Degradation of 2,4-dichorophenol by pulsed high voltage discharge in water

Abstract

2,4-dichorophenol (2,4-DCP) was degraded in a pulsed high voltage discharge system with particular focus on the optimum of processing parameters and identification of the intermediate products. By increasing peak voltage or frequency, the 2,4-dichorophenol degradation could be sped up. The energy input was mounted up from 0.0057 to 0.0397kWh and 2,4-DCP degradation efficiency was enhanced from 58% to 99% in 42min by increasing peak voltage from 18kV to 26kV. Under the same 2,4-DCP degradation efficiency, less energy input was required for higher pulse frequency with a shorter discharge time. Higher pH value was advantage for 2,4-DCP degradation while salt content was proved to have little effect on 2,4-DCP degradation in the present discharge reactor. From the identifications of main intermediates resulted from 2,4-DCP degradation, it is illustrated that the degradation is induced by OH, which could mainly attack the Ortho-position of the OH group to form 3,5-dichloro-1,2-benzenediol or substitute the Cl group in 2,4-DCP to produce 2-chlorohydroquinone. The 2-chlorohydroquinone could be further reacted with OH to produce 1,2,4-trihydyoxybenzene. Additional, some ring-opened products such as (e,e)-2,4-hexadienal, formic, oxalic, maleic and d-(+)-malic acid were recognized by GC-MS and Ion Chromatograph detection.