Recycling of cigarette filters: recovery of cellulose acetate for the preparation of low-cost sorbent materials

Biopolymers such as cellulose and cellulose acetate (CA), obtained from biomasses or recycled waste, are particularly indicated for developing new sorbent materials characterized by eco-compatibility, low toxicity, recyclability, and biodegradability in line with Green Analytical Chemistry and Green Sample Preparation prospectives. In particular, cigarette filters (CFs) recovered from cigarette butts (CBs) are an important resource of these two biopolymers, considering the billions of cigarettes smoked annually. Ways of recovering and re-using CA from this waste have not been thoroughly studied, and applications in analytical chemistry and industrial realities are still limited. In addition, the sorption properties of the recovered polymer in an international contest represent an important gap in the scientific literature that needs filling. The PhD research project was divided into two main parts: firstly, an effective procedure has been developed to regenerate CA from CB aimed at removing most of the impurities produced during the cigarettes combustion and the subsequent reprocessing of the polymer to obtain materials with chemical-physical and structural properties suitable for use as sorbent material. Different materials will be presented for applications in water remediation and laboratory scale in analytical sample preparation contests. A general introduction to tobacco industries on a global and environmental scale, the concerned CBs problem, and the state-of-the-art of CBs recycling routes will be presented in Chapter 1. The subsequent sections will provide, through the scientific paper presentation, the detailed strategies in which the project was faced. In particular, Chapter 2 highlights the most promising strategies to employ biopolymers in composite devices based on carbonaceous nanomaterials, Chapters 3, 4, and 5, 6 will be dedicated to the description and discussion of the employment of CA for water remediation and analytical applications, respectively. The final chapter will conclude the project, offering a summary of the obtained results and outlining future perspectives.