Associations of ajmaline and homatropine with bromocresol green and bromophenol blue in dichloromethane: thermodynamic and kinetic parameters

1987 ◽  
Vol 65 (6) ◽  
pp. 1279-1291 ◽  
Author(s):  
Alberto Hernández Gaínza
Keyword(s):  
Thermodynamic Parameters ◽  
Arrhenius Equation ◽  
Charge Transfer Complex ◽  
Ion Pairs ◽  
Bromocresol Green ◽  
Bromophenol Blue ◽  
Order Kinetic ◽  
Large Excess ◽  
First Order ◽  
Hoff Equation

Ajmaline (AJ) and homatropine (HM) react with bromocresol green (BCG) and bromophenol blue (BPB) in dichloromethane forming 1:1 and 1:2 ion pairs clearly in a chemical equilibrium. Thermodynamic parameters ΔG0, ΔH0, and ΔS0 are calculated using the Van't Hoff equation. In a large excess of HM a product P is formed from the 1:2 ion pair in a pseudo-first order kinetic process which fits Arrhenius' equation. The P product has been identified as a type of charge transfer complex. The thermodynamic parameters corresponding to the formation of the ion pairs BPB—(AJ)2, BCG—(AJ)2, BPB—(HM)2, and BCG—(HM)2 are, respectively: ΔG0 at 294 K, −26, −21, −26, and −19 kJ/mol; ΔH0, −63, −39, −63, and −61 kJ/mol; ΔS0, −125, −62, −125, and −138 J/K mol (ΔH0 and ΔS0 determined in a 288 to 313 K range). The values of the activation energy, Ea, for the reaction of HM (in large excess) with BCG and BPB are 58 and 91 kJ/mol.

Substitution reactions of benzethonium chloride with ion associates of bromocresol green – quinine and bromophenol blue – quinine in dichloromethane

1991 ◽  
Vol 69 (6) ◽  
pp. 937-944 ◽  
Author(s):  
Alberto Hernandez Gainza ◽  
Roy Ikemefula Konyeaso
Keyword(s):  
Thermodynamic Parameters ◽  
Equilibrium Constants ◽  
Formation Constants ◽  
Bromocresol Green ◽  
Bromophenol Blue ◽  
Substitution Reactions ◽  
Dichloromethane Solution ◽  
Benzethonium Chloride ◽  
Quinine Hydrochloride ◽  
Ion Associate

An excess concentration of base quinine (Q) reacts with a sulphonphthalein diacidic dye XH2, (bromocresol green, BCGH2, or bromophenol blue, BPBH2) in dichloromethane solution to form an ion associate (X2−(QH+)2) of stoichiometry 1:2 (dye:amine). Benzethonium chloride (ClB) reacts with the 1:2 ion associate to form an ion associate (QH+,X2−,B+) and quinine hydrochloride ClQH+. This substitution reaction is a chemical equilibrium with formation constants of 1.50 ± 0.67, 1.61 ± 0.54, 1.07 ± 0.29, 1.04 ± 0.20, and 0.84 ± 0.26 for BCG and 1.86 ± 0.59, 1.47 ± 0.23, 1.40 ± 0.65, 1.13 ± 0.37, and 1.11 ± 0.27 for BPB at 283.16, 288.16, 293.16, 298.16, and 303.16 K respectively. The thermodynamic parameters determined by van't Hoff's equation are ΔH0 = −21.766 ± 7.482 kJ mol−1, ΔS0 = −73 ± 51 J mol−1 K−1, and ΔG0 = −1.134 ± 0.972 kJ mol−1for BCG and ΔH0 = −18.678 ± 7.482 kJ mol−1, ΔS0 = −61 ± 26 J mol−1 K−1, ΔG0 = −0.916 ± 0.401 kJ mol−1 for BPB (ΔG0 at 293.16 K; and ΔH0 and ΔS0 determined in the range 283–303 K). Key words: bromocresol green – quinine–benzethonium, ion associate mixture, bromophenol blue – quinine–benzethonium, equilibrium constants, thermodynamic parameters.

