Radiolysis induced degradation of 1,3-dichlorobenzene and 4-chlorophenol in aqueous solution

Abstract

1,3-dichlorobenzene (1,3-DClB) degradation was studied to obtain radiolytic product yields (Gtotal = 0.546 μmol/J) and degradation in aerated or oxygen-free aqueous solutions, saturated with either N2O or N2O containing K3Fe(CN)6. In the four environments, several peaks were observed in the chromatograms, corresponding to byproducts, with more oxidized products produced in N2O saturated solutions. The absorbed dose necessary for the removal of 1,3-DClB increased with increasing solute concentrations in aerated solution. Further, 4-chlorophenol (4-ClP) degradation was investigated in a 0.3 mmol/dm3 solution by gamma radiolysis in the presence and absence of oxygen. The results showed that 4-ClP degrades more rapidly in a N2O environment, demonstrated by quantification of product concentrations in different doses, the value of Chemical oxygen demand, and a kinetics study. Hydroquinone, a radiolytic product, is very resistant to degradation. The dose necessary for the complete degradation of a 4-ClP solution containing air reached 9 kGy; however, in N2O saturated solution only 4.5 kGy were necessary for that purpose. The kinetics have a similar behavior in the two compounds, being pseudo-first-order. Importantly, the number of chlorine atoms in the molecule determined the chemical oxygen demand, as this determination was easy in 4-ClP but not possible in 1,3-DClB.