Beyond waste: cellulose-based biodegradable films from bio waste through a cradle-to-cradle approach

Abstract

The basis of circular economy is the use and valorization of renewable raw materials. Especially in developing countries, crop waste such as straw and rice straw have high potential for further utilization. Within this report, we present a holistic strategy including the selective isolation of cellulose via simple, environmental benign two-step process. Rice straw was easily dissolved in a non-derivatizing electrolyte solvent such as aqueous solution of tetrabutylphosphonium hydroxide (TBPH) (50 wt%) at room temperature followed by precipitation in water. Quantitative amount of raw cellulose was recovered within a short period of time without heating or cooling enabling a further application of biomass material. The structure and characterization of the raw cellulose were investigated by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and by scanning (SEM) and transmission electron microscopy (TEM). This method could be an excellent alternative to the current extraction methods such as the KRAFT process. Indeed, the same chemicals as for the isolation can be used to prepare regenerated cellulose film of high purity with the raw cellulose. Due to its sustainability and exceptional biodegradability, these films have a great potential for applications in environment, textile, and separation industry. No modification of the cellulose during the extraction and preparation process occurs thus, these films are no plastics and thus can be used without regulations. In general, a full “circular economy” process is provided: valuable raw materials (cellulose) are recovered selectively from natural resources such as rice straw and further to enable products with high applicability in life (cellulose packaging film). The cradle-to-cradle process is closed by fast biodegradation of the used products.