphous pharmaceutical solids and semiconductors. The proposed method was applied using the group-interaction contribution approach previously developed by Marrero-Morejon and Pardillo-Fontdevila [1], with some modifications to introduce two-order contributions: firstly, simple interaction contribution and secondly, binary interaction contribution. In this study, a comprehensive set of experimental data for 368 ionic liquids with different molecular structures was used to obtain the predictive model and all interaction contributions for all groups in the ionic liquids, including cation and anion groups. A wide range of Imidazolium, Pyridinium, Triazolium, Sulfonium, Pyrrolidinium, Piperidinium, Phosphonium, Oxazolidinium, Ammonium, Morpholinium, Guanidinium, Amino acids and Caprolactam-based ILs were considered in this study. The results show that, with an average absolute relative deviation (AARD) of 3.08% and a correlation coefficient of 0.96, this method represents an excellent alternative to previous approaches for the estimation of the glass transition temperature of diverse ionic liquids from the knowledge of their molecular structure.
Journal of the Taiwan Institute of Chemical Engineers, 2013
Journal of Chemical & Engineering Data, 2013
Ethene, ethyne, and propene are common and important industrial gases which are known to form hyd... more Ethene, ethyne, and propene are common and important industrial gases which are known to form hydrates. There exists in the open literature some hydrate dissociation data for simple hydrates of the three hydrocarbons. Unfortunately the data reported in literature are in some instances very limited, and the data sets are not always in agreement with each other. To evaluate the hydrate data for these hydrocarbons, new hydrate dissociation data were measured and are compared to that in the literature. Measurements for ethyne were undertaken in the temperature and pressure ranges of (273.2 to 285.5) K and (0.614 to 2.467) MPa, respectively. The temperature and pressure ranges for the propene measurements were (273.5 to 274.4) K and (0.492 to 0.613) MPa, respectively. The solid solution theory of van der Waals and Platteeuw, together with the Valderama–Patel–Teja equation of state and the non-density-dependent mixing rules were used to model the experimental hydrate dissociation conditions. Model predictions w...
Petroleum Science and Technology, 2018
In order to establish whether 2-methyl-2-butene and isoprene can form hydrates, experimental hydr... more In order to establish whether 2-methyl-2-butene and isoprene can form hydrates, experimental hydrate dissociation data were measured for the following systems: methane þ water, 2-methyl-2-butene þ methane þ water and isoprene þ methane þ water. An isochoric pressure search method was used to perform the measurements in the ranges of (274.6 to 288.3) K and (3.25 to 13.35) MPa. The reported results are discussed in terms of the ability of isoprene (2-methyl-1, 3-butadiene) and 2-methyl-2-butene to interfere with methane hydrate dissociation conditions. It is found that the two C 5 hydrocarbons are likely not hydrate formers. However, a further confirmation via appropriate analytical tools is recommended.
Journal of Natural Gas Science and Engineering, 2016
This study was aimed at developing a simple modeling tool for assessing gas hydrate formation as ... more This study was aimed at developing a simple modeling tool for assessing gas hydrate formation as a means to separate gas mixtures. In order to assess the feasibility of this technology for separation, phase equilibrium data obtained via experimental and modeling studies are required for the design and optimization of processes based on gas hydrate formation. Three selected gas mixtures (ethane + ethene, ethyne + propene, and ethyne + propane) under hydrate formation conditions were examined. This was done on the basis of pressure-composition plots obtained with the newly developed multi-phase-multi-component model. The procedure, based on the equality of fugacity and material balances, is presented for predicting compositions in coexisting phases for multi-component systems under hydrate stability conditions. The new multi-phase-multi-component model is simple and has been successfully validated against independent data, as well as experimental data obtained by our group.
