Tamal Banerjee

Genetic algorithm to estimate interaction parameters of multicomponent systems for liquid¿liquid equilibria

Abstract Genetic algorithm (GA) has been utilized to estimate the binary interaction parameters from multicomponent liquid–liquid equilibria data; and its applicability for NRTL and UNIQUAC thermodynamic models has been demonstrated. These models being highly non-convex can have several local extrema. GA leads to globally optimum values; it does not require any initial guess but only the upper and lower bounds of the interaction parameters. It has also been shown to perform better than inside variance estimation method (IVEM) and the techniques used in ASPEN, DECHEMA. The objective function and the root-mean-square deviation for these four techniques have been compared for methanol–diphenylamine–cyclohexane system using UNIQUAC. The applicability of GA to six ternary, two quaternary and two quinary systems has also been undertaken. Invariably the rmsd values for GA are better than reported in the literature.

Hydrolysis of bamboo biomass by subcritical water treatment

The aim of present study was to obtain total reducing sugars (TRS) from bamboo under subcritical water (SCW) treatment in a batch reactor at the temperature ranging from 170 °C to 220 °C and 40 min hydrolysis time. Experiments were performed to investigate the effects of temperature and time on TRS yield. The maximum TRS yield (42.21%) was obtained at lower temperature (180 °C), however longer reaction time (25 min). X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) analysis were used to characterise treated and untreated bamboo samples. The XRD profile revealed that crystallinity of bamboo increased to 71.90% with increase in temperature up to 210 °C and decreased thereafter to 70.92%. The first-order reaction kinetic model was used to fit the experimental data to obtain rate constants. From the Arrhenius plot, activation energy and pre-exponential factor at 25 min time were found to be 17.97 kJ mol(-1) and 0.154 min(-1), respectively.

Phase Behaviour of 1-Ethyl-3-methylimidazolium Thiocyanate Ionic Liquid with Catalytic Deactivated Compounds and Water at Several Temperatures: Experiments and Theoretical Predictions

Density, surface tension and refractive index were determined for the binary mixture of catalytic deactivated compounds with 1-ethyl-3-methylimidazolium thiocyanate {[EMIM][SCN]} at temperature of (298.15 to 323.15) K. For all the compounds with ILs, the densities varied linearly in the entire mole fraction with increasing temperature. From the obtained data, the excess molar volume and deviation of surface tension and refractive index have been calculated. A strong interaction was found between similar (cation-thiophene or cation-pyrrole) compounds. The interaction of IL with dissimilar compounds such as indoline and quinoline and other multiple ring compounds was found to strongly depend on the composition of IL at any temperatures. For the mixtures, the surface tension decreases in the order of: thiophene > quinoline > pyridine > indoline > pyrrole > water. In general from the excess volume studies, the IL-sulphur/nitrogen mixture has stronger interaction as compared to IL-IL, thiophene-thiophene or pyrrole-pyrrole interaction. The deviation of surface tension was found to be inversely proportional to deviation of refractive index. The quantum chemical based COSMO-RS was used to predict the non-ideal liquid phase activity coefficient for all mixtures. It indicated an inverse relation between activity coefficient and excess molar volumes.

Insights on the combustion and pyrolysis behavior of three different ranks of coals using reactive molecular dynamics simulation

The process of combustion and pyrolysis of coal can be considered to be convoluted where numerous intermediates are expected to form during the course of the reaction. In this work, we have investigated the reactive products using the ReaxFF force field for three different ranked (low to high) coals, namely lignite, bituminous, and anthracite. It was observed that during the pyrolysis and combustion processes, the gases CO and CO2 were predominant. The formation rate of CO and CO2 was found to be higher for lignite coal which agreed with the experimental trend reported in the literature. In a similar manner, the fraction of CO and CO2 was found to be higher in the pyrolysis process. Further, a large number of principal intermediates such as methane, ethane and ethylene are also generated for low to high ranking (lignite, bituminous, and anthracite) coal. The pyrolysis and combustion processes were affected by temperature (2000–4000 K) with respect to the formation of various intermediates (methane, ethane and ethylene). They were found to be high throughout irrespective of the rank of coal. A higher temperature (2000–4000 K) was adopted in the reactive molecular dynamics (MD) simulation so as to visualize the chemical reactions within a computationally affordable time.

