Environmental Nanotechnology, Monitoring & Management, 2021
Abstract Banana peel was used as the feedstock for the preparation of a magnetic adsorbent for th... more Abstract Banana peel was used as the feedstock for the preparation of a magnetic adsorbent for the adsorption of methylene blue (MB) in aqueous solutions. The Fe-modified banana peel was characterized by surface and spectrometric methods. The Box-Behnken design (BBD) was used for determining the conditions of each experimental run and optimization of adsorption was achieved through response surface methodology. The R2, adjusted R2, and predicted R2 coefficients of the employed BBD model were determined as 0.9820, 0.9686, and 0.9182, respectively, indicating a high level of agreement between the experimental data and the proposed theoretical model. The optimum MB adsorption of 91.89% was achieved at an adsorption time of 50 min, temperature of 45 °C, adsorbent dosage of 2.5 g and MB concentration of 5 mg L−1. Equilibrium was achieved in 48 min. The most influential process parameter was the adsorbent dosage, whereas the impact of time, MB concentration and temperature was considerably smaller. The Langmuir Qmax value of 28.1 mg g−1 compared favorably to respective values from other published adsorbents.
Abstract The objective of this study was the development of a novel, biochar-based Pd nanocatalys... more Abstract The objective of this study was the development of a novel, biochar-based Pd nanocatalyst and its evaluation for the promotion of the Suzuki-Miyaura coupling reaction. The Fe3O4-Pd-biochar composite was successfully characterized through a range of spectroscopic and elemental analysis techniques. Its catalytic activity was initially assessed using p-NO2C6H4I as a model reactant and later for the production of biaryls from a wide range of aryl halides, under microwave irradiation and solvent-free conditions. The optimum yield of 99% was obtained at a catalyst dosage of 8 mg, microwave irradiation of 400 W, 6 min residence time, using K2CO3 as the base. Furthermore, the catalyst promoted the Suzuki-Miyaura reaction of aryl iodides and bromides (yields in the range of 88-97 and 86-97%, respectively), but was less successful for aryl chlorides (yields 78-83%). The presence of Fe3O4 allowed for the quick recovery of the catalyst, whereas repeated runs established its recyclability.
Solutions of Acid Red 1 and Acid Red 114 were treated in H 2 O 2-modified subcritical water in th... more Solutions of Acid Red 1 and Acid Red 114 were treated in H 2 O 2-modified subcritical water in the temperature range of 100°C–200°C for up to 60 min. Response surface methodology based on the Box-Behnken design was used to optimize the process. For Acid Red 1, optimum decolorization of 97% can be achieved at 192°C, 181 mM H 2 O 2 , 51.3 min treatment time, and 121 mg/L dye concentration. For Acid Red 114, the optimum conditions were 195°C, 157 mM H 2 O 2 , 38 min treatment time and 110 mg/L dye concentration, where 91% decolorization could be obtained from the proposed model. It was determined that temperature is the most important factor, followed by the oxidant concentration. Degradation was less efficient for AR114 due to the double azo bonds, compared to the single azo bond of AR1. Application of the optimum treatment conditions on real reactive dye wastewater resulted in 92.7, 79.1 and 20.4% removal of BOD 5 , COD and TSS, respectively.
A sustainable biochar material for the synthesis of a novel heterogeneous catalyst for organic re... more A sustainable biochar material for the synthesis of a novel heterogeneous catalyst for organic reactions is reported.
The equilibrium solubility of benzoic acid in water and ethanol, as well as in nine {ethanol (1) ... more The equilibrium solubility of benzoic acid in water and ethanol, as well as in nine {ethanol (1) + water (2)} mixtures, was determined from T = (293.15 to 323.15) K. Benzoic acid mole fraction solubility in these aqueous-ethanolic mixtures was adequately correlated with some well-known correlation/prediction models, obtaining mean percentage deviations of 2.2 to 7.6%. Apparent thermodynamic quantities, namely, Gibbs energy, enthalpy, and entropy, for the dissolution, mixing and solvation processes, were computed by means of the van ’t Hoff and Gibbs equations. The enthalpy–entropy compensation plot of apparent enthalpy vs. apparent Gibbs energy of dissolution was not linear, indicating enthalpy and entropy mechanisms for transfer. Ultimately, by using the inverse Kirkwood–Buff integrals, it is observed that benzoic acid is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in those {ethanol (1) + water (2)} mixtures of ...