The Journal of Chemical Thermodynamics, 2015
Abstract (Vapour + liquid) equilibria (VLE), excess enthalpies (HE) and infinite dilution activit... more Abstract (Vapour + liquid) equilibria (VLE), excess enthalpies (HE) and infinite dilution activity coefficients (γ∞) were measured for ethanol, propan-1-ol, butan-1-ol and cyclohexane in the presence of the ionic liquid (IL), n-hexyl pyridinium bis (trifluoromethylsulphonyl) imide [HPy][NTf2]. Except for some limiting activity coefficients values, qualitative agreement was generally observed between the reported values and modified UNIFAC (Dortmund) predictions. Experimental results also suggest that the IL studied is less attractive as a separation solvent for the cyclohexane/benzene system than most of bis (trifluoromethylsulphonyl) imide-based ILs. Excess enthalpy values suggest endothermic behaviour when mixing [HPy][NTf2] with the solutes. All the reported results can be used to derive new modelling approaches as well as to improve existing thermodynamic models (including that used in this study) for the description of mixtures involving pyridinium-based ILs.
Energy & Fuels, 2014
ABSTRACT Quantitative assessments of the potential of a novel non-edible feedstock for biodiesel ... more ABSTRACT Quantitative assessments of the potential of a novel non-edible feedstock for biodiesel production are crucial for two reasons in addition to the primary concern of food security. The first is to find alternative fuels as replacements for dwindling reserves of fossil fuels. The second is to ascertain whether biodiesel produced from oil extracted from Croton gratissimus has properties close to that for biodiesel from other feedstock. C. gratissimus, a non-food grain, native to Africa, was collected from the Democratic Republic of the Congo. Its oil was extracted and characterized for its fatty acid profile and its acid and saponification values. The efficiencies of homogeneous (sulfuric acid) and heterogeneous (sulfated zirconia oxide) acid catalysts were evaluated. Sulfated zirconia oxide gave a better biodiesel yield of 84.65 ± 0.45% based on the oil weight compared to a biodiesel yield of 80.35 ± 1.05% given by sulfuric acid. The synthesized biodiesel, from C. gratissimus oil, was tested for its thermophysical properties, such as density, specific gravity, and refractive index, at various temperatures. In addition, differential thermal analysis was also performed. In general, the data from these studies indicate that C. gratissimus oil has great potential as a non-edible feedstock for industrial-scale synthesis of high-quality biodiesel.
Thermochimica Acta, 2012
ABSTRACT The aim of is this study is to develop molecular-based model for prediction of melting p... more ABSTRACT The aim of is this study is to develop molecular-based model for prediction of melting points of diverse classes of ionic liquids. For this purpose, exhaustive literature survey was conducted in order to collect comprehensive database of the melting points of ionic liquids. The melting points of 808 diverse ionic liquids belongs to Sulfonium, Ammonium, Pyridinium, 1,3-Dialkyl imidazolium, Tri-alkyl imidazolium, Phosphonium, Pyrrolidinium, Double imidazolium, 1-Alkyl imidazolium, Piperidinium, Pyrroline, Oxazolidinium, Amino acids, Guanidinium, Morpholinium, Isoquinolinium and Tetra-alkyl imidazolium have been collected from 131 various references. Quantitative Structure–Property Relationship (QSPR) approach was applied in order to develop a reliable model for the prediction of the melting points of ionic liquids. As far as the authors concern, the investigated data has the broadest range of anion and cation structures among the previous studies which enhances its generality to predict melting point of unknown ionic liquids. The final QSPR model derived by Genetic Function Approximation (GFA) contains 12 descriptors and quantified by the following statistical parameters: R2train = 0.658, R2test = 0.721 and Average Absolute Relative Deviation (AARD) = 7.3%. The Applicability Domain (AD) of the model is also investigated. It turns out that the model's domain is defined broadly enough to contain all the trained and test sets which verified the reliability of the model. Finally, the proposed model has been scrutinized by several validation techniques and its robustness and reliability is investigated. The results of the validation techniques indicate the present model is robust, stable and reliable one.
