Upcycling cellulose waste textile into aerogel beads via prilling technique
Abstract
The goal is to demonstrate the possibility of upcycling waste textile into high value-added materials, aerogels. Prilling (or jet-vibration) method was used to make aerogel beads based on viscose textile and also on microcrystalline cellulose (MCC), the latter used as a reference. The solvent was ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate ([DBNH][OAc]):DMSO = 50:50. The rheological properties of solutions were studied at temperatures 20–60 °C. Cellulose droplets formed under vibration were falling in ethanol coagulation bath forming alcogel beads, and the latter were dried with supercritical CO2 resulting in cellulose aerogel beads. Cellulose solution jet, droplet and alcogel bead diameters, as well as size distribution of MCC- and viscose-based aerogel beads were measured and evaluated as a function of processing conditions (nozzle size, frequency of vibration, distance between the nozzle and coagulation bath and its temperature). Correlation parameter was used to rate the impact of the processing conditions on aerogel bead roundness and aspect ratio. Highly spherical aerogel beads (aspect ratio 1.09–1.16 and roundness 94.6–96.2) based on viscose- and MCC-based solutions were obtained with the nozzle size 400 µm, vibration frequency 100 Hz and nozzle-to-bath distance 3.5 cm. Their density was 0.08–0.12 g.cm−3 and specific surface area around 400 m2.g−1. Cytotoxicity experiments demonstrated that both types of aerogels are harmless as tested on in vitro cultures.