Thermodynamic Parameters

This work represents the extraction of oil with high free fatty acid content from spent bleaching earth using sub-critical water technology as a greener production pathway. The extraction efficiencies under different conditions were investigated. The studied parameters include temperatures in the range of 180 to 270°C, the feed to solventfeed-to-solvent (in this case water) ratio (1:1, 1:2, 1:3, 1:4 and 1:5) and extraction times in the range of 5-60 minutes. The results showed that the optimum temperature, feed to solventfeed-to-solvent ratio, and extraction time were 270°C, 1:3, and 20 minutes, respectively. In another experiment, the extracted free fatty acids were converted into mono-, di-, and triglycerides through esterification with glycerol to increase the value added of the extracted products. The kinetics of the extraction process was found to be corresponding to an irreversible consecutive unimolecular-type first order reaction, consisting of the extraction step followed by the decomposition reaction step. Both reaction rates of extraction and decomposition were estimated using the reaction rate equations utilizing the nonlinear regression method. The apparent activation energy was calculated to be 46.1 kJ·mol-1. This result indicates a diffusion controlled reaction. For more exploration and deep understanding of the extraction mechanism, other thermodynamic parameters were also calculated and analyzed including,ΔH#, ΔS#, and ΔG# of the extraction step.

Stability constants are measured for complexes of Cd 2+ , Ni 2+ , Cu 2+ and Co 2+ with pyridine-2,6-dicarboxylic acid(PDA) in water, methanol and water-methanol binary solvent systems at 298.15, 308.15 and 318.15 K by conductometric method. The result shows that the stoichiometry of the complexes of PDA with all metals in all binary solvent systems is 1:2 [ML2]. The logKf values of PDA-M 2+ complexes in H2O-MeOH binary solvent systems increase with increasing % of MeOH and temperature. The ∆H 0 and ∆S 0 of the complexation reaction in the different H2O-MeOH binary solvent systems were evaluated by the temperature dependence of the formation constants using a linear least square analysis according to van't Hoff equation. Capsule Summary: Stability of Cd 2+ , Ni 2+ , Cu 2+ and Co 2+ complexes with pyridine-2,6-dicarboxylic acid (PDA) in water, methanol and water-methanol binary solvent systems at was measured at different temperature and both solvent and temperature affected the stability of PDA complexes with Cd 2+ , Ni 2+ , Cu 2+ and Co 2+. Cite This Article As: K. K. Mehta, R. S. Chandra, D. R. Mehta and M. M. Maisuria. Thermodynamic studies on metal complexes of Cd 2+ , Ni 2+ , Cu 2+ and Co 2+ with pyridine-2,6-dicarboxylic acid in water, methanol and water-methanol binary solvent systems at 298.15 , 308.15 and 318.15 K by conductometric method. Chemistry International 4(1) (2018) 33-42.

In this research, activated carbon (coconut husk waste) is prepared using sulfuric acid activation from coconut husk waste which is a cheap material that shows agreed scavenging actions by adsorption for eliminating the toxic textile dyes (methylene blue MB, crystal violet CV, as well as Brilliant Blue BB) from the aqueous solutions. In a shaker water bath, different physio-chemical factors like contact time, adsorbent dose, pH, temperature of the dye solution and initial concentration of the dye have been measured and the adsorption time is 120 minutes. The results show that adsorption of MB, CV is favorable at a high pH value, but at acidic pH, the brilliant blue BB dye is favorable. The activated carbon thermodynamic analysis is conducted using three dyes: The Gibbs free energy, entropy and also enthalpy. According to the results, the adsorption is a Physical (endothermic). It is also found that the activated carbon is regulated by the equations of Freundlich and Temkin. Finally,...

In this research, activated carbon (coconut husk waste) is prepared using sulfuric acid activation from coconut husk waste which is a cheap material that shows agreed scavenging actions by adsorption for eliminating the toxic textile dyes (methylene blue MB, crystal violet CV, as well as Brilliant Blue BB) from the aqueous solutions. In a shaker water bath, different physio-chemical factors like contact time, adsorbent dose, pH, temperature of the dye solution and initial concentration of the dye have been measured and the adsorption time is 120 minutes. The results show that adsorption of MB, CV is favorable at a high pH value, but at acidic pH, the brilliant blue BB dye is favorable. The activated carbon thermodynamic analysis is conducted using three dyes: The Gibbs free energy, entropy and also enthalpy. According to the results, the adsorption is a Physical (endothermic). It is also found that the activated carbon is regulated by the equations of Freundlich and Temkin. Finally,...

In this research, activated carbon (coconut husk waste) is prepared using sulfuric acid activation from coconut husk waste which is a cheap material that shows agreed scavenging actions by adsorption for eliminating the toxic textile dyes (methylene blue MB, crystal violet CV, as well as Brilliant Blue BB) from the aqueous solutions. In a shaker water bath, different physio-chemical factors like contact time, adsorbent dose, pH, temperature of the dye solution and initial concentration of the dye have been measured and the adsorption time is 120 minutes. The results show that adsorption of MB, CV is favorable at a high pH value, but at acidic pH, the brilliant blue BB dye is favorable. The activated carbon thermodynamic analysis is conducted using three dyes: The Gibbs free energy, entropy and also enthalpy. According to the results, the adsorption is a Physical (endothermic). It is also found that the activated carbon is regulated by the equations of Freundlich and Temkin. Finally, field emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FT-IR) have been used to show adsorption.