The degradation of emerging contaminant coumarin was separately investigated in anodic, electro-F... more The degradation of emerging contaminant coumarin was separately investigated in anodic, electro-Fenton and subcritical water oxidation processes. With respect to the anodic and electro-Fenton oxidation, the influence of constant current, treatment time and initial concentration of coumarin was studied. Regarding subcritical water oxidation, the effect of the oxidant concentration, temperature, treatment time and initial coumarin concentration was investigated. In anodic and electro-Fenton oxidation processes, coumarin degradation proceeded in a similar manner, achieving 99% degradation, after 180 min at a constant current of 200 mA. In both set-ups, further increasing the applied current lowered the degradation efficiency due to the formation of by-products and the increasing occurrence of side-reactions. The highest degradation of 88% was achieved in subcritical conditions, specifically at 200 °C, using 150 mM H2O2 and after 37.5 min of treatment. Under subcritical conditions, temperature was the most prominent parameter, followed by the H2O2 concentration. Under all methodologies, increasing treatment time had a small positive effect on coumarin degradation, indicating that time is not the most influential parameter. A comparison of the three methodologies in terms of performance as well as energy consumption and simplicity of operation highlighted the advantages of subcritical water oxidation.
The adsorption of 5-Fluorouracil (5-FLU), one of the most prescribed active substances in chemoth... more The adsorption of 5-Fluorouracil (5-FLU), one of the most prescribed active substances in chemotherapy and commonly found in wastewater treatment plant area, was achieved in ultrasonic medium on biochar produced from paper sludge and wheat husks. Biochar used as adsorbent was characterized by SEM, EDX, BET, FT-IR and XRF analyses. By using response surface modeling and Box-Behnken design, the optimum conditions and effects of 5-FLU concentration, adsorption time and adsorbent dosage parameters were investigated. The adsorbent was stated the most influential factor whereas the optimum adsorption conditions were predicted as: concentration = 5.48 mg/L, adsorbent dosage = 1.61g, adsorption time = 39.61 min, and was determined that adsorption would occur at a rate of 95.99% at these conditions. The Langmuir isotherm model provided a better fit (R2=0.999) for the experimental data and that maximum adsorption capacity (qmax) was found 5.75 mg/g as indicated by the Langmuir isotherm. Kinetic...
Green chemistry’, ‘benign chemistry’, ‘clean chemistry’, etc., are all terms used to describe app... more Green chemistry’, ‘benign chemistry’, ‘clean chemistry’, etc., are all terms used to describe approaches that consumption of reagents and energy, minimize the use of feedstock, as well as generation of wastes in the chemical industry. There are several approaches to achieve this goal such as using environmentally benign solvents and reagents, reducing the chromatographic separation times. High-temperature liquid chromatography (HTLC) is one of these techniques. This technique deals with liquid chromatography separations performed at temperatures typically within a range from 40â¦C to 200â¦C using organic solvent-water mixtures as the mobile phase. Working at high temperature is a promising approach to increase the analysis speed. Increasing the temperature leads to an increase in the mobile phase linear velocity. At the maximum operating pressure, the main benefit of an increase in the temperature is a reduction in the analysis time. In addition to decreasing the analysis time, r...
Abstract Fluconazole is a novel triazole antifungistatic drug, which can be administered both ora... more Abstract Fluconazole is a novel triazole antifungistatic drug, which can be administered both orally and intravenously and is currently used for the treatment of systemic and superficial fungal infections. In this study, the solubility of fluconazole in water at elevated temperature and pressure was investigated at temperatures in the range of 298 to 473 K under autogenous- 5.0 MPa pressure. The results showed that the solubility of fluconazole was increased 146-fold at the highest experimental temperature of 473 K. Based on the experimental data, a mathematical model was developed to predict the solubility of fluconazole in subcritical water. The model was validated successfully and the theoretical solubility values matched well with the experimental data. Furthermore, a modified Apelblat equation provided a good fit to the experimental values except at low temperature. The molar enthalpy and the molar entropy of dissolution of fluconazole in subcritical water at temperatures ranging from 298 to 473 K were calculated. The good solubility of fluconazole in subcritical water allowed us to perform high temperature liquid chromatography (HTLC) for the determination of this agent. Moreover, thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis confirmed that fluconazole had excellent thermal stability under subcritical conditions.
