Characterization and gasification of end-of-life banknotes rich in cotton content

Many central banks are reviewing their environmentally sustainable activities, including the disposal of end-of-life banknotes, within the scope of green finance policies aimed at reducing environmental impacts. The total amount of banknote production waste and end-of-life (non-reusable) banknotes is estimated to exceed 185.000 tons per year worldwide. End-of-life banknotes are commonly disposed of as combustion, incineration for energy recovery, and landfill. In this study, the characterization and gasification of end-of-life banknotes rich in cotton content, which are classified as lignocellulosic waste, were investigated to bring them into the economy more effectively. The proximate, calorific value, lignocellulosic, elemental, and metal analyses were performed as characterization tests. Thermogravimetric analysis was performed at six different heating rates from 5 to 30 °C. The gasification experiments were carried out in a laboratory-scale fluidized bed reactor. With the gas analyzer, CO, CO2, CH4, H2, and O2 compositions as the mole fraction were determined simultaneously. The effects of temperature, particle size, and H2O/O2 ratio at the inlet intake on the experimental mole fractions were examined. The gasification main reactions that could be effective in gas composition were examined. The cotton-based banknote sample presented high levels of calorific value, C, O, H, cellulose, and lignin concentrations. The sample contained various transition metals such as Fe, Cu, Co, and Cr, which can be used as catalysts in gasification. The activation energy was calculated as 171.13 kJ/mol according to Kissinger method. In gasification experiments, the production of CO (12.11 %) and H2 (8.77 %) in a high composition was carried out.