Recycling of cigarette filter wastes to prepare magnetic catalysts for biodiesel production: analysis of synthesis routes and catalytic properties

This paper reports the valorization of cigarette filter waste to prepare new magnetic catalysts to support the energy transition via biodiesel production. Two synthesis routes were proposed to produce the catalysts, from cigarette filter waste-derived cellulose acetate and Fe3O4 particles, to improve the formation of fatty acid methyl esters from the transesterification of soybean oil with methanol. The first route involved the pyrolysis of cigarette filters and the synthesis and loading of magnetite on pyrolyzed material, while the second route included the direct use of cellulose acetate fibers (without pyrolysis). The results showed that the catalytic properties of the magnetic materials obtained from the second route outperformed those observed for the materials from the first route. The best catalyst from route 2 was utilized to perform a sensitive analysis of transesterification conditions to maximize biodiesel production and for preliminary catalyst reuse tests. Transesterification kinetic studies were performed at 50–70 °C to obtain up to 99.5 % of fatty acid methyl esters formation. The results of this study can contribute to resolving some of the current challenges related to biodiesel production via heterogeneous transesterification using easily recoverable materials prepared from cigarette butts, which are relevant in waste management worldwide due to their environmental impact.