Ibuprofen (IBP) is an emerging environmental contaminant having low aqueous solubility which nega... more Ibuprofen (IBP) is an emerging environmental contaminant having low aqueous solubility which negatively affects the application of advanced oxidation and adsorption processes. It was determined that as the temperature increased to 473 K, the mole fraction solubility increased considerably from 0.02 × 10-3 to 212.88 × 10-3 (10600-fold). Calculation of the thermodynamic properties indicated an endothermic process, ΔsolH > 0, with relatively high ΔsolS values. Spectroscopic, thermal and chromatographic analyses established the IBP stability at subcritical conditions. In the second part of the study, the degradation of IBP in H2O2-modified subcritical was studied and the effect of each process variable was investigated. The optimum degradation of 88% was reached at an IBP concentration of 15 mg L-1, temperature of 250 °C, 105 min treatment time and 250 mM H2O2. The process was optimized by response surface methodology and a mathematical model was proposed and validated. Temperature was determined as the most influential parameter, followed by H2O2 concentration. At temperatures higher than 230 °C, a small but noticeable reduction in degradation % suggested that the OH· radicals are consumed at a higher rate than they are produced, through side reactions with other radicals and/or IBP by-products. Finally, potential by-products were determined by gas chromatographic-mass spectrometric analysis and potential by-products were proposed.
Abstract Equilibrium mole fraction solubility of coumarin in nine aqueous-ethanolic mixtures, as ... more Abstract Equilibrium mole fraction solubility of coumarin in nine aqueous-ethanolic mixtures, as well as in neat water and neat ethanol, was determined at seven temperatures from (293.15 to 323.15) K. Coumarin solubility in was adequately correlated with several well-known correlation models with the mean percentage deviations of 5.1–10.8%. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) for the dissolution, mixing and solvation processes were computed using the van’t Hoff and Gibbs equations. The enthalpy-entropy relationship for coumarin was non-linear in the plot of enthalpy vs. Gibbs energy of dissolution with negative slope from neat water to the mixture of w1 = 0.10 but positive from this mixture to neat ethanol. Accordingly, in the first case the coumarin transfer from neat water to the mixture of w1 = 0.10 is entropy-driven, which could be attributed to water molecules release originally bounded as “icebergs” around the non-polar groups of this drug. Otherwise, in mixtures of w1 ≥ 0.10 the driving mechanism for the transfer of coumarin from the more polar solvent systems to those less polar is the enthalpy, probably owing the better drug solvation. Moreover, by means of the inverse Kirkwood-Buff integrals is observed that apparently coumarin is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in mixtures of 0.23
ABSTRACT In this research, the equilibrium mole fraction solubility of 4-nitroaniline (4-NA) in s... more ABSTRACT In this research, the equilibrium mole fraction solubility of 4-nitroaniline (4-NA) in some aqueous-ethanolic mixtures was determined at seven temperatures from (293.15 to 323.15) K. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) of the dissolution processes were computed using the van’t Hoff and Gibbs equations. The enthalpy-entropy relationship for 4-NA was non-linear in the plot of enthalpy vs. Gibbs energy of solution with negative slopes from neat water to the mixture w 1 = 0.10 and from w 1 = 0.20 to neat ethanol but positive slope from w 1 = 0.10 to w 1 = 0.20. Therefore, the driving mechanism for 4-NA transfer processes is the entropy in water-rich mixtures. Additionally, by means of the inverse Kirkwood-Buff integrals is observed that 4-NA is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in the mixtures of 0.23 ≤ x 1 ≤ 1.00.