Optimization and hydrolysis of cellulose under subcritical water treatment for the production of total reducing sugars

Subcritical water (SCW) treatment has gained enormous attention as an environmentally friendly technique for organic matter and an attractive reaction medium for a variety of applications. In this work, hydrolysis of cellulose was studied under SCW conditions in a batch reactor to attain total reducing sugars (TRS) within a reaction temperature and time range of 150 to 250 °C and 10–60 min, respectively. From the experimental results, the highest yield of TRS was 45.04% as obtained at 200 °C and 20 min of hydrolysis time. The characterisation techniques, namely X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used as to determine the structural and compositional changes in the hydrolysed material. Reaction parameters such as temperature, time, and solute loading have been optimised using response surface methodology based on a central composite design. From ANOVA analysis, it was described that the second-order response surface model is highly significant as per Fishers F-test and P-value. A first-order reaction kinetic model was formulated to describe the hydrolysis of cellulose for TRS formation and decomposition. For TRS formation, the activation energy and pre-exponential factor of the Arrhenius equation was found to be 29.16 kJ mol−1 and 0.088 min−1 for 60 min, respectively.

Prediction of Selective Extraction of Cresols from Aqueous Solutions by Ionic Liquids Using Theoretical Approach

This work reports the prediction of selective extraction of cresol from aqueous solutions using ionic liquids (ILs) as the solvent. Judicious screening of various ILs was carried out for all the three forms of cresol (i.e., o-cresol, m-cresol, and p-cresol). A quantum chemical based theoretical model “conductor-like screening model for real solvents” (COSMO-RS) was used to predict the selectivity of cresol in aqueous medium at infinite dilution. A screening of 360 possible ILs from 15 cations and 24 anions was carried out to determine the best IL for the removal of cresol from water. Amongst the phosphonium and imidazolium based cations, trihexyl tetradecylphosphonium [THTDP] and 1-octyl-3-methylimidazolium [OMIM] gave the highest selectivity other than the anions bromide and chloride. The selectivities for different cresols followed the pattern: m-cresol > p-cresol > o-cresol. Similarly for pyridinium and quinolium based cations, 1-ethylpyridinium [EPY] and 1-octylquinolium [OQU] gave the highest selectivity. Amongst the two cations studied for pyrrolidinium based cations, 1-hexyl-1-methylpyrrolidinium [HMPL] was the best. Trihexyl tetradecylphosphonium salicyclate [THTDP][SAL] gave the highest selectivity of 662 amongst all the ILs screened.

Quantum chemical and experimental insights for the ionic liquid facilitated thermal dehydrogenation of ethylene diamine bisborane

The current work reports the judicial selection and subsequent dehydrogenation reaction with ionic liquid (IL) facilitated ethylene diamine bisborane (EDAB). Quantum chemical based COSMO-SAC (COnductor like Screening MOdel Segment Activity Coefficient) model was initially used to screen the ILs as available from Sigma Aldrich. LUMO–HOMO calculation was then performed to analyze the stability of EDAB/IL complexes. The molecular modeling studies converged on the two ILs, namely 1-ethyl-3-methyl imidazolium acetate ([EMIM][OAc]) and 1-butyl-3-methyl imidazolium acetate ([BMIM][OAc]), which were subsequently chosen for the dehydrogenation experiments. The thermal dehydrogenation of EDAB was carried out at 95 °C and 105 °C under vacuum so as to prevent generation of oxygen moieties. A total of 3.96 and 3.52 equivalents of hydrogen were released from the desorption of EDAB/[BMIM][OAc] and EDAB/[EMIM][OAc], respectively, at 105 °C. The purity of released gas was confirmed by gas chromatographic analysis, while the catalytic activity of ILs was confirmed by 1H NMR characterization of pure EDAB, ILs and EDAB/IL complexes both before and after the reaction. 11B NMR analysis confirms the presence of trigonal boron (sp2) BH2 group as the only hydrogen containing boron moiety in dehydrogenated EDAB. Further, the two-stage release mechanism of EDAB was also verified by thermogravimetric analysis. High resolution mass spectrometry was able to detect the mass of cyclic repeat units in the polymeric chain containing an sp2 BH2 group.

