Reduction of methylene blue by sulfide ion in the presence and absence of oxygen: simulation of the methylene blue-O2-HS- CSTR oscillations

Abstract

A mechanism is proposed that reproduces in simulations the oscillations seen during the methylene-blue-catalyzed reduction of 02 by HS" in a continuous-flow stirred tank reactor (CSTR). It contains 14 reactions and is based on experiments and simulations of simpler reactions, including the reduction of MB+ by HS" in the presence and absence of 02 and the reactions of H202 and 02 with HS". All experiments on component reactions as well as the CSTR oscillations can be simulated by the same set of reactions and rate constants. The major dynamic feature of the mechanism is competition for MB' by the oxidizing agents 02 and H202 and the reducing agents HS" and HS*.

Study of hydrogen generation and radionuclide release during wet damaged oxide spent fuel storage

“…It has previously been reported in the literature that H2S reacts with H2O2 (reactions 3.2 and 3.3) as well as other radiolytic oxidants. As can be seen, H2O2 reacted rapidly with sulfide, which is in line with the reported rate constant 0.5 M -1 s -1 [94][95][96]. The stoichiometry for the reaction between H2O2 and sulfide was found to be 3:1, which is in agreement with the reported ratio [96].…”

Analysis of methylene blue in human urine by capillary electrophoresis

“…Although we were able to separate LMB from MB in an artificial test mixture we could not determine both analytes in a single run from urine samples probably due to the fast oxidation of LMB to MB [7][8][9] and lacking LMB standard substance. In this context, we observed that colourless acidic solutions of LMB turned blue upon the addition to surplus urine after a few minutes which is in agreement with earlier findings [8,9].…”

“…LMB is not available as a standard substance and has only been obtained by diluting MB-solutions with reducing agents [4,7,9,10].…”

Kinetics and mechanism of autocatalyzed reaction between Phenyl Hydrazine and Toluidine blue in aqueous solution

“…Present experimental results suggest that in the rate-limiting step, toluidine blue reac- tion with phenyl hydrazine involves a two-electron reduction step. A one-electron reduction of toluidine blue would have resulted in fractional-order with respect to [6,10,11]. Based on the kinetic results ϩ TB and the reaction products, the following mechanistic steps may be proposed for the reaction sequence.…”