Milestones in microwave-assisted organophosphorus chemistry

2016 ◽  
Vol 88 (10-11) ◽  
pp. 931-939 ◽  
Author(s):  
György Keglevich ◽  
Nóra Zs. Kiss ◽  
Zoltán Mucsi
Keyword(s):  
Arrhenius Equation ◽  
Conventional Heating ◽  
Organic Chemical ◽  
Order Kinetic ◽  
First Order ◽  
Microwave Assisted ◽  
Pseudo First Order ◽  
Catalyst Systems ◽  
Organophosphorus Chemistry ◽  
Order Kinetic Equation

AbstractOur recent results in the field of microwave (MW)-assisted organophosphorus syntheses, especially regarding esterifications, condensations, substitutions and additions are surveyed. Beside making organic chemical reactions more efficient, it was possible to perform transformations that are reluctant on conventional heating. Another option is to substitute catalysts, or to simplify catalyst systems under MW conditions. It is also the purpose of this paper to elucidate the scope and limitations of the MW tool, to interpret the MW effects, and to model the distribution of the local overheatings and their beneficial effect. All these considerations are possible on the basis of the enthalpy of activations determined by us utilizing the Arrhenius equation and the pseudo first order kinetic equation.

scholarly journals Spectrophotometric Determination of Benzalkonium Chloride using Sulfonphthaleins

2021 ◽  
Vol 68 (1) ◽  
Author(s):  
Yousry M. Issa ◽  
Nora S. Abdel-kader ◽  
Ahmed E. Zahran
Keyword(s):  
Benzalkonium Chloride ◽  
Xylenol Orange ◽  
Ion Pairs ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Bromocresol Green ◽  
Bromophenol Blue ◽  
Highly Sensitive ◽  
Relative Standard

A highly sensitive method for the quantitative determination of Benzalkonium chloride (BKC), in its pure form and pharmaceutical formulations, is described. The method involves four spectrophotometric ways for the determination of BKC via forming ionassociates with bromocresol green (BCG), bromophenol blue (BPB), bromothymol blue (BTB), and xylenol orange (XO). The study involves characterization of the ion-pairs formed between the BKC and the above-mentioned reagents Using UV-Visible and IR spectroscopy. In order to optimize the reaction conditions, the effects of pH, the quantity of reagent, time, and extracting solvent were studied. Statistical student’s t-test and F test showed insignificant systematic error between proposed and official methods. The antibacterial disinfectant Zora C Lozenges contains 0.01 mg Benzalkonium chloride, 1 mg Benzocaine, and 50 mg Vitamin C. as the active substance was analyzed at pH 8.5. The strategy was validated for linearity range, precision, accuracy, specificity, and limits of detection (LOD) and quantification (LOQ). Beer's law is obeyed over a wide concentration range (up to 145 ?g/mL in case of BCG method). LOD and LOQ values reached 2.38 and 7.2 ?g/mL, respectively, upon using BCG. The relative standard deviation (%RSD) was ?1.33% while correlation coefficient values (r) were ? 0.998. High molar absorptivity values and low values of Sandell's sensitivity were calculated indicating that the proposed methods are highly sensitive. Applying the validated methods to the analysis of BKC in antibacterial disinfectant Zora C Lozenges revealed that the drug was successfully resolved from the pharmaceutical formulation with recoveries ?95.5%.

Removal of methylene blue by adsorption on aluminosilicate waste: equilibrium, kinetic and thermodynamic parameters

2016 ◽  
Vol 74 (10) ◽  
pp. 2437-2445 ◽  
Author(s):  
Carlos Alberto Policiano Almeida ◽  
Tânia Marina Palhano Zanela ◽  
Clodoaldo Machado ◽  
Juan Antônio Altamirano Flores ◽  
Luiz Fernando Scheibe ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Thermodynamic Parameters ◽  
Low Cost ◽  
Order Kinetic ◽  
X Ray ◽  
Isotherm Equation ◽  
First Order ◽  
Kinetic And Thermodynamic Parameters ◽  
Langmuir Isotherm Equation ◽  
Pseudo First Order

An aluminosilicate waste (AW) was investigated as adsorbent for methylene blue (MB) dye. AW was characterized by petrography, X-ray diffractometry, X-ray fluorescence, scanning electron microscopy, thermogravimetry and zeta potential measurements. It was found that AW contains kaolinite, and other minor components such as quartz, muscovite, smectite, siderite, pyrite and organic compounds. The chemical composition of AW is mainly SiO2 (49%) and Al2O3 (23%) and it has negative superficial charge above pH 1.73. Adsorption of MB dye was studied in a batch system under different conditions of initial dye concentration, contact time and temperature. The isothermal data from batch experiments were fitted to Langmuir and Freundlich equations, with a better fit shown by the Langmuir isotherm equation. Also, pseudo-first-order, pseudo-second-order and intraparticle diffusion models were considered to evaluate the rate parameters. The experimental data fitted the pseudo-first-order kinetic model best. Thermodynamic parameters were calculated, showing the adsorption to be an endothermic yet spontaneous process, with the activation energy of +37.8 kJ mol–1. The results indicate that AW adsorbs MB efficiently, and can be employed as a low-cost alternative in wastewater treatment for the removal of cationic dyes.

