Browsing by Author "Rajeshwar Singh"

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A study on non-faradaic yields of anodic contact glow discharge electrolysis using cerous ion as the OH• scavenger: An estimate of the primary yield of OH• radicals
(1998) Susanta K. Sengupta; Rajeshwar Singh; Ashok K. Srivastava
Chemical yields of contact glow discharge electrolysis (CODE) show strong deviations from faradaic behaviour. The products are novel for normal electrolysis and yields significantly exceed the Faraday law value. Anodic CODE gives rise to Ce4+ and H2O2 in the anolyte in yields significantly exceeding the faradaic value besides the faradaic yield of O2. The relative yield of Ce4+ and H2O2 depends on the concentration of Ce3+ and the quantity of electricity passed. A kinetic analysis of the variation of the initial differential yield of Ce4+, G0 (Ce4+) with the concentration of Ce3+ after applying certain approximations leads to an estimate of the generation of 12 moles of OH• radicals in the liquid phase reaction zone of anodic CGDE for the passage of each mol electron of electricity.
A study on the origin of nonfaradaic behavior of anodic contact glow discharge electrolysis: The relationship between power dissipated in glow discharges and nonfaradaic yields
(Electrochemical Society Inc., 1998) Susanta K. Sengupta; Rajeshwar Singh; Ashok K. Srivastava
Chemical effects of contact glow discharge electrolysis (CGDE) at an electrode where a plasma is sustained by dc glow discharges between the electrode and the surrounding electrolyte, are remarkably nonfaradaic. A critical analysis of the chemical results of anodic CGDE at varying voltages, currents, power supplies, and pHs clearly shows that nonfaradaic yields originate in two separate reaction zones: the plasma around the anode and the liquid anolyte near the plasma-anolyte interface. The yields from the former zone appear from 250 V onward (the beginning of the onset of partial glow discharge) and vary linearly with the power dissipated in the glow discharge. The yields from the latter zone appear from 410 V onward (the beginning of the full glow discharge) and are independent of the power dissipated in the glow discharge. The relative contribution of the two zones to the total nonfaradaic yields is dependent on the voltage applied: the plasma zone having a share of 100% up to 400 V, followed by 20% up to 450 V, and thereafter rising steadily to 57% at 500 V.
Contact glow discharge electrolysis: A study on its origin in the light of the theory of hydrodynamic instabilities in local solvent vaporisation by Joule heating during electrolysis
(Elsevier, 1997) Susanta K. Sengupta; Ashok K. Srivastava; Rajeshwar Singh
Normal electrolysis at high voltages switches over spontaneously to contact glow discharge electrolysis. The transition is profoundly facilitated by raising the temperature and/or lowering the surface tension of the electrolyte. Results of a systematic study on the influence of these two factors on the breakdown voltage for normal electrolysis have been critically analysed. It has been concluded that solvent vaporisation near an electrode by Joule heating during electrolysis and the onset of hydrodynamic instabilities in local solvent vaporisation are the prime causes for the breakdown of normal electrolysis. © 1997 Elsevier Science S.A.
Effects of alkaline ferrocyanide on non-faradaic yields of anodic contact glow discharge electrolysis: Determination of the primary yield of OH . radicals
(2012) Rajeshwar Singh; Urvashi Gangal; Susanta K. Sen Gupta
Non faradaic yields of anodic contact glow discharge electrolysis (CGDE) originate through H . and OH . radical generated during the process. Scavenging effects of Fe(CN) 4-6 on OH . radicals, in alkaline media have been investigated. A kinetic analysis of the competing reactions of O - with different species in the system leads to an yield of 9.8 mol mol electron -1 of OH . and H . radicals each in the liquid phase reaction zone of anodic CGDE in good agreement with the yield reported from a study involving H . radical scavengers. © Springer Science+Business Media, LLC 2011.
Origin of contact glow discharge electrolysis in aqueous solution : Effects of electrolyte temperature and surface tension
(1997) Susanta K. Sen Gupta; Ashok K. Srivastava; Rajeshwar Singh
The effects of electrolyte temperature and surface tension on the breakdown of normal electrolysis and its transition to contact glow discharge electrolysis (CGDE) in aqueous solutions have been studied. It is found that local vaporisation of the solvent close to an electrode by Joule heating and the breaking up of vapour- liquid boundary surfaces in the contiguous streams of vapour bubbles are the prime causes for gaseous,sheathing of the electrode and the breakdown of normal electrolysis vis-a-vis its transition to CGDE.