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Differential Pulse Voltammetric Determination of Paracetamol Using Activated Glassy Carbon Electrode
Meselu Eskezia Ayalew,
Dereje Yenealem Ayitegeb
Issue:
Volume 10, Issue 2, June 2021
Pages:
16-24
Received:
5 April 2021
Accepted:
11 May 2021
Published:
20 May 2021
Abstract: The electrochemical property of paracetamol was investigated at a glassy carbon electrode and activated glassy carbon electrode. Differential pulse voltammetry and cyclic voltammetry were used as diagnostic techniques in the determination of paracetamol. The activated glassy carbon electrode exhibited excellent electro-catalytic behaviour for the oxidation of PAR as evidenced by the enhancement of the oxidation peak current and the shift in the oxidation peak potential to less positive values by (13mv) in comparison with a bare GCE. In the present work the activated glassy carbon electrode was prepared by activating 200 s in a time base technique at a potential of 1750 mV. The electrode process of paracetamol was studied and some the experimental parameters which affect the response paracetamol, such as pH, effect of PAR concentration and scan rate on AGC electrode. The analysis of cyclic voltammogram gave fundamental electrochemical parameters including the electroactive surface coverage, the electron transfer coefficient and the heterogeneous rate constant (ks). The variation of scan rate study shows that the system undergoes adsorption controlled process. The equation of the calibration curve was found to be: Ip=0.429C + 6.43, R2=0.993. The LOD and LOQ for the developed method were determined to be 8×10-8 mol L-1 and 2.6×10-7mol L-1 respectively. Phosphate buffer pH 7.0 was selected for analytical purpose.
Abstract: The electrochemical property of paracetamol was investigated at a glassy carbon electrode and activated glassy carbon electrode. Differential pulse voltammetry and cyclic voltammetry were used as diagnostic techniques in the determination of paracetamol. The activated glassy carbon electrode exhibited excellent electro-catalytic behaviour for the o...
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Production Entropy and Negentropy
Issue:
Volume 10, Issue 2, June 2021
Pages:
25-30
Received:
29 April 2021
Accepted:
17 May 2021
Published:
27 May 2021
Abstract: Chemical reactions in an open system are accompanied by direct and reverse transformations of components. In this case, irreversible processes are characterized by production of entropy of both direct and reverse transformations. Negentropy is production of the entropy of the reverse transformation. According to the second law of thermodynamics, production of entropy is a positive value. The difference between production of entropy of direct and reverse transformations (negentropy) is called the useful production of entropy. Negentropy is a barrier to the growth of the useful production of entropy of the system, which not all reactions can overcome. The relationship between the useful production of entropy and negentropy determines the path of evolution of the system at the bifurcation point. Based on the "The Gibbs function normalized to the total number of electrons" and on the example of triangulation of the CaO-SiO2-H2O system, entropy production, negentropy, entropy flux, total entropy change, affinity, thermodynamic force, transformation temperature, rate constant at the interaction of Ca(OH)2 and Ca3Si2O6(OH)2.2H2O are calculated. In chemical reactions, production of entropy and negentropy exist in parallel.
Abstract: Chemical reactions in an open system are accompanied by direct and reverse transformations of components. In this case, irreversible processes are characterized by production of entropy of both direct and reverse transformations. Negentropy is production of the entropy of the reverse transformation. According to the second law of thermodynamics, pr...
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Characterization of Ethyl Violet Adsorption on Used Black Tea Leaves from Aquatic Environment: Kinetic, Isotherm and Thermodynamic Studies
Rasel Ahmed,
Santa Islam,
Mohammad Abul Hossain
Issue:
Volume 10, Issue 2, June 2021
Pages:
31-40
Received:
28 May 2021
Accepted:
15 June 2021
Published:
23 June 2021
Abstract: Ethyl violet (EV) is one of the common pollutants in industrial wastewaters. This study presents the kinetic, isotherm and thermodynamic characterization of the adsorptive removal of EV from aqueous solution by used black tea leaves (UBTL) as a low cost adsorbent. Batch adsorption experiments were performed to investigate the effects of initial dye concentration, solution pH and temperature on the adsorption kinetics. Experimental data were evaluated by inspecting the liner fitness of different kinetic model equations such as pseudo-first order, pseudo-second order, Elovich and Intra-particle diffusion models. The equilibrium amounts adsorbed at different equilibrium concentrations were determined from well fitted pseudo-second order kinetic plot to construct the adsorption isotherm. The maximum adsorption capacity, qm=91.82 mg/g was determined from the well fitted Langmuir plot compared with Freundlich and Temkin plots. Thermodynamic parameters such as free energy change (∆Gads), enthalpy change (∆Hads) and entropy change (∆Sads) of adsorption were determined from adsorption equilibrium constants at different temperatures. The values of thermodynamic parameters revealed that the adsorption of EV on UBTL was feasible, spontaneous and endothermic in nature leading to chemisorption. Again, the equilibrium amount adsorbed, calculated from pseudo-second order kinetic plots for different initial pH of solution was found to be minimum at neutral medium compared with acidic and basic media due to the amphoteric nature of Ethyl violet in aqueous solution and zero point charge of pH of UBTL.
Abstract: Ethyl violet (EV) is one of the common pollutants in industrial wastewaters. This study presents the kinetic, isotherm and thermodynamic characterization of the adsorptive removal of EV from aqueous solution by used black tea leaves (UBTL) as a low cost adsorbent. Batch adsorption experiments were performed to investigate the effects of initial dye...
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