Faisal Islam Chowdhury

Densities and excess molar volumes of aqueous solutions of some diethanolamines

Densities of aqueous diethanolamine (DEA), methyldiethanolamine (MDEA), ethyldiethanolamine (EDEA) and n-butyldiethanolamine (BDEA) solutions were determined from 303.15 to 323.15 K at different compositions in the range 0 ≤ x 1 ≤ 1, where x 1 is the mole fraction of alkanolamines. The densities of the diethanolamines are assumed to be related to the strength of association. Excess molar volumes have been calculated from the density data. The values have been found to be negative for all systems in the whole range of composition at all temperatures, and less negative with increasing temperature. Negative values of can be explained by the large difference in the molar volumes. For all systems, minima occur at about 0.35–0.40 mole fraction of diethanolamines. The depth of minima varies as EDEA + W > MDEA + W > BDEA + W > DEA + W. All the data have been correlated with six-degree polynomial equations.

A High Efficiency Chlorophyll Sensitized Solar Cell with Quasi Solid PVA Based Electrolyte

The objective of this work is to investigate the performance of chlorophyll sensitized solar cells (CSSCs) with gel electrolyte based on polyvinyl alcohol (PVA) with single iodide salt (potassium iodide (KI)) and double salt (KI and tetrapropylammonium iodide (TPAI)). Chlorophyll was extracted from the bryophyte Hyophila involuta. The CSSC with electrolyte containing only KI salt produced a short circuit current density () of 4.59 mA cm−2, open circuit voltage () of 0.61 V, fill factor (FF) of 0.64, and efficiency () of 1.77%. However, the CSSC with double salt electrolyte exhibited of 5.96 mA cm−2, of 0.58 V, fill factor FF of 0.58, and of 2.00%. Since CSSC with double salt electrolyte showed better efficiency, other cells fabricated will use the double salt electrolyte. On addition of 0.7 M tetrabutyl pyridine (TBP) to the double salt electrolyte, the cell’s efficiency increased to 2.17%, mA cm−2, V, and FF = 0.73. With 5 mM chenodeoxycholic acid (CDCA) added to the chlorophyll, the light to electricity efficiency increased to 2.62% with of 8.44 mA cm−2, of 0.54 V, and FF of 0.58.

Densities and excess molar volumes of tert-butanol with n-butylamine, di-n-butylamine and tri-n-butylamine

Densities of the systems of tert-butanol (TB) + n-butylamine (NBA), + di-n-butylamine (DBA) and + tri-n-butylamine (TBA) were determined between 303.15 and 323.15 K at different compositions in the range 0 ≤ x 2 ≤ 1, where x 2 is the mole fraction of butylamines BA, NBA, DBA and TBA. Excess molar volumes have been calculated from the density data. In the whole range of composition, systems of TB + NBA and TB + DBA show negative values, whereas the values are positive for TB + TBA. While the negative values are accounted for by the effects of specific interaction and interstitial accommodation, positive values are due to dispersive forces.

Vibrational, electrical, and structural properties of PVDF–LiBOB solid polymer electrolyte with high electrochemical potential window

Polyvinylidene difluoride (PVDF)–lithium bis(oxalato)borate (LiBOB) solid polymer electrolytes (SPEs) have been prepared by solution casting. The highest ionic conductivity achieved is 3.4610−3xa0Sxa0cm−1. Electrochemical potential window of the SPEs is found around 4.7xa0V. Interaction between PVDF and LiBOB is studied systematically. The changes of C–C, CF2, and CH2 vibration modes with an emerging shoulder are analyzed. At higher salt content, this shoulder becomes more prominent peak at the expense of CF2 vibration mode. This suggests the possible Li+⋯F coordination. Deconvolution of IR spectra region from 1750 to 1850xa0cm−1 has been carried out to estimate the relative percentage of free ions and contact ions. The finding is in good agreement with conductivity and XRD results. When more salt is present, the number of free ions percentage increases and the Full width at half-maximum (FWHM) of (110) plane is broadening. The Li+⋯F interaction breaks the folding patterns of polymer chain and enhances amorphousness domain.

Thermodynamics of Viscous Flow of tert-Butanol with Butylamines: UNIFAC–VISCO, Grunberg–Nissan and McAllister Three Body Interaction Models for Viscosity Prediction and Quantum Chemical (DFT) Calculations

Thermodynamic activation parameters, enthalpies (ΔH‡), entropies (ΔS‡) and Gibbs energies (ΔG‡) for viscous flow of the systems tert-butanol (TB)+n-butylamine (NBA), TB+di-n-butylamine (DBA) and TB+tri-n-butylamine (TBA) have been calculated from measured density and viscosity data at temperatures ranging from 303.l5 to 323.15xa0K over the composition range 0xa0≤xa0x2xa0≤xa01, where x2 is the mole fraction of TB. For all systems, the corresponding excess properties ΔH‡E, ΔS‡E and ΔG‡E have been determined, which are negative in the whole range of composition. The observed negative excess activation properties have been accounted for in terms of dispersive forces and H-bonding. The derived properties are well represented by fourth degree polynomial equations whereas the excess properties could be fitted to third degree Redlich–Kister polynomial equations. Furthermore, the viscosities have been predicted by using the UNIFAC–VISCO model, Grunberg–Nissan model and McAllister three-body interaction model. The UNIFAC–VISCO model and Grunberg–Nissan model do not show good agreement with the experimental data, whereas the McAllister three-body interaction model shows excellent agreement for all three systems, with small average absolute percent deviations (AAD%xa0=xa00.6–2.3). The DFT-B3LYP method with the 6-311 G (d, p) basis set has been employed for the optimization of the geometry and calculation of the total energies of the pure compounds and their binary complexes.