A preliminary study on the decontamination properties of different sorbent materials used for oil bleaching against mineral oils and selected alkylated polycyclic aromatic hydrocarbons

Abstract

Mineral oils are complex mixtures of saturated (MOSH) and aromatic hydrocarbons (MOAH) of petrogenic origin, which can contaminate edible oils. Some MOAH (>3 benzene rings) are suspected genotoxic carcinogens, as are polycyclic aromatic hydrocarbons (PAHs) with the same ring number, but without alkylation, mainly originating from the pyrolysis of organic matter. Heavy PAHs can be removed during oil bleaching, but no information is available on MOH and selected alkylated PAHs. Therefore, this study aimed to investigate the adsorption properties of activated carbon, and other sorbents commonly used for oil bleaching, against MOAH and selected alkylated compounds. For this purpose, batch experiments were carried out on mixtures of the target analytes in hexane (model system) using different contact times and sorbent amounts. On-line HPLC-GC-FID was used for quantification. Activated carbon alone or in combination with acid activated bleaching earth proved able to remove not only parent PAHs, but also MOAH and single alkylated PAHs, according to their ring number and alkylation degree. Natural and acid activated bleaching earths alone removed 30-45% of perylene and 7-methylbenzo[a]pyrene. Further studies are needed to better understand the decontamination properties of different sorbent materials and their behavior in the oil matrix.