Journal of Industrial and Engineering Chemistry, 2021
Abstract Herein, Pumice (PM)-TiO2-Pd nanocomposite as an efficient catalyst was prepared by modif... more Abstract Herein, Pumice (PM)-TiO2-Pd nanocomposite as an efficient catalyst was prepared by modified sol-gel method and used for sonophotocatalytic removal of ciprofloxacin (CIP). Various analyses were used to investigate the properties of the catalysts. Based on the SEM results, the TiO2 and Pd nanoparticles on the PM surface were immobilized regularly without aggregation. Also, the crystalline structure and functional groups of PM-TiO2-Pd nanocomposite were identified successfully by XRD and FTIR analyses. The bandgap energy of 2.52, 3.17, and 3.29 eV were calculated for PM-TiO2-Pd, PM-TiO2, and PM indicating higher sonophotocatalytic activity of PM-TiO2-Pd nanocomposite. 79.44 % of CIP was removed within 120 min of treatment time using in the optimum condition ([PM-TiO2-Pd] = 0.5 g/L, [CIP]0 = 20 mg/L and pH = 6). By adding radical scavengers like EDTA, CrO3, formic acid, and enhancers like K2S2O8 and H2O2 the degradation efficiency was as follows respectively: 37.72, 31.71, 28.29, 88.78, and 72.43%. The reusability and stability of the composite after four consecutive runs was decreased only 9.44%. Also, 8 intermediate byproducts generated under sonophotocatalytic degradation of CIP by PM-TiO2-Pd nanocomposite were identified.
Abstract Equilibrium mole fraction solubility of vanillin in nine aqueous-ethanolic mixtures, as ... more Abstract Equilibrium mole fraction solubility of vanillin in nine aqueous-ethanolic mixtures, as well as in neat water and neat ethanol, was determined at seven temperatures from T = 293.15 to T = 323.15 K. Vanillin solubility in these mixtures was adequately correlated with several well-known correlation models with the mean percentage deviations of 5.9 to 18.3%. Respective apparent thermodynamic functions, i.e. Gibbs energy, enthalpy, and entropy, for the dissolution, mixing and solvation processes, were computed using the van’t Hoff and Gibbs equations. The enthalpy–entropy relationship for vanillin was non-linear in the plot of enthalpy vs. Gibbs energy of dissolution with positive slopes from neat water to the mixture of w1 = 0.10 and the interval 0.50
Environmental Nanotechnology, Monitoring & Management, 2021
Abstract Banana peel was used as the feedstock for the preparation of a magnetic adsorbent for th... more Abstract Banana peel was used as the feedstock for the preparation of a magnetic adsorbent for the adsorption of methylene blue (MB) in aqueous solutions. The Fe-modified banana peel was characterized by surface and spectrometric methods. The Box-Behnken design (BBD) was used for determining the conditions of each experimental run and optimization of adsorption was achieved through response surface methodology. The R2, adjusted R2, and predicted R2 coefficients of the employed BBD model were determined as 0.9820, 0.9686, and 0.9182, respectively, indicating a high level of agreement between the experimental data and the proposed theoretical model. The optimum MB adsorption of 91.89% was achieved at an adsorption time of 50 min, temperature of 45 °C, adsorbent dosage of 2.5 g and MB concentration of 5 mg L−1. Equilibrium was achieved in 48 min. The most influential process parameter was the adsorbent dosage, whereas the impact of time, MB concentration and temperature was considerably smaller. The Langmuir Qmax value of 28.1 mg g−1 compared favorably to respective values from other published adsorbents.
Abstract The objective of this study was the development of a novel, biochar-based Pd nanocatalys... more Abstract The objective of this study was the development of a novel, biochar-based Pd nanocatalyst and its evaluation for the promotion of the Suzuki-Miyaura coupling reaction. The Fe3O4-Pd-biochar composite was successfully characterized through a range of spectroscopic and elemental analysis techniques. Its catalytic activity was initially assessed using p-NO2C6H4I as a model reactant and later for the production of biaryls from a wide range of aryl halides, under microwave irradiation and solvent-free conditions. The optimum yield of 99% was obtained at a catalyst dosage of 8 mg, microwave irradiation of 400 W, 6 min residence time, using K2CO3 as the base. Furthermore, the catalyst promoted the Suzuki-Miyaura reaction of aryl iodides and bromides (yields in the range of 88-97 and 86-97%, respectively), but was less successful for aryl chlorides (yields 78-83%). The presence of Fe3O4 allowed for the quick recovery of the catalyst, whereas repeated runs established its recyclability.