Leaching Kinetics of Atrazine and Inorganic Chemicals in Tilled and Orchard Soils

2014 ◽  
Vol 28 (2) ◽  
pp. 231-237 ◽  
Author(s):  
Lech W. Szajdak ◽  
Jerzy Lipiec ◽  
Anna Siczek ◽  
Artur Nosalewicz ◽  
Urszula Majewska
Keyword(s):  
Reaction Rate ◽  
Inorganic Compounds ◽  
Model Performance ◽  
Order Reaction ◽  
First Order Reaction ◽  
Order Kinetic ◽  
Time Data ◽  
First Order ◽  
Concentration Changes ◽  
Reaction Constants

Abstract The aim of this study was to verify first-order kinetic reaction rate model performance in predicting of leaching of atrazine and inorganic compounds (K+1, Fe+3, Mg+2, Mn+2, NH4 +, NO3 - and PO4 -3) from tilled and orchard silty loam soils. This model provided an excellent fit to the experimental concentration changes of the compounds vs. time data during leaching. Calculated values of the first-order reaction rate constants for the changes of all chemicals were from 3.8 to 19.0 times higher in orchard than in tilled soil. Higher first-order reaction constants for orchard than tilled soil correspond with both higher total porosity and contribution of biological pores in the former. The first order reaction constants for the leaching of chemical compounds enables prediction of the actual compound concentration and the interactions between compound and soil as affected by management system. The study demonstrates the effectiveness of simultaneous chemical and physical analyses as a tool for the understanding of leaching in variously managed soils.

Kinetics and mechanism of the reaction between oxidized cytochrome c and ascorbic acid

1991 ◽  
Vol 56 (2) ◽  
pp. 478-490 ◽  
Author(s):  
Joaquin F. Perez-Benito ◽  
Conchita Arias
Keyword(s):  
Ascorbic Acid ◽  
Cytochrome C ◽  
Redox Reactions ◽  
Arrhenius Equation ◽  
Horse Heart Cytochrome ◽  
First Order ◽  
Acidic Form ◽  
Ph Range ◽  
Horse Heart Cytochrome C ◽  
Mechanism Of The Reaction

The reaction between horse-heart cytochrome c and ascorbic acid has been investigated in the pH range 5.5 – 7.1 and at 10.0 – 25.0 °C. The rate shows a first-order dependence on the concentration of cytochrome c, it increases in a non-linear way as the concentration of ascorbic acid increases, it increases markedly with increasing pH and, provided that the ionic strength of the medium is high enough, it fulfills the Arrhenius equation. The apparent activation energy increases as the pH of the solution increases. The results have been explained by means of a mechanism that includes the existence of an equilibrium between two forms (acidic and basic) of oxidized cytochrome c: cyt-H+ -Fe3+ + OH- cyt -Fe3+ + H2O, whose equilibrium constant is (6.7 ± 1.4). 108 at 25.0 °C, the acidic form being more reducible than the basic one. It is suggested that there is a linkage of hydrogenascorbate ion to both forms of cytochrome c previous to the redox reactions. Two possibilities for the oxidant-reductant linkage (binding and adsorption) are discussed in detail.

scholarly journals Adsorption and Photocatalytic Mineralization of Bromophenol Blue Dye with TiO2 Modified with Clinoptilolite/Activated Carbon

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 7
Author(s):  
Emmanuel Kweinor Tetteh ◽  
Sudesh Rathilal
Keyword(s):  
Activated Carbon ◽  
Photocatalytic Degradation ◽  
Oxygen Demand ◽  
Freundlich Isotherm ◽  
Reaction Rate Constant ◽  
Coefficient Of Determination ◽  
Bromophenol Blue ◽  
Blue Dye ◽  
Order Kinetic ◽  
Co Precipitation

This study presents a hybridized photocatalyst with adsorbate as a promising nanocomposite for photoremediation of wastewater. Photocatalytic degradation of bromophenol blue (BPB) in aqueous solution under UV-irradiation of wavelength 400 nm was carried out with TiO2 doped with activated carbon (A) and clinoptilolite (Z) via the co-precipitation technique. The physiochemical properties of the nanocomposite (A–TiO2 and Z–TiO2) and TiO2 were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy. Results of the nanocomposite (A–TiO2 and Z–TiO2) efficiency was compared to that with the TiO2, which demonstrated their adsorption and synergistic effect for the removal of chemical oxygen demand (COD) and color from the wastewater. At an optimal load of 4 g, the photocatalytic degradation activity (Z–TiO2 > A–TiO2 > TiO2) was found favorably by the second-order kinetic model. Consequently, the Langmuir adsorption isotherms favored the nanocomposites (Z–TiO2 > A–TiO2), whereas that of the TiO2 fitted very well on the Freundlich isotherm approach. Z–TiO2 evidently exhibited a high photocatalytic efficacy of decomposition over 80% of BPB (COD) at reaction rate constant (k) and coefficient of determination (R2) values of 5.63 × 10−4 min−1 and 0.989, respectively.

