Degradation of polychlorinated dibenzo‐p‐dioxins and polychlorinated dibenzofurans during the UV/ozone treatment of pentachlorophenol‐containing water

Abstract

UV/ozone treatment of seepage water from waste deposits is an upcoming method for water purification to avoid residues contaminated with toxic organic compounds. PCDD and PCDF are components of several seepage waters of special waste deposits. The behaviour of PCDD and PCDF during UV/ozone treatment of aqueous model solutions in a laboratory reactor was examined. The degradation of hepta-and octachlorinated dioxins and the octachlorinated furan follows a first order kinetic. The combination of UV and ozone is more effective than the single application of ozone or UV. The concentrations of the lower chlorinated dioxins and furans reached a maximum after 2 minutes treatment time and decreased rapidly in the further minutes of treatment time. The toxicity equivalent value (TE value) also reached a maximum (36.8 ng/1) after 2 minutes of reaction time. The formation of lower chlorinated PCDD/PCDF as degradation products of the octachlorinated congeneres and their degradation can be explained by a model of successive parallel reactions.

Dynamic Tracking of Highly Toxic Intermediates in Photocatalytic Degradation of Pentachlorophenol by Continuous Flow Chemiluminescence

“…Advanced oxidation processes (AOPs) such as ozonation, , Fenton, , H 2 O 2 /UV, , sonolysis, and photocatalysis have been widely and extensively explored to degrade environmental contaminants such as pentachlorophenol (PCP). − Heterogeneous photocatalysis by TiO 2 is of considerable interest in AOPs due to its low toxicity and strong oxidizing power, − which has been widely concerned as one of the most efficient methods to eliminate chlorophenols from water. ,− However, many reports focused solely on the degradation efficiency and remove conditions of the target compound. It should be worth noting that even after complete removal of PCP, acute toxicity was still observed, ,,,, which might be caused by the generation of toxic PCP byproducts including polychlorinated dibenzodioxins/furans, , tetrachloro-1,4-benzoquinone (TCBQ), − ,, or other toxic intermediates. Therefore, determination of the only pristine PCP concentration may not be sufficient for evaluating an overall efficiency of wastewater treatment.…”

“…8,11−13 However, many reports focused solely on the degradation efficiency and remove conditions of the target compound. It should be worth noting that even after complete removal of PCP, acute toxicity was still observed, 2,8,11,12,14 which might be caused by the generation of toxic PCP byproducts including polychlorinated dibenzodioxins/furans, 15,16 tetrachloro-1,4benzoquinone (TCBQ), [8][9][10][11][12]17,18 or other toxic intermediates. Therefore, determination of the only pristine PCP concentration may not be sufficient for evaluating an overall efficiency of wastewater treatment.…”