Correlation functions in Liouville theory are meromorphic functions of the Liouville momenta, as is shown explicitly by the DOZZ formula for the three-point function on the sphere. In a certain physical region, where a real classical solution exists, the semiclassical limit of the DOZZ formula is known to agree with what one would expect from the action of the classical solution. In this paper, we ask what happens outside of this physical region. Perhaps surprisingly we find that, while in some range of the Liouville momenta the semiclassical limit is associated to complex saddle points, in general Liouville's equations do not have enough complex-valued solutions to account for the semiclassical behavior. For a full picture, we either must include "solutions" of Liouville's equations in which the Liouville field is multivalued (as well as being complex-valued), or else we can reformulate Liouville theory as a Chern-Simons theory in three dimensions, in which the re...

Relative tautomerization energies, dipole moments for the tautomers of 2-pyrrolidinone was studied by quantum-chemical calculations, using the B3LYP level of calculation with the 6-311G(d,p) basis set in the gas phase with full geometry optimization. Entropies, enthalpies and Gibbs free energies for the tautomerization process of 2-pyrrolidinone was obtained using the RHF/6-31G(d) level of computation. The calculations showed that, the Keto form is the most stable form in the gas phase. The entropy effect on the Gibbs free energy change of the tautomerization process 2-pyrrolidinone is found to be very small, and has practically no significance for the tautomeric equilibria of the 2-pyrrolidinone. The enthalpic term is dominant in the determination of the equilibrium constant. The ability to form dimer, trimer and tetramer was investigated concerning the energetical changes; dipole moments using the RHF/6-31Gd level of computation. The thermodynamic parameters at different temperatu...

Calcium–sodium exchange equilibria were studied at 15 and 25 °C in 2 smectite dominant soils belonging to Typic Haplustalf (Bundi Series) and Typic Pellustert (Chambal series) of Chambal Command Area of Rajasthan (India). These soils had preference for Na⁺ over Ca²⁺; however, the soil of Bundi Series at low Na saturation (10%) showed a preference for Ca²⁺ at lower temperature only. Higher specificity for Na⁺ in Chambal Series was related to the presence of zeoloites. The relationship between exchangeable sodium ratio and sodium adsorption ratio was nonlinear, and Chambal Series could maintain relatively lower sodium adsorption ratio even at higher exchangeable sodium ratio. Among different calculated selectivity coefficients, Gapon selectivity coefficient (KG) registered the lowest coefficient of variation. The values of thermodynamic equilibrium constant (K) were greater than unity indicating higher preference for Na⁺, especially in Chambal Series. The Ca↔Na exchange reaction was associated with an increase in the entropy of the system in these soils.

The non-isothermal kinetics of dehydroxylation of Ca(OH)2 have been studied in dynamic helium atmosphere using TG, DTG, DTA and XRD techniques at different heating rates. The apparent activation energy Eα is determined using Friedman and advanced isoconversional methods (Model-Free). The results indicate that dehydroxylation process occurs predominantly by an irreversible major step, preceded by a rapid and reversible one. The Malek's kinetic procedure associated with non-linear regression approach was used to determine the pre-exponential factor (A) and the kinetic model function. The autocatalytic SB (Systak-Berggren) reaction model corresponding to differential function f(α) = α m .(1-α) n is the most probable for the dehydroxylation process of Ca(OH)2. The best fit has led to following kinetic triplet: Ln A = 16.85, E = 132.20 kJ.mol -1 and f(α) = α 0.203 .(1-α) 0.380 . The thermodynamic functions (ΔS*, ΔH*, ΔG*) of the studied

Calcium–sodium exchange equilibria were studied at 15 and 25 °C in 2 smectite dominant soils belonging to Typic Haplustalf (Bundi Series) and Typic Pellustert (Chambal series) of Chambal Command Area of Rajasthan (India). These soils had preference for Na + over Ca 2+ ; however, the soil of Bundi Series at low Na saturation (10%) showed a preference for Ca 2+ at lower temperature only. Higher specificity for Na + in Chambal Series was related to the presence of zeoloites. The relationship between exchangeable sodium ratio and sodium adsorption ratio was nonlinear, and Chambal Series could maintain relatively lower sodium adsorption ratio even at higher exchangeable sodium ratio. Among different calculated selectivity coefficients, Gapon selectivity coefficient (K G) registered the lowest coefficient of variation. The values of thermodynamic equilibrium constant (K) were greater than unity indicating higher preference for Na + , especially in Chambal Series. The Ca↔Na exchange reaction was associated with an increase in the entropy of the system in these soils.

Effluent arising from kraft or soda pulping section of a pulp and paper mill is difficult to treat due to the presence of recalcitrant organics such as lignin. In this study, FeCl3 pretreated pulping effluent was subjected to Fenton-like oxidation. Residual dissolved iron from pretreatment step and H2O2 were utilized as catalyst and oxidant, respectively while the initial wastewater pH was 4.0 (unadjusted). The maximum lignin and total organic carbon (TOC) removals of 85% and 48% could be achieved within 2 h of reaction. The oxidation reaction was mediated by hydroxyl radicals (HO) which were detected by electron spin resonance (ESR) spectroscopy. Moreover, the addition of tertiary butyl alcohol and chloroform (both radical scavengers) as well hydroxyl amine (a ferrous ion recycler) affected TOC removal significantly. The TOC degradation data could adequately be fit in a lumped kinetic model (LKM) and the activation energy was calculated as 50.85 kJ/mol. The nature of chemical compounds in treated wastewater was also predicted using Fourier transforms infrared (FTIR) spectroscopy.