Solutions of Acid Red 1 and Acid Red 114 were treated in H 2 O 2-modified subcritical water in th... more Solutions of Acid Red 1 and Acid Red 114 were treated in H 2 O 2-modified subcritical water in the temperature range of 100°C–200°C for up to 60 min. Response surface methodology based on the Box-Behnken design was used to optimize the process. For Acid Red 1, optimum decolorization of 97% can be achieved at 192°C, 181 mM H 2 O 2 , 51.3 min treatment time, and 121 mg/L dye concentration. For Acid Red 114, the optimum conditions were 195°C, 157 mM H 2 O 2 , 38 min treatment time and 110 mg/L dye concentration, where 91% decolorization could be obtained from the proposed model. It was determined that temperature is the most important factor, followed by the oxidant concentration. Degradation was less efficient for AR114 due to the double azo bonds, compared to the single azo bond of AR1. Application of the optimum treatment conditions on real reactive dye wastewater resulted in 92.7, 79.1 and 20.4% removal of BOD 5 , COD and TSS, respectively.
A sustainable biochar material for the synthesis of a novel heterogeneous catalyst for organic re... more A sustainable biochar material for the synthesis of a novel heterogeneous catalyst for organic reactions is reported.
The equilibrium solubility of benzoic acid in water and ethanol, as well as in nine {ethanol (1) ... more The equilibrium solubility of benzoic acid in water and ethanol, as well as in nine {ethanol (1) + water (2)} mixtures, was determined from T = (293.15 to 323.15) K. Benzoic acid mole fraction solubility in these aqueous-ethanolic mixtures was adequately correlated with some well-known correlation/prediction models, obtaining mean percentage deviations of 2.2 to 7.6%. Apparent thermodynamic quantities, namely, Gibbs energy, enthalpy, and entropy, for the dissolution, mixing and solvation processes, were computed by means of the van ’t Hoff and Gibbs equations. The enthalpy–entropy compensation plot of apparent enthalpy vs. apparent Gibbs energy of dissolution was not linear, indicating enthalpy and entropy mechanisms for transfer. Ultimately, by using the inverse Kirkwood–Buff integrals, it is observed that benzoic acid is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in those {ethanol (1) + water (2)} mixtures of ...
The degradation of emerging contaminant coumarin was separately investigated in anodic, electro-F... more The degradation of emerging contaminant coumarin was separately investigated in anodic, electro-Fenton and subcritical water oxidation processes. With respect to the anodic and electro-Fenton oxidation, the influence of constant current, treatment time and initial concentration of coumarin was studied. Regarding subcritical water oxidation, the effect of the oxidant concentration, temperature, treatment time and initial coumarin concentration was investigated. In anodic and electro-Fenton oxidation processes, coumarin degradation proceeded in a similar manner, achieving 99% degradation, after 180 min at a constant current of 200 mA. In both set-ups, further increasing the applied current lowered the degradation efficiency due to the formation of by-products and the increasing occurrence of side-reactions. The highest degradation of 88% was achieved in subcritical conditions, specifically at 200 °C, using 150 mM H2O2 and after 37.5 min of treatment. Under subcritical conditions, temperature was the most prominent parameter, followed by the H2O2 concentration. Under all methodologies, increasing treatment time had a small positive effect on coumarin degradation, indicating that time is not the most influential parameter. A comparison of the three methodologies in terms of performance as well as energy consumption and simplicity of operation highlighted the advantages of subcritical water oxidation.
The adsorption of 5-Fluorouracil (5-FLU), one of the most prescribed active substances in chemoth... more The adsorption of 5-Fluorouracil (5-FLU), one of the most prescribed active substances in chemotherapy and commonly found in wastewater treatment plant area, was achieved in ultrasonic medium on biochar produced from paper sludge and wheat husks. Biochar used as adsorbent was characterized by SEM, EDX, BET, FT-IR and XRF analyses. By using response surface modeling and Box-Behnken design, the optimum conditions and effects of 5-FLU concentration, adsorption time and adsorbent dosage parameters were investigated. The adsorbent was stated the most influential factor whereas the optimum adsorption conditions were predicted as: concentration = 5.48 mg/L, adsorbent dosage = 1.61g, adsorption time = 39.61 min, and was determined that adsorption would occur at a rate of 95.99% at these conditions. The Langmuir isotherm model provided a better fit (R2=0.999) for the experimental data and that maximum adsorption capacity (qmax) was found 5.75 mg/g as indicated by the Langmuir isotherm. Kinetic...
