The Role of Gamma Irradiation in the Remediation of Hexachlorobenzene: A Study in 2-Propanol

This study demonstrates the effective dechlorination of hexachlorobenzene (HCB) in 2-propanol using γ-irradiation from a 60 Co source, showcasing the potential of radiolysis for persistent organic pollutants (POPs) remediation. Utilizing Gas Chromatography-Mass Spectrometry (GC-MS), we achieved nearly 100% degradation of HCB, quantifying and identifying the breakdown products throughout the process. The kinetic analysis revealed that HCB consumption follows pseudo-first-order kinetics, with an effective rate constant of 4 x 10⁻⁵ L mol⁻¹ s⁻¹. Our findings indicate a systematic reduction in HCB to less chlorinated benzenes (CBs), including penta-(PCB), tetra-(TeCB), and trichlorobenzene (TCB), as confirmed by the mass spectra. The full pathway of HCB degradation involves sequential dechlorination steps: starting from HCB, it is first reduced to PCB, followed by TeCB, and then TCB. Although dichlorobenzenes (DCB), monochlorobenzene (MCB), and benzene formation are theoretically predicted, they were not detected in our experiments. The detailed examination of the radiation chemical yield (G value), the degree of consumption, and the concentration change as a function of absorbed dose highlights the robust capability of γ-radiolysis in the targeted decomposition of chlorinated compounds. These results underscore γ-radiolysis as a highly efficient method for the remediation of POPs.