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Kinetic study of graphene oxide synthesis by electrochemical exfoliation of graphite
Pratiksha M. Biranje,Ashwin W. Patwardhan,Jyeshtharaj B. Joshi,Jyoti Prakash,Kinshuk Dasgupta 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.119 No.-
A kinetic study of graphene oxide (GO) synthesis using electrochemical exfoliation of graphite in theacidic and alkaline electrolyte has been carried out. The effects of temperature (301–333 K), sulfuric acidconcentration (0.3–0.6 M), pH (0.3–11.2), current density (12–40 mA/cm2), and graphite density (1.72–1.92 g/cc) on the rate of GO formation have been examined. The GO exfoliation rate was found to be unaffectedby graphite density; therefore, all the kinetic was studied with the graphite density of 1.82 g/cc. The GO exfoliation rate increased with a sulfuric acid concentration in the electrolyte. The temperaturewas seen to enhance the rate of GO synthesis. The activation energy of GO exfoliation was found to be33.53 kJ/mol in a temperature range of 301–333 K. Based on the findings the mechanism was proposedand the rate law was deduced.. The surface reaction of anions during intercalation and de-intercalation inthe interstices of graphite has been found to be the rate-controlling step. Synthesized GO was characterizedwith transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), and Xrayphotoelectron spectroscopy (XPS). The kinetic model has been developed to fit the GO exfoliation ratewithin a pH range of 0.3–1.1.
Subhankar Manna,Raj Kumar,Santosh K. Satpati,Saswati B. Roy,Jyeshtharaj B. Joshi 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.3
Uranium metal used for fabrication of fuel for research reactors in India is generally produced by magnesio-thermic reduction of UF4. Performance of magnesio-thermic reaction and recovery and quality of uranium largely depends on properties of UF4. As ammonium diuranate (ADU) is first product in powder form in the process flow-sheet, properties of UF4 depend on properties of ADU. ADU is generally produced from uranyl nitrate solution (UNS) for natural uranium metal production and from uranyl fluoride solution (UFS) for low enriched uranium metal production. In present paper, ADU has been produced via both the routes. Variation of uranium recovery and crystal structure and composition of ADU with progress in precipitation reaction has been studied with special attention on first appearance of the precipitate Further, ADU produced by two routes have been calcined to UO3, then reduced to UO2 and hydroflorinated to UF4. Effect of two different process routes of ADU precipitation on the characteristics of ADU, UO3, UO2 and UF4 were studied here.