Electrochemical oxidation of chlorinated benzenes

Radiolytic degradation of 1,2,4-trichlorobenzene (TCB) in some organic solvents by gamma rays: The kinetic properties of complete dechlorination of TCB and its pathway

This study investigates the degradation of TCB in methanol, ethanol, hexane, and benzene solutions using gamma radiolysis. Kinetic properties of TCB dechlorination and its pathway are examined, with TCB selected as a representative chlorinated organic compound. Chromatograms of irradiated samples and mass spectra of liquid-phase products are presented. The change in concentration of TCB, dichlorobenzenes (DCB), chlorobenzene (MCB), and benzene with absorbed doses are observed. The radiation-chemical yield (G values) of TCB in the solvents are calculated as 1.83, 2.56, 1.93, and 1.84 100eV-1 in methanol, ethanol, hexane, and benzene solutions, respectively. 100 % degradation of TCB by gamma irradiation is found to be efficient in polar solvents but leads to a wide variety of byproducts in low polar solvents, particularly the formation of polychlorinated biphenyls in TCB + benzene solutions, making benzene an incompatible medium. The main dechlorination pathway of TCB involves the formation of 1,4-DCB, MCB, and benzene. Environmental Implication. The gamma irradiation of chlorinated organic compounds, focusing on TCB as a model compound, was investigated due to its status as a hazardous material for the environment and living organisms. TCB is a byproduct of the dechlorination of certain chlorinated pesticides listed under the Stockholm Convention's Persistent Organic Pollutants (POPs) list, which prohibits their production and use. Gamma irradiation was found to be an effective method for the degradation of chlorinated compounds, achieving 100 % degradation during irradiation. The study underscores the potential of gamma irradiation as a viable approach for the treatment of chlorinated compounds, particularly in addressing environmental and health concerns associated with TCB and related compounds.

Chlorobenzene degradation by electro-heterogeneous catalysis in aqueous solution: intermediates and reaction mechanism

This study was performed to investigate the variables that influence chlorobenzene (CB) degradation in aqueous solution by electro-heterogeneous catalysis. The effects of current density, pH, and electrolyte concentration on CB degradation were determined. The degradation efficiency of CB was almost 100% with an initial CB concentration of 50 mg/L, current density 15 mA/cm2, initial pH 10, electrolyte concentration 0.1 mol/L, and temperature 25 degrees C after 90 min of reaction. Under the same conditions, the degradation efficiency of CB was only 51% by electrochemical (EC) process, which showed that electro-heterogeneous catalysis was more efficient than EC alone. The analysis results of Purge-and-Trap chromatography-mass spectrometry (P&T/GC/MS) and ion chromatography (IC) indicated that in the reaction process, the initial *OH attack could occur at the C-Cl bond of CB, yielding phenol and biphenyl with the release of Cl-. Further oxidation of phenol and biphenyl produced p-Vinylbenzoic acid and hydroquinol. Finally, the compounds were oxidized to butenedioic acid and other small-molecule acids.