Author
S. B. Roy
Bio: S. B. Roy is an academic researcher from Bhabha Atomic Research Centre. The author has contributed to research in topics: Nitric acid & Uranium. The author has an hindex of 11, co-authored 41 publications receiving 408 citations.
Topics: Nitric acid, Uranium, Phosphoric acid, Extraction (chemistry), Raffinate
Papers
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TL;DR: In this article, experiments have been performed for leaching (recovery) of uranium from MgF 2 (byproduct from the uranium ore recovery process) under various conditions of leach acid concentration with and without the presence of ultrasound, under different energy dissipation rates (different rotational speeds of conventional stirring by impeller), and on different Mg F 2 particle size distributions.
Abstract: In the present work, experiments have been performed for leaching (recovery) of uranium from MgF 2 (byproduct from the uranium ore recovery process) under various conditions of leach acid concentration with and without the presence of ultrasound, under different energy dissipation rates (different rotational speeds of conventional stirring by impeller), and on different MgF 2 particle size distributions. The enhancement of the leaching rate due to ultrasound is found to occur in two steps: (1) MgF 2 particle fragmentation leading to high specific solid-liquid interfacial area and by increase in the surface diffusional rate of the reactive species; (2) enhancement in the convective diffusivity of the leach acid solvent through micropores of the MgF 2 agglomerate structure due to convective motion created by the cavitation phenomena (shock wave propagation, microjet formation) at the solid-liquid interface. Thus, the overall recovery has been increased by the application of ultrasound with several additional advantages such as low leach acid concentration and decrease in the leaching operation time. The energy dissipation rate with the use of ultrasound was very high, yet, at an equivalent energy dissipation rate in the form of conventional stirring, leaching rates or the final extent of the leaching could not be matched. This indicated that the scale (time and spatial) of energy dissipation has important effect on the overall leaching rate. Kinetics shows that the leaching operation can be explained as a classical shrinking core kinetics phenomenon with pore diffusion resistance as the rate-limiting step.
56 citations
TL;DR: In this article, a fundamental study on the mechanism of uranium leaching in nitric acid and sulphuric acid media has been carried out to understand the effect of the ultrasound on leaching.
Abstract: A fundamental study on the mechanism of uranium leaching in nitric acid and sulphuric acid media has been carried out to understand the effect of the ultrasound on leaching. The use of ultrasound clearly improves the leaching rate within the studied leach acid media. The enhancement in the leaching rate in the presence of ultrasound is higher with low leach acid concentration of nitric acid (HNO3), and it is high at high leach acid concentration in the case of sulphuric acid (H2SO4) being used as a leachant, when compared to conventional mechanical agitation. The basic reason behind this observed variation is explained on the basis of the reaction mechanism involving the oxidative conversion of acid insoluble tetravalent uranium form to the soluble hexavalent form of uranium in the presence of ultrasound at a faster rate.
43 citations
TL;DR: Nitrate removal kinetics indicated that denitrification with SCOD as a carbon source gives higher specificDenitrification rate (by approximately 200%) as compared to conventional carbon source (sodium acetate).
36 citations
TL;DR: In this article, a carrier facilitated transport of U(VI) from nitric acid medium across supported liquid membrane (SLM) has been studied under varying experimental conditions, namely feed, carrier, receiver phase compositions, pore size and membrane thickness etc.
34 citations
TL;DR: A quaternary ammonium based room temperature ionic liquid (IL) trioctylmethylammonium hydrogen phthalate has been reported as promising extractant for separation of U(VI) from other metal ions from aqueous media as discussed by the authors.
Abstract: In this paper a quaternary ammonium based room temperature ionic liquid (IL) trioctylmethylammonium hydrogen phthalate has been reported as promising extractant for separation of U(VI) from other metal ions from aqueous media. The IL was synthesized via metathesis route and characterized using various techniques such as hydrogen nuclear magnetic resonance, electron spray ionization mass spectrometry and infra red etc. The newly synthesized IL was evaluated for extraction of U(VI), Th(IV), La(III), Y(III), Nd(III) and Fe(III) from aqueous solutions and follow the order: U(VI) > Th(IV) > Fe(III) > Y(III) >> Nd(III) ~ La(III).
27 citations
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TL;DR: In this paper, the application of ultrasonic-assisted technology to the leaching of cobalt and lithium from the cathode active materials of spent LIBs was reported, and three acids were tested for the leach process: two inorganic acids (H2SO4 and HCl) and one organic acid (C6H8O7·H2O).
218 citations
TL;DR: An overview of various technologies of biological nitrogen removal including nitrification, denitrification, anaerobic ammonium oxidation (anammox), as well as bioelectrochemical systems and microalgal growth for nitrogen recovery are presented.
154 citations
TL;DR: The PD-Anammox process offers an economically and technically attractive approach in the high NO3--N wastewater treatment since it has great advantages of much low carbon demand, minimal sludge production, enabling simultaneous treatment of municipal sewage, and avoiding the common issues in traditional denitrification process.
138 citations
TL;DR: It was proved that ultrasound significantly enhanced SMX ozonation by assisting ozone in producing more hydroxyl radicals in UOOP by assisting the cleavage of S-N bond.
131 citations