Green chemistry’, ‘benign chemistry’, ‘clean chemistry’, etc., are all terms used to describe app... more Green chemistry’, ‘benign chemistry’, ‘clean chemistry’, etc., are all terms used to describe approaches that consumption of reagents and energy, minimize the use of feedstock, as well as generation of wastes in the chemical industry. There are several approaches to achieve this goal such as using environmentally benign solvents and reagents, reducing the chromatographic separation times. High-temperature liquid chromatography (HTLC) is one of these techniques. This technique deals with liquid chromatography separations performed at temperatures typically within a range from 40â¦C to 200â¦C using organic solvent-water mixtures as the mobile phase. Working at high temperature is a promising approach to increase the analysis speed. Increasing the temperature leads to an increase in the mobile phase linear velocity. At the maximum operating pressure, the main benefit of an increase in the temperature is a reduction in the analysis time. In addition to decreasing the analysis time, r...
Abstract Fluconazole is a novel triazole antifungistatic drug, which can be administered both ora... more Abstract Fluconazole is a novel triazole antifungistatic drug, which can be administered both orally and intravenously and is currently used for the treatment of systemic and superficial fungal infections. In this study, the solubility of fluconazole in water at elevated temperature and pressure was investigated at temperatures in the range of 298 to 473 K under autogenous- 5.0 MPa pressure. The results showed that the solubility of fluconazole was increased 146-fold at the highest experimental temperature of 473 K. Based on the experimental data, a mathematical model was developed to predict the solubility of fluconazole in subcritical water. The model was validated successfully and the theoretical solubility values matched well with the experimental data. Furthermore, a modified Apelblat equation provided a good fit to the experimental values except at low temperature. The molar enthalpy and the molar entropy of dissolution of fluconazole in subcritical water at temperatures ranging from 298 to 473 K were calculated. The good solubility of fluconazole in subcritical water allowed us to perform high temperature liquid chromatography (HTLC) for the determination of this agent. Moreover, thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis confirmed that fluconazole had excellent thermal stability under subcritical conditions.
Ibuprofen (IBP) is an emerging environmental contaminant having low aqueous solubility which nega... more Ibuprofen (IBP) is an emerging environmental contaminant having low aqueous solubility which negatively affects the application of advanced oxidation and adsorption processes. It was determined that as the temperature increased to 473 K, the mole fraction solubility increased considerably from 0.02 × 10-3 to 212.88 × 10-3 (10600-fold). Calculation of the thermodynamic properties indicated an endothermic process, ΔsolH > 0, with relatively high ΔsolS values. Spectroscopic, thermal and chromatographic analyses established the IBP stability at subcritical conditions. In the second part of the study, the degradation of IBP in H2O2-modified subcritical was studied and the effect of each process variable was investigated. The optimum degradation of 88% was reached at an IBP concentration of 15 mg L-1, temperature of 250 °C, 105 min treatment time and 250 mM H2O2. The process was optimized by response surface methodology and a mathematical model was proposed and validated. Temperature was determined as the most influential parameter, followed by H2O2 concentration. At temperatures higher than 230 °C, a small but noticeable reduction in degradation % suggested that the OH· radicals are consumed at a higher rate than they are produced, through side reactions with other radicals and/or IBP by-products. Finally, potential by-products were determined by gas chromatographic-mass spectrometric analysis and potential by-products were proposed.
