the interest to develop environmentally benign, simple, selective, economical methods using environment friendly and cheap oxidants like molecular oxygen (O 2 ) and hydrogenperoxide (H 2 O 2 ). O 2 is one of the cheap and abundantly available
Authors:Anna Katafias, Monika Lipińska, and Karol Strutyński
Methylene blue degradation has been studied spectrophotometrically in alkaline and alkaline peroxide solutions. In both systems,
the reaction proceeds via successive N-demethylation and deamination steps determined applying TLC and HPLC techniques. Disappearance of the dye obeys first-order
kinetics under the excess of all other reactants. The rate expression for the hydrolytic process (in the absence of hydrogen
peroxide) is as follows: –d[MB]/dt = (b[OH–]/(1 + c[OH–]))[MB]. Analogous forms of the reaction rate dependence on [OH–] (at constant hydrogen peroxide concentration) and on [HO2−] (at constant OH− ion concentration) are observed: –d[MB]/dt = ((a′ + b′[OH–])/(1 + c′[OH–]))[MB] and –d[MB]/dt = ((a″+ b″[HO2–])/(1 + c″[HO2–]))[MB], respectively. A higher-order than linear dependence of the pseudo first-order rate constant on the nucleophiles (OH– and/or HO2–) concentrations results from the competitive formation of the ion pair of the cationic dye with the chloride of the supporting
electrolyte and adducts of the dye with OH– and/or HO2– anions.
Authors:Kwang-Wook Kim, Jae-Won Lee, Dong-Young Chung, Eil-Hee Lee, Kweon-Ho Kang, Kune-Woo Lee, Kee-Chan Song, Myung-June Yoo, Geun-Il Park, and Jei-Kwon Moon
This work studied a way to reclaim uranium from contaminated UO2 oxide scraps as a sinterable UO2 powder for UO2 fuel pellet fabrication, which included a dissolution of the uranium oxide scraps in a carbonate solution with hydrogen peroxide
and a UO4 precipitation step. Dissolution characteristics of reduced and oxidized uranium oxides were evaluated in a carbonate solution
with hydrogen peroxide, and the UO4 precipitation were confirmed by acidification of uranyl peroxo–carbonate complex solution. An agglomerated UO4 powder obtained by the dissolution and precipitation of uranium in the carbonate solution could not be pulverized into fine
UO2 powder by the OREOX process, because of submicron-sized individual UO4 particles forming the agglomerated UO4 precipitate. The UO2 powder prepared from the UO4 precipitate could meet the UO2 powder specifications for UO2 fuel pellet fabrication by a series of steps such as dehydration of UO4 precipitate, reduction, and milling. The sinterability of the reclaimed UO2 powder for fuel pellet fabrication was improved by adding virgin UO2 powder in the reclaimed UO2 powder. A process to reclaim the contaminated uranium scraps as UO2 fuel powder using a carbonate solution was finally suggested.
. and Kogel, K.-H.(1999): Hypersensitive cell death and papilla formation in barley attacked by the powdery mildew fungus are associated with hydrogenperoxide but not with salicylic acid accumulation. Plant Physiol. 119, 1251