The Journal of Physical Chemistry B, 2010
The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfo... more The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfonyl}imide ([BM 4 Py][NTf 2 ]) with water, an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol), an aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), an alkane (n-hexane, n-heptane, n-octane), or cyclohexane have been measured at atmospheric pressure using a dynamic method. This work includes the characterization of the synthesized compound by water content and also by differential scanning calorimetry. Phase diagrams for the binary systems of [BM 4 Py][NTf 2 ] with all solvents reveal eutectic systems with regards to (solid-liquid) phase equilibria and show immiscibility in the liquid phase region with an upper critical solution temperature (UCST) in most of the mixtures. The phase equilibria (solid, or liquid-liquid) for the binary systems containing aliphatic hydrocarbons reported here exhibit the lowest solubility and the highest immiscibility gap, a trend which has been observed for all ILs. The reduction of experimental data has been carried out using the nonrandom two-liquid (NRTL) correlation equation. The phase diagrams reported here have been compared with analogous phase diagrams reported previously for systems containing the IL N-butyl-4-methylpyridinium tosylate and other pyridiniumbased ILs. The influence of the anion of the IL on the phase behavior has been discussed.
Journal of Molecular Liquids, 2013
Originally, Quantitative Structure Property Relationship (QSPR) models for the surface tension of... more Originally, Quantitative Structure Property Relationship (QSPR) models for the surface tension of ionic liquids are developed based on molecular descriptors. A large data set of 930 experimental surface tension data points for 48 ionic liquids is applied to derive the model. Seven descriptors are selected by genetic function approximation to relate the surface tension of ionic liquids to their corresponding anions and cation structures. To capture the nonlinear nature of surface tension, a model based on Least-Squared Supported Vector Machine (LSSVM) is also developed. The derived models are authenticated with several statistical validation techniques.
Journal of Chemical & Engineering Data, 2013
Dissociation conditions for simple and mixed hydrates of ethane and ethene (ethylene) have been m... more Dissociation conditions for simple and mixed hydrates of ethane and ethene (ethylene) have been measured using the isochoric pressure-search technique. Simple hydrate dissociation data for ethane and ethene measured in this work are compared to existing literature data. The agreement between the measured ethane hydrate dissociation data with the literature data is acceptable while some deviations between the measured ethene hydrate dissociation data and those reported in the literature are observed. All new data for simple and mixed hydrates of ethene and ethane are well-correlated using an empirical correlation proposed by Adisasmito and coworkers. However, agreement between the experimental data with the predictions of the CSMGem model is found to be unsatisfactory. A gas chromatography technique combined with the isochoric-pressure search method is used to measure composition of the vapor phase in equilibrium with the hydrate and aqueous phases inside the hydrate stability region. The feed compositions investigated were 0.174, 0.420, and 0.810 mole fractions of ethane. In addition, dissociation points were found to be in the vicinity of the ethane hydrate dissociation conditions regardless of the initial content of ethane in the feed. It was also found that temperature does not have a considerable effect on ethane content of the vapor phase in equilibrium with hydrate and aqueous phases inside the hydrate stability region at given pressures.
AIChE Journal, 1972
A simple thermodynamic expression determining the infinite dilution activity coefficients from th... more A simple thermodynamic expression determining the infinite dilution activity coefficients from the dew point isobar is presented. A flow method measuring the dew point temperature for ternary and binary isobaric systems is proposed. An analysis determining the infinite diluvion ternary activity coefficients for ethanol-isopropyl alcohol-water system at 1 atm. is illustrated.
