Bromate ion (BrO 3 − ), an oxyhalide disinfection byproduct (DBP) formed during the ozonation of water containing bromide ion (Br − ), draw a great attention in the last two decades for its carcinogenic potential
Authors:V. M. Abdul Mujeeb, K. Muraleedharan, M. P. Kannan, and T. Ganga Devi
Potassium bromate (KBrO 3 ) is a white crystalline powder, which is colorless, odorless, and tasteless with a molecular mass of 167 g. It is an oxidizing agent and is typically used as a flour improver
The thermal decomposition of -irradiated cadmium bromate was studied by dynamic thermogravimetry. The reaction order, activation energy, frequency factor and entropy of activation were computed using the Coats-Redfern method and were compared with those of the unirradiated salt. Irradiation enhances the decomposition and the effect increases with irradiation dose. The activation energy decreases on irradiation. The mechanism for the decomposition of unirradiated and irradiated cadmium bromate follows the Avrami model equation, 1-/1-/1/3=kt, and the ratecontrolling process is a phase-boundary reaction assuming spherical symmetry.
Authors:M. Krishnaratnam, K. Sudhakar Rao, B. Viswanathan, and R. Ramaswamy
The oscillatory characteristics of a catalyzed bromate system is altered by gammairradiation. The alterations observed are probably due to the activation of the reduced form of the metal ion catalyst under gamma-irradiation. However, these alterations could not be accounted for in terms of an effective concentration of bromate acting as a quenching agent under gamma-irradiation conditions as reported in the literature.
Authors:M. Krishnaratnam, B. Viswanathan, and R. Ramaswamy
The characteristics of uncatalyzed bromate oscillator are altered in presence of -irradiation. These alterations could not be accounted for in terms of substrates acting as scavengers for hydrogen atoms. The alteration of the effective activity of the key species in presence of -irradiation can also account for the changes observed in the oscillation characteristics.
The kinetics of annealing of -irradiation damage in sodium bromate has been studied. The data are analyzed using the Fletcher-Brown and Waite models and also by conventional kinetic method. The energy of activation for annealing reactions obtained by these different methods are in reasonable agreement.
The initial retentions (at ∼20°C) of (n, γ) activated rare earth bromates were studied using a252Cf fission neutron source with respect to80Br,80mBr and82Br. They lay over the ranges 19–23, 21–23 and 28–32%, respectively. On heating, retention progressively increases and closes
on ∼100% for Sm-bromate while for other systems the optimum values reach <85%. Thus, cation effect becomes more pronounced
during thermal annealing. The isothermal data show that the weight-loss is due to dehydration. The cation effect on retention
is discussed in the light of various parameters like lanthanide contraction, crystal structure, lattice energy, crystal water,
properties of anion and mode of thermal decomposition.