Conversion of Waste Cigarette Filter into Recycled Cellulose Acetate: An Industrial Feedstock

Abstract

One of the largest contributors to waste are cigarette filters, which contribute an estimated 4.5 trillion tons of waste into the environment every year. This study proposes a plausible waste conversion protocol for the preparation of cellulose acetate from cigarette filters, an essential industrial feedstock. The collected cigarette filters were decolourised and deodorised with bleaching and surface acting agents, respectively. Cellulose obtained was converted to cellulose acetate by acetylation in the presence of acetic acid, acetic anhydride, and sulphuric acid. Further, spectroscopic methods (FT-IR and NMR) were used to confirm the synthesis of cellulose acetate, while the thermogravimetric analysis, scanning electron microscope (SEM), and X-ray diffractogram (XRD) were used to determine the thermal stability, crystalline size, and morphology of the materials, respectively. The high percentage yields of both cellulose and acetylated cellulose are indicative of the high conversion rate or recovery rate of cellulose and cellulose acetate. The XRD analysis was used to determine the size of the particles, crystallinity, and amorphous nature of the cellulose and cellulose acetate. A reduction in the average crystalline size was observed using the Scherer equation alongside the XRD data. The spectrum of cellulose showed the occurrence of a broad absorption band at around 3450 cm-1 corresponding to an-OH stretching vibration, indicating a moisture peak due to interaction between the cellulose hydroxyl group and water, while the C-H vibrations at 2950 cm-1 are due to alkyl groups. The appearance of several new absorption peaks was observed in the spectrum of cellulose acetate; at 1752 cm1 and 1232 cm1 represent the stretching vibrations of the C=O and C-O of the acetate, respectively. The 13C NMR of cellulose acetate shows the presence of ten carbon atoms. The peaks at 173.84–172.08 ppm indicated the presence of quaternary carbon atoms in the acetate. The signals at 102.55 and 94.61 ppm are the (14) carbon linkage of D-glucose units, while the signals at 80.08-69.57 ppm are the oxymethine carbon atoms. These results have established the possibility of obtaining a good yield of acetate from cigarette filters as a route to reducing the amount of cigarette waste generated.