Journal of Food Engineering
Optimization studies for the esterification and transesterification of oil extracted from Croton ... more Optimization studies for the esterification and transesterification of oil extracted from Croton gratissimus grains were carried out using the response surface methodology (RMS) that utilizes the central composite design (CCD) and the analysis of variance (ANOVA). A 23 full-factorial rotatable CCD for three independent variables at five levels was developed in each case, giving a total of 20 experiments needed per study. The three design factors chosen for study were the catalyst concentration, methanol-to-oil ratio, and the reaction temperature. The values of the acid value of oil (in esterification) and the percentage FAME yield and FAME purity (in transesterification) were taken as the responses of the designed experiments. In the optimization of the esterification and transesterification processes, the ANOVA showed that both quadratic regression models developed were significant. The optimum operating conditions for the esterification process that could give an optimum acid valu...
Fluid Phase Equilibria, 2016
Abstract The glass transition temperature (Tg) of ionic liquids (ILs) was estimated with a group-... more Abstract The glass transition temperature (Tg) of ionic liquids (ILs) was estimated with a group-interaction contribution method. This temperature is very important for phenomena in polymeric materials, amorphous pharmaceutical solids and semiconductors. The proposed method was applied using the group-interaction contribution approach previously developed by Marrero-Morejon and Pardillo-Fontdevila [1], with some modifications to introduce two-order contributions: firstly, simple interaction contribution and secondly, binary interaction contribution. In this study, a comprehensive set of experimental data for 368 ionic liquids with different molecular structures was used to obtain the predictive model and all interaction contributions for all groups in the ionic liquids, including cation and anion groups. A wide range of Imidazolium, Pyridinium, Triazolium, Sulfonium, Pyrrolidinium, Piperidinium, Phosphonium, Oxazolidinium, Ammonium, Morpholinium, Guanidinium, Amino acids and Caprolactam-based ILs were considered in this study. The results show that, with an average absolute relative deviation (AARD) of 3.08% and a correlation coefficient of 0.96, this method represents an excellent alternative to previous approaches for the estimation of the glass transition temperature of diverse ionic liquids from the knowledge of their molecular structure.
Journal of the Taiwan Institute of Chemical Engineers, 2013
Journal of Chemical & Engineering Data, 2013
Ethene, ethyne, and propene are common and important industrial gases which are known to form hyd... more Ethene, ethyne, and propene are common and important industrial gases which are known to form hydrates. There exists in the open literature some hydrate dissociation data for simple hydrates of the three hydrocarbons. Unfortunately the data reported in literature are in some instances very limited, and the data sets are not always in agreement with each other. To evaluate the hydrate data for these hydrocarbons, new hydrate dissociation data were measured and are compared to that in the literature. Measurements for ethyne were undertaken in the temperature and pressure ranges of (273.2 to 285.5) K and (0.614 to 2.467) MPa, respectively. The temperature and pressure ranges for the propene measurements were (273.5 to 274.4) K and (0.492 to 0.613) MPa, respectively. The solid solution theory of van der Waals and Platteeuw, together with the Valderama–Patel–Teja equation of state and the non-density-dependent mixing rules were used to model the experimental hydrate dissociation conditions. Model predictions w...
Petroleum Science and Technology, 2018
In order to establish whether 2-methyl-2-butene and isoprene can form hydrates, experimental hydr... more In order to establish whether 2-methyl-2-butene and isoprene can form hydrates, experimental hydrate dissociation data were measured for the following systems: methane þ water, 2-methyl-2-butene þ methane þ water and isoprene þ methane þ water. An isochoric pressure search method was used to perform the measurements in the ranges of (274.6 to 288.3) K and (3.25 to 13.35) MPa. The reported results are discussed in terms of the ability of isoprene (2-methyl-1, 3-butadiene) and 2-methyl-2-butene to interfere with methane hydrate dissociation conditions. It is found that the two C 5 hydrocarbons are likely not hydrate formers. However, a further confirmation via appropriate analytical tools is recommended.
