Identification and fate of halogenated PAHs formed during electrochemical treatment of saline aqueous solutions

Abstract

a b s t r a c tHalogenations of polycyclic aromatic hydrocarbons (PAHs) comprise a serious problem, when electrochemical oxidation (EO) is applied for treatment of chloride and bromide containing polluted sea water. In this study, the possible non-polar halogenated byproducts formed were identified in a series of chemical hypochlorination experiments using GC-MS, and the analytical information from these experiments was used in the primary EO treatment tests. An electrochemical cell equipped with a Ti/Pt 90 -Ir 10 anode was used in a batch recirculation setup with naphthalene, pyrene, and fluoranthene as the parent PAHs. Contrary to the chemical hypochlorination experiments, naphthalene as the most soluble compound was the only one to be halogenated in detectable amounts during EO. In a single sodium chloride electrolyte, up to 13% of the initial naphthalene was chlorinated at the peak concentration during treatment before it was subsequently removed. Even small concentrations of added bromide in a mixed electrolyte completely dominated the byproduct pattern with formation of primarily mono brominated naphthalene in peak concentrations up to 30-39% of the initial naphthalene. All of the considered byproducts were despite a more recalcitrant behavior degraded at prolonged treatment times, which need to be applied to ensure a safe discharge of the treated water.

Photochlorination of Polycyclic Aromatic Hydrocarbons in Acidic Brine Solution

“…Indeed, the production of ClPAHs were confirmed by the aqueous reactions of chlorine treatment with PAHs (Oyler et al 1978(Oyler et al , 1983. For other treatment of PAHs in aqueous condition, formations of ClPAHs have been confirmed by the electrochemical treatment in saline solutions (Muff and Søgaard 2011).…”

DFT Study of Monochlorinated Pyrene Compounds

“…A recent study by Muff et al aimed at studying the extent of formation of chlorinated pyrene during electrochemical oxidation processes detected, using mass spectroscopy, very small amounts of 1-chloropyrene while 2-and 4-chloropyrenes were not detected [9]. DFT calculations have been successfully applied to the study of polyaromatic hydrocarbons [10].…”

Step by step procedures: Degradation of polycyclic aromatic hydrocarbons in potable water using photo-Fenton oxidation process

“…To date, the application of the photo-Fenton oxidation process for PAHs treatment were from contaminated soil (review paper) [12] , landfill leachate [13] , municipal solid waste leachate [14] , sanitary landfill leachate (Tânia et al, 2013), aniline wastewater [15] , ammunition wastewater [16] and saline aqueous solutions [17] . As for potable water, the application of Fenton reagent aided with photo treatment [5] , [6] or electrolysis [4] were not focusing on PAHs removal.…”

“…Firstly, parameters such as concentration of 17 USEPA-PAHs prepared aqueous solution (4 μg/L of PAHs), the actual pH of the aqueous solution (pH 6.96), molarity of hydrogen peroxide (H 2 O 2 ) (0.0075 M) and ferrous sulfate (FeSO 4 ) (0.00075 M), room temperature (27 °C), rotational frequency (300 rpm) and UV irradiation (emitting radiation wavelength of 365 nm) should be taken into account. The concentration of 17 USEPA-PAHs was chosen based on the ranges of PAHs concentration documented in Vela et al [22] , Muff and Søgaard [17] and Bertilsson and Widenfalk [23] for their PAHs treatments. The molarity of H 2 O 2 and FeSO 4 for the photo-Fenton oxidation process were theoretically calculated and referred to Baker et al [3] .…”