Quantitative Assessment of the Formation of Polychlorinated Derivatives, PCDD/Fs, in the Electrochemical Oxidation of 2-Chlorophenol As Function of the Electrolyte Type

Abstract

The electrochemical degradation of 2-chlorophenol (2-CP) on boron-doped diamond (BDD) anodes was carried out using two electrolytes, NaCl and Na2SO4. Both electrolytes supported complete mineralization of 2-CP, but faster rates of degradation were observed in NaCl. After 4 h of oxidation, the total organic carbon (TOC) balance neared 100% with Na2SO4 for identifiable compounds, whereas 4 mM of TOC remained unidentified with NaCl. Since chlorophenols are known to be precursors of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), a rigorous assessment of intermediate products was carried out. When near complete mineralization was achieved, the use of NaCl resulted in the concentration of total PCDD/Fs increasing 2.68 × 10(4) times compared to the untreated sample, and to toxicity values several times higher than the maximum level established by U.S. Environmental Protection Agency for water ingestion. When Na2SO4 was used, the increase in total PCDD/Fs concentration was 134 times lower than with NaCl and there was no significant 2,3,7,8-PCDD/Fs formation. Thus, we emphasize the importance of electrolyte selection in electro-oxidation processes, especially when PCDD/Fs precursors are initially present or may be formed in the treated water samples.

Recent developments of electro-oxidation in water treatment — A review

“…There is severe risk for production of toxic precursors, such as polychlorinated dibenzo-ρ-dioxins and dibenzofurans (PCDD/Fs) e.g. on chlorophenol degradation [137].…”

Two Heterometallic–Organic Frameworks Composed of Iron(III)‐Salen‐Based Ligands and d10 Metals: Gas Sorption and Visible‐Light Photocatalytic Degradation of 2‐Chlorophenol

“…[10] The generated ·OH radicals react immediately with 2-CP resulting in its degradation. [20] To exclude the possibility that the photocatalytic activities of 1 and 2 at low pH (pH 3) resulted from dissolved molecular fragments of the solid catalysts, further control experiments were performed. Typically, the suspensions at pH 3 were filtered to remove the solid catalysts 1 and 2, and 2-CP was added to the respective filtrates for photocatalytic testing.…”

A Novel Voltammetric Sensor Based on Reduced Graphene Oxide‐Platinum Nanohybrid‐modified Electrode for Facile and Effective Determination of 4‐Chlorophenol in Real Water Samples

“…[1][2][3] On the other hand, 4-CP in environment is characterized by toxicological effects on humans, animals and plants, including dysrhythmia, coma and kidney trauma even at very low concentrations. [1][2][3] On the other hand, 4-CP in environment is characterized by toxicological effects on humans, animals and plants, including dysrhythmia, coma and kidney trauma even at very low concentrations.…”