Journal of Natural Gas Science and Engineering, 2016
This study was aimed at developing a simple modeling tool for assessing gas hydrate formation as ... more This study was aimed at developing a simple modeling tool for assessing gas hydrate formation as a means to separate gas mixtures. In order to assess the feasibility of this technology for separation, phase equilibrium data obtained via experimental and modeling studies are required for the design and optimization of processes based on gas hydrate formation. Three selected gas mixtures (ethane + ethene, ethyne + propene, and ethyne + propane) under hydrate formation conditions were examined. This was done on the basis of pressure-composition plots obtained with the newly developed multi-phase-multi-component model. The procedure, based on the equality of fugacity and material balances, is presented for predicting compositions in coexisting phases for multi-component systems under hydrate stability conditions. The new multi-phase-multi-component model is simple and has been successfully validated against independent data, as well as experimental data obtained by our group.
The Journal of Chemical Thermodynamics, 2015
Abstract (Vapour + liquid) equilibria (VLE), excess enthalpies (HE) and infinite dilution activit... more Abstract (Vapour + liquid) equilibria (VLE), excess enthalpies (HE) and infinite dilution activity coefficients (γ∞) were measured for ethanol, propan-1-ol, butan-1-ol and cyclohexane in the presence of the ionic liquid (IL), n-hexyl pyridinium bis (trifluoromethylsulphonyl) imide [HPy][NTf2]. Except for some limiting activity coefficients values, qualitative agreement was generally observed between the reported values and modified UNIFAC (Dortmund) predictions. Experimental results also suggest that the IL studied is less attractive as a separation solvent for the cyclohexane/benzene system than most of bis (trifluoromethylsulphonyl) imide-based ILs. Excess enthalpy values suggest endothermic behaviour when mixing [HPy][NTf2] with the solutes. All the reported results can be used to derive new modelling approaches as well as to improve existing thermodynamic models (including that used in this study) for the description of mixtures involving pyridinium-based ILs.
Energy & Fuels, 2014
ABSTRACT Quantitative assessments of the potential of a novel non-edible feedstock for biodiesel ... more ABSTRACT Quantitative assessments of the potential of a novel non-edible feedstock for biodiesel production are crucial for two reasons in addition to the primary concern of food security. The first is to find alternative fuels as replacements for dwindling reserves of fossil fuels. The second is to ascertain whether biodiesel produced from oil extracted from Croton gratissimus has properties close to that for biodiesel from other feedstock. C. gratissimus, a non-food grain, native to Africa, was collected from the Democratic Republic of the Congo. Its oil was extracted and characterized for its fatty acid profile and its acid and saponification values. The efficiencies of homogeneous (sulfuric acid) and heterogeneous (sulfated zirconia oxide) acid catalysts were evaluated. Sulfated zirconia oxide gave a better biodiesel yield of 84.65 ± 0.45% based on the oil weight compared to a biodiesel yield of 80.35 ± 1.05% given by sulfuric acid. The synthesized biodiesel, from C. gratissimus oil, was tested for its thermophysical properties, such as density, specific gravity, and refractive index, at various temperatures. In addition, differential thermal analysis was also performed. In general, the data from these studies indicate that C. gratissimus oil has great potential as a non-edible feedstock for industrial-scale synthesis of high-quality biodiesel.
Thermochimica Acta, 2012
ABSTRACT The aim of is this study is to develop molecular-based model for prediction of melting p... more ABSTRACT The aim of is this study is to develop molecular-based model for prediction of melting points of diverse classes of ionic liquids. For this purpose, exhaustive literature survey was conducted in order to collect comprehensive database of the melting points of ionic liquids. The melting points of 808 diverse ionic liquids belongs to Sulfonium, Ammonium, Pyridinium, 1,3-Dialkyl imidazolium, Tri-alkyl imidazolium, Phosphonium, Pyrrolidinium, Double imidazolium, 1-Alkyl imidazolium, Piperidinium, Pyrroline, Oxazolidinium, Amino acids, Guanidinium, Morpholinium, Isoquinolinium and Tetra-alkyl imidazolium have been collected from 131 various references. Quantitative Structure–Property Relationship (QSPR) approach was applied in order to develop a reliable model for the prediction of the melting points of ionic liquids. As far as the authors concern, the investigated data has the broadest range of anion and cation structures among the previous studies which enhances its generality to predict melting point of unknown ionic liquids. The final QSPR model derived by Genetic Function Approximation (GFA) contains 12 descriptors and quantified by the following statistical parameters: R2train = 0.658, R2test = 0.721 and Average Absolute Relative Deviation (AARD) = 7.3%. The Applicability Domain (AD) of the model is also investigated. It turns out that the model's domain is defined broadly enough to contain all the trained and test sets which verified the reliability of the model. Finally, the proposed model has been scrutinized by several validation techniques and its robustness and reliability is investigated. The results of the validation techniques indicate the present model is robust, stable and reliable one.
