Researchers Turn Wood Waste Into Packaging Material Using Green Chemistry
Scientists have developed a method to convert wood pulp into ultra-lightweight foam that could replace petroleum-based packaging materials. The technique recovers valuable chemicals in the process, potentially creating a profitable circular economy around food and product packaging.
Originaltitel: Cellulose foams from organosolv pulps with potential application as active packaging
**Cellulosa-skum från organosolv-massa öppnar väg för aktiv förpackning** Forskare vid Luleå tekniska universitet har utvecklat en grön metod för att framställa lågtät cellulosa-skum (20 kg/m³) från organosolv-behandlad granmassa. Processen använder natriumhydroxid som katalysator och producerar samtidigt högrent hemicellulosa och lignin för kemikalieframställning. Skummen skapas genom att påfresta cellulosfiber med ytaktiva ämnen, vilket ger en 3D-nätverksstruktur med 98 procent porvolym. Resultatet visar god mekanisk hållfasthet (75 procent) och högt fuktupsugningsförmåga. Ligninets placering i cellväggarna ger långsammare frisättning av antioxidanter — en egenskap som gör skummen lämplig för bioaktiv förpackning. Potentialen ligger i att ersätta syntetiska förpackningsmaterial och samtidigt utnyttja hela massapulpan. För leverantörer av cellulosa- och ligninprodukter öppnas nya marknadssegment inom funktionell förpackning under de närmaste två till tre åren.
<p>This study demonstrates a green method to produce low-density cellulose using organosolv pretreated pulp, which also yields high-purity fractions of hemicelluloses and lignin that can be processed further to obtain different chemicals. A base-catalyzed organosolv pretreatment was employed on Norway spruce woodchips to release the cellulose fibrils, which were used to make low-density (20 kg/m3) porous foams (98%). Sodium hydroxide was used as a catalyst, ranging from 0.25 to 1.5 M. The fibers obtained from these pretreatment conditions were characterized and correlated to the foam formation and properties. Furthermore, the samples were compared to foams made from commercially available unbleached and bleached sulfite pulp. A simple production technique was employed by rapidly agitating cellulose pulp with surfactant and additives to induce air into the system. The cellulose fibers arranged around the bubbles and formed a 3-D network upon drying. The lignin content and fiber aspect ratio of the organosolv fibers showed a positive correlation to the foam formation and stability. The foams presented good mechanical resistance (75%), and this property was tuned by the additives. High moisture adsorption tendency and comparably slower scavenging of antioxidant molecules were hypothesized to be due to the position of lignin in the interiors of the cell wall; these properties make the organosolv foams interesting for bioactive packaging applications. </p>