scholarly journals Enhancing methane production from the invasive macroalga Rugulopteryx okamurae through anaerobic co-digestion with olive mill solid waste: process performance and kinetic analysis

2021 ◽  
Author(s):  
D. de la Lama-Calvente ◽  
M. J. Fernández-Rodríguez ◽  
J. Llanos ◽  
J. M. Mancilla-Leytón ◽  
R. Borja
Keyword(s):  
Anaerobic Digestion ◽  
Solid Waste ◽  
Methane Production ◽  
Methane Yield ◽  
Specific Rate ◽  
Order Kinetic ◽  
Two Phase ◽  
First Order ◽  
Olive Mill Solid Waste ◽  
Olive Mill

AbstractThe biomass valorisation of the invasive brown alga Rugulopteryx okamurae (Dictyotales, Phaeophyceae) is key to curbing the expansion of this invasive macroalga which is generating tonnes of biomass on southern Spain beaches. As a feasible alternative for the biomass management, anaerobic co-digestion is proposed in this study. Although the anaerobic digestion of macroalgae barely produced 177 mL of CH4 g−1 VS, the co-digestion with a C-rich substrate, such as the olive mill solid waste (OMSW, the main waste derived from the two-phase olive oil manufacturing process), improved the anaerobic digestion process. The mixture improved not only the methane yield, but also its biodegradability. The highest biodegradability was found in the mixture 1 R. okamurae—1 OMSW, which improved the biodegradability of the macroalgae by 12.9% and 38.1% for the OMSW. The highest methane yield was observed for the mixture 1 R. okamurae—3 OMSW, improving the methane production of macroalgae alone by 157% and the OMSW methane production by 8.6%. Two mathematical models were used to fit the experimental data of methane production time with the aim of assessing the processes and obtaining the kinetic constants of the anaerobic co-digestion of different combination of R. okamurae and OMSW and both substrates independently. First-order kinetic and the transference function models allowed for appropriately fitting the experimental results of methane production with digestion time. The specific rate constant, k (first-order model) for the mixture 1 R. okamurae- 1.5 OMSW, was 5.1 and 1.3 times higher than that obtained for the mono-digestion of single OMSW and the macroalga, respectively. In the same way, the transference function model revealed that the maximum methane production rate (Rmax) was also found for the mixture 1 R. okamurae—1.5 OMSW (30.4 mL CH4 g−1 VS day−1), which was 1.6 and 2.2 times higher than the corresponding to the mono-digestions of the single OMSW and sole R. okamurae (18.9 and 13.6 mL CH4 g−1 VS day−1), respectively.

MODELLING NITROGEN PROCESSES IN SOIL: MATHEMATICAL DEVELOPMENT AND RELATIONSHIPS

1976 ◽  
Vol 56 (2) ◽  
pp. 71-78 ◽  
Author(s):  
D. R. CAMERON ◽  
C. G. KOWALENKO
Keyword(s):  
Time Dependent ◽  
Rate Coefficients ◽  
Nitrification Rate ◽  
Order Kinetic ◽  
Nitrogen Flow ◽  
First Order ◽  
Interaction Term ◽  
Flow Pathways ◽  
Adsorption Desorption ◽  
Temperature Water

A small subsystem model was developed to simulate the major nitrogen flow pathways in an unsaturated soil treated with ammonium sulphate. A nonlinear Freundlich equilibrium model and a Langmuir kinetic model were used to describe mathematically the adsorption–desorption of soluble NH4+ to the exchangeable and clay-fixed phases, respectively. Time dependent, microbial mediated first-order kinetic models were used to quantify the ammonification and nitrification processes. The subsystem model was then used as a research tool to derive ammonification and nitrification rate coefficients for a preceding incubation experiment conducted using different soil moisture contents and temperatures. The model yields reasonably good fits to the observed data. A subsequent regression analysis relating the coefficients to temperature and moisture pointed out the importance of the temperature–water content interaction term in quantifying microbial mediated processes.

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