The Journal of Physical Chemistry B, 2010
The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfo... more The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfonyl}imide ([BM 4 Py][NTf 2 ]) with water, an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol), an aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), an alkane (n-hexane, n-heptane, n-octane), or cyclohexane have been measured at atmospheric pressure using a dynamic method. This work includes the characterization of the synthesized compound by water content and also by differential scanning calorimetry. Phase diagrams for the binary systems of [BM 4 Py][NTf 2 ] with all solvents reveal eutectic systems with regards to (solid-liquid) phase equilibria and show immiscibility in the liquid phase region with an upper critical solution temperature (UCST) in most of the mixtures. The phase equilibria (solid, or liquid-liquid) for the binary systems containing aliphatic hydrocarbons reported here exhibit the lowest solubility and the highest immiscibility gap, a trend which has been observed for all ILs. The reduction of experimental data has been carried out using the nonrandom two-liquid (NRTL) correlation equation. The phase diagrams reported here have been compared with analogous phase diagrams reported previously for systems containing the IL N-butyl-4-methylpyridinium tosylate and other pyridiniumbased ILs. The influence of the anion of the IL on the phase behavior has been discussed.
Journal of Molecular Liquids, 2013
Originally, Quantitative Structure Property Relationship (QSPR) models for the surface tension of... more Originally, Quantitative Structure Property Relationship (QSPR) models for the surface tension of ionic liquids are developed based on molecular descriptors. A large data set of 930 experimental surface tension data points for 48 ionic liquids is applied to derive the model. Seven descriptors are selected by genetic function approximation to relate the surface tension of ionic liquids to their corresponding anions and cation structures. To capture the nonlinear nature of surface tension, a model based on Least-Squared Supported Vector Machine (LSSVM) is also developed. The derived models are authenticated with several statistical validation techniques.
Journal of Chemical & Engineering Data, 2013
Dissociation conditions for simple and mixed hydrates of ethane and ethene (ethylene) have been m... more Dissociation conditions for simple and mixed hydrates of ethane and ethene (ethylene) have been measured using the isochoric pressure-search technique. Simple hydrate dissociation data for ethane and ethene measured in this work are compared to existing literature data. The agreement between the measured ethane hydrate dissociation data with the literature data is acceptable while some deviations between the measured ethene hydrate dissociation data and those reported in the literature are observed. All new data for simple and mixed hydrates of ethene and ethane are well-correlated using an empirical correlation proposed by Adisasmito and coworkers. However, agreement between the experimental data with the predictions of the CSMGem model is found to be unsatisfactory. A gas chromatography technique combined with the isochoric-pressure search method is used to measure composition of the vapor phase in equilibrium with the hydrate and aqueous phases inside the hydrate stability region. The feed compositions investigated were 0.174, 0.420, and 0.810 mole fractions of ethane. In addition, dissociation points were found to be in the vicinity of the ethane hydrate dissociation conditions regardless of the initial content of ethane in the feed. It was also found that temperature does not have a considerable effect on ethane content of the vapor phase in equilibrium with hydrate and aqueous phases inside the hydrate stability region at given pressures.