Physiochemical Properties of Hydrodenitrification and Hydrodesulphurization Inhibiting Compounds with 1-Ethyl-3-Methylimidazolium Ethylsulphate at T = (298.15 to 323.15) K and =1 Bar

This work investigates the ability of 1-ethyl-3-methylimidazolium ethylsulphate ([emim][EtSO4]) as a green and tuneable solvent for denitrification and desulphurization of diesel oil. Experimental density, surface tension, and refractive index data have been measured for the following systems: [emim][EtSO4](1)

Performance of different ionic liquids to remove phenol from aqueous solutions using supported liquid membrane

AbstractAn experimental study was carried out for the removal of phenol from aqueous solutions using supported liquid membranes containing ionic liquid (IL) as the carrier solvent. The commercial grade ILs namely: [CYPHOS® 101], [CYPHOS® 102], [CYPHOS® 103], [CYPHOS® 104], [Aliquat 336®], and [C8MIM][PF6] were used as membrane phase in this work. The effect of various parameters such feed phase pH, operation time, and stirring speed on the removal of phenol has been investigated using the six different ILs. Supported ionic liquid membrane (SILM) through vacuum immobilization method was used for the removal of phenol. The maximum permeation rate of 75.63% was achieved over an experimental run of 24 h at pH 4. High permeation rate was obtained by [CYPHOS® 104] among all the six ILs studied. The order of the permeation rates followed: [CYPHOS® 104] > [CYPHOS® 103] > [CYPHOS® 102] > [CYPHOS® 101] > [C8MIM][PF6] > [Aliquat 336®]. The operational stability and performance of the supported liquid membranes were ...

Ionic Liquids as Green Solvents for the Extraction of Endosulfan from Aqueous Solution: A Quantum Chemical Approach

Abstract This work presents a judicious screening of 986 possible ionic liquid (IL) combinations for the removal of Endosulfan using COSMO-RS (Conductor-like Screening Model for Real Solvents) model. Initially, benchmarking studies have been carried out for α-Endosulfan, β-Endosulfan, Endosulfan sulfate, Endosulfan-alcohol, Endosulfan lactone, and Endosulfan ether by comparing COSMO-RS experimental and predicted octanol–water partition coefficients. Thereafter, COSMO-RS selectivity predictions were done on 986 ionic liquid combinations at infinite dilution. The order of selectivity for the five cation groups were found to be as follows: [TBP] > [TIBMP] > [TBMP] > [C2DMIM] > [BEPYR] > [DPPYR] > [C4DMIM] > [C8MPY] > [BTNH] > [BETNH]. Highest selectivity was obtained for phosphonium based IL namely: [TBP][TOS] (212.5). Anions such as [C8H17SO4], [Br], [Sal], [TOS], [MDEGSO4], and [DEC] contributed high selectivities because of the absence of sterical shielding effect around their charge centers. Further capacity and the performance index (PI) values were calculated and predicted along with selectivity. The increasing order of performance index values were found to follow: [TBP][Sal] (1.71+E5) > [DPPYR][Br] (1.07+E6) > [C2DMIM] (1.01+E6) > [C8MPY][Cl] (1.6+E5) > [BETNH][DEC] (1.2+E5).