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Hexachlorobenzene (HCB) is a chlorinated aromatic compound classified among POPs due to its high chemical stability and resistance to natural degradation. Because of its persistence and potential environmental toxicity, the development of efficient methods for the destruction of HCB remains an important research objective. Ionizing radiation represents a promising approach for the degradation of stable organic pollutants because it produces highly reactive species capable of initiating complex chemical reactions in solution.
In this study, the radiolytic transformation of hexachlorobenzene dissolved in propan-2-ol was investigated under gamma irradiation. Experiments were performed using a cobalt-60 radiation source, with absorbed doses reaching up to 170 kGy. The irradiation time was varied between 0.5 and 27 hours in order to monitor the chemical transformation of the compound under increasing radiation exposure. All experiments were conducted under controlled laboratory conditions without degassing the solutions, allowing the radiolysis of both the solvent and dissolved oxygen to participate in the reaction system.
After irradiation, the reaction mixtures were analyzed using GC–MS. This analytical technique enabled the separation and identification of compounds formed during the radiolytic process. Several transformation products were detected in the irradiated samples. Among the most significant compounds identified were 2,5-hexanedione, 1,1-diethoxypentan-4-one, methylpentachlorobenzoate, and 1-propoxy-2-propanol.
The formation of these compounds indicates that the degradation of HCB in propan-2-ol occurs through a series of radical-driven reactions involving both solvent-derived intermediates and transformation of the chlorinated aromatic substrate.
The evolution of the detected byproducts was evaluated by monitoring their chromatographic peak areas obtained from GC–MS measurements.
The data demonstrate that the formation of several products increases progressively with irradiation time, reflecting the gradual decomposition of the parent HCB molecule and the development of secondary reaction pathways in the irradiated solution.
These observations confirm that gamma irradiation effectively initiates the transformation of HCB in propan-2-ol. However, the diversity of products detected suggests that the degradation process proceeds through relatively non-selective reaction pathways. The solvent therefore plays an important role in determining the distribution of radiolytic products formed during the process. Further research should focus on investigating alternative solvent systems or reaction conditions that may promote more selective degradation pathways while minimizing the formation of potentially undesirable intermediates. Such studies may contribute to the development of more efficient radiation-based approaches for the remediation of environments contaminated with persistent organic pollutants.
Keywords: POPs, HCB, Gamma radiolysis, Nuclear energy, Environmental remediation
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