Effect of selected scavengers on radiolytic degradation of 2,4-dichlorophenol for environmental purposes

Abstract

The effect of pH of irradiated aerated solutions and the presence of various concentrations of bicarbonate and nitrate on radiolytic degradation of 2,4-dichlorophenol in aqueous solutions with T-irradiation was examined using reversed phase HPLC and ion chromatography. The obtaining complete decomposition and dehalogenation of 2,4-dichlorophenol in the presence of naturally occurring inorganic scavengers may require to increase the irradiation dose in batch conditions up to 10 kGy. The presence of scavengers at different doses affects both efficiency of radiolytic degradation and its mechanism.

Kinetic and mechanism investigation on the gamma irradiation induced degradation of endosulfan sulfate

“…The HO 2 Å and O 2 ÅÀ being less reactive can, however, facilitate the removal of the target contaminant in the presence of Å OH (Drzewicz et al, 1999). However in the absence of dissolve oxygen (N 2 saturated solution), the reactive radicals (i.e., Å OH, e aq À and Å H) are all available for reaction with endosulfan sulfate.…”

Radiation dechlorination of some chlorinated hydrocarbons particularly of carbon tetrachloride in presence of HCO3−- or NO3−-ions

“…According to the action of the OH-radicals and the solvated/hydrated electrons in the radiation dechlorination a specific influence of various scavengers on the reaction kinetics was observed. As an example may serve the influence of hydrogen carbonate (or carbonate [58]) and nitrate ions on the dechlorination of chloroform [62], PCE [68,75], chlorophenol [28,68] or an effect of N 2 O oxide in dechlorination of PCE [72,75] (the bimolecular rate constants of the reactions of the above mentioned scavengers with e − aq and OH-radicals are given in Table 1). Besides typical scavengers, an influence of some solids (catalysts) on radiation dechlorination was studied.…”

“…dichlorobenzenes [15][16][17][18][19][20][21][22], chlorophenols [22][23][24][25][26][27][28][29][30], chloroanilines [31,32], chlorinated benzaldehydes [33], pesticides [34], or herbicides [35], dioxin contained soils [36,37] or incinerator offgas [38] and, last but not least, polychlorinated biphenyls (PCBs) [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56]) and aliphatic (e.g. halomethanes [21,[57][58][59][60][61][62], haloethanes …”

Estudo da degradação do herbicida ácido 2,4- diclorofenoxiacético (2,4-D) por meio da radiação gama do cobalto-60 em solução aquosa contendo ácido húmico

“…A possibilidade de utilização da tecnologia nuclear e o emprego de radiações ionizantes (gama, elétrons e raios-x) como indutora da decomposição dos mais diversos poluentes orgânicos tem-se mostrado instrumento eficiente na descontaminação ambiental causada por esses agentes, além de mostrar ser também economicamente competitiva [1][2][3][4][5] .Com esse intuito GRAY et al 6 comparam os custos da utilização de radiação gama e a incineração na degradação de dioxinas em solos, concluindo que a radiação, além de ter gerado melhores resultados de descontaminação, também mostrou ser economicamente atrativa. No Brasil o Instituto de Pesquisas Energéticas e Nucleares (IPEN) vem utilizando uma fonte de radiação piloto de elétrons acelerados em estudos de degradação dos mais diversos poluentes.…”