Photocatalytic conversion of D5 siloxane in water: An exploratory research and mechanism of the process

[EN] Siloxanes, challenging contaminants in biogas, can severely impact the combustion engine performance, necessitating their removal. Typically, siloxanes are removed from biogas through adsorption on activated carbon. However, the potential for eliminating siloxanes from wastewater prior to methane fermentation remains underexplored. Therefore, in this work the possibility of photocatalytic conversion of decamethylcyclopentasiloxane (D5) in aqueous phase using UV radiation and titanium dioxide (TiO2) as photocatalysts is investigated. The effects of several factors on the process, including the effect of UV light and the presence of the photocatalyst on the reaction pathway are examined. Gained findings indicate that the final product of D5 conversion in the aqueous phase is amorphous silica. Given the non-volatility of this product, results in the context of minimizing undesirable desorption of siloxane from the aqueous phase into the gas phase are discussed. Through a detailed analysis, key intermediate species were identified and a reaction mechanism that elucidates the transformation of D5 under photocatalytic conditions in water is proposed.