Abstract Equilibrium mole fraction solubility of coumarin in nine aqueous-ethanolic mixtures, as ... more Abstract Equilibrium mole fraction solubility of coumarin in nine aqueous-ethanolic mixtures, as well as in neat water and neat ethanol, was determined at seven temperatures from (293.15 to 323.15) K. Coumarin solubility in was adequately correlated with several well-known correlation models with the mean percentage deviations of 5.1–10.8%. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) for the dissolution, mixing and solvation processes were computed using the van’t Hoff and Gibbs equations. The enthalpy-entropy relationship for coumarin was non-linear in the plot of enthalpy vs. Gibbs energy of dissolution with negative slope from neat water to the mixture of w1 = 0.10 but positive from this mixture to neat ethanol. Accordingly, in the first case the coumarin transfer from neat water to the mixture of w1 = 0.10 is entropy-driven, which could be attributed to water molecules release originally bounded as “icebergs” around the non-polar groups of this drug. Otherwise, in mixtures of w1 ≥ 0.10 the driving mechanism for the transfer of coumarin from the more polar solvent systems to those less polar is the enthalpy, probably owing the better drug solvation. Moreover, by means of the inverse Kirkwood-Buff integrals is observed that apparently coumarin is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in mixtures of 0.23
ABSTRACT In this research, the equilibrium mole fraction solubility of 4-nitroaniline (4-NA) in s... more ABSTRACT In this research, the equilibrium mole fraction solubility of 4-nitroaniline (4-NA) in some aqueous-ethanolic mixtures was determined at seven temperatures from (293.15 to 323.15) K. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) of the dissolution processes were computed using the van’t Hoff and Gibbs equations. The enthalpy-entropy relationship for 4-NA was non-linear in the plot of enthalpy vs. Gibbs energy of solution with negative slopes from neat water to the mixture w 1 = 0.10 and from w 1 = 0.20 to neat ethanol but positive slope from w 1 = 0.10 to w 1 = 0.20. Therefore, the driving mechanism for 4-NA transfer processes is the entropy in water-rich mixtures. Additionally, by means of the inverse Kirkwood-Buff integrals is observed that 4-NA is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in the mixtures of 0.23 ≤ x 1 ≤ 1.00.
Journal of Industrial and Engineering Chemistry, 2021
Abstract Herein, Pumice (PM)-TiO2-Pd nanocomposite as an efficient catalyst was prepared by modif... more Abstract Herein, Pumice (PM)-TiO2-Pd nanocomposite as an efficient catalyst was prepared by modified sol-gel method and used for sonophotocatalytic removal of ciprofloxacin (CIP). Various analyses were used to investigate the properties of the catalysts. Based on the SEM results, the TiO2 and Pd nanoparticles on the PM surface were immobilized regularly without aggregation. Also, the crystalline structure and functional groups of PM-TiO2-Pd nanocomposite were identified successfully by XRD and FTIR analyses. The bandgap energy of 2.52, 3.17, and 3.29 eV were calculated for PM-TiO2-Pd, PM-TiO2, and PM indicating higher sonophotocatalytic activity of PM-TiO2-Pd nanocomposite. 79.44 % of CIP was removed within 120 min of treatment time using in the optimum condition ([PM-TiO2-Pd] = 0.5 g/L, [CIP]0 = 20 mg/L and pH = 6). By adding radical scavengers like EDTA, CrO3, formic acid, and enhancers like K2S2O8 and H2O2 the degradation efficiency was as follows respectively: 37.72, 31.71, 28.29, 88.78, and 72.43%. The reusability and stability of the composite after four consecutive runs was decreased only 9.44%. Also, 8 intermediate byproducts generated under sonophotocatalytic degradation of CIP by PM-TiO2-Pd nanocomposite were identified.
Abstract Equilibrium mole fraction solubility of vanillin in nine aqueous-ethanolic mixtures, as ... more Abstract Equilibrium mole fraction solubility of vanillin in nine aqueous-ethanolic mixtures, as well as in neat water and neat ethanol, was determined at seven temperatures from T = 293.15 to T = 323.15 K. Vanillin solubility in these mixtures was adequately correlated with several well-known correlation models with the mean percentage deviations of 5.9 to 18.3%. Respective apparent thermodynamic functions, i.e. Gibbs energy, enthalpy, and entropy, for the dissolution, mixing and solvation processes, were computed using the van’t Hoff and Gibbs equations. The enthalpy–entropy relationship for vanillin was non-linear in the plot of enthalpy vs. Gibbs energy of dissolution with positive slopes from neat water to the mixture of w1 = 0.10 and the interval 0.50
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